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Last Updated :2024/08/25

Researcher Profile and Settings

Master

Affiliation (Master)

  • Research Faculty of Agriculture　Fundamental AgriScience Research　Bioresource and Environmental Engineering

Affiliation (Master)

  • Research Faculty of Agriculture　Fundamental AgriScience Research　Bioresource and Environmental Engineering

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Profile and Settings

Degree

  • Ph.D.（1992 Osaka Prefecture University）

Profile and Settings

  • Name (Japanese)

    Hirano

  • Name (Kana)

    Takashi

  • Name

    200901029666712699

Alternate Names

Achievement

Research Interests

  • Forest ecosystems   Forest fire   GHGs   CO2 balance   Land use change   Evapotranspiration   Energy balance   Tropical peatland   Eddy covariance technique   Soil respiration   Eddy flux   Northern peatland   Micrometeorology   Agricultural meteorology   Disturbance   

Research Areas

  • Environmental science/Agricultural science / Agricultural environmental and information engineering
  • Natural sciences / Atmospheric and hydrospheric science
  • Environmental science/Agricultural science / Environmental agriculture
  • Environmental science/Agricultural science / Environmental impact assessment
  • Environmental science/Agricultural science / Environmental dynamics

Research Experience

  • 2006/05 - Today Hokkaido University Graduate School of Agriculture Professor
  • 2001/04 - Today National Institute for Environmental Studies Visiting Researcher
  • 2020/04 - 2024/03 Japan Society for the Promotion of Science Research Center for Science Systems Program Officer
  • 1998/04 - 2006/04 Hokkaido University Graduate School of Agriculture Associate Professor
  • 1995/04 - 1998/03 Osaka Prefecture University College of Agriculture Associate Professor
  • 1993/04 - 1995/03 Osaka Prefecture University College of Agriculture Senior Lecturer
  • 1988/04 - 1993/03 Osaka Prefecture University College of Agriculture Assistant Professor
  • 1986/04 - 1988/03 Japan Weather Association Engineer

Education

  • 1984/04 - 1986/03  Hokkaido University  Graduate School of Agriculture  Division of Agricultural Engineering
  • 1981/10 - 1984/03  Hokkaido University  Faculty of Agriculture  Department of Agricultural Engineering
  • 1980/04 - 1981/09  Hokkaido University  Faculty of Liberal Arts

Committee Memberships

  • 2011 - Today   Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists   Executive Board Member
  • 2008 - Today   Agricultural and Forest Meteorology   Editorial board memeber
  • 2024/01 -2026/12   Malaysian Oil Palm Board   The Programme Advisory Committee
  • 2024/01 -2025/12   Malaysian Palm Oil Board   Journal of Oil Palm Research Editorial Board
  • 2021/09 -2023/09   Science Council of Japan   Member
  • 2019/03 -2023/03   The Society of Agricultural Meteorology of Japan   President
  • 2018/01 -2021/12   Malaysian Palm Oil Board   International Advisory Panel
  • 2018/01 -2021/03   AsiaFlux   Vice Chair
  • 2014/10 -2020/09   Science Council of Japan   Member
  • 2017/01 -2019/12   Malaysian Palm Oil Board   The Programme Advisory Committee
  • 2017/03 -2019/03   The Society of Agricultural Meteorology of Japan   Vice President
  • 2006 -2017/12   JapanFlux   Chair
  • 2002 -2017/12   AsiaFlux   Science Steering Committee Member
  • 2013/03 -2017/03   Journal of Agricultural Meteorology   Editor-in-chief
  • 2012 -2016/03   Journal of Forest Research   Editorial board memeber
  • 2010/01 -2012/12   The Society of Agricultural Meteorology of Japan   Chief of Hokkaido Branch
  • 2007/03 -2011/03   The Society of Agricultural Meteorology of Japan   Director
  • 2009 -2010   Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists   Councilor
  • 2002/03 -2006/03   The Society of Agricultural Meteorology of Japan   Editor
  • 2001 -2006   The Japan Society of Tropical Ecology   Editorial board memeber

Awards

  • 2016/06 尾瀬財団 尾瀬賞
     熱帯泥炭生態系の炭素動態に関するフィールド研究 
    受賞者: 平野 高司
  • 2010/03 日本農業気象学会 学術賞
     長期フラックス観測に基づく森林生態系の炭素収支に関する研究
  • 1992/07 日本農業気象学会 奨励賞
     植物葉の光合成への粉じんの影響に関する研究

Published Papers

  • Kanokrat Buareal, Tomomichi Kato, Tomoki Morozumi, Naohisa Nakashima, Kitpanuwat Tanatarakeree, Masahito Ueyama, Takashi Hirano
    Journal of Geophysical Research: Biogeosciences 129 (7) 2169-8953 2024/07/23 
    Abstract Wetlands play an essential role in the global greenhouse gas budget via carbon dioxide sequestration as well as methane emission. In recent decades, solar‐induced chlorophyll fluorescence (SIF) has been recognized as a remotely sensed proxy of gross primary productivity (GPP), which generates substrates for methane production. To examine the suitability of SIF for estimation of these two fluxes, we conducted ground tower‐based SIF observation with an ultrafine‐resolution spectroradiometer in conjunction with eddy covariance measurement in a cool‐temperate bog. The daily SIF retrieved in the red (687 nm) and far‐red (760 nm) bands (SIFred and SIFfar‐red, respectively) increased nonlinearly with GPP and linearly with absorbed photosynthetically active radiation (APAR). The relatively weak correlation between apparent SIF yield (ΦSIF = SIF/APAR) and light use efficiency implied that both APAR and plant physiology constrained the SIF emission in this wetland. The SIFred/SIFfar‐red ratio showed a significant negative relationship with vegetation greenness indices, and the similar seasonal variation in SIFred and SIFfar‐red indicated that the SIFred reabsorption effect only weakly influenced the SIFred–GPP relationship. Episodic temporal reduction in the water table did not distinctly influence SIF and ΦSIF. Estimation of the methane emission rate was subtly improved by incorporating SIF, which was substituted for GPP as the methanogenesis substrate, in a multivariable regression analysis together with two environmental factors: soil temperature and water table depth. This study illustrates the potential of both SIFred and SIFfar‐red to monitor GPP and to predict methane emission in wetlands.
  • Nikaan Koupaei‐Abyazani, Iuliia Burdun, Ankur R. Desai, Kristell Hergoualc'h, Takashi Hirano, Lulie Melling, Erin Swails, Angela Che Ing Tang, Guan Xhuan Wong
    Journal of Geophysical Research: Biogeosciences 129 (6) 2169-8953 2024/06/18 [Refereed]
     
    Abstract Tropical peatlands store copious amounts of carbon (C) and play a critical role in the global C cycle. However, this C store is vulnerable to natural and anthropogenic disturbances, leading these ecosystems to become weaker C sinks or even net C sources. Variabilities in water table (WT) greatly influence the magnitude of greenhouse gas flux in these biomes. Despite its importance in C cycling, observations of the spatiotemporal dynamics of tropical peatland WT are limited in spatial extent and length. Here, we use in situ WT measurements from tropical peatlands in Indonesia, Malaysia, and Peru to evaluate the satellite‐based Optical Trapezoid Model (OPTRAM). The model uses the pixel distribution in the shortwave infrared transformed reflectance and normalized difference vegetation index (NDVI) space to calculate indices that are then compared against in situ WT data. 30‐m resolution Landsat 7 and Landsat 8 images were utilized for model parameterization. We found OPTRAM to best capture tropical peatland WT dynamics in minimally forested and non‐forested areas (low to intermediate NDVI) (0.7 < R < 1) using the “best pixel” approach (the pixel with the highest Pearson‐R correlation value). In areas with relatively higher NDVI, OPTRAM index did not correlate with WT (average R of −0.04 to 0.24), likely due to trees being less sensitive to WT fluctuations. OPTRAM shows potential for reliably estimating tropical peatland WT without the need for direct measurements, which is challenging due to site remoteness and harsh conditions.
  • Takashi Hirano, Shinjiro Ohkubo, Masayuki Itoh, Hayato Tsuzuki, Ayaka Sakabe, Hidenori Takahashi, Kitso Kusin, Mitsuru Osaki
    Communications Earth & Environment 5 (1) 1 - 9 2024/04/25 [Refereed][Not invited]
     
    Abstract The huge carbon stock of tropical peat swamp forest (PSF) in Southeast Asia has been threatened by environmental disturbances due to quasi-periodic El Niño-Southern Oscillation (ENSO) droughts, biomass and peat burning, smoke haze, drainage, and deforestation. Carbon dioxide (CO2) emissions from such disturbances have not been well quantified because of insufficient field data. Therefore, we quantified the ecosystem-scale CO2 balance and examine the disturbance effects from a long-term field experiment for 12–15 years at three PSF sites with different degrees of degradation in Indonesia. Here, we show a drastic change of an undrained PSF from a CO2 sink to a source owing to the transient groundwater lowering by the droughts, a significant decrease in ecosystem photosynthesis due to the radiation attenuation by smoke haze in drought years, and long-lasting CO2 emissions through enhanced peat decomposition by drainage. The impact on CO2 emissions was greater from drainage than drought-induced disturbances.
  • Gavin McNicol, Etienne Fluet‐Chouinard, Zutao Ouyang, Sara Knox, Zhen Zhang, Tuula Aalto, Sheel Bansal, Kuang‐Yu Chang, Min Chen, Kyle Delwiche, Sarah Feron, Mathias Goeckede, Jinxun Liu, Avni Malhotra, Joe R. Melton, William Riley, Rodrigo Vargas, Kunxiaojia Yuan, Qing Ying, Qing Zhu, Pavel Alekseychik, Mika Aurela, David P. Billesbach, David I. Campbell, Jiquan Chen, Housen Chu, Ankur R. Desai, Eugenie Euskirchen, Jordan Goodrich, Timothy Griffis, Manuel Helbig, Takashi Hirano, Hiroki Iwata, Gerald Jurasinski, John King, Franziska Koebsch, Randall Kolka, Ken Krauss, Annalea Lohila, Ivan Mammarella, Mats Nilson, Asko Noormets, Walter Oechel, Matthias Peichl, Torsten Sachs, Ayaka Sakabe, Christopher Schulze, Oliver Sonnentag, Ryan C. Sullivan, Eeva‐Stiina Tuittila, Masahito Ueyama, Timo Vesala, Eric Ward, Christian Wille, Guan Xhuan Wong, Donatella Zona, Lisamarie Windham‐Myers, Benjamin Poulter, Robert B. Jackson
    AGU Advances 4 (5) 1 - 24 2576-604X 2023/09/06 [Refereed][Not invited]
     
    Abstract Wetlands are responsible for 20%–31% of global methane (CH4) emissions and account for a large source of uncertainty in the global CH4 budget. Data‐driven upscaling of CH4 fluxes from eddy covariance measurements can provide new and independent bottom‐up estimates of wetland CH4 emissions. Here, we develop a six‐predictor random forest upscaling model (UpCH4), trained on 119 site‐years of eddy covariance CH4 flux data from 43 freshwater wetland sites in the FLUXNET‐CH4 Community Product. Network patterns in site‐level annual means and mean seasonal cycles of CH4 fluxes were reproduced accurately in tundra, boreal, and temperate regions (Nash‐Sutcliffe Efficiency ∼0.52–0.63 and 0.53). UpCH4 estimated annual global wetland CH4 emissions of 146 ± 43 TgCH4 y−1 for 2001–2018 which agrees closely with current bottom‐up land surface models (102–181 TgCH4 y−1) and overlaps with top‐down atmospheric inversion models (155–200 TgCH4 y−1). However, UpCH4 diverged from both types of models in the spatial pattern and seasonal dynamics of tropical wetland emissions. We conclude that upscaling of eddy covariance CH4 fluxes has the potential to produce realistic extra‐tropical wetland CH4 emissions estimates which will improve with more flux data. To reduce uncertainty in upscaled estimates, researchers could prioritize new wetland flux sites along humid‐to‐arid tropical climate gradients, from major rainforest basins (Congo, Amazon, and SE Asia), into monsoon (Bangladesh and India) and savannah regions (African Sahel) and be paired with improved knowledge of wetland extent seasonal dynamics in these regions. The monthly wetland methane products gridded at 0.25° from UpCH4 are available via ORNL DAAC (https://doi.org/10.3334/ORNLDAAC/2253).
  • Rui Hu, Takashi Hirano, Kaho Sakaguchi, Syunpei Yamashita, Rui Cui, Lifei Sun, Naishen Liang
    Soil Biology and Biochemistry 184 109094 - 109094 0038-0717 2023/09 [Refereed][Not invited]
  • Tomohiro Shiraishi, Ryuichi Hirata, Masato Hayashi, Takashi Hirano
    Scientific Reports 13 (1) 2023/08/11 [Refereed][Not invited]
     
    Abstract Borneo has accumulated an abundance of woody carbon in its forests and peat. However, agricultural land conversion accompanied by plantation development, dead wood burning, and peat drying from drainage are major challenges to climate change mitigation. This study aimed to develop a method of estimating carbon dioxide (CO2) emissions from land use change, forest and peat fires, and oxidative peat decomposition, and CO2 uptake from biomass growth across Borneo using remote sensing data from 2001 to 2016. Although CO2 uptake by biomass growth in vast forests has shown a significant increasing trend, an annual net release of 461.10 ± 436.51 (average ± 1 standard deviation) Tg CO2 year−1 was observed. The estimated emissions were predominantly characterized by land use changes from 2001 to 2003, with the highest emissions in 2001. Land use change was evaluated from annual land use maps with an accuracy of 92.0 ± 1.0% (average ± 1 standard deviation). Forest and peat fires contributed higher emissions in 2002, 2006, 2009, 2014, and 2015 compared to other years and were strongly correlated with the Southern Oscillation Indexes. These results suggest that more CO2 may have been released into the atmosphere than previously thought.
  • Shinjiro Ohkubo, Takashi Hirano, Kitso Kusin
    Journal of Hydrology 620 129523 - 129523 0022-1694 2023/05 [Refereed][Not invited]
  • Chandra S. Deshmukh, Ari P. Susanto, Nardi Nardi, Nurholis Nurholis, Sofyan Kurnianto, Yogi Suardiwerianto, M. Hendrizal, Ade Rhinaldy, Reyzaldi E. Mahfiz, Ankur R. Desai, Susan E. Page, Alexander R. Cobb, Takashi Hirano, Frédéric Guérin, Dominique Serça, Yves T. Prairie, Fahmuddin Agus, Dwi Astiani, Supiandi Sabiham, Chris D. Evans
    Nature 616 (7958) 740 - 746 0028-0836 2023/04/05 [Refereed][Not invited]
     
    Abstract Tropical peatlands cycle and store large amounts of carbon in their soil and biomass1–5. Climate and land-use change alters greenhouse gas (GHG) fluxes of tropical peatlands, but the magnitude of these changes remains highly uncertain6–19. Here we measure net ecosystem exchanges of carbon dioxide, methane and soil nitrous oxide fluxes between October 2016 and May 2022 from Acacia crassicarpa plantation, degraded forest and intact forest within the same peat landscape, representing land-cover-change trajectories in Sumatra, Indonesia. This allows us to present a full plantation rotation GHG flux balance in a fibre wood plantation on peatland. We find that the Acacia plantation has lower GHG emissions than the degraded site with a similar average groundwater level (GWL), despite more intensive land use. The GHG emissions from the Acacia plantation over a full plantation rotation (35.2 ± 4.7 tCO2-eq ha−1 year−1, average ± standard deviation) were around two times higher than those from the intact forest (20.3 ± 3.7 tCO2-eq ha−1 year−1), but only half of the current Intergovernmental Panel on Climate Change (IPCC) Tier 1 emission factor (EF)20 for this land use. Our results can help to reduce the uncertainty in GHG emissions estimates, provide an estimate of the impact of land-use change on tropical peat and develop science-based peatland management practices as nature-based climate solutions.
  • Albertus Sulaiman, Mitsuru Osaki, Hidenori Takahashi, Manabu D. Yamanaka, Raden Dwi Susanto, Sawahiko Shimada, Keiji Kimura, Takashi Hirano, Rahmawati Ihsani Wetadewi, Silsigia Sisva, Tsuyoshi Kato, Osamu Kozan, Hideyuki Kubo, Awaluddin Awaluddin, Nobuyuki Tsuji
    Scientific Reports 13 (1) 939  2023/01/18 [Refereed][Not invited]
     
    Abstract In general, it is known that extreme climatic conditions such as El Niño and positive Indian Ocean Dipole (IOD+) cause prolonged drought in Indonesia's tropical peatlands so that groundwater levels (GWL) drop and peat is prone to fire. However, 27 years of GWL measurements in Central Kalimantan peat forests show the opposite condition, where the lowest GWL occurs several weeks before El Niño and after IOD+ reaches its peaks. We show that the dropped sea surface temperature anomaly induced by anomalously easterly winds along the southern Java-Sumatra occurs several weeks before the GWL drop to the lowest value. Local rainfall decreased, and GWL dropped sharply by 1.0 to 1.5 m, during the super El Niño events in 1997/98 and 2015, as well as remarkable events of IOD+ in 2019. It is suggested that the tropical peatland ecohydrological system (represented by the GWL), El Niño Southern Oscillation (ENSO), and IOD+ are teleconnected. Hence, monitoring GWL variability of peatland over the IMC is a possibility an alert for extreme climate events associated with El Niño and/or moderate IOD+.
  • Masahito Ueyama, Sara H. Knox, Kyle B. Delwiche, Sheel Bansal, William J. Riley, Dennis Baldocchi, Takashi Hirano, Gavin McNicol, Karina Schafer, Lisamarie Windham‐Myers, Benjamin Poulter, Robert B. Jackson, Kuang‐Yu Chang, Jiquen Chen, Housen Chu, Ankur R. Desai, Sébastien Gogo, Hiroki Iwata, Minseok Kang, Ivan Mammarella, Matthias Peichl, Oliver Sonnentag, Eeva‐Stiina Tuittila, Youngryel Ryu, Eugénie S. Euskirchen, Mathias Göckede, Adrien Jacotot, Mats B. Nilsson, Torsten Sachs
    Global Change Biology 1354-1013 2023/01/11 [Refereed][Not invited]
  • Wakhid N, Hirano T
    Journal of Oil Palm Research 1511-2780 2022/10/19 [Refereed][Not invited]
  • Takashi Hirano, Guan Xhuan Wong, Joseph Wenceslaus Waili, Kim San Lo, Frankie Kiew, Edward Baran Aeries, Ryuichi Hirata, Kiwamu Ishikura, Masato Hayashi, Shoko Murata, Tomohiro Shiraishi, Masayuki Itoh, Lulie Melling
    Journal of Agricultural Meteorology 78 (4) 137 - 146 0021-8588 2022/10/10 [Refereed][Not invited]
  • M. Helbig, T. Živković, P. Alekseychik, M. Aurela, T. S. El-Madany, E. S. Euskirchen, L. B. Flanagan, T. J. Griffis, P. J. Hanson, J. Hattakka, C. Helfter, T. Hirano, E. R. Humphreys, G. Kiely, R. K. Kolka, T. Laurila, P. G. Leahy, A. Lohila, I. Mammarella, M. B. Nilsson, A. Panov, F. J. W. Parmentier, M. Peichl, J. Rinne, D. T. Roman, O. Sonnentag, E.-S Tuittila, M. Ueyama, T. Vesala, P. Vestin, S. Weldon, P. Weslien, S. Zaehle
    Nature Climate Change 12 (8) 743 - 749 1758-678X 2022/08 [Refereed][Not invited]
  • Takashi Hirano, Rui Cui, Lifei Sun, Munemasa Teramoto, Naishen Liang
    PLANT AND SOIL 0032-079X 2022/08 [Refereed][Not invited]
     
    Purpose Fine roots play an essential role in global carbon cycles, but phenological variations in root function and metabolism are poorly understood. To illustrate the dynamics of fine root function and metabolism in the field, we partitioned root respiration (R-r) into growth (R-g), maintenance (R-m), and ion uptake (R-ion) components using a modified traditional model.Methods A year-round experiment was conducted in a young larch-dominated forest regrowing on bare soil. Soil respiration was measured with a chamber method and partitioned into R-r and heterotrophic respiration by trenching. Fine root biomass and production were measured simultaneously. Using the field data, the model was parameterized, and R-r was further partitioned.Results Annually, R-r (210-253 g C m(-2) yr(-1)) accounts for 45-47% of the total soil respiration. The contribution of fine root R-g, fine root R-m, coarse root R-m, and fine root R-ion were 26-40, 46-51, 10-16, and 12%, respectively. The R-g contribution showed a clear seasonal variation, with a peak in mid-spring and a minimum in early fall, mainly because of different seasonality between fine root production and soil temperature.Conclusion The model parameters were consistent with those from our previous study conducted by the same method in the same site. Thus, we believe that our approach was robust under a relatively simple condition. However, our growth respiration parameter resulting from only field data was much higher than those from laboratory experiments. To further improve our understanding of root respiration, more field data should be accumulated.
  • Maria Strack, Scott J. Davidson, Takashi Hirano, Christian Dunn
    Current Climate Change Reports 8 (3) 71 - 82 2022/06/13 [Refereed][Invited]
  • Masahito UEYAMA, Tomotsugu YAZAKI, Takashi HIRANO, Ryosuke ENDO
    Agricultural and Forest Meteorology 316 108852 - 108852 0168-1923 2022/04 [Refereed]
  • S. Apers, G. J, M. De Lannoy, A. J. Baird, A. R. Cobb, G. C. Dargie, J. Pasquel, A. Gruber, A. Hastie, H. Hidayat, T. Hirano, A. M. Hoyt, A. J. Jovani‐Sancho, A. Katimon, A. Kurnain, R. D. Koster, M. Lampela, S. P. P. Mahanama, L. Melling, S. E. Page, R. H. Reichle, M. Taufik, J. Vanderborght, M. Bechtold
    Journal of Advances in Modeling Earth Systems 14 (3) 1942-2466 2022/03 [Refereed]
  • Net primary production of oil palm plantations on tropical peat
    Wakhid N, Hirano T, Dariah A, Agus F
    Mires and Peat 28 (2) 1 - 12 2022 [Refereed][Not invited]
  • Yoshikawa K, Takagi K, Yazaki T, Hirano T, Hayakashi S, Ide R, Oguma H, Hirose Y, Kurihara J
    Journal of Agricultural Meteorology 78 (4) 223 - 261 0021-8588 2021/10 [Refereed][Not invited]
     
    Liquid crystal tunable filter (LCTF) can change the transmissible wavelength by changing the applied voltage to the filter, which enables the drastic increase in the observable wavelength resolution in a small size system and is considered to be a powerful tool for the spectral earth observation from flying units or microsatellites. However, there is limited knowledge about its season-long application for the vegetation monitoring and the prediction of the ecosystem photosynthetic capacity. We compared the seasonal variation of spectral reflectance obtained by a LCTF camera with that obtained by a popular spectral radiometer in a cool-temperate young larch plantation in northern Hokkaido, Japan. Then we tried to find the best normalized difference spectral index (NDSI) to explain the seasonal variation of the ecosystem photosynthetic capacity using all pairs of two reflectances observed in the range of wavelength between 500 and 770 nm with 10-nm intervals (28 wavelength bands) by the LCTF. The best NDSI among all combinations (28×27) of two reflectances was NDSI[770, 720] for the maximum gross primary production at light saturation and NDSI[530, 600] for the initial slope of the light-response curve, which reflect the red edge shift owing to the change in the chlorophyll content and relative strength of the light absorbance in the visible red wavelength region compared with that in the green wavelength region, respectively. Predicted daily gross primary production of the plantation using these NDSI agreed well with the observed values. NDSI[530, 600] was better to distinguish each vegetation type of the studied plantation.
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  • Cui R, Hirano T, Sun L, Teramoto M, Liang N
    Journal of Agricultural Meteorology 77 (3) 167 - 178 0021-8588 2021/07 [Refereed][Not invited]
     
    Root respiration (R-r) plays a crucial role in the global carbon balance, because R-r accounts for about a half of soil respiration in typical forest ecosystems. Plant roots are different in metabolism and functions according to size. Fine roots, which are typically defined as roots < 2 mm in diameter, perform important ecosystem functions and consequently govern belowground carbon cycles mainly because of their high turnover rates. However, the phenological variation of fine root functions is not well understood yet. To quantitatively examine the fine mot functions, we adopted an approach to partition R-r into growth respiration (R-g) and maintenance respiration (R-m) using a modified traditional model, in which R-s was proportional to root production, and R-m was proportional to root biomass and exponentially related to soil temperature. We conducted a field experiment on soil respiration and fine root biomass and production over a year in a larch-dominated young forest developing on the bare ground after removing surface organic soil to parameterize the model. The model was significantly parameterized using the field data measured in such simplified field conditions, because we could control spatial variation in heterotrophic respiration and contamination from roots other than fine roots. The annual R-r of all roots was 94 g C m(-2) yr(-1) and accounted for 25% of total soil respiration on average. The annual R-r was partitioned into fine root R-g , fine root R-m and coarse root R-m by 30,44 and 26%, respectively; coarse root R-g was presumed to be negligible. Fine root R-g and R-m varied according to the seasonal variations of fine root production and soil temperature, respectively; the contribution of fine root biomass was minor because of its small seasonality. The contribution of R-g to total fine root respiration was lower in the cold season with low production.
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  • Takashi Hirano
    Chikyu Kankyo 26 (1-2) 57 - 68 2021 [Refereed][Invited]
  • Ohkubo S, Hirano T, Kusin K
    Journal of Hydrology 603 126906 - 126906 0022-1694 2021 [Refereed][Not invited]
  • Irvin J, Zhou S, McNicol G, Lu F, Liu V, Fluet-Chouinard E, Ouyang Z, Knox SH, Lucas-Moffat A, Trotta C, Papale D, Vitale D, Mammarella I, Alekseychik P, Aurela M, Avati A, Baldocchi D, Bansal S, Bohrer G, Campbell DI, Chen J, Chu H, Dalmagro HJ, Delwiche KB, Desai AR, Euskirchen E, Feron S, Goeckede M, Heimann M, Helbig M, Helfter C, Hemes KS, Hirano T, Iwata H, Jurasinski G, Kalhori A, Kondrich A, Lai DYF, Lohila A, Malhotra A, Merbold L, Mitra B, Ng A, Nilsson MB, Noormets A, Peichl M, Rey-Sanchez AC, Richardson AD, Runkle BRK, Schafer KVR, Sonnentag O, Stuart-Ha, entjens E, Sturtevant C, Ueyama M, Valach AC, Vargas R, Vourlitis GL, Ward EJ, Wong GX, Zona D, Alberto MCR, Billesbach DP, Celis G, Dolman H, Friborg T, Fuchs K, Gogo S, Gondwe MJ, Goodrich JP, Gottschalk P, Hortnagl L, Jacotot L, Koebsch L, Kasak K, Maier R, Morin TH, Nemitz E, Oechel WC, Oikawa PY, Ono K, Sachs T, Sakabe A, Schuur EA, Shortt R, Sullivan RC, Szutu DJ, Tuittila ES, Varlagin A, Verfaillie JG, Wille C, Windham-Myers L, Poulter B, Jackson RB
    Agricultural and Forest Meteorology 308-309 108528 - 108528 0168-1923 2021 [Refereed][Not invited]
  • Wakhid N, Hirano T
    Mires and Peat 27 Article 13  2021 [Refereed][Not invited]
  • Ohkubo S, Hirano T, Kusin K
    Agricultural and Forest Meteorology 306 108448  0168-1923 2021 [Refereed][Not invited]
     
    Tropical peat swamp forest is a unique ecosystem rich in carbon and water, accumulating a huge amount of carbon as peat. However, the huge carbon pool has been threatened by oxidative peat decomposition and fire loss mainly because of deforestation and drainage. Fire causes acute carbon dioxide (CO2) emissions through the combustion of biomass and peat. Also, fire should change the CO2 balance of postfire ecosystems. Although it is crucial to quantify CO2 balance even after a fire event to understand the total fire impact, information based on field measurement is lacking. Thus, we had measured eddy CO2 flux above a repeatedly burned degraded peat forest for about 13 years since 2004. The site was a stable CO2 source of 147 290 g C m(-2) yr(-1) for five years after a stand-replacing fire in 2002. Unexpectedly, a moderate-severity fire in 2009 changed the site to a CO2 sink of about 600 g C m(-2) yr(-1). The drastic change would have been caused by a large decrease in the decomposition of plant debris, which had accumulated since the 2002 fire but was burned by the 2009 fire. In contrast, gross primary production (GPP) remained about the same even though vegetation was damaged, mainly because year-round wet conditions caused by a La Nina event promoted the regrowth of hygrophilous herbaceous plants and were favorable to their GPP. The site also had a low-severity fire and was drained in 2014 but did not return to a CO2 source. However, the net ecosystem CO2 uptake after the 2009 fire was insufficient to recover a large amount of fire CO2 emission. If CO2 emissions from four fires in 1999, 2002, 2009 and 2014 are counted, the site is expected to owe an outstanding CO2 debt of 25 kg C m(-2).
  • New inventories of global carbon dioxide emissions through 2 biomass burning in 2001–2018
    Tomohiro Shiraishi, Ryuichi Hirata, Takashi Hirano
    Remote Sensing 13 1914  2021 [Refereed][Not invited]
  • Kyle B. Delwiche, Sara Helen Knox, Avni Malhotra, Etienne Fluet-Chouinard, Gavin McNicol, Sarah Feron, Zutao Ouyang, Dario Papale, Carlo Trotta, Eleonora Canfora, You-Wei Cheah, Danielle Christianson, M. Carmelita, R. Alberto, Pavel Alekseychik, Mika Aurela, Dennis Baldocchi, Sheel Bansal, David P. Billesbach, Gil Bohrer, Rosvel Bracho, Nina Buchmann, David I. Campbell, Gerardo Celis, Jiquan Chen, Weinan Chen, Housen Chu, Higo J. Dalmagro, Sigrid Denge, Ankur R. Desai, Matteo Detto, Han Dolman, Elke Eichelmann, Eugenie Euskirchen, Daniela Famulari, Thomas Friborg, Kathrin Fuchs, Mathias Goeckede, Sébastien Gogo, Mangaliso J. Gondwe, Jordan, P. Goodrich, Pia Gottschalk, Scott L. Graham, Martin Heimann, Manuel Helbig, Carole Helfter, Kyle S. Hemes, Takashi Hirano, David Hollinger, Lukas Hörtnagl, Hiroki Iwata, Adrien Jacotot, Joachim Jansen, Gerald Jurasinski, Minseok Kang, Kuno Kasak, John King, Janina Klatt, Franziska Koebsch, Ken W. Krauss, Derrick Y, F. Lai, Ivan Mammarella, Giovanni Manca, Luca Belelli Marchesini, Jaclyn Hatala Matthes, Trofim Maximon, Lutz Merbold, Bhaskar Mitra, Timothy H. Morin, Eiko Nemitz, Mats B. Nilsson, Shuli Niu, Walter C. Oechel, Patricia Y. Oikawa, Keisuke Ono, Matthias Peichl, Olli Peltola, Michele L. Reba, Andrew D. Richardson, William Riley, Benjamin R, K. Runkle, Youngryel Ryu, Torsten Sachs, Ayaka Sakabe, Camilo Rey Sanchez, Edward A. Schuur, Karina V, R. Schäfer, Oliver Sonnentag, Jed, P. Sparks, Ellen Stuart-Haëntjens, Cove Sturtevant, Ryan C. Sullivan, Daphne J. Szutu, Jonathan E. Thom, Margaret S. Torn, Eeva-Stiina Tuittila, Jessica Turner, Masahito Ueyama, Alex C. Valach, Rodrigo Vargas, Andrej Varlagin, Alma Vazquez-Lule, Joseph G. Verfaillie, Timo Vesala, George L. Vourlitis, Eric J. Ward, Christian Wille, Georg Wohlfahrt, Guan Xhuan Wong, Zhen Zhang, Donatella Zona, Lisamarie Windham-Myers, Benjamin Poulter, Robert B. Jackson
    Earth System Science Data 13 367 - 3689 2021 [Refereed]
     
    Abstract. Methane (CH4) emissions from natural landscapes constitute roughly half of global CH4 contributions to the atmosphere, yet large uncertainties remain in the absolute magnitude and the seasonality of emission quantities and drivers. Eddy covariance (EC) measurements of CH4 flux are ideal for constraining ecosystem-scale CH4 emissions, including their seasonality, due to quasi-continuous and high temporal resolution of flux measurements, coincident measurements of carbon, water, and energy fluxes, lack of ecosystem disturbance, and increased availability of datasets over the last decade. Here, we 1) describe the newly published dataset, FLUXNET-CH4 Version 1.0, the first global dataset of CH4 EC measurements (available at https://fluxnet.org/data/fluxnet-ch4- community-product/). FLUXNET-CH4 includes half-hourly and daily gap-filled and non gap-filled aggregated CH4 fluxes and meteorological data from 79 sites globally: 42 freshwater wetlands, 6 brackish and saline wetlands, 7 formerly drained ecosystems, 7 rice paddy sites, 2 lakes, and 15 uplands. Then, we 2) evaluate FLUXNET-CH4 representativeness for freshwater wetland coverage globally, because the majority of sites in FLUXNET-CH4 Version 1.0 are freshwater wetlands and because freshwater wetlands are a substantial source of total atmospheric CH4 emissions; and 3) provide the first global estimates of the seasonal variability and seasonality predictors of freshwater wetland CH4 fluxes. Our representativeness analysis suggests that the freshwater wetland sites in the dataset cover global wetland bioclimatic attributes (encompassing energy, moisture, and vegetation-related parameters) in arctic, boreal, and temperate regions, but only sparsely cover humid tropical regions. Seasonality metrics of wetland CH4 emissions vary considerably across latitudinal bands. In freshwater wetlands (except those between 20° S to 20° N) the spring onset of elevated CH4 emissions starts three days earlier, and the CH4 emission season lasts 4 days longer, for each degree C increase in mean annual air temperature. On average, the onset of increasing CH4 emissions lags soil warming by one month, with very few sites experiencing increased CH4 emissions prior to the onset of soil warming. In contrast, roughly half of these sites experience the spring onset of rising CH4 emissions prior to the spring increase in gross primary productivity (GPP). The timing of peak summer CH4 emissions does not correlate with the timing for either peak summer temperature or peak GPP. Our results provide seasonality parameters for CH4 modeling, and highlight seasonality metrics that cannot be predicted by temperature or GPP (i.e., seasonality of CH4 peak). The FLUXNET-CH4 dataset provides an open-access resource for CH4 flux synthesis, has a range of applications, and is unique in that it includes coupled measurements of important CH4 drivers such as GPP and temperature. Although FLUXNET-CH4 could certainly be improved by adding more sites in tropical ecosystems and by increasing the number of site-years at existing sites, it is a powerful new resource for diagnosing and understanding the role of terrestrial ecosystems and climate drivers in the global CH4 cycle. All seasonality parameters are available at https://doi.org/10.5281/zenodo.4408468. Additionally, raw FLUXNET-CH4 data used to extract seasonality parameters can be downloaded from https://fluxnet.org/data/fluxnet-ch4-community-product/, and a complete list of the 79 individual site data DOIs is provided in Table 2 in the Data Availability section of this document.
  • Sara Helen Knox, Sheel Bansal, Gavin McNicol, Karina Schafer, Cove Sturtevant, Masahito Ueyama, Alex C. Valach, Dennis Baldocchi, Kyle Delwiche, Ankur R Desai, Eugenie Euskirchen, Jinxun Liu, Annalea Lohila, Avni Malhotra, Lulie Melling, William Riley, Benjamin R, K. Runkle, Jessica Turner, Rodrigo Vargas, Qing Zhu, Tuula Alto, Etienne Fluet-Chouinard, Mathias Goeckede, Joe R. Melton, Oliver Sonnentag, Timo Vesala, Eric Ward, Zhen Zhang, Sarah Feron, Zutao Ouyang, Pavel Alekseychik, Mika Aurela, Gil Bohrer, David I. Campbell, Jiquan Chen, Housen Chu, Higo J, Dalmagro, Jordan, P. Goodrich, Pia Gottschalk, Takashi Hirano, Hiroki Iwata, Gerald Jurasinski, Minseok Kang, Franziska Koebsch, Ivan Mammarella, Mats B. Nilsson, Keisuke Ono, Matthias Peichl, Olli Peltola, Youngryel Ryu, Torsten Sachs, Ayaka Sakabe, Jed Sparks, Eeva-Stiina Tuittila, George L Vourlitis, Guan Xhuan Wong, Lisamarie Windham-Myers, Ben Poulter, Robert B. Jackson
    Global Change Biology 27 (15) 3582 - 3604 1354-1013 2021 [Refereed][Not invited]
  • Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions
    Kuang-Yu Chang, William J. Riley, Sara H. Knox, Robert B. Jackson, Gavin McNicol, Benjamin Poulter, Mika Aurela, Dennis Baldocchi, Sheel Bansal, Gil Bohrer, David I. Campbell, Alessandro Cescatti, Housen Chu, Kyle B. Delwiche, Ankur R. Desai, Eugenie Euskirchen, Thomas Friborg, Mathias Goeckede, Manuel Helbig, Kyle S. Hemes, Takashi Hirano, Hiroki Iwata, Minseok Kang, Trevor Keenan, Ken W. Krauss, Annalea Lohila, Ivan Mammarella, Bhaskar Mitra, Akira Miyata, Mats B. Nilsson, Asko Noormets, Walter C. Oechel, Dario Papale, Matthias Peichl, Michele L. Reba, Janne Rinne, Benjamin R, K. Runkle, Youngryel Ryu, Torsten Sachs, Karina V, R. Schäfer, Hans Peter Schmid, Narasinha Shurpali, Oliver Sonnentag, Angela C. I. Tang, Margaret S. Torn, Carlo Trotta, Eeva-Stiina Tuittila, Masahito Ueyama, Rodrigo Vargas, Timo Vesala, Lisamarie Windham-Myers, Zhen Zhang, Donatella Zona
    Nature Communications 12 2266  2021 [Refereed][Not invited]
  • Ohkubo S, Hirano T, Kusin K
    Agricultural and Forest Meteorology 301-302 108348  0168-1923 2021 [Refereed][Not invited]
     
    Tropical peat swamp forests have been experiencing drastic disturbances, such as deforestation, drainage, and fire. We examined how such disturbances influence albedo, which regulates radiative energy exchange between the terrestrial surface and the atmosphere. We conducted continuous field observations at three sites: undrained forest (UF), drained forest (DF), and drained burned ex-forest (DB), in Central Kalimantan, Indonesia, for over 13 years.Observed albedo was strongly influenced by haze caused by fire because the haze layer covering the canopy has a relatively high reflectance. Under severe haze conditions in October 2015, apparent albedo increased to 0.156, 0.162, and 0.183 at the UF, DF, and DB sites respectively. Mean monthly albedos excluding fire periods were 0.094 +/- 0.005, 0.092 +/- 0.006, and 0.099 +/- 0.017 (mean +/- 1 standard deviation) at the UF, DF, and DB sites respectively. Seasonal fluctuation in albedo at the DB site, where ferns were dominant, was greater than at the UF and DF sites.Albedo at the DF site was significantly lower than that at the UF site from February to August (p < 0.05). At the forest sites the albedo increased as groundwater level decreased. Albedo was higher under high vapor pressure deficit at all sites. At the DB site albedo decreased when the soil surface was water-saturated and patched with puddles, potentially due to the low albedo of open water. The albedo at the DB site was lower than that at the forest sites at the beginning of the observation period. Subsequently, the albedo increased and exceeded those at the UF and DF sites immediately after fire damage in 2009. This could be explained by the expansion of bright-colored ferns and sedges over dark-colored peat soil. According to our results, haze, groundwater level, and vegetation cover significantly influence albedo in tropical peat swamp forests.
  • Ueyama, Masahito, Ichii, Kazuhito, Kobayashi, Hideki, Kumagai, Tomo'omi, Beringer, Jason, Merbold, Lutz, Euskirchen, Eugenie S, Hirano, Takashi, {Belelli Marchesini}, Luca, Baldocchi, Dennis, Saitoh, Taku M., Mizoguchi, Yasuko, Ono, Keisuke, Kim, Joon, Varlagin, Andrej, Kang, Minseok, Shimizu, Takanori, Kosugi, Yoshiko, Bret-Harte, Marion Syndonia (Donie), Machimura, Takashi, Matsuura, Yojiro, Ohta, Takeshi, Takagi, Kentaro, Takanashi, Satoru, Yasuda, Yukio
    Environmental Research Letters 15 084009  2020/02 [Refereed][Not invited]
  • Ben Bond-Lamberty, Danielle S. Christianson, Avni Malhotra, Stephanie C. Pennington, Debjani Sihi, Amir AghaKouchak, Hassan Anjileli, M. Altaf Arain, Juan J. Armesto, Samaneh Ashraf, Mioko Ataka, Dennis Baldocchi, Thomas Andrew Black, Nina Buchmann, Mariah S. Carbone, Shih-Chieh Chang, Patrick Crill, Peter S. Curtis, Eric A. Davidson, Ankur R. Desai, John E. Drake, Tarek S. El-Madany, Michael Gavazzi, Carolyn-Monika Görres, Christopher M. Gough, Michael Goulden, Jillian Gregg, Omar Gutiérrez del Arroyo, Jin-Sheng He, Takashi Hirano, Anya Hopple, Holly Hughes, Järvi Järveoja, Rachhpal Jassal, Jinshi Jian, Haiming Kan, Jason Kaye, Yuji Kominami, Naishen Liang, David Lipson, Catriona A. Macdonald, Kadmiel Maseyk, Kayla Mathes, Marguerite Mauritz, Melanie A. Mayes, Steve McNulty, Guofang Miao, Mirco Migliavacca, Scott Miller, Chelcy F. Miniat, Jennifer G. Nietz, Mats B. Nilsson, Asko Noormets, Hamidreza Norouzi, Christine S. O’Connell, Bruce Osborne, Cecilio Oyonarte, Zhuo Pang, Matthias Peichl, Elise Pendall, Jorge F. Perez-Quezada, Claire L. Phillips, Richard P. Phillips, James W. Raich, Alexandre A. Renchon, Nadine K. Ruehr, Enrique P, Sánchez-Cañete, Matthew Saunders, Kathleen E. Savage, Marion Schrumpf, Russell L. Scott, Ulli Seibt, Whendee L. Silver, Wu Sun, Daphne Szutu, Kentaro Takagi, Masahiro Takagi, Munemasa Teramoto, Mark G. Tjoelker, Susan Trumbore, Masahito Ueyam, Rodrigo Vargas, Ruth K. Varner, Joseph Verfaillie, Christoph Vogel, Jinsong Wang, Greg Winston, Tana E. Wood, Juying Wu, Thomas Wutzler, Jiye Zeng, Tianshan Zha, Quan Zhang, Junliang Zou
    Global Change Biology 26 (12) 7268 - 7283 1354-1013 2020 [Refereed][Not invited]
     
    Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil-to-atmosphere CO(2)flux, commonly though imprecisely termed soil respiration (R-S), is one of the largest carbon fluxes in the Earth system. An increasing number of high-frequencyR(S)measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open-source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long-term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measuredR(S), the database design accommodates other soil-atmosphere measurements (e.g. ecosystem respiration, chamber-measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package.
  • Kiew F, Hirata R, Hirano T, Wong GX, Aries EB, Kemudang K, Wenceslaus J, Lo KS, Melling L
    Agricultural and Forest Meteorology 295 108189  2020 [Refereed][Not invited]
  • Environmental controls on methane fluxes in a cool temperate bog
    Ueyama M, Yazaki T, Hirano T, Futakuchi Y, Okamura M
    Agricultural and Forest Meteorology 281 107852  2020 [Refereed][Not invited]
  • Wong G, Hirata R, Hirano T, Kiew F, Aeries E, Musin K, Waili J, Lo K, Melling L
    Agricultural and Forest Meteorology 282-283 107869  2020 [Refereed][Not invited]
  • Ishikura K, Hirata R, Hirano T, Okimoto Y, Wong GX, Melling L, Aeries EB, Kiew F, Lo KS, Musin KK, Waili JW, Ishii Y
    Ecosystems 22 (8) 1852 - 1868 1432-9840 2019/12 [Refereed][Not invited]
  • Sun L, Hirano T, Yazaki T, Teramoto M, Liang N
    Plant and Soil 446 (1-2) 471 - 486 0032-079X 2019/11 [Refereed][Not invited]
  • Wu L, Kato T, Sato H, Hirano T, Yazaki T
    Forest Ecology and Management 451 117529 - 117529 0378-1127 2019/11 [Refereed][Not invited]
  • Masato Hayashi, Takahiro Abe, Takashi Hirano, Ryuichi Hirata, Tomohiro Shiraishi, Lulie Melling
    IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium 2019/07
  • Surface conductance for evapotranspiration of tropical forests: calculations, variations, and controls
    Zheng-Hong Tan, JUNFU ZHAO, Guanze Wang, Meng-Ping Chen, Lianyan Yang, Chunsheng He, Natalia Restrepo-Coupe, Shushi Peng, Xueyan Liu, Humberto R da Rocha, Yoshiko Kosugi, Takashi Hirano, Scott Saleska, Michael Goulden, Jiye Zeng, Fangjun Ding, Fu Gao, Liang Song
    Agricultural and Forest Meteorology 275 317 - 328 2019 [Refereed][Not invited]
  • FLUXNET-CH4 Synthesis Activity: Objectives, Observations, and Future Directions
    Sara H. Knox, Robert Jackson, Benjamin Poulter, Gavin McNicol, Etienne Fluet-Chouinard, Zhen Zhang, Gustaf Hugelius, Philippe Bousquet, Josep G. Canadell, Marielle Saunois, Dario Papale, Housen Chu, Trevor F. Keenan, DenniS Baldocchi, Margaret S. Torn, Ivan Mammarella, Carlo Trotta, Mika Aurela, Gil Bohrer, David I. Campbell, Alessandro Cescatti, Samuel Chamberlain, Jiquan Chen, Weinan Chen, Sigrid Dengel, Ankur R. Desai, Eugenie Euskirchen, Thomas Friborg, Daniele Gasbarra, Ignacio Goded, Mathias Goeckede, Martin Heimann, Manuel Helbig, Takashi Hirano, David Y. Hollinger, Hiroki Iwata, Minseok Kang, Janina Klatt, Ken W. Krauss, Lars Kutzbach, Annalea Lohila, Bhaskar Mitra, Timothy H. Morin, Mats B. Nilsson, Shuli Niu, Asko Noormets, Walter C. Oechel, Matthias Peichl, Olli Peltola, Michele L. Reba, Andrew D. Richardson, Benjamin R, K. Runkle, Youngryel Ryu, Torsten Sachs, Karina V, R. Schäfer, Hans Peter Schmid, Narasinha Shurpali, Oliver Sonnentag, Angela C. I. Tang, Masahito Ueyama, Rodrigo Vargas, Timo Vesala, Eric J. Ward, Lisamarie Windham-Myers, Georg Wohlfahrt, Donatella Zona
    Bulletin of the American Meteorological Society 100 (12) 2607 - 2632 2019 [Refereed][Not invited]
  • Guan Xhuan Wong, Ryuichi Hirata, Takashi Hirano, Frankie Kiew, Edward Baran Aeries, Kevin Kemudang Musin, Joseph Wenceslaus Waili, Kim San Lo, Lulie Melling
    Agricultural and Forest Meteorology 256-257 353 - 361 0168-1923 2018/06/15 [Refereed][Not invited]
     
    Tropical peat swamp forest is a unique ecosystem, in which both swamp forest and peat soil have coexisted over millennia and accumulated a significant amount of soil carbon as peat. Owing to the huge soil carbon stock and high groundwater level (GWL), tropical peatlands potentially represent a significant source of methane (CH4) to the atmosphere. However, a few studies of CH4 flux by the soil chamber technique have reported that annual CH4 emissions from tropical peat swamp forest were very low as compared to mid- and high-latitude peatlands. Recently, it has been reported that some tree species growing in peat swamp forest emit CH4 from their stems. It is impossible to continuously measure ecosystem-scale CH4 flux including both soil and plant-mediated CH4 emissions by the chamber technique. Thus, we have measured net ecosystem CH4 exchange (FCH4) above a tropical peat swamp forest in Sarawak, Malaysia using the eddy covariance technique from February 2014 to July 2015 (18 months). The mean (±1 standard deviation) of half-hourly measured FCH4 was 24.0 ± 42.2 nmol m–2 s–1. Monthly mean FCH4 was always positive during the 18 months, even in the driest month with mean GWL of –30 cm. FCH4 was positively associated with GWL or soil moisture in a quadratic form. Annual FCH4 from March 2014 through February 2015 was 7.5–10.8 g C m–2 yr–1. The annual FCH4 was much higher than annual soil CH4 emissions from tropical peatlands, because the FCH4 included aboveground CH4 emissions mainly from tree stems. However, the annual FCH4 was relatively low in comparison with those measured by the eddy covariance technique in mid- and high-latitude peatlands.
  • Kiwamu Ishikura, Takashi Hirano, Yosuke Okimoto, Ryuichi Hirata, Frankie Kiew, Lulie Melling, Edward Baran Aeries, Kim San Lo, Kevin Kemudang Musin, Joseph Wenceslaus Waili, Guan Xhuan Wong, Yoshiyuki Ishii
    Agriculture, Ecosystems and Environment 254 202 - 212 0167-8809 2018/02/15 [Refereed][Not invited]
     
    Soil carbon dioxide (CO2) efflux was measured continuously for two years using an automated chamber system in an oil palm plantation on tropical peat. This study investigated the factors controlling the CO2 efflux and quantified the annual cumulative CO2 emissions through soil respiration and heterotrophic respiration, which is equivalent to oxidative peat decomposition. Soil respiration was measured in close-to-tree (< 2.5 m, CT) and far-from-tree (> 3 m, FT) plots, and heterotrophic respiration was measured in root-cut (RC) plots by a trenching method. The daily mean CO2 efflux values (mean ± 1 standard deviation) were 2.80 ± 2.18, 1.59 ± 1.18, and 1.94 ± 1.58 μmol m−2 s−1 in the CT, FT, and RC plots, respectively. Daily mean CO2 efflux increased exponentially as the groundwater level or water-filled pore space decreased, indicating that oxidative peat decomposition and gas diffusion in the soil increased due to enhanced aeration resulting from lower groundwater levels. Mean annual gap-filled CO2 emissions were 1.03 ± 0.53, 0.59 ± 0.26, and 0.69 ± 0.21 kg C m−2 yr−1 in the CT, FT, and RC plots, respectively. Soil CO2 emissions were significantly higher in the CT plots (P < 0.05), but did not differ significantly between the FT and RC plots. This implies that root respiration was negligible in the FT plots. Heterotrophic respiration accounted for 66% of soil respiration. Annual CO2 emissions through both soil and heterotrophic respiration were smaller than those of other oil palm plantations on tropical peat, possibly due to the higher groundwater levels, land compaction, and continuous measurement of soil CO2 efflux in this study. Mean annual total subsidence was 1.55 to 1.62 cm yr−1, of which oxidative peat decomposition accounted for 72 to 74%. In conclusion, water management to raise groundwater levels would mitigate soil CO2 emissions from oil palm plantations on tropical peatland.
  • Fu Z, Gerken T, Bromley G, Araújo A, Bonal D, Burban B, Ficklin D, Fuentes J, Goulden M, Hirano T, Kosugi Y, Liddell M, Nicolini G, Niu S, Roupsard O, Stefani P, Mi, C, Tofte Z, Xiao J, Valentini R, Wolf S, Stoy P
    Agricultural and Forest Meteorology 263 292 - 307 2018 [Refereed][Not invited]
  • Sakabe A, Itoh M, Hirano T, Kitso K
    Global Change Biology 24 (11) 5123 - 5136 2018 [Refereed][Not invited]
     
    Data on ecosystem-scale methane (CH4 ) fluxes in tropical peatlands are currently lacking in the global CH4 budget. Although the waterlogged Indonesian peatlands contain the largest share of peat carbon in South-East Asia, ecosystem-scale CH4 budgets have not yet been reported, although these peatlands have the potential to emit CH4 . We observed 1-year variations in the ecosystem-scale CH4 flux in an undrained secondary peat swamp forest in central Kalimantan, Indonesia, using the eddy covariance method. We found that the peat swamp forest switched from being a CH4 sink during the dry season (as low as -8.9 mg C m-2  day-1 ) to a source of CH4 during the wet season (up to 10.7 mg C m-2  day-1 ), and this was dependent on changes in the groundwater level (GWL). The high GWL during the wet season enhanced the anaerobic CH4 production in the surface layer that had more labile organic matter. However, the CH4 emission also increased when the GWL dropped during dry spells in the wet season. The annual CH4 budget in the studied tropical peat swamp forest (0.09-0.17 g C m-2  year-1 ) was much lower than that in northern, temperate, and subtropical wetlands. We found that CH4 fluxes had almost no effect on the global warming gas budget of the peat swamp forest, and values were only a few percent less than the CO2 fluxes at the same site. In addition, we conducted anaerobic soil incubation experiments to examine the effect of land-use change on CH4 production. The results indicated much higher CH4 production potential in undrained forest soil than in drained or drained and burned ex-forest soils. However, although CH4 production decreased in drained soils relative to undrained soils, conserving pristine peat swamp forests with high GWLs is important to suppress global warming because CO2 emissions increase in drained peatlands.
  • Frankie Kiew, Ryuichi Hirata, Takashi Hirano, Guan Xhuan Wong, Edward Baran Aeries, Kevin Kemudang Musin, Joseph Wenceslaus Waili, Kim San Lo, Mariko Shimizu, Lulie Melling
    AGRICULTURAL AND FOREST METEOROLOGY 248 494 - 501 0168-1923 2018/01 [Refereed][Not invited]
     
    Tropical peat swamp forest (PSF) has accumulated a huge amount of carbon as peat over millennia, though the carbon rich ecosystem is now threatened with disturbances due to land-use change to industrial plantations of oil palm and pulp woods. Through the land conversion, peat carbon has become vulnerable and potentially changes to a great carbon dioxide (CO2) source to the atmosphere. It is essential to quantify the CO2 balance of the ecosystem and understand how the CO2 balance responds to environmental changes to predict the role of PSF in global carbon cycles. However, filed studies based on the ecosystem-scale monitoring of CO2 flux are quite limited. Thus, we began CO2 flux monitoring over a secondary PSF in Sarawak, Malaysia, by the eddy covariance technique in 2010. Daily NEE and RE were significantly different between the dry and wet periods (p < 0.01), respectively, whereas no significant difference was found in daily GPP. As a result, the seasonal difference in NEE between the two periods (0.52 g C m(-2) d(-1)) was due to that in RE (0.57 g C m(-2) d(-1)). Daily RE was significantly greater in the dry period mainly because of lower groundwater level (GWL). Lower GWL enhances peat aeration and potentially increases oxidative peat decomposition, which results in higher soil CO2 efflux. Annual NEE was -136 +/- 51 g C m(-2) yr(-1) (mean +/- 1 standard deviation) during the four years until 2014. The negative annual NEE was equivalent to those of some tropical rain forests on mineral soil, but was more negative than 174 g C m(-2) yr(-1) for an almost undrained PSF in Central Kalimantan, Indonesia (Hirano et al., 2012). The difference in annual NEE between the two sites is attributable to higher leaf area index and less distinct seasonality in precipitation in this site.
  • Masayuki Itoh, Yosuke Okimoto, Takashi Hirano, Kitso Kusin
    SCIENCE OF THE TOTAL ENVIRONMENT 609 906 - 915 0048-9697 2017/12 [Refereed][Not invited]
     
    The increasing frequency of fire due to drainage of tropical peatland has become a major environmental problemin Southeast Asia. To clarify the effects of changes in land use on carbon dioxide emissions, wemeasured oxidative peat decomposition (PD) at different stages of disturbance at three sites in Central Kalimantan, Indonesia: an undrained peat swamp forest (UF), a heavily drained peat swamp forest (DF), and a drained and burned ex-forest (DB). PD exhibited seasonality, being less in the wet season and greater in the dry season. From February 2014 to December 2015, mean PD (+/-SE) were 1.90 +/- 0.19, 2.30 +/- 0.33, and 1.97 +/- 0.25 mu mol m(-2) s(-1) at UF, DF, and DB, respectively. The groundwater level (GWL) was a major controlling factor of PD at all sites. At UF and DF, PD and GWL showed significant quadratic relationships. At DB, PD and GWL showed significant positive and negative relationships during the dry and wet seasons, respectively. Using these relationships, we estimated annual PD from GWL data for 2014 and 2015 as 698 and 745 g C m(-2) yr(-1) at UF (mean GWL: -0.23 and -0.39 m), 775 and 825 g C m(-2) yr(-1) at DF (-0.55 and -0.59 m), and 646 and 748 g C m(-2) yr(-1) at DB (-0.22 and -0.62 m), respectively. The annual PD was significantly higher in DF than in UF or DB, in both years. Despite the very dry conditions, the annual PD values at these sites were much lower than those reported for tropical peat at plantations (e.g., oil palm, rubber, and acacia). The differences in the relationship between PD and GWL indicate that separate estimations are required for each type of land. Moreover, our results suggest that PD can be enhanced by drainage both in forests and at burned sites. (C) 2017 Elsevier B.V. All rights reserved.
  • Zhiyuan Zhang, Renduo Zhang, Alessandro Cescatti, Georg Wohlfahrt, Nina Buchmann, Juan Zhu, Guanhong Chen, Fernando Moyano, Jukka Pumpanen, Takashi Hirano, Kentaro Takagi, Lutz Merbold
    SCIENTIFIC REPORTS 7 3108  2045-2322 2017/06 [Refereed][Not invited]
     
    The net ecosystem CO2 exchange is the result of the imbalance between the assimilation process (gross primary production, GPP) and ecosystem respiration (RE). The aim of this study was to investigate temperature sensitivities of these processes and the effect of climate warming on the annual terrestrial net ecosystem CO2 exchange globally in the boreal and temperate regions. A database of 403 site-years of ecosystem flux data at 101 sites in the world was collected and analyzed. Temperature sensitivities of rates of RE and GPP were quantified with Q(10), defined as the increase of RE (or GPP) rates with a temperature rise of 10 degrees C. Results showed that on the annual time scale, the intrinsic temperature sensitivity of GPP (Q(10sG)) was higher than or equivalent to the intrinsic temperature sensitivity of RE (Q(10sR)). Q(10sG) was negatively correlated to the mean annual temperature (MAT), whereas Q(10sR) was independent of MAT. The analysis of the current temperature sensitivities and net ecosystem production suggested that temperature rise might enhance the CO2 sink of terrestrial ecosystems both in the boreal and temperate regions. In addition, ecosystems in these regions with different plant functional types should sequester more CO2 with climate warming.
  • Zheng-Hong Tan, Jiye Zeng, Yong-Jiang Zhang, Martijn Slot, Minoru Gamo, Takashi Hirano, Yoshiko Kosugi, Humberto R. da Rocha, Scott R. Saleska, Michael L. Goulden, Steven C. Wofsy, Scott D. Miller, Antonio O. Manzi, Antonio D. Nobre, Plinio B. de Camargo, Natalia Restrepo-Coupe
    ENVIRONMENTAL RESEARCH LETTERS 12 (5) 054022  1748-9326 2017/05 [Refereed][Not invited]
  • Kazuhito Ichii, Masahito Ueyama, Masayuki Kondo, Nobuko Saigusa, Joon Kim, Ma. Carmelita Alberto, Jonas Ardoe, Eugenie S. Euskirchen, Minseok Kang, Takashi Hirano, Joanna Joiner, Hideki Kobayashi, Luca Belelli Marchesini, Lutz Merbold, Akira Miyata, Taku M. Saitoh, Kentaro Takagi, Andrej Varlagin, M. Syndonia Bret-Harte, Kenzo Kitamura, Yoshiko Kosugi, Ayumi Kotani, Kireet Kumar, Sheng-Gong Li, Takashi Machimura, Yojiro Matsuura, Yasuko Mizoguchi, Takeshi Ohta, Sandipan Mukherjee, Yuji Yanagi, Yukio Yasuda, Yiping Zhang, Fenghua Zhao
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 122 (4) 767 - 795 2169-8953 2017/04 [Refereed][Not invited]
     
    The lack of a standardized database of eddy covariance observations has been an obstacle for data-driven estimation of terrestrial CO2 fluxes in Asia. In this study, we developed such a standardized database using 54 sites from various databases by applying consistent postprocessing for data-driven estimation of gross primary productivity (GPP) and net ecosystem CO2 exchange (NEE). Data-driven estimation was conducted by using a machine learning algorithm: support vector regression (SVR), with remote sensing data for 2000 to 2015 period. Site-level evaluation of the estimated CO2 fluxes shows that although performance varies in different vegetation and climate classifications, GPP and NEE at 8days are reproduced (e.g., r(2)=0.73 and 0.42 for 8day GPP and NEE). Evaluation of spatially estimated GPP with Global Ozone Monitoring Experiment 2 sensor-based Sun-induced chlorophyll fluorescence shows that monthly GPP variations at subcontinental scale were reproduced by SVR (r(2)=1.00, 0.94, 0.91, and 0.89 for Siberia, East Asia, South Asia, and Southeast Asia, respectively). Evaluation of spatially estimated NEE with net atmosphere-land CO2 fluxes of Greenhouse Gases Observing Satellite (GOSAT) Level 4A product shows that monthly variations of these data were consistent in Siberia and East Asia; meanwhile, inconsistency was found in South Asia and Southeast Asia. Furthermore, differences in the land CO2 fluxes from SVR-NEE and GOSAT Level 4A were partially explained by accounting for the differences in the definition of land CO2 fluxes. These data-driven estimates can provide a new opportunity to assess CO2 fluxes in Asia and evaluate and constrain terrestrial ecosystem models.
  • Lifei Sun, Munemasa Teramoto, Naishin Liang, Tomotsugu Yazaki, Takashi Hirano
    JOURNAL OF AGRICULTURAL METEOROLOGY 73 (2) 59 - 67 0021-8588 2017/04 [Refereed][Not invited]
     
    Leaf litter decomposition strongly affects the global carbon cycle through carbon dioxide (CO2) emissions to the atmosphere. The litter bag method (LB) and chamber method with litter addition and removal treatments (C-LART) have been used to quantify the litter decomposition rate and its resultant CO2 flux. The C-LART method measures soil CO2 fluxes in control, litter addition, and litter removal plots, and thereby decomposition rates are calculated from differences of the fluxes. However, no report has described the applicability of C-LART in comparison with LB. This study measured the litter decomposition rate and its resultant CO2 flux using C-LART and LB in a temperate evergreen forest in central Japan to assess the applicability of the two methods. Annual soil respiration in the control plot was 1572 gC m(-2) yr(-1), which was approximately twice as high as the mean of temperate evergreen forests in the world. The litter decomposition rate was 0.42 g g(-1) yr(-1) in mass loss or 0.49 gC gC(-1) yr(-1) in carbon loss by LB, which are compatible with those reported from other temperature forests. In contrast, the decomposition rate of litter carbon ascertained using C-LART was greater than I (1.96-3.76 gC gC(-1) yr(-1)), meaning that carbon emissions increased more than applied, and that the carbon emissions were decreased more than those removed by litter treatments. The incredibly high decomposition was attributed to the enhanced or restricted microbial activities in the underlying mineral soil. Changes in microbial activity are probably caused by the alteration of material supply from the leaf litter layer to the soil by litter treatment (the priming effect). In conclusion, C-LART is not applicable to evaluate CO2 emissions through litter decomposition. Another approach must be used to compensate the priming effect for application of the chamber method.
  • Lahiru S. Wijedasa, Jyrki Jauhiainen, Mari Kononen, Maija Lampela, Harri Vasander, Marie-Claire Leblanc, Stephanie Evers, Thomas E. L. Smith, Catherine M. Yule, Helena Varkkey, Massimo Lupascu, Faizal Parish, Ian Singleton, Gopalasamy R. Clements, Sheema Abdul Aziz, Mark E. Harrison, Susan Cheyne, Gusti Z. Anshari, Erik Meijaard, Jenny E. Goldstein, Susan Waldron, Kristell Hergoualc'h, Rene Dommain, Steve Frolking, Christopher D. Evans, Mary Rose C. Posa, Paul H. Glaser, Nyoman Suryadiputra, Reza Lubis, Truly Santika, Rory Padfield, Sofyan Kurnianto, Panut Hadisiswoyo, Teck Wyn Lim, Susan E. Page, Vincent Gauci, Peter J. Van der Meer, Helen Buckland, Fabien Garnier, Marshall K. Samuel, Liza Nuriati Lim Kim Choo, Patrick O'Reilly, Matthew Warren, Surin Suksuwan, Elham Sumarga, Anuj Jain, William F. Laurance, John Couwenberg, Hans Joosten, Ronald Vernimmen, Aljosja Hooijer, Chris Malins, Mark A. Cochrane, Balu Perumal, Florian Siegert, Kelvin S. -H. Peh, Louis-Pierre Comeau, Louis Verchot, Charles F. Harvey, Alex Cobb, Zeehan Jaafar, Henk Wosten, Solichin Manuri, Moritz Muller, Wim Giesen, Jacob Phelps, Ding Li Yong, Marcel Silvius, Beatrice M. M. Wedeux, Alison Hoyt, Mitsuru Osaki, Takashi Hirano, Hidenori Takahashi, Takashi S. Kohyama, Akira Haraguchi, Nunung P. Nugroho, David A. Coomes, Le Phat Quoi, Alue Dohong, Haris Gunawan, David L. A. Gaveau, Andreas Langner, Felix K. S. Lim, David P. Edwards, Xingli Giam, Guido Van der Werf, Rachel Carmenta, Caspar C. Verwer, Luke Gibson, Laure Gandois, Laura Linda Bozena Graham, Jhanson Regalino, Serge A. Wich, Jack Rieley, Nicholas Kettridge, Chloe Brown, Romain Pirard, Sam Moore, B. Ripoll Capilla, Uwe Ballhorn, Hua Chew Ho, Agata Hoscilo, Sandra Lohberger, Theodore A. Evans, Nina Yulianti, Grace Blackham, Onrizal, Simon Husson, Daniel Murdiyarso, Sunita Pangala, Lydia E. S. Cole, Luca Tacconi, Hendrik Segah, Prayoto Tonoto, Janice S. H. Lee, Gerald Schmilewski, Stephan Wulffraat, Erianto Indra Putra, Megan E. Cattau, R. S. Clymo, Ross Morrison, Aazani Mujahid, Jukka Miettinen, Soo Chin Liew, Samu Valpola, David Wilson, Laura D'Arcy, Michiel Gerding, Siti Sundari, Sara A. Thornton, Barbara Kalisz, Stephen J. Chapman, Ahmad Suhaizi Mat Su, Imam Basuki, Masayuki Itoh, Carl Traeholt, Sean Sloan, Alexander K. Sayok, Roxane Andersen
    GLOBAL CHANGE BIOLOGY 23 (3) 977 - 982 1354-1013 2017/03 [Refereed][Not invited]
  • Nur Wakhid, Takashi Hirano, Yosuke Okimoto, Siti Nurzakiah, Dedi Nursyamsi
    SCIENCE OF THE TOTAL ENVIRONMENT 581 857 - 865 0048-9697 2017/03 [Refereed][Not invited]
     
    Land-use change in tropical peatland potentially results in a large amount of carbon dioxide (CO2) emissions owing to drainage, which lowers groundwater level (GWL) and consequently enhances oxidative peat decomposition. However, field information on carbon balance is lacking for rubber plantations, which are expanding into Indonesia's peatlands. To assess soil CO2 emissions from an eight-year-old rubber plantation established on peat after compaction, soil CO2 efflux was measured monthly using a closed chamber system from December 2014 to December 2015, in which a strong El Nino event occurred, and consequently GWL lowered deeply.Total soil respiration (SR) and oxidative peat decomposition (PD) were separately quantified by trenching. In addition, peat surface elevation was measured to determine annual subsidence along with GWL. With GWL, SR showed a negative logarithmic relationship (p < 0.01), whereas PD showed a strong negative linearity (p < 0.001). Using the significant relationships, annual SR and PD were calculated from hourly GWL data to be 3293 1039 and 1408 214 g C m(-2) yr(-1) (mean 1 standard deviation), respectively. PD accounted for 43% of SR on an annual basis. SR showed no significant difference between near and far positions from rubber trees (p > 0:05). Peat surface elevation varied seasonally in almost parallel with GWL. After correcting for GWL difference, annual total subsidence was determined at 5.64 3.20 and 5.96 0.43 cm yr(-1) outside and inside the trenching, respectively. Annual subsidence only through peat oxidation that was calculated from the annual PD, peat bulk density and peat carbon content was 1.50 cm yr(-1). As a result, oxidative peat decomposition accounted for 25% of total subsidence (5.96 cm yr(-1)) on average on an annual basis. The contribution of peat oxidation was lower than those of previous studies probably because of compaction through land preparation. (C) 2017 Elsevier B.V. All rights reserved.
  • Takashi Hirano, Keiji Suzuki, Ryuichi Hirata
    AGRICULTURAL AND FOREST METEOROLOGY 232 457 - 468 0168-1923 2017/01 [Refereed][Not invited]
     
    Larch, a deciduous needle-leaf gymnosperm, is widely distributed in cool temperate and boreal forests of the Northern Hemisphere. Thus, evaluating evapotranspiration (ET) in larch forests is important to elucidate energy and water cycles on a global scale. In addition, severe forest disturbance is expected to change ET and energy balance through a drastic change in the canopy structure. However, knowledge related to the environmental functions of larch forests in cool temperate regions remains lacking compared with Siberian larch forests. Furthermore, few reports describe quantified changes in ET and energy balance before and after forest disturbance. Therefore, for more than a decade, we measured sensible and latent heat fluxes using the eddy covariance technique above a larch forest in northern Japan and its succeeding ex-forest after a stand-replacing disturbance caused by windthrow. In general, the larch forest's ET was not limited by water in contrast to that of a Siberian larch forest. Although the aboveground biomass decreased by 97% through the disturbance, both cumulative ET and latent heat flux normalized by incident solar radiation (IE/R-g) during the snow-free period of about seven months were decreased by only 24% in the second year after disturbance. The 24% decrease was caused by 17% decrease in the partition of incident solar radiation to net radiation (R-g/R-n) and 9% decrease in the partition of net radiation to ET (IE/R-n). The former resulted from increased albedo and decreased net longwave radiation, and the latter was mainly due to decrease in surface conductance. According to the vegetation recovery of shrubs and herbaceous plants, cumulative ET during the snow-free period increased gradually and almost reached pre-disturbance levels in six years. However, normalized ET by solar radiation (IE/Rg) decreased in the 11th and 12th years after reaching the pre-disturbance level. Positive relationship between cumulative ET and vegetation indices indicates that the ET recovery was due to vegetation recovery. (C) 2016 Elsevier B.V. All rights reserved.
  • Tomotsugu Yazaki, Takashi Hirano, Tomohito Sano
    FORESTS 7 (11) doi:10.3390/f7110287  1999-4907 2016/11 [Refereed][Not invited]
     
    Quantitative evaluations of biomass accumulation after disturbances in forests are crucially important for elucidating and predicting forest carbon dynamics in order to understand the carbon sink/source activities. During early secondary succession, understory vegetation often affects sapling growth. However, reports on biomass recovery in naturally-regenerating sites are limited in Japan. Therefore, we traced annual or biennial changes in plant species, biomass, and net primary production (NPP) in a naturally regenerating site in Japan after windthrow and salvage-logging plantation for nine years. The catastrophic disturbance depleted the aboveground biomass (AGB) from 90.6 to 2.7 Mg.ha(-1), changing understory dominant species from Dryopteris spp. to Rubus idaeus. The mean understory AGB recovered to 4.7 Mg.ha(-1) in seven years with the dominant species changing to invasive Solidago gigantea. Subsequently, patches of deciduous trees (mainly Betula spp.) recovered whereas the understory AGB decreased. Mean understory NPP increased to 272 g.C.m(-2).year(-1) within seven years after the disturbance, but decreased thereafter to 189 g.C.m(-2).year(-1). Total NPP stagnated despite increasing overstory NPP. The biomass accumulation is similar to that of naturally regenerating sites without increase of trees in boreal and temperate regions. Dense ground vegetation and low water and nutrient availability of the soil in the study site restrict the recovery of canopy-forming trees and eventually influence the biomass accumulation.
  • 吉川慶, 矢崎友嗣, 井手玲子, 栗原純一, 小熊宏之, 平野高司
    北海道の農業気象 68 (68) 11 - 20 0915-6062 2016/10 [Refereed][Not invited]
  • Takashi Hirano, Hiroyuki Yamada, Masayuki Takada, Yoshiyasu Fujimura, Hiroko Fujita, Hidenori Takahashi
    AGRICULTURAL AND FOREST METEOROLOGY 220 90 - 100 0168-1923 2016/04 [Refereed][Not invited]
     
    Plant succession triggered by drainage, which results in the expansion or invasion of vascular plants, has been reported from many peatlands. However, the effects of the vascular plant's expansion on evapotranspiration (ET), which is a key component of the water balance of ombrotophic bog, are still contradictory. To investigate the effects, ET was measured at a Sphagnum-dominated bog and an adjacent transition peatland dominated by Sasa, dwarf bamboo, in Hokkaido Island, northern Japan, using the eddy covariance technique during the four growing seasons from 2007 through 2010. Cumulative gap-filled ET during a snow-free period of 6.5 months was 362(2008) and 374 mm (2010) at the Sphagnum site and 300 (2008) and 372 mm (2010) at the Sasa site. In the mid-growing season (late June to mid-September) with the highest leaf area index (LAI) at the Sasa site, ET was 2.14 +/- 0.03 (mean 1 standard deviation of the four years) and 1.92 +/- 0.19 mm d(-1), respectively, at the Sphagnum and Sasa sites. ET was smaller at the Sasa site, except for 2010 with an unusual hot wet summer; mean air temperature and precipitation were higher than their 30-year normal values by 1.75 degrees C and 172 mm, respectively. At the Sphagnum site, ET was stable despite such interannual variation in meteorological conditions. However, ET increased significantly at the Sasa site in 2010 probably because of LAI increase due to the enhanced growth of Sasa plants. The ET increase at the Sasa site suggests that ET will increase at the Sasa-dominated area, if the future warming environment accompanies more precipitation. (C) 2016 Elsevier B.V. All rights reserved.
  • M. Mezbahuddin, R. F. Grant, T. Hirano
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 120 (11) 2132 - 2157 2169-8953 2015/11 [Refereed][Not invited]
     
    Soil carbon stocks in tropical peatlands have declined recently from water table depth (WTD) drawdown caused by increased frequency and intensity of climate extremes like El Nino and by artificial drainage. Restoration of these carbon stocks under these climatic and anthropogenic disturbances requires improved predictive capacity for hydrological feedbacks to ecological processes. Process-based modeling of tropical peatland ecohydrology could provide us with such capacity, but such modeling has thus far been limited. We aimed at using basic processes for water and O-2 transport and their effects on ecosystem water, carbon, and nitrogen cycling to model seasonal and interannual variations of WTD and surface energy exchange. We tested these processes in a process-based model ecosys in a drained tropical Indonesian peatland from an El Nino year 2002 to a wetter year 2005. WTD was modeled from hydraulically driven water transfers controlled vertically by precipitation versus evapotranspiration (ET) and laterally by discharge versus recharge to or from an external reference WTD. These transfers caused WTD drawdown and soil drying to be modeled during dry seasons, which reduced ET and increased Bowen ratio by lowering stomatal conductance. More pronounced dry seasons in drier years 2002-2004 versus wetter year 2005 caused deeper WTD, more intense peat drying, and greater plant water stress. These modeled trends were well corroborated by site measurements as apparent in regression statistics of modeled versus observed WTD (R-2 > 0.8), latent heat (R-2 > 0.8), and sensible heat (R-2 > 0.7) fluxes. Insights gained from this modeling would aid in predicting the fate of tropical peatlands under future drier climates.
  • Takashi Hirano, Kitso Kusin, Suwido Limin, Mitsuru Osaki
    GLOBAL CHANGE BIOLOGY 21 (5) 1914 - 1927 1354-1013 2015/05 [Refereed][Not invited]
     
    In Southeast Asia, peatland is widely distributed and has accumulated a massive amount of soil carbon, coexisting with peat swamp forest (PSF). The peatland, however, has been rapidly degraded by deforestation, fires, and drainage for the last two decades. Such disturbances change hydrological conditions, typically groundwater level (GWL), and accelerate oxidative peat decomposition. Evapotranspiration (ET) is a major determinant of GWL, whereas information on the ET of PSF is limited. Therefore, we measured ET using the eddy covariance technique for 4-6years between 2002 and 2009, including El Nino and La Nina events, at three sites in Central Kalimantan, Indonesia. The sites were different in disturbance degree: a PSF with little drainage (UF), a heavily drained PSF (DF), and a drained burnt ex-PSF (DB); GWL was significantly lowered at DF, especially in the dry season. The ET showed a clear seasonal variation with a peak in the mid-dry season and a large decrease in the late dry season, mainly following seasonal variation in net radiation (R-n). The R-n drastically decreased with dense smoke from peat fires in the late dry season. Annual ET forced to close energy balance for 4years was 1636 +/- 53, 1553 +/- 117, and 1374 +/- 75mmyr(-1) (mean +/- 1 standard deviation), respectively, at UF, DF, and DB. The undrained PSF (UF) had high and rather stable annual ET, independently of El Nino and La Nina events, in comparison with other tropical rainforests. The minimum monthly-mean GWL explained 80% of interannual variation in ET for the forest sites (UF and DF); the positive relationship between ET and GWL indicates that drainage by a canal decreased ET at DF through lowering GWL. In addition, ET was decreased by 16% at DB in comparison with UF chiefly because of vegetation loss through fires.
  • Masato Hayashi, Nobuko Saigusa, Yoshiki Yamagata, Takashi Hirano
    CARBON MANAGEMENT 6 (1-2) 19 - 33 1758-3004 2015/03 [Refereed][Not invited]
     
    Background: We aimed to clarify the potential of spaceborne light detection and ranging (LiDAR) to meet the increased demand for large-scale monitoring of forest resources.Results: We developed empirical models to estimate aboveground biomass (AGB) and canopy height in Borneo from Ice, Cloud, and land Elevation Satellite (ICESat)/Geoscience Laser Altimeter System (GLAS) data, and obtained root-mean-square errors of 38.7 Mg ha(-1) and 4.0 m, respectively. GLAS-estimated AGB averaged 191.8 Mg ha(-1). From 2004 to 2007, AGB decreased by an average of 33.1 Mg ha(-1), and the rate of forest loss was 2.4% year(-1). The total AGB in Borneo was estimated as 10.34 Gt.Conclusions: The results demonstrate the potential of spaceborne LiDAR for monitoring forest resources, and its potential to play an important role in REDD+ implementations.
  • Takashi Hirano, Siti Sundari, Hiroyuki Yamada
    Tropical Peatland Ecosystems 329 - 337 2015/01/01 [Refereed][Not invited]
     
    We reanalyzed long-term field data of CO2 flux, including net ecosystem CO2 exchange (NEE), ecosystem respiration (RE), and soil CO2 efflux (RS) to examine their seasonal and interannual variations for three conditions of disturbance (almost undrained peat swamp forest (PSF), drained PSF, and drained burnt ex- PSF) in a tropical peat area in Central Kalimantan, Indonesia. In addition, we simulated the CO2 flux on a monthly basis using empirical equations shown by our previous studies under four scenarios of seasonal variations in groundwater levels (GWL). The GWL has a large interannual variation in October and November. The rainy season usually begins in October, but the onset is delayed until November in El Niño years, making the interannual variation in CO2 fluxes the largest in these 2 months owing to the large GWL variations. On an annual basis, minimum monthly-mean GWL explained 82 % of interannual variations in NEE for the two PSFs. The linearity suggests that 10-cm drawdown of minimum monthly-mean GWL increases NEE or net ecosystem CO2 emission by 48.5 gC m-2 year-1 from PSF, independently of drainage degree. It can be said that minimum monthly-mean GWL is a practical measure to assess annual NEE of PSF.
  • Kentaro Takagi, Ryuichi Hirata, Reiko Ide, Masahito Ueyama, Kazuhito Ichii, Nobuko Saigusa, Takashi Hirano, Jun Asanuma, Sheng-Gong Li, Takashi Machimura, Yuichiro Nakai, Takeshi Ohta, Yoshiyuki Takahashi
    SOIL SCIENCE AND PLANT NUTRITION 61 (1) 61 - 75 0038-0768 2015/01 [Refereed][Not invited]
     
    Larch (Larix spp.) forests are predominantly distributed across high latitudes of Eurasia. They potentially have a strong influence on the terrestrial carbon and energy cycles, because of their vast area and the large carbon stocks in their peat soils in the permafrost. In this study, we elucidated intersite variation of ecosystem photosynthetic and respiratory parameters of eight larch forests in East Asia using the CarboEastAsia carbon flux and micrometeorology dataset. These parameters were determined using the empirical relationship between the carbon fluxes (photosynthesis and respiration) and micrometeorological variables (light and temperature). In addition, we examined leaf area index (LAI) determined by Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data to explain the intersite variation. Linear or exponential relationships with annual mean temperature or seasonal maximum LAI at the study sites were found for the annual carbon fluxes (gross primary production [GPP] and total ecosystem respiration [RE]) as well as for four of the five seasonal maximum values of determined photosynthetic and respiratory parameters (maximum GPP at light saturation, initial slope of the light-response curve, daytime respiration, and RE at the reference temperature of 10 degrees C). Phenological indices, such as start day of the growing season, growing season length and growing season degree days explained much of the intersite variation of GPP and RE of the studied larch forests; however, the relationship between MODIS LAI and photosynthetic or respiratory parameters implies that the intersite variation in GPP and RE was caused not only by the temperature variation (abiotic factor), but also by the variation in the photosynthetic and respiration activity by vegetation (biotic factor) through the change in leaf (or whole vegetation) biomass. Our analysis shows that MODIS LAI serves as a good index to explain the variation of the ecosystem photosynthetic and respiratory characteristics of East Asian larch forests.
  • K. Mallick, A. Jarvis, G. Wohlfahrt, G. Kiely, T. Hirano, A. Miyata, S. Yamamoto, L. Hoffmann
    BIOGEOSCIENCES 12 (2) 433 - 451 1726-4170 2015 [Refereed][Not invited]
     
    This paper introduces a relatively simple method for recovering global fields of monthly midday (13: 30 LT) near-surface net available energy (the sum of the sensible and latent heat flux or the difference between the net radiation and surface heat accumulation) using satellite visible and infrared products derived from the AIRS (Atmospheric Infrared Sounder) and MODIS (MODerate Resolution Imaging Spectroradiometer) platforms. The method focuses on first specifying net surface radiation by considering its various shortwave and longwave components. This was then used in a surface energy balance equation in conjunction with satellite day-night surface temperature difference to derive 12 h discrete time estimates of surface system heat capacity and heat accumulation, leading directly to retrieval for surface net available energy. Both net radiation and net available energy estimates were evaluated against ground truth data taken from 30 terrestrial tower sites affiliated with the FLUXNET network covering 7 different biome classes. This revealed a relatively good agreement between the satellite and tower data, with a pooled root-mean-square deviation of 98 and 72Wm(-2) for monthly 13: 30 LT net radiation and net available energy, respectively, although both quantities were underestimated by approximately 25 and 10 %, respectively, relative to the tower observation. Analysis of the individual shortwave and longwave components of the net radiation revealed the downwelling shortwave radiation to be main source of this systematic underestimation.
  • Fiolenta Marpaung, Takashi Hirano
    JOURNAL OF AGRICULTURAL METEOROLOGY 70 (4) 223 - 232 0021-8588 2014/12 [Refereed][Not invited]
     
    Changes in cloud cover and atmospheric aerosol loading strongly affect the diffuse proportion of solar radiation (R-d/R-g). It has been reported that plant photosynthesis is more efficient under diffuse light conditions, but diffuse radiation (R-d) regimes in tropical peatland frequently subjected to large-scale fires are poorly described, and there are few or no site-based datasets to date. Therefore, we continuously measured R-d for more than three years at a burnt ex-forest on tropical peatland in Central Kalimantan, Indonesia. Daily R-d/R-g was significantly related to the clearness index (R-g/R-o) with a linear threshold model. The model parameters showed that R-d/R-g under a clear sky is larger in tropical peatland with a humid climate than in Australia. Using the model, long-term variation in R-d/R-g for more than 12 years was estimated from R-g measured above a nearby forest. As a result, R-d/R-g showed a seasonal variation with its minimum of 0.51 in June (the transition between the wet and dry seasons) and its maximum of 0.68 in October (the late dry season) on a monthly basis. The decreasing pattern from the late wet season to the early dry season corresponded to decreasing precipitation due to fewer clouds. In contrast, the increasing pattern through the latter half of the dry season was due to shading by smoke emitted through burning biomass and peat fires. In particular, during the El Nino droughts in 2002, 2006 and 2009, the monthly mean R-d/R-g rose above 0.72, because the ground was densely covered with smoke from large-scale fires.
  • Mi Zhang, Xuhui Lee, Guirui Yu, Shijie Han, Huimin Wang, Junhua Yan, Yiping Zhang, Yide Li, Takeshi Ohta, Takashi Hirano, Joon Kim, Natsuko Yoshifuji, Wei Wang
    ENVIRONMENTAL RESEARCH LETTERS 9 (3) doi.10.1088/1748-9326/9/303400  1748-9326 2014/03 [Refereed][Not invited]
     
    Climate models simulating continental scale deforestation suggest a warming effect of land clearing on the surface air temperature in the tropical zone and a cooling effect in the boreal zone due to different control of biogeochemical and biophysical processes. Ongoing land-use/cover changes mostly occur at local scales (hectares), and it is not clear whether the local-scale deforestation will generate temperature patterns consistent with the climate model results. Here we paired 40 and 12 flux sites with nearby weather stations in North and South America and in Eastern Asia, respectively, and quantified the temperature difference between these paired sites. Our goal was to investigate the response of the surface air temperature to local-scale (hectares) land clearing across latitudes using the surface weather stations as proxies for localized land clearing. The results show that north of 10 degrees N, the annual mean temperature difference (open land minus forest) decreases with increasing latitude, but the temperature difference shrinks with latitude at a faster rate in the Americas [-0.079 (+/- 0.010) degrees C per degree] than in Asia [-0.046 (+/- 0.011) degrees C per degree]. Regression of the combined data suggests a transitional latitude of about 35.5 degrees N that demarks deforestation warming to the south and cooling to the north. The warming in latitudes south of 35 degrees N is associated with increase in the daily maximum temperature, with little change in the daily minimum temperature while the reverse is true in the boreal latitudes.
  • Junbang Wang, Jingwei Dong, Jiyuan Liu, Mei Huang, Guicai Li, Steven W. Running, W. Kolby Smith, Warwick Harris, Nobuko Saigusa, Hiroaki Kondo, Yunfen Liu, Takashi Hirano, Xiangming Xiao
    REMOTE SENSING 6 (3) 2108 - 2133 2072-4292 2014/03 [Refereed][Not invited]
     
    Gross primary production (GPP) plays an important role in the net ecosystem exchange of CO2 between the atmosphere and terrestrial ecosystems. It is particularly important to monitor GPP in Southeast Asia because of increasing rates of tropical forest degradation and deforestation in the region in recent decades. The newly available, improved, third generation Normalized Difference Vegetation Index (NDVI3g) from the Global Inventory Modelling and Mapping Studies (GIMMS) group provides a long temporal dataset, from July 1981 to December 2011, for terrestrial carbon cycle and climate response research. However, GIMMS NDVI3g-based GPP estimates are not yet available. We applied the GLOPEM-CEVSA model, which integrates an ecosystem process model and a production efficiency model, to estimate GPP in Southeast Asia based on three independent results of the fraction of photosynthetically active radiation absorbed by vegetation (FPAR) from GIMMS NDVI3g (GPP(NDVI3g)), GIMMS NDVI1g (GPP(NDVI1g)), and the Moderate Resolution Imaging Spectroradiometer (MODIS) MOD15A2 FPAR product (GPP(MOD15)). The GPP results were validated using ground data from eddy flux towers located in different forest biomes, and comparisons were made among the three GPPs as well as the MOD17A2 GPP products (GPP(MOD17)). Based on validation with flux tower derived GPP estimates the results show that GPP(NDVI3g) is more accurate than GPP(NDVI1g) and is comparable in accuracy with GPP(MOD15). In addition, GPP(NDVI3g) and GPP(MOD15) have good spatial-temporal consistency. Our results indicate that GIMMS NDVI3g is an effective dataset for regional GPP simulation in Southeast Asia, capable of accurately tracking the variation and trends in long-term terrestrial ecosystem GPP dynamics.
  • Ayaka Sakabe, Masahito Ueyama, Yoshiko Kosugi, Ken Hamotani, Takashi Hirano, Ryuichi Hirata
    JOURNAL OF ATMOSPHERIC CHEMISTRY 71 (1) 79 - 94 0167-7764 2014/03 [Refereed][Not invited]
     
    The relaxed eddy accumulation (REA) method is an attractive alternative to the eddy covariance method to measure trace-gas flux, because it allows the use of analyzers with an optimal integration time to reduce the noise. However, the use of an empirical coefficient b results in uncertainties in the REA method. The consistency of b for temperature was investigated using a 1 year dataset obtained at three forest sites in East Asia: a temperate evergreen coniferous forest, a tropical evergreen broadleaf forest, and a cool-temperate deciduous coniferous forest. The observational b ranged from 0.54 to 0.57 under unstable conditions. Although the values for observational b were within narrow ranges among the sites, there were slight site-specific differences. We introduced new expression of b, similarity b, based on scalar similarity using the integral turbulence characteristics to investigate the nature of b. Both the observational and similarity b increased with increasing atmospheric stability under stable conditions, when lower values for the standard deviation of the vertical wind velocity resulted in higher values for b. The variations in b under stable conditions differed among sites. There were no seasonal variations in the observational b at all sites. Consequently, the present study recommends determining the coefficient b for unstable conditions for each site and considering changes in b associated with atmospheric stability in order to minimize errors in the REA method.
  • Takashi Hirano, Kitso Kusin, Suwido Limin, Mitsuru Osaki
    GLOBAL CHANGE BIOLOGY 20 (2) 555 - 565 1354-1013 2014/02 [Refereed][Not invited]
     
    In Southeast Asia, a huge amount of peat has accumulated under swamp forests over millennia. Fires have been widely used for land clearing after timber extraction, thus land conversion and land management with logging and drainage are strongly associated with fire activity. During recent El Nino years, tropical peatlands have been severely fire-affected and peatland fires enlarged. To investigate the impact of peat fires on the regional and global carbon balances, it is crucial to assess not only direct carbon emissions through peat combustion but also oxidative peat decomposition after fires. However, there is little information on the carbon dynamics of tropical peat damaged by fires. Therefore, we continuously measured soil CO2 efflux [peat respiration (RP)] through oxidative peat decomposition using six automated chambers on a burnt peat area, from which about 0.7m of the upper peat had been lost during two fires, in Central Kalimantan, Indonesia. The RP showed a clear seasonal variation with higher values in the dry season. The RP increased logarithmically as groundwater level (GWL) lowered. Temperature sensitivity or Q(10) of RP decreased as GWL lowered, mainly because the vertical distribution of RP would shift downward with the expansion of an unsaturated soil zone. Although soil temperature at the burnt open area was higher than that in a near peat swamp forest, model simulation suggests that the effect of temperature rise on RP is small. Annual gap-filled RP was 382 +/- 82 (the mean +/- 1 SD of six chambers) and 362 +/- 74gCm(-2)yr(-1) during 2004-2005 and during 2005-2006years, respectively. Simulated RP showed a significant negative relationship with GWL on an annual basis, which suggests that every GWL lowering by 0.1m causes additional RP of 89gCm(-2)yr(-1). The RP accounted for 21-24% of ecosystem respiration on an annual basis.
  • M. Mezbahuddin, R. F. Grant, T. Hirano
    BIOGEOSCIENCES 11 (3) 577 - 599 1726-4170 2014 [Refereed][Not invited]
     
    Seasonal variation in water table depth (WTD) determines the balance between aggradation and degradation of tropical peatlands. Longer dry seasons together with human interventions (e. g. drainage) can cause WTD drawdowns making tropical peatland C storage highly vulnerable. Better predictive capacity for effects of WTD on net CO2 exchange is thus essential to guide conservation of tropical peat deposits. Mathematical modelling of basic eco-hydrological processes under site- specific conditions can provide such predictive capacity. We hereby deploy a process- based mathematical model ecosys to study effects of seasonal variation in WTD on net ecosystem productivity (NEP) of a drainage affected tropical peat swamp forest at Palangkaraya, Indonesia. Simulated NEP suggested that the peatland was a C source (NEP similar to -2 gCm(-2) d(-1), where a negative sign represents a C source and a positive sign a C sink) during rainy seasons with shallow WTD, C neutral or a small sink (NEP similar to + 1 gCm(-2) d(-1)) during early dry seasons with intermediate WTD and a substantial C source (NEP similar to - 4 gCm(-2) d(-1)) during late dry seasons with deep WTD from 2002 to 2005. These values were corroborated by regressions (P < 0.0001) of hourly modelled vs. eddy covariance (EC) net ecosystem CO2 fluxes which yielded R-2 > 0.8, intercepts approaching 0 and slopes approaching 1. We also simulated a gradual increase in annual NEP from 2002 (-609 gCm(-2)) to 2005 (-373 gCm(-2)) with decreasing WTD which was attributed to declines in duration and intensity of dry seasons following the El Nino event of 2002. This increase in modelled NEP was corroborated by ECgap filled annual NEP estimates. Our modelling hypotheses suggested that (1) poor aeration in wet soils during shallow WTD caused slow nutrient (predominantly phosphorus) min-eralization and consequent slow plant nutrient uptake that suppressed gross primary productivity (GPP) and hence NEP (2) better soil aeration during intermediate WTD enhanced nutrient mineralization and hence plant nutrient uptake, GPP and NEP and (3) deep WTD suppressed NEP through a combination of reduced GPP due to plant water stress and increased ecosystem respiration (R-e) from enhanced deeper peat aeration. These WTD effects on NEP were modelled from basic eco-hydrological processes including microbial and root oxidation- reduction reactions driven by soil and root O-2 transport and uptake which in turn drove soil and plant carbon, nitrogen and phosphorus transformations within a soil- plant- atmosphere water transfer scheme driven by water potential gradients. Including these processes in ecosystem models should therefore provide an improved predictive capacity for WTD management programs intended to reduce tropical peat degradation.
  • K. Mallick, A. Jarvis, G. Wohlfahrt, G. Kiely, T. Hirano, A. Miyata, S. Yamamoto, L. Hoffmann
    BIOGEOSCIENCES 11 (24) 7369 - 7382 1726-4170 2014 [Refereed][Not invited]
     
    This paper introduces a relatively simple method for recovering global fields of latent heat flux. The method focuses on specifying Bowen ratio estimates through exploiting air temperature and vapour pressure measurements obtained from infrared soundings of the AIRS (Atmospheric Infrared Sounder) sensor onboard NASA's Aqua platform. Through combining these Bowen ratio retrievals with satellite surface net available energy data, we have specified estimates of global noontime surface latent heat flux at the 1 degrees x 1 degrees scale. These estimates were provisionally evaluated against data from 30 terrestrial tower flux sites covering a broad spectrum of biomes. Taking monthly average 13: 30 data for 2003, this revealed promising agreement between the satellite and tower measurements of latent heat flux, with a pooled root-mean-square deviation of 79Wm(-2), and no significant bias. However, this success partly arose as a product of the underspecification of the AIRS Bowen ratio compensating for the underspecification of the AIRS net available energy, suggesting further refinement of the approach is required. The error analysis suggested that the landscape level variability in enhanced vegetation index (EVI) and land surface temperature contributed significantly to the statistical metric of the predicted latent heat fluxes.
  • R. Hirata, K. Takagi, A. Ito, T. Hirano, N. Saigusa
    BIOGEOSCIENCES 11 (18) 5139 - 5154 1726-4170 2014 [Refereed][Not invited]
     
    We evaluated the long-term (52-year) effect of climate, disturbance, and subsequent recovery on the carbon balance of cool temperate forests by using the process-based ecosystem model VISIT. The study sites were artificial larch forests planted after clear-cutting of mixed forest in Hokkaido, Japan. The model was validated, scenarios were computed, and a sensitivity analysis was performed. First, we performed a baseline simulation of carbon dynamics and compared these values with those observed across a wide range of stand ages (old mixed forest and young and middle-aged larch forests). Second, we ran scenarios to investigate how disturbance and several climate factors affect long-term carbon fluxes. Third, we analyzed the sensitivity of carbon balance to the amount of disturbance-generated tree biomass residues. By taking into account seasonal variation in the understory leaf area index, which played an important role, especially in the initial stage of recovery, the simulated net ecosystem production (NEP), gross primary production, ecosystem respiration, and biomass for the three types of forest were consistent with observed values (mean +/- SD of R-2 of monthly NEP, GPP and RE for the three types of forest were 0.63 +/- 0.26, 0.93 +/- 0.07, 0.94 +/- 0.2, respectively). The effect of disturbances such as clear-cutting, land-use conversion, and thinning on the long-term trend of NEP was larger than that of climate variation, even 50 years after clear-cutting. In contrast, interannual variation in the carbon balance was primarily driven by climate variation. These findings indicate that disturbance controlled the long-term trend of the carbon balance, whereas climate factors controlled yearly variation in the carbon balance. Among the meteorological factors considered, temperature and precipitation were the main ones that affected NEP and its interannual variation. The carbon balance in the initial post-disturbance period, which is strongly affected by the amount of residues, influenced the subsequent long-term carbon budget, implying the importance of residue management. Consequently, carbon release just after disturbance and the length of the recovery period required to balance the carbon budget are controlled by the amount of residues.
  • Zhi Chen, Guirui Yu, Jianping Ge, Xiaomin Sun, Takashi Hirano, Nobuko Saigusa, Qiufeng Wang, Xianjin Zhu, Yiping Zhang, Junhui Zhang, Junhua Yan, Huimin Wang, Liang Zhao, Yanfen Wang, Peili Shi, Fenghua Zhao
    AGRICULTURAL AND FOREST METEOROLOGY 182 266 - 276 0168-1923 2013/12 [Refereed][Not invited]
     
    Carbon exchange between terrestrial ecosystems and the atmosphere is one of the most important processes in the global carbon cycle. Understanding the spatial variation and controlling factors of carbon exchange fluxes is helpful for accurately predicting and evaluating the global carbon budget. In this study, we quantified the carbon exchange fluxes of different terrestrial ecosystems in the Asian region, and analyzed their spatial variation and controlling factors based on long-term observation data from ChinaFLUX (19 sites) and published data from AsiaFlux (37 sites) and 32 other sites in Asia. The results indicated that the majority of Asian terrestrial ecosystems are currently large carbon sinks. The average net ecosystem production (NEP) values were 325+/-187, 274+/-207, 236+/-260, 89+/-134g C m(-2) yr(-1) in cropland, forest, wetland and grassland ecosystems, respectively. The spatial variation of gross primary production (GPP) and ecosystem respiration (Re) were mainly controlled by the mean annual temperature (MAT) and the mean annual precipitation (MAP) in the Asian region. There was a clear linear relationship between GPP and MAT, and a strong sigmoid relationship between GPP and MAP. Re was exponentially related to MAT and linearly related to MAP. Interestingly, those response modes were consistent across different ecosystem types. The different responses of GPP and Re to MAT and MAP determined the spatial variation of NEP. The combined effects of MAT and MAP contributed 85%, 81% and 36% to the spatial variations of GPP, Re and NEP, respectively. Our findings confirmed that the spatial variation of carbon exchange fluxes was mainly controlled by climatic factors, which further strongly supports the use of the climate-driven theory in the Asian region. (C) 2013 Elsevier B.V. All rights reserved.
  • カラマツ林の蒸発散とエネルギー収支
    鈴木啓司, 平田竜一, 平野高司
    北海道の農業気象 65 32 - 41 2013/10 [Refereed][Not invited]
  • 植生遷移が進む森林跡地のCO2フラックスに与える環境要因の影響
    東健太, 平野高司, 寺本宗正, 梁乃申
    北海道の農業気象 65 23 - 31 2013/10 [Refereed][Not invited]
  • Ma Carmelita R. Alberto, Roland J. Buresh, Takashi Hirano, Akira Miyata, Reiner Wassmann, James R. Quilty, Teodoro Q. Correa, Joseph Sandro
    FIELD CROPS RESEARCH 146 51 - 65 0378-4290 2013/05 [Refereed][Not invited]
     
    A growing scarcity of irrigation water could progressively lead to changes in rice production to systems using less irrigation water for rice or more crop diversification. A shift from current production of rice on flooded soils to production of rice on non-flooded soil with water-saving irrigation or to production of more water-efficient crops will have profound effects on carbon, water, and energy exchanges. This study used the eddy covariance technique to examine C uptake and water use efficiencies for water-saving, dry-seeded rice production and production of hybrid maize under overhead sprinkler irrigation as an alternative to flooded rice during two growing seasons. Maize with its C-4 physiology has greater photosynthetic capacity than rice. In 2011, maize had 1.4 times higher net C uptake than rice and twice as much grain yield as rice (10.4 vs 5.3 Mg ha(-1)). In 2012, lower solar radiation due to increased cloudiness and heavy rainfall during critical growth stages (late vegetative to early reproductive) decreased LAI and resulted to about 20% less net C uptake and maize yield (8.2 Mg ha(-1)), but the rice yield was unchanged (5.3 Mg ha(-1)) presumably because of improved crop management which included effective crop establishment at lower seed rate and efficient N application using fertigation. Canopy light use efficiency, crop water productivity (WPET), and photosynthetic water use efficiency were 1.8, 1.9, and 1.6 times higher for maize than rice, respectively, despite sensitivity of maize to excess water. Net C uptake, evapotranspiration, and WPET of dry-seeded rice under overhead sprinkler irrigation were comparable to those reported elsewhere for flooded rice. Average total water input (irrigation + rainfall) for rice was only 908 mm, as compared to 1300-1500 mm reported in literature for typical puddled transplanted rice. (C) 2013 Elsevier B.V. All rights reserved.
  • Nobuko Saigusa, Sheng-Gong Li, Hyojung Kwon, Kentaro Takagi, Lei-Ming Zhang, Reiko Ide, Masahito Ueyama, Jun Asanuma, Young-Jean Choi, Jung Hwa Chun, Shi-Jie Han, Takashi Hirano, Ryuichi Hirata, Minseok Kang, Tomomichi Kato, Joon Kim, Ying-Nian Li, Takahisa Maeda, Akira Miyata, Yasuko Mizoguchi, Shohei Murayama, Yuichiro Nakai, Takeshi Ohta, Taku M. Saitoh, Hui-Ming Wang, Gui-Rui Yu, Yi-Ping Zhang, Feng-Hua Zhao
    JOURNAL OF FOREST RESEARCH 18 (1) 41 - 48 1341-6979 2013/02 [Refereed][Not invited]
     
    The datasets of net ecosystem CO2 exchange (NEE) were acquired from 21 forests, 3 grasslands, and 3 croplands in the eastern part of Asia based on the eddy covariance measurements of the international joint program, CarboEastAsia. The program was conducted by three networks in Asia, ChinaFLUX, JapanFlux, and KoFlux, to quantify, synthesize, and understand the carbon budget of the eastern part of Asia. An intercomparison was conducted for NEE estimated by three gap-filling procedures adopted by ChinaFLUX, JapanFlux, and KoFlux to test the range of uncertainty in the estimation of NEE. The overall comparison indicated good agreement among the procedures in the seasonal patterns of NEE, although a bias was observed in dormant seasons depending on the different criteria of data screening. Based on the gap-filled datasets, the magnitude and seasonality of the carbon budget were compared among various biome types, phenology, and stress conditions throughout Asia. The annual values of gross primary production and ecosystem respiration were almost proportional to the annual air temperature. Forest management, including clear-cutting, plantation, and artificial drainage, was significant and obviously affected the annual carbon uptake within the forests. Agricultural management resulted in notable seasonal patterns in the crop sites. The dataset obtained from a variety of biome types would be an essential source of knowledge for ecosystem science as well as a valuable validation dataset for modeling and remote sensing to upscale the carbon budget estimations in Asia.
  • Kazuhito Ichii, Masayuki Kondo, Young-Hee Lee, Shao-Qiang Wang, Joon Kim, Masahito Ueyama, Hee-Jeong Lim, Hao Shi, Takashi Suzuki, Akihiko Ito, Hyojung Kwon, Weimin Ju, Mei Huang, Takahiro Sasai, Jun Asanuma, Shijie Han, Takashi Hirano, Ryuichi Hirata, Tomomichi Kato, Sheng-Gong Li, Ying-Nian Li, Takahisa Maeda, Akira Miyata, Yojiro Matsuura, Shohei Murayama, Yuichiro Nakai, Takeshi Ohta, Taku M. Saitoh, Nobuko Saigusa, Kentaro Takagi, Yan-Hong Tang, Hui-Min Wang, Gui-Rui Yu, Yi-Ping Zhang, Feng-Hua Zhao
    JOURNAL OF FOREST RESEARCH 18 (1) 13 - 20 1341-6979 2013/02 [Refereed][Not invited]
     
    Based on the model-data comparison at the eddy-covariance observation sites from CarboEastAsia datasets, we report the current status of the terrestrial carbon cycle modeling in monsoon Asia. In order to assess the modeling performance and discuss future requirements for both modeling and observation efforts in Asia, we ran eight terrestrial biosphere models at 24 sites from 1901 to 2010. By analyzing the modeled carbon fluxes against the CarboEastAsia datasets, the strengths and weaknesses of terrestrial biosphere modeling over Asia were evaluated. In terms of pattern and magnitude, the carbon fluxes (i.e., gross primary productivity, ecosystem respiration, and net ecosystem exchange) at the temperate and boreal forest sites were simulated best, whereas the simulation results from the tropical forest, cropland, and disturbed sites were poor. The multi-model ensemble mean values showed lower root mean square errors and higher correlations, suggesting that composition of multiple terrestrial biosphere models would be preferable for terrestrial carbon budget assessments in Asia. These results indicate that the current model-based estimation of terrestrial carbon budget has large uncertainties, and future research should further refine the models to permit re-evaluation of the terrestrial carbon budget.
  • Jing Chen, Baozhang Chen, T. Andrew Black, John L. Innes, Guangyu Wang, Gerard Kiely, Takashi Hirano, Georg Wohlfahrt
    Journal of Geophysical Research: Biogeosciences 118 (4) 1715 - 1731 2169-8961 2013 [Refereed][Not invited]
     
    The mass transfer (MT) equation and the Penman-Monteith (PM) equation are two common approaches used in various land surface models for simulating evapotranspiration (ET). Yet assessments are rarely conducted to determine how well these structurally differing equations simulate ET across various biomes and climatic environments with different canopy upscaling strategies. We evaluated the capacity of models to estimate ET using the MT equation with the one-leaf strategy in the Community Land Model version 4 and the PM equation in the Dynamic Land Model using the one-leaf and two-leaf upscaling approaches for 22 selected eddy covariance flux towers representing 10 typical plant functional types. Overall, across half-hourly, daily, monthly, and seasonal scales, the MT equation performed less robust than the PM equation in forests. The former had 8-15% higher root-mean-square error and 1-4% lower index of agreement and a large uncertainty in warm and wet seasons for several sites. It leaves a doubt about its application of estimating ET across regional to global scales. Considering the net radiation available on the surface of leaf/soil and adopting the two-leaf approach made the PM equation closer to the EC measurements on average but still could not capture the variation during the cold season. We suggest that further improvements in simulation of ET require seasonal variation of some key parameters and quantification of spatial heterogeneity. Key Points The MT equation performs less robust than the PM equation in LSMs ET estimated by the MT equation has a large uncertainty in warm and wet seasons ET estimated by the PM equation is closer to the EC measurements on average ©2013. American Geophysical Union. All Rights Reserved.
  • Takashi Hirano, Hendrik Segah, Kitso Kusin, Suwido Limin, Hidenori Takahashi, Mitsuru Osaki
    GLOBAL CHANGE BIOLOGY 18 (11) 3410 - 3422 1354-1013 2012/11 [Refereed][Not invited]
     
    Tropical peatlands have accumulated huge soil carbon over millennia. However, the carbon pool is presently disturbed on a large scale by land development and management, and consequently has become vulnerable. Peat degradation occurs most rapidly and massively in Indonesia, because of fires, drainage, and deforestation of swamp forests coexisting with tropical peat. Peat burning releases carbon dioxide (CO2) intensively but occasionally, whereas drainage increases CO2 emission steadily through the acceleration of aerobic peat decomposition. Therefore, tropical peatlands present the threat of switching from a carbon sink to a carbon source to the atmosphere. However, the ecosystem-scale carbon exchange is still not known in tropical peatlands. A long-term field experiment in Central Kalimantan, Indonesia showed that tropical peat ecosystems, including a relatively intact peat swamp forest with little drainage (UF), a drained swamp forest (DF), and a drained burnt swamp forest (DB), functioned as net carbon sources. Mean annual net ecosystem CO2 exchange (NEE) (+/- a standard deviation) for 4 similar to years from July 2004 to July 2008 was 174 +/- 203, 328 +/- 204 and 499 +/- 72 similar to gC similar to m-2 similar to yr-1, respectively, for the UF, DF, and DB sites. The carbon emissions increased according to disturbance degrees. We found that the carbon balance of each ecosystem was chiefly controlled by groundwater level (GWL). The NEE showed a linear relationship with GWL on an annual basis. The relationships suggest that annual CO2 emissions increase by 79-238 C-g m(-2) every 0.1m of GWL lowering probably because of the enhancement of oxidative peat decomposition. In addition, CO2 uptake by vegetation photosynthesis was reduced by shading due to dense smoke from peat fires ignited accidentally or for agricultural practices. Our results may indicate that tropical peatland ecosystems are no longer a carbon sink under the pressure of human activities.
  • Tomohito Sano, Takashi Hirano, Tomomi Takeda, Yasumi Fujinuma
    Journal of Agricultural Meteorology 68 (1) 35 - 43 1881-0136 2012/09/01 [Refereed][Not invited]
     
    Leaf area index (LAI) is an important parameter used to characterize the canopy structure of forest ecosystems. Disturbances such as thinning change the canopy structure and influence various ecosystem functions. A larch plantation in Hokkaido, Japan was thinned during the winter of 2003-2004, decreasing its basal area density by 23% from 29.7 to 22.8 m2 ha-1. To evaluate the LAI change caused by the thinning, we measured LAI in 2003 and 2004 using a direct method with litter collection (LC) and two indirect methods using a plant canopy analyzer (PCA) and a ground-based laser scanner (LS), although a September 2004 typhoon disaster halted LC measurements. In 2003, the annual maximum LAI measured via the LC (LAILC) was 5.6 m2 m-2, of which the LAILC of broadleaf trees accounted for about half. Using rings 1-5 of five sky sectors, the annual maximum LAI indicated by the PCA (LAIPCA) was 3.4 m2 m-2, demonstrating that the PCA underestimated LAI. However, using rings 1-4 and 1-3, LAIPCA increased to 4.4 and 4.8 m2 m-2,respectively. This result shows that eliminating the outer rings of the PCA improves LAI underestimation because some scattering light reflected by leaves engenders underestimation of LAIPCA when the zenith angle is large. The maximum LAI by the LS (LAILS) was equal to LAILC. However, the LS greatly overestimated LAI in the leaf-fall and leafless seasons. The laser beam is thought to have increased in diameter with distance and consequently underestimated the gap fraction. Maximum LAIPCA and LAILS after thinning were each half of that before thinning. The rates of decrease were greater than the basal area density, which is linearly related with LAI, because canopy inhomogeneity is expected to cause LAI underestimation after thinning. LAI probably decreased to about 4.6 m2 m-2, assuming that the ratio of LAI to basal area remained constant despite thinning. © 2012, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Siti Sundari, Takashi Hirano, Hiroyuki Yamada, Kitso Kusin, Suwido Limin
    Journal of Agricultural Meteorology 68 (2) 121 - 134 1881-0136 2012/09/01 [Refereed][Not invited]
     
    Tropical peatlands store soil carbon constituting up to 15-19% of global peat carbon. That huge carbon pool is presently being disturbed on a large scale by land development and management, and has consequently become vulnerable. Peat degradation occurs most rapidly and massively in Indonesia fs peatlands because of fires, drainage and deforestation of swamp forests. Peat burning releases carbon dioxide (CO2) intensively but occasionally, whereas drainage increases CO2 emissions steadily through accelerated aerobic peat decomposition. Under such circumstances, tropical peatlands might become a huge source of carbon emissions to the atmosphere. Nevertheless, the effects of drainage on the carbon balance of tropical peatland ecosystems are not well understood more field data must be accumulated. Therefore, we measured soil respiration (RS), which is a major source of CO2 efflux, continuously for more than one year using automated chamber systems, with consideration of microtopography, at two sites in Central Kalimantan, Indonesia: undrained and drained peat swamp forests. The RS was determined mainly by local hydrology. In the undrained forest, RS decreased sharply under flooded conditions because of anoxia. In contrast, in the drained forest, with its lower groundwater level (GWL), RS showed a quadratic relationship with GWL and gradually increased as GWL decreased when GWL was lower than about -0.8 m, which was caused chiefly by the enhancement of peat decomposition. These relationships indicate that lowering GWL by drainage increased RS, whereas annual RS was larger in the undrained forest (1347 gC m-2 y-1) than in the drained forest (1225 gC m-2 y-1) in 2005. The difference in annual RS was probably attributable to higher forest productivity in the undrained forest. © 2012, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Ma Carmelita R. Alberto, Takashi Hirano, Akira Miyata, Reiner Wassmann, Arvind Kumar, Agnes Padre, Modesto Amante
    FIELD CROPS RESEARCH 134 80 - 94 0378-4290 2012/08 [Refereed][Not invited]
     
    Seasonal rainfall in the Philippines is known to be modulated by ENSO phenomenon, with El Nino frequently contributing to reduced rainfall and drought while La Nina resulting in excessive rainfalls, floods and more intense typhoons. The alterations in rainfall patterns can have considerable feedback on solar radiation, air temperature, and soil moisture which can affect the ecosystem CO2 exchange. In this paper, we assessed the effects of the ENSO events (2008-mid 2010) on the seasonal climate conditions and determined how it affected the gross primary production (GPP), ecosystem respiration (Re), and net ecosystem production (NEP) of two contrasting rice environments: flooded and non-flooded. The 2008 dry season (DS) was under a La Nina event while the 2008 wet season (WS) was a neutral one with strong tropical cyclones associated during the wet season. The 2009DS was also La Nina while the 2009WS was El Nino; however, the northern part of the Philippines experienced strong tropical cyclones. The 2010DS was under an El Nino event. The La Nina in 2008DS resulted in about 15% lower solar radiation (SR), 0.3 degrees C lower air temperature (T-a) and 60% higher precipitation compared to the 28-year climate normal patterns. Both flooded and non-flooded rice fields had lower NEP in 2008 DS (164 and 14 gC m(-2), respectively) than in 2008 WS (295 and 82 gC m(-2), respectively) because the climate anomaly resulted in SR - driven decrease in GPP. The La Nina in 2009DS even resulted in 0.2 degrees C lower air temperature and 40% more precipitation than the 2008DS La Nina. This cooler temperature resulted in lower Re in flooded rice fields while the higher precipitation resulted in higher GPP in non-flooded fields since the climate was favorable for the growth of the aerobic rice, the ratoon crops and the weeds. This climate anomaly benefitted both flooded and non-flooded rice fields by increasing NEP (351 and 218 gC m(-2), respectively). However, NEP decreased in 2009WS in both flooded and non-flooded rice fields (225 and 39 gC m(-2), respectively) due to the devastating effects of the strong tropical cyclones that hit the northern part of the Philippines. On the other hand, the El Nino event during 2010DS resulted in about 6% higher solar radiation, 0.4 degrees C higher air temperature and 67% lower precipitation than the 28-year climate normal pattern. The NEP of flooded and non-flooded rice fields were closely similar at 187 and 174 gC m(-2), respectively. This climate anomaly resulted in T-a - driven increase in Re, as well as vapor pressure deficit (VPD) - driven decrease in GPP in flooded rice fields. The GPP and Re in non-flooded rice fields were less sensitive to higher VPD and higher T-a, respectively. It appears that the net ecosystem CO2 exchange in non-flooded rice field was less sensitive to an El Nino event. (C) 2012 Elsevier B.V. All rights reserved.
  • Shuli Niu, Yiqi Luo, Shenfeng Fei, Wenping Yuan, David Schimel, Beverly E. Law, Christof Ammann, M. Altaf Arain, Almut Arneth, Marc Aubinet, Alan Barr, Jason Beringer, Christian Bernhofer, T. Andrew Black, Nina Buchmann, Alessandro Cescatti, Jiquan Chen, Kenneth J. Davis, Ebba Dellwik, Ankur R. Desai, Sophia Etzold, Louis Francois, Damiano Gianelle, Bert Gielen, Allen Goldstein, Margriet Groenendijk, Lianhong Gu, Niall Hanan, Carole Helfter, Takashi Hirano, David Y. Hollinger, Mike B. Jones, Gerard Kiely, Thomas E. Kolb, Werner L. Kutsch, Peter Lafleur, David M. Lawrence, Linghao Li, Anders Lindroth, Marcy Litvak, Denis Loustau, Magnus Lund, Michal Marek, Timothy A. Martin, Giorgio Matteucci, Mirco Migliavacca, Leonardo Montagnani, Eddy Moors, J. William Munger, Asko Noormets, Walter Oechel, Janusz Olejnik, Kyaw Tha Paw U, Kim Pilegaard, Serge Rambal, Antonio Raschi, Russell L. Scott, Guenther Seufert, Donatella Spano, Paul Stoy, Mark A. Sutton, Andrej Varlagin, Timo Vesala, Ensheng Weng, Georg Wohlfahrt, Bai Yang, Zhongda Zhang, Xuhui Zhou
    NEW PHYTOLOGIST 194 (3) 775 - 783 0028-646X 2012/05 [Refereed][Not invited]
     
    It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystemclimate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.
  • Masahito Ueyama, Ryuichi Hirata, Masayoshi Mano, Ken Hamotani, Yoshinobu Harazono, Takashi Hirano, Akira Miyata, Kentaro Takagi, Yoshiyuki Takahashi
    TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY 64 http://dx.doi.org/10.3402/tell  0280-6509 2012 [Refereed][Not invited]
     
    Synthesis studies using multiple-site datasets for eddy covariance potentially contain uncertainties originating from the use of different flux calculation options, because the choice of the process for calculating half-hourly fluxes from raw time series data is left to individual researchers. In this study, we quantified the uncertainties associated with different flux calculation methods at seven sites. The differences in the half-hourly fluxes were small, generally of the order less than a few percentiles, but they were substantial for the annual fluxes. After the standardisation under current recommendations in the FLUXNET communities, we estimated the uncertainties in the annual fluxes associated with the flux calculations to be 2.6 +/- 2.7 W m(-2) (the mean 90% +/- confidence interval) for the sensible heat flux, 72 +/- 37 g C m(-2) yr(-1) for net ecosystem exchange (NEE), 12 +/- 6% for evapotranspiration, 12 +/- 6% for gross primary productivity and 16 +/- 10% for ecosystem respiration. The self-heating correction strongly influenced the annual carbon balance (143 +/- 93 g C m(-2) yr(-1)), not only for cold sites but also for warm sites, but did not fully account for differences between the open- and closed-path systems (413 +/- 189 g C m(-2) yr(-1)).
  • Geographical assessment of factors for Sasa expansion in the Sarobetsu Mire, Japan
    Takada M, Inoue T, Mishima Y, Fujita H, Hirano T, Fujimura Y
    Journal of Landscape Ecology 5 58 - 71 2012 [Refereed][Not invited]
  • Toshikazu Kizuka, Hiroyuki Yamada, Takashi Hirano
    Ecology and Civil Engineering 応用生態工学会 15 (1) 45 - 59 1882-5974 2012 [Refereed][Not invited]
     
    Water chemistry deterioration has become increasingly evident at mire pools with agricultural development occurring in pool catchment areas. Improvement of hydrochemical conditions is urgently necessary for the conservation of such mire pools' ecosystems. We investigated the hydrological and chemical budgets of Lake Miyajima-numa, a Ramsar Convention wetland, which is surrounded by paddy fields in Ishikari Peatland, northern Japan, during its ice-free period in 2007-2008. Surface water inflow and outflow via ditches dominate its hydrological budget, respectively constituting 88% of total input and 78% of total output. Similarly, chemical budgets including Ca2+, total nitrogen, and total phosphorus were dominated by ditch inflow and outflow Chemical constituents of the ditch inflow were derived from mineral-rich and nutrient-rich river water supplied to paddy fields as irrigation water. Therefore, the input fluxes of Ca2+, total nitrogen, and total phosphorus were much greater than those of a pristine mire pool. Increased input fluxes of chemical constituents induced by irrigation changed the hydrological and chemical budgets of mire pools, which degraded the water chemistry through eutrophication and other processes.
  • Akira Tani, Daisuke Tozaki, Motonori Okumura, Susumu Nozoe, Takashi Hirano
    ATMOSPHERIC ENVIRONMENT 45 (34) 6261 - 6266 1352-2310 2011/11 [Refereed][Not invited]
     
    Effect of drought on isoprene emission from 2 major Quercus species native to East Asia is investigated. Three individuals of Quercus serrata and 2 individuals of Quercus crispula continued to emit isoprene under moderate and severe drought conditions, although the emission rates were lower than under normal conditions. Diurnal variation in the isoprene emission rates was monitored in real-time when temperature and light intensity were changed stepwise to imitate natural conditions. Under normal and moderate drought conditions, isoprene emission showed hysteresis with regard to the environmental parameters, but generally followed the common G93 model. Under severe drought conditions, isoprene emission rates were not explained using given coefficients in the G93 model, probably due to a depletion of isoprene substrate. (C) 2011 Elsevier Ltd. All rights reserved.
  • Ma Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Ryusuke Hatano, Arvind Kumar, Agnes Padre, Modesto Amante
    AGRICULTURAL WATER MANAGEMENT 98 (9) 1417 - 1430 0378-3774 2011/07 [Refereed][Not invited]
     
    The seasonal and annual variability of sensible heat flux (H), latent heat flux (LE), evapotranspiration (ET), crop coefficient (K-c) and crop water productivity (WPET) were investigated under two different rice environments, flooded and aerobic soil conditions, using the eddy covariance (EC) technique during 2008-2009 cropping periods. Since we had only one EC system for monitoring two rice environments, we had to move the system from one location to the other every week. In total, we had to gap-fill an average of 50-60% of the missing weekly data as well as those values rejected by the quality control tests in each rice field in all four cropping seasons. Although the EC method provides a direct measurement of LE, which is the energy used for ET, we needed to correct the values of H and LE to close the energy balance using the Bowen ratio closure method before we used LE to estimate ET. On average, the energy balance closure before correction was 0.72 +/- 0.06 and it increased to 0.99 +/- 0.01 after correction. The Gin both flooded and aerobic fields was very low. Likewise, the energy involved in miscellaneous processes such as photosynthesis, respiration and heat storage in the rice canopy was not taken into consideration. Average for four cropping seasons, flooded rice fields had 19% more LE than aerobic fields whereas aerobic rice fields had 45% more H than flooded fields. This resulted in a lower Bowen ratio in flooded fields (0.14 +/- 0.03) than in aerobic fields (0.24 +/- 0.01). For our study sites, evapotranspiration was primarily controlled by net radiation. The aerobic rice fields had lower growing season ET rates (3.81 +/- 0.21 mm d(-1)) than the flooded rice fields (4.29 +/- 0.23 mm d(-1)), most probably due to the absence of ponded water and lower leaf area index of aerobic rice. Likewise, the crop coefficient, K-c, of aerobic rice was significantly lower than that of flooded rice. For aerobic rice, K-c values were 0.95 +/- 0.01 for the vegetative stage, 1.00 +/- 0.01 for the reproductive stage, 0.97 +/- 0.04 for the ripening stage and 0.88 +/- 0.03 for the fallow period, whereas, for flooded rice, K-c values were 1.04 +/- 0.04 for the vegetative stage, 1.11 +/- 0.05 for the reproductive stage, 1.04 +/- 0.05 for the ripening stage and 0.93 +/- 0.06 for the fallow period. The average annual ET was 1301 mm for aerobic rice and 1440 mm for flooded rice. This corresponds to about 11% lower total evapotranspiration in aerobic fields than in flooded fields. However, the crop water productivity (WPET) of aerobic rice (0.42 +/- 0.03 g grain kg(-1) water) was significantly lower than that of flooded rice (1.26 +/- 0.26 g grain kg(-1) water) because the grain yields of aerobic rice were very low since they were subjected to water stress. The results of this investigation showed significant differences in energy balance and evapotranspiration between flooded and aerobic rice ecosystems. Aerobic rice is one of the promising water-saving technologies being developed to lower the water requirements of the rice crop to address the issues of water scarcity. This information should be taken into consideration in evaluating alternative water-saving technologies for environmentally sustainable rice production systems. (C) 2011 Elsevier B.V. All rights reserved.
  • Toshikazu Kizuka, Hiroyuki Yamada, Takashi Hirano
    JOURNAL OF HYDROLOGY 401 (1-2) 106 - 116 0022-1694 2011/04 [Refereed][Not invited]
     
    Mire pools - permanently water-filled depressions on peatlands - provide important habitats for myriad organisms. Recently, water balance change and eutrophication resulting from agricultural development are increasingly evident in mire pools of alluvial lowlands. Conservation of mire pool hydrochemistry is necessary. We investigated the hydrological and chemical budgets of a pristine mire pool, Akanuma Pool (95,280 m(2) area; 1.8 m mean depth), located in Kushiro Mire in Hokkaido, northern Japan, during its ice-free period (April-November) in 2007-2008. Thereby we elucidated the hydrochemical characteristics of mire pools formed on alluvial lowlands. Surface water inflow and surface water outflow dominated the hydrological budget, respectively representing 18.3 and 20.2 mm day(-1). Groundwater seepage through the pool bottom and surface water inflow mainly supplied the lake water with total nitrogen and Ca(2+). Total phosphorus was supplied mostly by groundwater seepage through the bottom. These chemical constituents were run off from the pool mostly by surface water outflow. The input and output fluxes of water were 16-20 times greater than those of North American mire pools because of Hokkaido's higher values of precipitation minus evapotranspiration (P-En. Moreover, the Ca(2+) input into the Akanuma Pool was several times greater than those reported from North American studies. Alluvial mineral soil under the peat layer supplied large amounts of nutrients and mineral ions including Ca(2+). These results demonstrate that Hokkaido mire pools' hydrochemical characteristics differ greatly from those of pools in North America. Furthermore, each hydrological budget component maintained a constant fraction throughout the two year study period, although the absolute flow rate varied concomitantly with the precipitation level. Maintaining this budget stability is important for the conservation of mire pool hydrochemistry. (C) 2011 Elsevier B.V. All rights reserved.
  • Khatun R, Ohta T, Kotani A, Asanuma J, Gamo M, Han S, Hirano T, Nakai Y, Saigusa N, Takagi K, Wang H, Yoshifuji N
    Hydrological Research Letters THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES 5 88 - 92 1882-3416 2011 [Refereed][Not invited]
     
    Evapotranspiration over forest surfaces is mainly constrained by environmental and forest structural components through their influence on surface conductance (Gs) and aerodynamic conductance (Ga). Tower based eddy covariance data from 16 forest sites in East Asia (2°S to 64°N) were used to examine the sensitivity of Matsumoto and Nakai models for predicting Gs and Ga, respectively. Daytime dry-canopy data for the growing season were used in this study. Comparisons between model predictions and observed Gs and Ga showed good agreement, suggesting that the models were suitable for predicting Gs and Ga with reasonable accuracy. However, the model for Gs was unable to predict Gs accurately when soil water content was low (∼10%). In this circumstance, effective soil water content and a more comprehensive method for modelling the soil water content function must be used. Gs in East Asia was largely depended on vapour pressure deficit and secondarily on soil water content. Ga was largely affected by leaf area index compared with stand density.
  • Khatun R, Ohta T, Kotani A, Asanuma J, Gamo M, Han S, Hirano T, Nakai Y, Saigusa N, Takagi K, Wang H, Yoshifuji N
    Hydrological Research Letters THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES 5 83 - 87 1882-3416 2011 [Refereed][Not invited]
     
    Evapotranspiration (ET) is not only a vital component of water budget, but also plays an important role in the energy budget of the earth-atmospheric system, ultimately driving many regional and global scale climatological processes. This paper describes the ET characteristics and factors controlling ET across the 17 forest sites in East Asia (2°S to 64°N latitude). ET was measured using the eddy covariance technique at each site. Daytime dry-canopy data for the growing season were used in this study. Growing season mean ET gradually decreased as latitude increased, with a range of 4.4 to 1.2 mm d−1. The growing season mean decoupling coefficient (Ω) ranged from 0.42 to 0.11 across the studied sites. At low-latitude forest sites, Ω was close to 0.50, indicating that the bulk surface was partially decoupled from the atmosphere and ET was strongly controlled by net radiation and vapour pressure deficit. At high-latitude forest sites, Ω was low (∼0.12), indicating that the bulk surface was well coupled to the atmosphere and ET was mainly controlled by surface conductance. The value of Ω was determined mainly by the ratio of aerodynamic conductance to surface conductance across the studied forests of East Asia.
  • Tomohito Sano, Takashi Hirano, Naishen Liang, Ryuichi Hirata, Yasumi Fujinuma
    FOREST ECOLOGY AND MANAGEMENT 260 (12) 2214 - 2223 0378-1127 2010/12 [Refereed][Not invited]
     
    A typhoon event catastrophically destroyed a 45-year-old Japanese larch plantation in southern Hokkaido, northern Japan in September 2004, and about 90% of trees were blown down. Vegetation was measured to investigate its regeneration process and CO2 flux, or net ecosystem production (NEP), was measured in 2006-2008 using an automated chamber system to investigate the effects of typhoon disturbance on the ecosystem carbon balance. Annual maximum aboveground biomass (AGB) increased from 2.7 Mg ha(-1) in 2006 to 4.0 Mg ha(-1) in 2007, whereas no change occurred in annual maximum leaf area index (LAI), which was 3.7 m(2) m(-2) in 2006 and 3.9 m(2) m(-2) in 2007. Red raspberry (Rubus idaeus) had become dominant within 2 years after the typhoon disturbance, and came to account for about 60% and 50% of AGB and LAI, respectively. In comparison with CO2 fluxes measured by the eddy covariance technique in 2001-2003, for 4.5 months during the growing season, the sum of gross primary production (GPP) decreased on average by 739 gC m(-2) (64%) after the disturbance, whereas ecosystem respiration (RE) decreased by 501 gC m(-2) (51%). As a result, NEP decreased from 159 +/- 57 gC m(-2) to -80 +/- 30 gC m(-2), which shows that the ecosystem shifted from a carbon sink to a source. Seasonal variation in RE was strongly correlated to soil temperature. The interannual variation in the seasonal trend of RE was small. Light-saturated GPP (P-max) decreased from 30-45 mu mol m(-2) s(-1) to 8-12 mu mol m(-2) s(-1) during the summer season through the disturbance because of large reduction in LAI. (C) 2010 Elsevier B.V. All rights reserved.
  • Rodrigo Vargas, Dennis D. Baldocchi, Michael F. Allen, Michael Bahn, T. Andrew Black, Scott L. Collins, Jorge Curiel Yuste, Takashi Hirano, Rachhpal S. Jassal, Jukka Pumpanen, Jianwu Tang
    ECOLOGICAL APPLICATIONS 20 (6) 1569 - 1582 1051-0761 2010/09 [Refereed][Not invited]
     
    We seek to understand how biophysical factors such as soil temperature (T-s), soil moisture (theta), and gross primary production (GPP) influence CO2 fluxes across terrestrial ecosystems. Recent advancements in automated measurements and remote-sensing approaches have provided time series in which lags and relationships among variables can be explored. The purpose of this study is to present new applications of continuous measurements of soil CO2 efflux (F-0) and soil CO2 concentrations measurements. Here we explore how variation in T-s, theta, and GPP (derived from NASA's moderate-resolution imaging spectroradiometer [MODIS]) influence F-0 and soil CO2 production (P-s). We focused on seasonal variation and used continuous measurements at a daily timescale across four vegetation types at 13 study sites to quantify: (1) differences in seasonal lags between soil CO2 fluxes and T-s, theta, and GPP and (2) interactions and relationships between CO2 fluxes with T-s, theta, and GPP. Mean annual T-s did not explain annual F-0 and P-s among vegetation types, but GPP explained 73% and 30% of the variation, respectively. We found evidence that lags between soil CO2 fluxes and T-s or GPP provide insights into the role of plant phenology and information relevant about possible timing of controls of autotrophic and heterotrophic processes. The influences of biophysical factors that regulate daily F-0 and P-s are different among vegetation types, but GPP is a dominant variable for explaining soil CO2 fluxes. The emergence of long-term automated soil CO2 flux measurement networks provides a unique opportunity for extended investigations into F-0 and P-s processes in the near future.
  • Ueyama M., Ichii K., Hirata R., Takagi K., Asanuma J., Machimura T., Nakai Y., Ohta T., Saigusa N., Takahashi Y., Hirano T.
    Biogeosciences Copernicus Publications 7 (3) 959 - 977 1726-4189 2010/03/10 [Refereed][Not invited]
     
    Larch forests are widely distributed across many cool-temperate and boreal regions, and they are expected to play an important role in global carbon and water cycles. Model parameterizations for larch forests still contain large uncertainties owing to a lack of validation. In this study, a process-based terrestrial biosphere model, BIOME-BGC, was tested for larch forests at six AsiaFlux sites and used to identify important environmental factors that affect the carbon and water cycles at both temporal and spatial scales. The model simulation performed with the default deciduous conifer parameters produced results that had large differences from the observed net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (RE), and evapotranspiration (ET). Therefore, we adjusted several model parameters in order to reproduce the observed rates of carbon and water cycle processes. This model calibration, performed using the AsiaFlux data, substantially improved the model performance. The simulated annual GPP, RE, NEE, and ET from the calibrated model were highly consistent with observed values. The observed and simulated GPP and RE across the six sites were positively correlated with the annual mean air temperature and annual total precipitation. On the other hand, the simulated carbon budget was partly explained by the stand disturbance history in addition to the climate. The sensitivity study indicated that spring warming enhanced the carbon sink, whereas summer warming decreased it across the larch forests. The summer radiation was the most important factor that controlled the carbon fluxes in the temperate site, but the VPD and water conditions were the limiting factors in the boreal sites. One model parameter, the allocation ratio of carbon between belowground and aboveground, was site-specific, and it was negatively correlated with the annual climate of annual mean air temperature and total precipitation. Although this study substantially improved the model performance, the uncertainties that remained in terms of the sensitivity to water conditions should be examined in ongoing and long-term observations.
  • Hendrik Segah, Hiroshi Tani, Takashi Hirano
    INTERNATIONAL JOURNAL OF REMOTE SENSING 31 (20) 5297 - 5314 0143-1161 2010 [Refereed][Not invited]
     
    Multitemporal Principal Component Analysis (MPCA) was used for processing Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper plus (ETM+) satellite images. MPCA was able to merge spectral data corresponding to TM-1996 (pre-fire in 1997), ETM-2000 (post-fire 1997 and pre-fire 2002) and ETM-2003 (post-fire in 2002), which was crucial for detecting the fire impact and vegetation recovery. Results indicate that the burnt areas of 1997 and 2002 were 89,086 ha (16.5%) and 31,859 ha (5.9%), respectively, within the study area of 540,000 ha. Satellite Pour 1'Observation de la Terre (SPOT)-VEGETATION 10-day Maximum Value Composite (MVC) data were also used and compared with Normalized Difference Vegetation Index (NDVI) from ground-based NDVI. Our research demonstrates the strong relationship between Landsat- TM/ETM+, SPOT-VEGETATION data and ground-based NDVI in identifying land-cover changes and vegetation recovery over the tropical peat swamp forest area in Central Kalimantan, Indonesia that is affected by forest fires that occurred in 1997 and 2002.
  • N. Liang, T. Hirano, Z. -M. Zheng, J. Tang, Y. Fujinuma
    BIOGEOSCIENCES 7 (11) 3447 - 3457 1726-4170 2010 [Refereed][Not invited]
     
    We had continuously measured soil CO2 efflux (R-s) in a larch forest in northern Japan at hourly intervals for the snow-free period in 2003 with an automated chamber system and partitioned R-s into heterotrophic respiration (R-h) and autotrophic respiration (R-r) by using the trench method. In addition, we applied the soil CO2 concentration gradients method to continuously measure soil CO2 profiles under snowpack in the snowy period and to partition R-s into topsoil (O-a and A horizons) CO2 efflux (F-t) with a depth of 0.13 m and sub-soil (C horizon) CO2 efflux (F-c). We found that soil CO2 effluxes were strongly affected by the seasonal variation of soil temperature but weakly correlated with soil moisture, probably because the volumetric soil moisture (30-40% at 95% confidence interval) was within a plateau region for root and microbial activities. The soil CO2 effluxes changed seasonally in parallel with soil temperature in topsoil with the peak in late summer. On the other hand, the contribution of R-r to R-s was the largest at about 50% in early summer, when canopy photosynthesis and plant growth were more active. The temperature sensitivity (Q(10)) of R-r peaked in June. Under snowpack, R-s was stable until mid-March and then gradually increased with snow melting. R-s summed up to 79 gC m(-2) during the snowy season for 4 months. The annual R-s was determined at 934 gC m(-2) y(-1) in 2003, which accounted for 63% of ecosystem respiration. The annual contributions of R-h and R-r to R-s were 57% and 43%, respectively. Based on the gradient approach, R-s was partitioned vertically into litter (O-i and O-e horizons) with a depth of 0.01-0.02 m, topsoil and sub-soil respirations with proportions of 6, 72 and 22%, respectively, on an annual basis. The vertical distribution of CO2 efflux was consistent with those of soil carbon and root biomass.
  • Joshua B. Fisher, Yadvinder Malhi, Damien Bonal, Humberto R. Da Rocha, Alessandro C. De Araujo, Minoru Gamo, Michael L. Goulden, Takashi Hirano, Alfredo R. Huete, Hiroaki Kondo, Tomo'Omi Kumagai, Henry W. Loescher, Scott Miller, Antonio D. Nobre, Yann Nouvellon, Steven F. Oberbauer, Samreong Panuthai, Olivier Roupsard, Scott Saleska, Katsunori Tanaka, Nobuaki Tanaka, Kevin P. Tu, Celso Von Randow
    GLOBAL CHANGE BIOLOGY 15 (11) 2694 - 2714 1354-1013 2009/11 [Refereed][Not invited]
     
    Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from X decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr(-1), but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr(-1)) is considered in discussion on the use of flux data to validate and interpolate models.
  • Ma. Carmelita R. Alberto, Reiner Wassmann, Takashi Hirano, Akira Miyata, Arvind Kumar, Agnes Padre, Modesto Amante
    AGRICULTURAL AND FOREST METEOROLOGY 149 (10) 1737 - 1750 0168-1923 2009/10 [Refereed][Not invited]
     
    The seasonal fluxes of heat, moisture and CO2 were investigated under two different rice environments: flooded and aerobic soil conditions, using the eddy covariance technique during 2008 dry season. The fluxes were correlated with the microclimate prevalent in each location. This study was intended to monitor the environmental impact, in terms of C budget and heat exchange, of shifting from lowland rice production to aerobic rice cultivation as an alternative to maintain crop productivity under water scarcity. The aerobic rice fields had higher sensible heat flux (H) and lower latent heat flux (LE) compared to flooded fields. On seasonal average, aerobic rice fields had 48% more sensible heat flux while flooded rice fields had 20% more latent heat flux. Consequently, the aerobic rice fields had significantly higher Bowen ratio (0.25) than flooded fields (0.14), indicating that a larger proportion of the available net radiation was used for sensible heat transfer or for warming the surrounding air. The total C budget integrated over the cropping period showed that the net ecosystem exchange (NEE) in flooded rice fields was about three times higher than in aerobic fields while gross primary production (GPP) and ecosystem respiration (R-e) were 1.5 and 1.2 times higher, respectively. The high GPP of flooded rice ecosystem was evident because the photosynthetic capacity of lowland rice is naturally large. The R, of flooded rice fields was also relatively high because it was enhanced by the high photosynthetic activities of lowland rice as manifested by larger above-ground plant biomass. The NEE, GPP, and R, values for flooded rice fields were -258, 778, and 521 g C m(-2), respectively. For aerobic rice fields, values were -85, 515, and 430 g C m(-2) for NEE, GPR and R-e respectively. The ratio of R-e/GPP in flooded fields was 0.67 while it was 0.83 for aerobic rice fields. This short-term data showed significant differences in C budget and heat exchange between flooded and aerobic rice ecosystems. Further investigation is needed to clarify seasonal and inter-annual variations in microclimate, carbon and water budget of different rice production systems. (C) 2009 Elsevier B.V. All rights reserved.
  • Takashi Hirano, Jyrki Jauhiainen, Takashi Inoue, Hidenori Takahashi
    ECOSYSTEMS 12 (6) 873 - 887 1432-9840 2009/09 [Refereed][Not invited]
     
    The carbon balance of tropical peatlands was investigated using measurements of gaseous fluxes of carbon dioxide (CO(2)) and methane (CH(4)) at several land-use types, including nondrained forest (NDF), drained forest (DF), drained regenerating forest (DRF) after clear cutting and agricultural land (AL) in Central Kalimantan, Indonesia. Soil greenhouse gas fluxes depended on land-use, water level (WL), microtopography, temperature and vegetation physiology, among which WL was the strongest driver. All sites were CH(4) sources on an annual basis and the emissions were higher in sites providing fresh litter deposition and water logged conditions. Soil CO(2) flux increased exponentially with soil temperature (T(s)) even within an amplitude of 4-5 degrees C. In the NDF soil CO(2) flux sharply decreased when WLs rose above -0.2 and 0.1 m for hollows and hummocks, respectively. The sharp decrease suggests that the contribution of surface soil respiration (RS) to total soil CO(2) flux is large. In the DF soil CO(2) flux increased as WL decreased below -0.7 m probably because the fast aerobic decomposition continued in lower peat. Such an increase in CO(2) flux at low WLs was also found at the stand level of the DF. Soil CO(2) flux showed diurnal variation with a peak in the daytime, which would be caused by the circadian rhythm of root respiration. Among the land-use types, annual soil CO(2) flux was the largest in the DRF and the smallest in the AL. Overall, the global warming potential (GWP) of CO(2) emissions in these land-use types was much larger than that of CH(4) fluxes.
  • Nobuko Saigusa, Susumu Yamamoto, Ryuichi Hirata, Yoshikazu Ohtani, Reiko Ide, Jun Asanuma, Minoru Gamo, Takashi Hirano, Hiroaki Kondo, Yoshiko Kosugi, Sheng-Gong Li, Yuichiro Nakai, Kentaro Takagi, Makoto Tani, Huimin Wang
    AGRICULTURAL AND FOREST METEOROLOGY 148 (5) 700 - 713 0168-1923 2008/05 [Refereed][Not invited]
     
    Measurements of net ecosystem production (NEP) over forest stands were conducted from 11 flux towers in sub-arctic, temperate, and tropical regions in East Asia between 2000 and 2005. The sites extend over a wide latitude, ranging from 3 to 64 degrees N, and include sub-arctic and temperate needle-leaf deciduous forests (larch) (central Siberia, Mongolia, China, and northern Japan), temperate mixed, broadleaf deciduous, needle-leaf evergreen forests (northern and central japan), and seasonal and tropical rain forests (Thailand and Malaysia). The sub-arctic larch forests had short growing periods of 3-4 months. The temperate deciduous forests showed the greatest positive NEP after leaf expansion in early summer. Among the 11 sites, the maximum gross primary production (GPP) was observed in a temperate larch forest during the early stages of the growing period due to the high productivity of the larch species. The temperate evergreen sites displayed positive NEP earlier in the spring than the deciduous sites and had long growing periods (>10 months). The tropical seasonal forests showed negative NEP during the dry period from February to April, and turned positive after the rainy season started. The tropical rain forest showed a small flux (<30 g C m(-2) month(-1)) throughout the year without a clear seasonal change. In 2002 and 2003, several significant weather anomalies were observed, such as increased temperature in the temperate sites and less precipitation than average in the tropical sites in the beginning of 2002, and decreased solar radiation in the temperate sites in the 2003 summer. The seasonal patterns of NEP were sensitive to the anomalies, and the variations were caused by: (1) high spring air temperature, which induced an early start of the growing period in the temperate forests, (2) summer solar radiation, which controlled the summer GPP in the temperate forests with a slight variation among sites due to different responses of GPP to the temperature and water vapor pressure deficit (VPD) conditions, and (3) a long dry season, which significantly reduced GPP in a tropical seasonal forest. The dataset, which was obtained from a wide variety of forest ecosystems in East Asia over several years, is essential to validate ecosystem models and to generate technological developments of satellite remote sensing in the distribution of the terrestrial carbon budget in Asia. (C) 2007 Elsevier B.V. All rights reserved.
  • Ryuichi Hirata, Nobuko Saigusa, Susumu Yamamoto, Yoshikazu Ohtani, Reiko Ide, Jun Asanuma, Minoru Gamo, Takashi Hirano, Hiroaki Kondo, Yoshiko Kosugi, Sheng-Gong Li, Yuichiro Nakai, Kentaro Takagi, Makoto Tani, Huimin Wang
    AGRICULTURAL AND FOREST METEOROLOGY 148 (5) 761 - 775 0168-1923 2008/05 [Refereed][Not invited]
     
    The objective of this paper is to clarify what kind of environmental factors that regulate net ecosystem production (NEP), gross primary production (GPP), and ecosystem respiration (RE) in forest ecosystems across East Asia. Study sites were widely distributed and included diverse ecosystems, such as evergreen and deciduous, coniferous and broadleaf, planted and natural forests, from subarctic to tropical zones. We measured NEP using the eddy covariance technique at 13 forest sites in East Asia. Annual values of GPP and RE are simply regulated by annual mean air temperature across East Asia. There is a clear linear relationship between annual GPP and annual mean air temperature because the air temperature influences both growing period length and the seasonal variation of the maximum photosynthetic capacity, which, together, regulate the annual GPP. On the other hand, there is a strong exponential relationship between annual RE and annual mean air temperature on an East Asia scale, which is quite similar to the relation obtained on a canopy scale. The dependency of annual RE on air temperature on the East Asia scale was similar to that of monthly RE on air temperature on an individual site scale excepting for temperate larch and mixed forests in northern Japan. The reason why the relation is simple is that severe stress, which affects GPP or RE, is small in East Asia. The present study suggests that RE is sensitive to non-climate environmental factors when compared to GPP, thus the annual RE-air temperature relationship is more scattered than the annual GPP-air temperature relationship. The NEP is small at high latitude, relatively large at mid-latitude, and scattered at low latitude. As a whole, the NEP is more influenced by RE than GPP in East Asia. Compared to North America and Europe, the increase in the ratio of GPP to air temperature is slightly higher in East Asia. One of the possible reasons for this is that GPP in East Asia is not exposed to severe environmental stresses, such as summer drought. (C) 2007 Elsevier B.V. All rights reserved.
  • 木塚俊和, 山田浩之, 平野高司
    Papers on environmental information science 環境情報科学センター 22 (22) 493 - 498 0389-6633 2008 [Refereed][Not invited]
  • Ryuichi Hirata, Takashi Hirano, Nobuko Saigusa, Yasumi Fujinuma, Koh Inukai, Yasuyuki Kitamori, Yoshiyuki Takahashi, Susumu Yamamoto
    AGRICULTURAL AND FOREST METEOROLOGY 147 (3-4) 110 - 124 0168-1923 2007/12 [Refereed][Not invited]
     
    This paper reports 3-year measurements (2001-2003) of the net ecosystem CO, exchange (NEE) over a northern Japan larch plantation forest, using an eddy covariance technique with both open- and closed-path systems. The study evaluates interannual variations in the seasonal patterns of NEE, the annual NEE, clarifying the factors controlling the carbon balance. NEE for both open- and closed-path systems look equivalent from the half-hourly mean values; however, there is a small systematic bias in the annual cumulative totals. In this study, we used closed-path data because open-path data during winter are doubtful and the annual NEE from closed-path data was closer to the biometric NEP than that from open-path data. The 3-year averages of annual NEE, gross primary production (GPP), and ecosystem respiration (RE) were -212 +/- 43 (standard deviation), -1673 +/- 59, and 1462 +/- 42 gC m(-2) y(-1), respectively. The larch plantation forest absorbed large amounts of CO2 during just 1 month, June. During that period, photosynthetic photon flux density (PPFD) was large while the temperature was not high. These meteorological conditions were suitable for CO, absorption before the leaf area index (LAI) reached its peak. Maximum GPP at light saturation (P-max) was also large. During the 3-year measurement period, PPFD in summer, and temperatures in spring and summer engendered remarkable interannual differences of GPP, RE, and NEE. In spring, snowmelt and larch foliation occurred about 2 weeks earlier in 2002 than in either 2001 or 2003 because of higher temperatures; consequently, the ecosystem began to photosynthesize earlier. In July, NEE was more negative in 2003 than in other years. The GPP became larger because of higher PPFD, larger P-max; while the RE became smaller because of lower temperatures. Compared with similar forests, the amounts of GPP and RE measured here were large, but NEE was similar. The reason is that the photosynthetic capacity of larch is naturally large: the ample PPFD, and the lack of environmental stresses from dry air or soil, consequently allows high photosynthesis rates to be maintained. Moreover, it can be inferred that RE values are enhanced by the high photosynthetic activity of larch forest during the growing season. (c) 2007 Elsevier B.V. All rights reserved.
  • N. Kobayashi, T. Hiyama, Y. Fukushima, M. L. Lopez, T. Hirano, Y. Fujinuma
    WATER RESOURCES RESEARCH 43 (3) W03407, doi:10.1029/2006WR005556  0043-1397 2007/03 [Refereed][Not invited]
     
    Nighttime transpiration in a larch forest in northern Japan was investigated using concurrent measurements of the energy budget below and above the canopy and sap flow velocities. Upward latent heat flux ( lE) above the canopy was observed on similar to 20% of nights during the growing season. Nighttime lE was similar to 7% of daily totals during the dry season (September-October) and averaged similar to 3% over the entire growing season. A relatively low contribution of the understory to lE (<30%) and strong synchronicity between larch sap flow rates and lE on two warm windy nights indicated nighttime lE, occurring when warm dry air intruded from above, was largely due to transpiration from the larch overstory. High canopy conductance on some nights relative to reported maximum cuticular conductance and a strong correlation between canopy conductance and air humidity on these nights indicate the stomata of the larch trees did not close tightly at night.
  • Takashi Hirano, Hendrik Segah, Tsuyoshi Harada, Suwido Limin, Tania June, Ryuichi Hirata, Mitsuru Osaki
    GLOBAL CHANGE BIOLOGY 13 (2) 412 - 425 1354-1013 2007/02 [Refereed][Not invited]
     
    Tropical peatlands, which coexist with swamp forests, have accumulated vast amounts of carbon as soil organic matter. Since the 1970s, however, deforestation and drainage have progressed on an enormous scale. In addition, El Nino and Southern Oscillation (ENSO) drought and large-scale fires, which grow larger under the drought condition, are accelerating peatland devastation. That devastation enhances decomposition of soil organic matter and increases the carbon release to the atmosphere as CO2. This phenomenon suggests that tropical peatlands have already become a large CO2 source, but related quantitative information is limited. Therefore, we evaluated the CO2 balance of a tropical peat swamp forest in Central Kalimantan, Indonesia, using 3 years of CO2 fluxes measured using the eddy covariance technique from 2002 through 2004. The forest was disturbed by drainage; consequently, groundwater level (GL) was reduced. The net ecosystem CO2 production (NEP) measurements showed seasonal variation, which was slightly positive or almost zero in the early dry season, and most-negative late in the dry season or early the rainy season. This seasonality is attributable to the seasonal pattern of climate, tree phenology and fires. Slightly positive NEP resulted from smaller ecosystem respiration (RE) and larger gross primary production (GPP) under conditions of high photosynthetic photon flux density (PPFD) and large leaf area index (LAI). The most-negative NEP resulted from smaller GPP and larger RE. The smaller GPP was related to high vapor pressure deficit (VPD), small LAI and low PPFD because of smoke from fires. The larger RE was related to low GL. Annual NEP values were estimated respectively as -602, -382 and -313 g C m(-2) yr(-1) for 2002, 2003 and 2004. These negative NEP values show that the tropical peat swamp forest, disturbed by drainage, functioned as a CO2 source. That source intensity was highest in 2002, an ENSO year, mainly because of low PPFD caused by dense smoke emitted from large fires.
  • Makoto Ooba, Takashi Hirano, Jun-Ichi Mogami, Ryuichi Hirata, Yasumi Fujinuma
    ECOLOGICAL MODELLING 198 (3-4) 473 - 486 0304-3800 2006/10 [Refereed][Not invited]
     
    In many cases of field measurements, missing data of net ecosystem CO2 exchange (NEE) constitute a quarter to almost half of all data. Those omissions result from accidents of instruments, unfavorable weather, and quality-control screening. Accurate gap-filling methods are needed for interpolating these missing data. This study evaluated the performance of interpolation methods for gap-filling of NEE data: a conventional method with empirical equations of bioreaction whose parameters were estimated using nonlinear regression (NR) methods, an artificial neural network (ANN) method, and an automated ANN method (genetic neural network, GNN). In the GNN method, parameters of an ANN model, such as initial weight matrixes and input-data-selections, were determined automatically using a genetic algorithm (GA). A tested dataset was observed in a Japanese larch plantation in northern Japan for 5 months from May to September 2002. The available dataset was divided into two subsets to train and validate the models. Averaged coefficients of determination (r(2)) of ANN models between observed and estimated values of NEE were almost identical to that of the NR method (r(2) = 0.86). The performance of the GNN method (r(2) = 0.88, averaged value) was somewhat better than those of the two methods. Using the GNN method, the mean daily NEE was estimated at -0.29 mol m(-1) d(-1) for the S-month period using ANNs, thereby showing better performance. The mean daily NEE, which was reported previously, was compatible with that from the NR method (-0.23 mol m(-2) d(-1)). From those results, it was concluded that the proposed GNN method offers better performance for gap-filling and high availability because of the obviated need for specialization of ecological or physiological mechanisms. (c) 2006 Elsevier B.V. All rights reserved.
  • Wenjie Wang, Yuangang Zu, Song Cui, Takashi Hirano, Yoko Watanabe, Takayoshi Koike
    TREE PHYSIOLOGY 26 (10) 1363 - 1368 0829-318X 2006/10 [Refereed][Not invited]
     
    Larch (Larix gmelinii (Rupr.) Rupr.) cone scales are green, but little is known of their photosynthetic role in cone development or about how they differ in gas exchange characteristics from needle leaves. In contrast to leaf photosynthesis (P-leaf), we found that stomatal regulation of cone photosynthetic rate (P-cone) was marginal because the photosynthetic carbon came from internal recycling of respiratory carbon dioxide (CO2). Photosynthetic recycling of respired CO2 was confirmed by the finding that the intercellular CO2 concentration (C-i) in cone scales was much higher than ambient [CO2]; also, there was a positive correlation between P-cone and C-i, whereas P-leaf was almost constant as C-i varied. Low chlorophyll (Chl) concentration was a limiting factor for P-leaf but not for P-leaf, as indicated by the correlation between P-cone, and chlorophyll concentration. Moreover, chlorophyll utilization efficiency (P-sat/Chl a+b) for cone scales was lower than that for leaves. In both cones and leaves, nitrogen (N) was positively correlated with photosynthetic capacity (P), but the P/N value was much lower for cones than for leaves. For both organs, the ratio of respiration to N was broadly similar. Although mature cones have no photosynthetic capacity, P-cone, of young cones was as high as 5.3 mu mol m(-2) s(-1), about 1.26 times the value of P-leaf, and accounted for the refixation of 30-40% of the respiratory CO2 produced by cones, equivalent to the photosynthetic capacity of a bundle of short shoots near each cone. Thus, P-cone may be an important additional source of photosynthate for cones, given the weak assimilating capacity of leaves that are not fully expanded during cone development.
  • Teruyo Ieda, Yasuyuki Kitamori, Michihiro Mochida, Ryuichi Hirata, Takashi Hirano, Kou Inukai, Yasumi Fujinuma, Kimitaka Kawamura
    TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY 58 (3) 177 - 186 0280-6509 2006/07 [Refereed][Not invited]
     
    Volatile and semi-volatile organic compounds (VOCs and SVOCs) in the atmosphere control oxidative capacity of the air and formation of organic aerosols. To investigate sources, variations and fluxes of VOCs and SVOCs in the forest atmosphere, samples were collected in a larch forest at different heights in Tomakomai, Japan, from 3 to 5 September 2003 and were analyzed for VOCs (isoprene and a-pinene) and SVOCs (n-nonanal, n-decanal, glycolaldehyde, hydroxyacetone. glyoxal and methylglyoxal) using GC-FID and GC-MS. Isoprene (8-851 pptv) showed a diurnal variation with a maximum in daytime, whereas diurnal pattern was indistinct for a-pinene (6-145 pptv). SVOCs showed diurnal variations similar to isoprene, suggesting their origin to be biogenic. Denuder samplings of SVOCs demonstrated that up to 60% of SVOCs were present in aerosol particles. n-Nonanal and n-decanal were more abundant at lower altitude, suggesting their primary emissions from vegetations. In contrast, other four SVOCs showed an opposite or no trend and are considered as oxidation products of biogenic precursors such as isoprene. The averaged upward fluxes of isoprene and a-pinene were obtained to be 34.8 and 9.8 ng m(-2) s(-1), respectively. Magnitudes of SVOC fluxes were comparable to those of a-pinene, indicating that SVOCs affect budgets of organic gases/aerosols over the forest.
  • Oxana V. Masyagina, Takashi Hirano, Dong Hun Ji, Dong Su Choi, Laiye Qu, Yasumi Fujinuma, Kaichiro Sasa, Yojiro Matsuura, Stanislav G. Prokushkin, Takayoshi Koike
    Forest Science and Technology 2 (2) 80 - 91 2158-0715 2006 [Refereed][Not invited]
     
    Harvesting of trees or the loss of trees due to strong winds may lead to large variations at the ground surface that, in turn, causes spatial and temporal variability of soil respiration. We performed thinning (partial harvest) on a mature larch plantation (ca. 50 yr-old) in Tomakomai National Forest (Japan) with the purpose of studying the effects of thinning on soil respiration (Rs). We conducted field measurements to determine how soil temperature (Ts), mineral soil water content (MSWC), litter water content (LWC), fine root density, litter density, and carbon to nitrogen ratio (C/N) individually influence soil respiration. Soil respiration values did not differ significantly at the disturbed site. Soil temperature was significantly greater at the disturbed site than at the control site (t-test= -12.7, P< 0.05), and the MSWC and LWC did not differ between sites. Despite these observations we found no proof that Ts or MSWC influences Rs. At the disturbed site, LWC appeared to be a primary microclimatic factor driving spatial variations in Rs (r= -0.41, P< 0.05). Thinning led to large variations in Rs, Ts, fine root density, and litter density. Root and litter densities were 18% (insignificant value) and 15% (t-test=2.86, P< 0.05) lower in the disturbed site, respectively. In fact, variations in soil respiration can be explained on the basis of litter density and C/N. © 2006, Taylor & Francis Group, LLC.
  • WJ Wang, YG Zu, HM Wang, XY Li, T Hirano, T Koike
    PHOTOSYNTHETICA 44 (1) 147 - 150 0300-3604 2006 [Refereed][Not invited]
     
    A stem-girdling experiment was carried out on an evergreen conifer, the Korean pine (Pinus koraiensis Sieb. et Zucc.), in mid summer in Northeast China. A 50 % higher respiration rate at the upper part of the stem was observed 3 d after stem girdling, and a stable higher rate (1.2-2.8 times) one week later. However, no higher soluble sugar or starch contents were found in the upper bark of the girdled stems in measurements over three weeks. These findings indicate that most of the newly-formed photosynthates were consumed by the high respiratory activity; this is also implied by the strong correlation between the photosynthetic photon flux over the canopy (PPF) and respiration at the upper parts of girdled stems. Moreover, the maximum PPF and cumulative PPF one day before measurement (PPFmax-Y and CPPF-Y, respectively) were closely correlated with the respiratory difference between the upper and the lower parts, but no such correlation was found with the instantaneous PPF (PPF-I) and Cumulative PPF on the current day from sunrise to measured time point (CPPF-C). This shows that photosynthates newly formed by canopy needles need at least one day for transportation in order to increase the stem respiration at tree breast height.
  • Changes in CO2 exchanges during the development of larch (Larix gmelinii) cones
    Wang W, Zu Y, Cui S, Hirano T, Watanabe Y, Koike T
    Tree Physiology 26 1363 - 1368 2006 [Refereed][Not invited]
  • T Hirano
    GLOBAL BIOGEOCHEMICAL CYCLES 19 (2) GB2011, doi:10.1029/2004GB002259  0886-6236 2005/04 [Refereed][Not invited]
     
    We measured soil CO2 concentration at half-hour intervals with infrared gas analyzers buried in soil at four depths throughout the snow cover season extending from early December to early April in a deciduous temperate forest. We evaluated soil CO2 efflux or total soil respiration, topsoil (the A-horizon) respiration, and subsoil (the C-horizon) respiration using a modified flux gradient method. Thereby, we investigated seasonal and diurnal variations in these soil respirations under snowpack. Soil CO2 concentration and soil respiration changed dynamically under the condition of constant soil temperature. Topsoil respiration decreased rapidly in late autumn and relatively constant until mid-winter, whereas it increased in late winter when snowmelt progressed. On the other hand, subsoil respiration decreased gradually until mid-winter and increased slightly in late winter. Both topsoil and subsoil respirations showed similar diurnal variations with a peak in early or mid-afternoon, respectively, independently of soil temperature. These seasonal and diurnal variations in soil respiration were inferred to result from the supply of labile carbon compounds, which were respiratory substrates for microorganisms, into soil from litter with meltwater. The seasonal sum of topsoil, subsoil, and total respirations for the snow cover period of 4 months were 21.4, 48.0, and 69.4 gC m(-2), respectively; these accounted for 3.0, 27.3, and 7.7% of the annual sum, respectively. The ratio of topsoil respiration to total soil respiration was 0.31 on average during the snow period, which was considerably lower than that in the summer season.
  • WJ Wang, YG Zu, HM Wang, T Hirano, K Takagi, K Sasa, T Koike
    JOURNAL OF FOREST RESEARCH 10 (1) 57 - 60 1341-6979 2005/02 [Refereed][Not invited]
     
    Little information is available on the effect of root cutting by the collar pre-insertion technique on soil respiration. In this study, we found that soil respiration rates decreased with increasing depth of collar insertion in both the "with live roots intact" and "with live roots severed" treatments, but the rate of decrease was substantially higher in the former. The cutting of roots, especially fine roots, may be responsible for this result.
  • Yamamoto S, Saigusa N, Gamo M, Fujinuma Y, Inoue G, Hirano T
    Journal of Geographical Sciences 15 (2) 142 - 148 1009-637X 2005 [Refereed][Not invited]
  • 生物複雑系に適応するモデルとその背景
    大場 真, 平野高司
    北海道の農業気象 57 49 - 63 2005 [Refereed][Not invited]
  • Hirano T, Urano S, Yazaki T, Yabe K, Kawauchi K, Okada K, Hinzman L, Ishikawa N
    Journal of Agricultural Meteorology 日本農業気象学会 60 (5) 737 - 740 0021-8588 2005 [Refereed][Not invited]
  • Hirata R, Hirano T, Okada K, Fujinuma Y, Inukai K, Saigusa N, Yamamoto S
    Journal of Agricultural Meteorology 日本農業気象学会 60 (5) 741 - 744 0021-8588 2005 [Refereed][Not invited]
  • Machimura T, Kobayashi Y, Iwahana G, Hirano T, Lopez L, Fukuda M, Fedorov A
    Journal of Agricultural Meteorology 日本農業気象学会 60 (5) 653 - 656 0021-8588 2005 [Refereed][Not invited]
  • H. Kim, T. Hirano, T. Koike, S. Urano
    PHYTON-ANNALES REI BOTANICAE 45 (4) 385 - 388 0079-2047 2005 [Refereed][Not invited]
     
    CO2 efflux from a forest floor is produced in subsoil, topsoil and litter layers. We evaluated topsoil respiration (R-t), subsoil respiration (R-s) and litter CO2 production (R-L) seperately in a deciduous broadleaf forest and a larch forest in northern Japan from April through November to investigate the contribution of R-L to total soil respiration (R-all: R-L + R-t + R-s). In the broadleaf forest, R-L peaked at 0.97 gC m(-2) d(-1) in late May. The R-L contribution to R-all (R-L / R-all) was large at 0.15-0.40 in spring, whereas it was less than 0.07 in summer. In the larch forest, only larch litter was examined. R-L of larch litter decreased gradually from 0.32 to 0.08 gC m(-2) d(-1) between April and November. R-L /R-all decreased rapidly during April and May from 0.19 to 0.04 and was almost constant in summer at 0.01-0.03. Seasonal sums of R-L, R-s and R-t were 85, 683 and 145 gC m(-2) for the broadleaf forest and 34, 700 and 253 gC m(-2) for the larch forest, respectively, for 8 months; R-L accounted for 9.3 and 3.4% of R-all for the broadleaf and larch forests, respectively.
  • Mogami J, Hirano T, Hirata R, Kitaoka S, Koike T, Fujinuma Y
    Journal of Agricultural Meteorology 日本農業気象学会 60 (6) 1161 - 1163 0021-8588 2005 [Refereed][Not invited]
  • Urano S, Okada K, Ide K, Sano T, Kimura M, Hirano T, Funakoshi H, Takenoshita Y, Dohkoshi J
    Journal of Agricultural Meteorology 日本農業気象学会 60 (5) 801 - 804 0021-8588 2005 [Refereed][Not invited]
  • T. Hirano, H. Segah, S. Limin, T. June, S. J. Tuah, K. Kusin, R. Hirata, M. Osaki
    PHYTON-ANNALES REI BOTANICAE 45 (4) 67 - 71 0079-2047 2005 [Refereed][Not invited]
     
    Tropical peat swamp forests grow over tropical peatlands, which are widely distributed in flat lowlands in Southeast Asia. Recently, however, deforestation and drainage are in progress on a large scale because of growing demands for timber and farmland. In addition, the El Nino drought and its consequent fires are accelerating the forest devastation. The forest devastation alters energy balance and will influence regional climate. Thus, we have measured eddy energy fluxes above a tropical peat swamp forest left in a devastated peatland in Central Kalimantan, Indonesia since November 2001. Both in the rainy and dry seasons, latent heat flux (lE) considerably exceeded sensible heat flux (H). Net radiation (R-n) was mainly used by evapotranspiration (ET). The El Nino event occurred in 2002, and the consequent drought caused large-scale peatland fires in Central Kalimantan. A large amount of smoke emitted from the fires decreased Rn from mid-August through October. Bowen ratio (H/lE) decreased gradually from January through July in the range of 0.20-0.35. Although Bowen ratio decreased to a minimum of 0.15 in late September, it continued to increase during the late fire period and was high at 0.35-0.45 after the fires. ET accounted for 67% of precipitation (1856 mm) on an annual basis in 2002. Annual mean daily ET was 3.4 mm d(-1).
  • H. Wang, N. Saigusa, Y. Zu, S. Yamamoto, H. Kondo, F. Yang, W. Wang, T. Hirano, Y. Fujinuma
    PHYTON-ANNALES REI BOTANICAE 45 (4) 339 - 346 0079-2047 2005 [Refereed][Not invited]
     
    The relationships between CO2 fluxes in larch forest ecosystems and environmental variables were investigated. The results indicate that the ecosystem CO2 uptake tended to decrease with an increasing vapor pressure deficit (VPD) when the VPD exceeded 15 hPa at both the Laoshan site (LS) in Northeast China and at the Tomakomai site (TFS) in northern Japan. The similarity of the VPD threshold value indicates that the larch forests at these two sites have a similar response to a dry environment. The carbon uptake rate of the larch forest was significantly lower on cloudy days (3.62 mu mol m(-2) s(-1) at LS and 3.76 mu mol m(-2) s(-1) at TFS) than on clear days (6.18 mu mol m(-2) s(-1) at LS and 6.53 mu mol m(-2) s(-1) at TFS) due to the significantly reduced incident radiation on cloudy days. However, the light-use efficiency of larch forests was much higher on cloudy than on clear days. This was due not only to the more diffused radiation on the cloudy days but also to a low VPD. Beyond our expectation, the air temperature showed almost no effect on the light-use efficiency of the larch forests.
  • Honghyun Kim, Takashi Hirano, Shin-Ichi Urano
    Journal of Agricultural Meteorology 61 (2) 95 - 104 1881-0136 2005 [Refereed][Not invited]
     
    We collected leaf litter from a deciduous broadleaf forest and a larch forest in Hokkaido, Japan naturally without using litter traps or litter bags. The litter collection was conducted every month from October 2001 through October 2002 except in the snowy season. We measured the CO2 production rate of the litter samples through microbial respiration using the chamber method in a laboratory under different temperature and moisture conditions to investigate the seasonal pattern and temperature and moisture responses of CO2 production at the early stage of litter decomposition. Seasonal variation was found in the CO2 production rate per unit of litter dry weight (Pdw), or the litter decomposition rate, for both broadleaf and larch litters. Although seasonal patterns differed somewhat according to temperatures and species, Pdw reached the minimum in June. The moisture sensitivity of Pdw decreased with time and reached the minimum in summer for both broadleaf and larch litters, whereas the seasonal pattern of the temperature sensitivity (Q10) was not clear. The seasonal pattern of Pdw was explained by its C: N ratio for broadleaf litter. For larch litter, however, the relationship between Pdw and the C:N ratio was complicated because of fresh litterfall supplied gradually before defoliation. The temperature and moisture sensitivities of Pdw changed in parallel with the C:N ratio for both broadleaf and larch litters, respectively. These facts suggest the importance of litter chemical quality in the early decomposition process of fresh litter and the validity of the C:N ratio as an index of litter quality. © 2005, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • カラマツ林におけるLAIの季節変化が林内気象に与える影響
    福田達也, 平野高司, 佐野智人, 平田竜一, 犬飼 孔, 藤沼康実
    北海道の農業気象 57 29 - 38 2005 [Refereed][Not invited]
  • Segah H, Tani H, Hirano T, Kasahara T, Limin S
    Journal of Agricultural Meteorology 60 (5) 415 - 420 0021-8588 2005 [Refereed][Not invited]
  • R. Hirata, T. Hirano, J. Mogami, Y. Fujinuma, K. Inukai, N. Saigusa, S. Yamamoto
    PHYTON-ANNALES REI BOTANICAE 45 (4) 347 - 351 0079-2047 2005 [Refereed][Not invited]
     
    In the northern part of Japan, snow covers the land for several months in winter. It is necessary to estimate the CO2 flux during the snow-cover season to evaluate annual net CO2 exchange between the atmosphere and ecosystems (NEE); CO2 flux is probably small because of snow accumulation and low temperature. This paper reports NEE, as measured using an open-path system (NEEO) over a larch forest during the snow-cover season. NEEO ranged from -2 to -6 mu mol m(-2) s(-1) under sunshine conditions, whereas NEE measured with a closed-path system was always slightly positive. Such negative NEEO was unexpected because the forest canopy had no leaves and floor vegetation was under snowpack. One reason for negative NEEO under sunshine conditions is that the CO2 resolution of the open-path analyzer was low when CO2 fluctuation was small. During the snow-cover season, eddy energy flux accounted for 70% of available energy. Therefore, incomplete WPL correction of CO2 flux resulting from underestimated sensible heat flux would partly explain the unexpected negative NEEO.
  • HM Wang, N Saigusa, S Yamamoto, H Kondo, T Hirano, A Toriyama, Y Fujinuma
    ATMOSPHERIC ENVIRONMENT 38 (40) 7021 - 7032 1352-2310 2004/12 [Refereed][Not invited]
     
    Larch forests are distributed extensively in the cast Eurasian continent and are expected to play a significant role in the terrestrial ecosystem carbon cycling process. In view of the fact that studies on carbon exchange for this important biome have been very limited, we have initiated a long-term flux observation in a larch forest ecosystem in Hokkaido in northern Japan since 2000. The net ecosystem CO2 exchange (NEE) showed large seasonal and diurnal variation. Generally, the larch forest ecosystem released CO2 in nighttime and assimilated CO2 in daytime during the growing season from May to October. The ecosystem started to become a net carbon sink in May, reaching a maximum carbon uptake as high as 186 g C m(-2) month(-1) in June. With the yellowing, senescing and leaf fall, the ecosystem turned into a carbon source in November. During the non-growing season, the larch forest ecosystem became a net source Of CO2, releasing an average of 16.7 g C m(-2) month(-1). Overall, the ecosystem sequestered 141-240 g C m(-2) yr(-1) in 2001. The NEE was significantly influenced by environmental factors. Respiration of the ecosystem, for example, was exponentially dependent on air temperature, while photosynthesis was related to the incident PAR in a manner consistent with the Michaelis-Menten model. Although the vapor pressure deficit (VPD) was scarcely higher than 15 hPa, the CO2 uptake rate was also depressed when VPD surpassed 10 hPa. (C) 2004 Elsevier Ltd. All rights reserved.
  • NS Liang, T Nakadai, T Hirano, LY Qu, T Koike, Y Fujinuma, G Inoue
    AGRICULTURAL AND FOREST METEOROLOGY 123 (1-2) 97 - 117 0168-1923 2004/05 [Refereed][Not invited]
     
    Soil surface CO2 efflux (F-c) in a 45-year-old northern larch forest was continuously measured, using a multichannel automated chamber system, between June and October, 2001. The results were compared with periodic measurements obtained at the same site with an LI-6400 chamber system and an open-top chamber system, and also with continuous measurements obtained at the same site with a soil CO2 gradient system. The diurnal and seasonal changes in F-c measured by the automated chamber and Soil CO2 gradient approaches followed the soil temperature patterns. We found only a weak correlation between F-c and soil moisture, probably because the volumetric soil moisture (30-40% at 95% confidence interval) in this larch forest favors microbial and root activities. Among the four approaches, the LI-6400 chamber yielded a substantially higher F-c value than the other three approaches. The open-top chamber gave higher values of F-c than the automated chamber at efflux rates below 3.0 mumol m(-2) s(-1) and lower values above this level; however, the results of both these approaches were closely correlated (R-2 = 0.87, n = 105). Although F-c measured with the Soil CO2 gradient approach was, on average, 45% higher than the results of the automated chamber approach, the correlation between the two techniques was good (R-2 = 0.77, n = 2945). The annual soil CO2 efflux estimated by the automated chamber (665 g C m(-2)) and open-top chamber (720 g C m(-2)) matched the total annual ecosystem respiration, as estimated by the above-canopy eddy covariance method. However, the LI-6400 chamber and soil CO2 gradient approaches gave higher values for annual Soil CO2 efflux than the eddy covariance method. (C) 2003 Elsevier B.V. All rights reserved.
  • T Hirano, H Kim, Y Tanaka
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 (D20) doi:10.1029/2003JD003766  2169-897X 2003/10 [Refereed][Not invited]
     
    [1] We conducted a field experiment in a cool-temperate deciduous forest to investigate the dynamic behavior of soil CO2 and the vertical distribution of soil respiration. Soil CO2 concentration (C) was measured half-hourly at four depths for 6 months in 2000 with infrared gas analyzers installed below ground. Using C profiles, soil surface CO2 efflux (F-0), CO2 production rates of the topsoil (P-A), and CO2 flux from the subsoil to topsoil (F-CA) were evaluated half-hourly by applying Fick's first law. Some remarkable short-term and long-term variations were found in C, F-0, P-A, F-CA, and the contribution of topsoil respiration to total soil respiration (P-A/F-0), which include (1) rapid increase in C and decrease in F-0 and P-A due to rainwater infiltration, (2) diurnal variation in C coupled with that of the atmosphere, (3) diurnal variation in F-0 and P-A similar to that of topsoil temperature, (4) decrease in C, F-0, and P-A following soil drying in August, (5) linearly increasing F-CA between late May and mid-September, and (6) decrease in P-A/F-0 from around 0.9 during summer to 0.3 in November. The variation of P-A was mainly controlled by soil temperature at -0.07 m between 7degrees and 17degreesC, although P-A did not respond well to soil temperature above and below this temperature range. Above 17degreesC, P-A increased linearly with soil moisture, and moisture variation accounted for the P-A decrease in August. Neither temperature nor moisture explained the P-A behavior below 7degreesC. Subsoil respiration (F-CA) showed an exponential relationship with soil temperature at -1 m.
  • T Hirano, R Hirata, Y Fujinuma, N Saigusa, S Yamamoto, Y Harazono, M Takada, K Inukai, G Inoue
    TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY 55 (2) 244 - 257 0280-6509 2003/04 [Refereed][Not invited]
     
    In the northern part of East Asia, forests dominated by larch are extensively distributed and probably play an important role in the global carbon cycle. However, a knowledge of the CO2 balance of larch forests based on long-term flux measurements is very restricted in East Asia. Thus, a long-term flux measurement has been started in 2000 at a larch plantation on a flat terrain in Hokkaido, Japan to obtain more information on the CO2 and energy balances of larch forests. From September 2000 to August 2001 the net ecosystem CO2 exchange (NEE) changed seasonally in accordance with the annual cycles of phenology and climate. NEE was negative for six months of the growing season, May-September; the larch ecosystem was a carbon sink with a peak intensity of -0.38 mol m(-2) d(-1) for this period. In the leafless season from November to April the forest ecosystem was a carbon source with an intensity ranging between 0 and 0.05 mol m(-2) d(-1). Annual NEE from September 2000 to August 2001 was -24.4 to -32.4 mol m(-2) yr(-1) (= -293 to -389 gC m(-2) yr(-1)); this value is compatible with those reported from other temperate forests. Annual evapotranspiration for the same period was 367 turn, which was only 29% of annual precipitation.
  • Genichi Hirai, Tatsuya Inamura, Toshikatsu Okumura, Kaoru Ashida, Osamu Tanaka, Hiroyoshi Chujo, Takasi Hirano
    Japanese Journal of Crop Science 日本作物学会 72 (2) 196 - 202 0011-1848 2003 [Not refereed][Not invited]
     
    The effects of atmospheric humidity on vegetative growth of paddy and upland rice were compared. A low atmospheric humidity (60%RH) significantly decreased the dry-matter production in paddy rice but not in upland rice. In paddy rice, exposure to low atmospheric humidity significantly increased the stomatal density in leaves, stomatal aperture and the ratio of stomatal apparatus to leaf area. Thus, stomatal opening was only slightly decreased by the low humidity, resulting in a striking increase in transpiration rate per unit leaf area and marked reduction in water potential of leaf blade. On the other hand, in upland rice, stomatal density and stomatal apparatus area were not influenced by exposure to a low humidity and the ratio of stomatal apparatus area to leaf area was not influenced by atmospheric humidity up to 60%RH. In paddy rice, the relative leaf expansion rate was significantly reduced by exposure to a low humidity, but in upland rice, it was not. Thus, in the present study the low atmospheric humidity reduced the leaf expansion rate without reducing the net assimilation rate in paddy rice, but not in upland rice. This may be why the effect of atmospheric humidity on growth and dry-matter production differed between paddy and upland rice.
  • 森林でのフラックス観測における欠測値補間法の比較
    最上純一, 平田竜一, 平野高司, 三浦昌孝, 藤沼康実, 犬飼孔
    北海道の農業気象 55 9 - 16 2003 [Refereed][Not invited]
  • Taro Nakai, Shin-Ichi Urano, Takamitsu Sato, Takashi Hirano
    Journal of Agricultural Meteorology 59 (2) 155 - 164 1881-0136 2003 [Refereed][Not invited]
     
    Sensible heat advection from a 3-m-tall cornfield to a short grassland with a height of 0.3m was evaluated by wind speed and turbulent diffusivity, which were numerically calculated with a standard k-ε model including the effect of plant-atmosphere interaction, together with measured air temperature. The calculated wind speed agreed with the measurements. Air temperature was interpolated at each grid point by a bicubic spline method the grid dataset of air temperature was used as a boundary condition to solve the advection-diffusion equation. At noon on a sunny day in late summer, air temperature showed a horizontally-decreasing distribution from the cornfield to the grassland and a vertical lapse over the grassland. Horizontal wind accelerated between the cornfield and grassland, and downward wind existed over the grassland. Under these conditions, the horizontal advection increased the vertical gradient of sensible heat flux ∂H/∂z, while the vertical advection decreased it. Since the horizontal advection was predominant, ∂H/∂z was generally positive. The effect of the vertical advection was significant near the leading edge. However, the effect decreased with downwind distance from the edge and was negligible near the grassland surface. © 2003, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Yoshinobu Harazono, Takashi Hirano, Nobuko Saigusa, Yoshikazu Ohtani, Akira Miyata, Eiji Ohtaki, Nobutaka Monji
    Journal of Agricultural Meteorology 59 (1) 69 - 80 1881-0136 2003 [Refereed][Not invited]
     
    Continuous long term micrometeorological CO2 flux observation has become an essential component to accurate determine CO2 uptake in terrestrial ecosystems after COP3. Because the intergovernmental agreement on CO2 emission control (Kyoto protocol) allows each country to subtract the annual accumulation of CO2 uptake by their ecosystems from the total anthropogenic CO2 emission. Hence, the demands to determine the CO2 uptake more accurately at the ecosystem level, and to make the long term CO2 flux observation a major research within multidisciplinary study fields such as ecology, biology, meteorology and agriculture have been increased significantly. Several flux observation sites have been operating in ecosystems of North America and Europe since 90's. These sites were initially independent research projects, but were later organized into networks such as AmeriFlux and EUROFLUX. FLUXNET was also established to enhance the understanding of ecosystem CO2 exchange including data exchange and to promote the measurement methodology among the networks. AsiaFlux was established in fall of 1999 as part of a flux observation research network in Japan and some Asian countries. The Study Group for Flux Measurement and Evaluation (S-FluME), the Society of Agricultural Meteorology of Japan (SAMJ) was organized to enhance the research activities of flux observations, and has been contributing to the activities of AsiaFlux. This paper reviews the development of theoretical and practical methodology of flux observation and discusses topics that arose from previous long term flux observations. Some suggestions and comments to improve the flux determination are also shown. © 2003, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Wang W, Osaki M, Hirano T, Hiura T and Koike T
    Wang W, Osaki M, Hirano T, Hiura T, Koike T
    Bamboo Journal 20 19 - 32 2003 [Refereed][Not invited]
  • Masataka Miura, Takashi Hirano, Ryuichi Hirata, Jun-Ichi Mogami, Koh Inukai, Yasumi Fujinuma
    Journal of Agricultural Meteorology 59 (3) 245 - 250 1881-0136 2003 [Refereed][Not invited]
     
    Sum of sensible and latent heat fluxes measured by the eddy covariance technique is systematically smaller than available energy in many terrestrial ecosystems, which includes forests. This energy imbalance is an essential issue for the flux measurement. In this study, we evaluated heat storage flux and investigated its effect on energy balance in a larch plantation developing on a flat terrain. Above-ground biomass was the largest component producing the heat storage flux of the forest ecosystem about 70-80% of the heat storage flux was generated in above-ground biomass for summer and fall. Moreover, the heat storage flux of topsoil over heat plates had a considerable bearing on the evaluation of soil heat flux. Adding these heat storage fluxes improved energy balance by 6-10% it increased the slope of the ordinary least square between eddy energy fluxes and available energy, which was used as an index of energy balance closure, from 0.83 to 0.88 in summer and from 0.93 to 1.03 in fall. This suggests that we have to measure and consider heat storage flux when we investigate the energy balance of forest ecosystems. © 2003, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Genichi Hirai, Tatsuya Inamura, Toshikatsu Okumura, Kaoru Ashida, Osamu Tanaka, Hiroyoshi Chujo, Takasi Hirano
    Japanese Journal of Crop Science 72 (2) 196 - 202 0011-1848 2003 [Refereed][Not invited]
     
    The effects of atmospheric humidity on vegetative growth of paddy and upland rice were compared. A low atmospheric humidity (60%RH) significantly decreased the dry-matter production in paddy rice but not in upland rice. In paddy rice, exposure to low atmospheric humidity significantly increased the stomatal density in leaves, stomatal aperture and the ratio of stomatal apparatus to leaf area. Thus, stomatal opening was only slightly decreased by the low humidity, resulting in a striking increase in transpiration rate per unit leaf area and marked reduction in water potential of leaf blade. On the other hand, in upland rice, stomatal density and stomatal apparatus area were not influenced by exposure to a low humidity and the ratio of stomatal apparatus area to leaf area was not influenced by atmospheric humidity up to 60%RH. In paddy rice, the relative leaf expansion rate was significantly reduced by exposure to a low humidity, but in upland rice, it was not. Thus, in the present study the low atmospheric humidity reduced the leaf expansion rate without reducing the net assimilation rate in paddy rice, but not in upland rice. This may be why the effect of atmospheric humidity on growth and dry-matter production differed between paddy and upland rice.
  • Nobutaka Monji, Ken Hamotani, Ryuichi Tosa, Toshifumi Fukagawa, Kazutoshi Yabuki, Takashi Hirano, Vipak Jintana, Somsak Piriyayota, Akifumi Nishimiya, Masahiro Iwasaki
    Journal of Agricultural Meteorology 58 (2) 63 - 69 1881-0136 2002/09/01 [Refereed][Not invited]
     
    Two types of the modified gradient method for CO2 and water vapor flux estimation, in which the eddy correlation is applied only to the sensible heat flux, are presented. One type uses the eddy diffusivity for the sensible heat flux, and the other establishes the flux-gradient relation in the form of the product Φm Φh as a function of the gradient Richardson number. The latter method can be used even in heavy rains. In order to confirm the applicability of these methods, the dimensionless profile relations for momentum, sensible heat, latent heat and CO2 are estimated over a mangrove forest. Although these dimensionless profiles indicate smaller values than the Businger-Dyer representation under stable conditions, they indicate similar tendency with each other. The two modified gradient methods agree with each other although the scatter in the individual comparison is large. © 2002, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • G Hirai, T Okumura, K Ashida, T Inamura, O Tanaka, H Chujo, T Hirano
    PLANT PRODUCTION SCIENCE 5 (2) 101 - 109 1343-943X 2002/06 [Refereed][Not invited]
     
    High atmospheric humidity promotes vegetative growth and dry-matter production in japonica rice. In this study, the varietal differences in the response to atmospheric humidity were examined using three japonica varieties (Nipponbare, Kinmaze, Yamadanishiki), one indica variety IR24 and japonica X indica variety (Milyang 23). The indica and japonica X indica varieties are referred to as indica varieties hereafter. The growth of the japonica varieties was greatly promoted by high humidity (90%) and greatly reduced by low humidity (60%), but that of the indica varieties was less sensitive to humidity and the growth was hardly affected by low humidity. We compared the responses of the above varieties to low humidity (water stress) using the plants under high humidity as a control. Under low humidity, as compared to the indica varieties, the japonica varieties had a higher stomatal density, longer stomata and larger stomatal aperture, resulting in a lower water potential in leaf blades and lower water -use efficiency. Under high humidity, the japonica and indica varieties showed a similar transpiration rate (per unit area), stomatal aperture and water-use efficiency, but the japonica varieties had a higher water content than the indica varieties. This may be why the japonica varieties show greatly suppressed growth and dry matter production under low humidity. These differences between the japonica and indica varieties in morphophysiological characters under low humidity might cause the varietal differences in the plant growth and dry matter production in rice.
  • Y Kitaya, K Yabuki, M Kiyota, A Tani, T Hirano, Aiga, I
    TREES-STRUCTURE AND FUNCTION 16 (2-3) 155 - 158 0931-1890 2002/03 [Refereed][Not invited]
     
    We conducted in situ measurements of gas exchange and O-2 concentration in pneumatophores of Sonneratia alba, Avicennia marina and Bruguiera gymnorrhiza and prop roots of Rhizophora stylosa. The mean rates of photosynthesis were 0.6 and 0.2 mumol CO2 m(-2)s(-1) in the raised pneumatophores of S. alba and A. marina, respectively, at a photosynthetic photon flux density of 100 mumol m(-2)s(-1). Photosynthetic activity was also detected in the prop roots of R. stylosa but the photosynthetic rate was lower than in A. marina. B. gymnorrhiza had no photosynthetic activity in knee pneumatophores. O-2 concentrations in the pneumatophores of these four species decreased by 4-8% when the pneumatophores were submerged under water. The O-2 concentrations in submerged pneumatophores of S. alba and A. marina were higher with higher solar radiation. Such photosynthetically generated O-2 could diffuse down through the pneumatophores into the roots, particularly when sunlit pneumatophores were submerged by high tide. This may contribute to the success of S. alba and A. marina in zones where tidal inundation is common.
  • 中井裕一郎, 三枝信子, 平野高司, ロバート エバンス, 大谷義一, 平田竜一, 鳥山敦, 北村兼三, 鈴木覚, 山本晋
    水文・水資源学会誌 THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES 15 (6) 665 - 672 0915-1389 2002 [Refereed][Not invited]
  • 風蓮川湿原におけるミズゴケハンモックとホローの地中熱環境
    矢崎友嗣, 浦野慎一, 矢部和夫, 河内邦夫, 高橋宣之, 隈部篤興, 犬飼孔, 平野高司
    北海道の農業気象 54 45 - 52 2002 [Refereed][Not invited]
  • 平田竜一, 杉本和之, 平野高司, 小池孝良, 北岡哲, 油津雄夫, 藤田玲, 藤沼康実, 高田雅之, 犬飼孔
    北海道の農業気象 54 (54) 53 - 62 0915-6062 2002 [Refereed][Not invited]
  • 夏期における水稲個体群の葉温と大阪府立大学農学部附属農場の水稲収量
    平井源一, 稲野藤一郎, 簗瀬雅則, 中條博良, 平野高司, 田中修, 奥村俊勝
    近畿作物育種研究 47 13 - 17 2002 [Refereed][Not invited]
  • Monji N, Hamotani K, Hamada Y, Agata Y, Hirano T, Yabuki K, Jintana V, Piriyayota S, Nishimiya A, Iwasaki M
    Journal of Agricultural Meteorology 養賢堂 58 (2) 71 - 77 0021-8588 2002 [Refereed][Not invited]
     
    タイ南部のマングローブ林でC02と熱の交換の特性を雨季と乾季について調べた。林上のC02と熱フラックスの測定には2種類の改良傾度法(Monji et al.,2002)を用いた。1つは顕熱フラックスを渦相関法で求めて傾度との関係から拡散係数を求め、それをC02と水蒸気フラックスに適用する方法で、もう一つはこの森林の特定高度についてフラックスと傾度の関係、ここではΦm、Φh、とリチャードソン数の関係を求めておき、傾度法を適用する方法である。後者はかなり雨が激しいときに顕熱フラックスが渦相関法で求まらないときに用いた。熱フラックスについては雨季と乾季では大きな違いが見られた。雨天日には大きな上方向の潜熱フラックスがあり、これを補うように顕熱は大きく下方に運ばれていた。また、雨天日にはC02フラックスは日中でもわずかに上方向であった。全天日射量とC02フラックスの関係は雨季と乾季では大きな相違を示さなかった。 マングローブ林内の微気象を調べるために、プローブを上下させて測定を行った。林内に進入する汽水は熱環境やC02分布に影響を与えることがわかった。また、林内のCO2、は夜間に貯留され朝の日射の開始と共にそれが消費される様子が認められた。貯留の割合は風が強いときは林上のC02フラックスに比べると小さいが、弱風時には10％を超え、無視できない量であることがわかった。
  • Tomomi Takeda, Takashi Hirano, Shin-Ichi Urano, Ikuo Horiguchi
    Journal of Agricultural Meteorology 57 (3) 145 - 153 1881-0136 2001/09/01 [Refereed][Not invited]
     
    Canopy structure of crops is an important factor determining the radiation environment of the canopy. Although many researchers have dealt with foliage distribution by using a probability density function, studies that reproduce a spatial destribution and spatial form of foliage in 3 dimensional (3D) space have only recently been reported. In this study, we developed a geometric model by using L-system to reproduce the form of sunflower plants in 3D space. The model consisits of frame and leaf models. In order to obtain functions to illustrate the frame model, positions of nodes, leaf bases, and leaf tips were measured from photographs of sunflower plants taken at five different stages in a growing season, and lengths of internode, petiole and leaf were determined. Moreover, lengths of five lateral veins, and divergence angle between midrib and fifth lateral vein were measured. Growth curve of internode and petiole could be expressed as a logistic function of step number in L-system. Leaves elongated as a function of petiole length. Zenith angle of petiole decreased with step number from 1 to 7, and then stabilized at about 35°. Leaf zenith angle was related to petiole zenith angle. Divergence angles between successive leaves differed in different phyllotaxis. In distichous phyllotaxis, divergence angle was 180° between the leaves at the same node, and 90° between the leaves at successive nodes. On the other hand, in alternate phyllotaxis, divergence angle was about 135°. Leaf expansion could be related to increase in leaf length. In conclusion, the geometric model using L-system successfully reproduced the growth of sunflower plants with increase in node number. © 2001, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • SHIGEHISA Shinji, HIRANO Takashi, KIYOTA Makoto
    Papers on environmental information science 環境情報科学センター 14 249 - 254 0389-6633 2000 [Refereed][Not invited]
  • T Hirano, K Morimoto
    ENVIRONMENTAL POLLUTION 106 (1) 5 - 12 0269-7491 1999 [Refereed][Not invited]
     
    Changes of tree-ring widths of Japanese black pine (Pinus thunbergii Par1.) trees growing in air-polluted and unpolluted areas were analyzed. In the stand close to an industrial complex, a large reduction in the series of tree-ring index (TRI), which were computed by removing endogenous effects from the measured series, appeared from the 1960s to 1970s. This reduction in radial tree growth was not explained by the climatic response model calibrated for a pre-pollution period. TRI changes corresponding with changes in concentrations of sulfur dioxide (SO2), and a significant negative correlation between the TRI and SO2 concentration were found in the polluted area. Reduction in tree-ring growth was not seen in the unpolluted area. These results indicate that the past reduction in the growth of Japanese black pine trees growing in an industrial area was mainly caused by SO2. (C) 1999 Elsevier Science Ltd. All rights reserved.
  • Sung I, Kiyota M, Hirano T
    Life Support & Biosphere Science 5 137 - 142 1998 [Refereed][Not invited]
  • 大阪府下における通称フェニックスの植栽分布と寒さによる葉の被害程度
    平井源一郎, 平野高司, 西田実
    南紀生物 40 79 - 81 1998 [Refereed][Not invited]
  • SUNG II Kyung, KIYOTA Makoto, TANI Akira, HIRANO Takashi, MURAKAMI Katsusuke, TAIRA Tomoaki
    Environmental Control in Biology Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists 36 (2) 85 - 90 0582-4087 1998 [Refereed][Not invited]
     
    Cucumber (Cucumis sativus L. cv. Naoyosi) plants were grown hydroponically at air temperatures of 28/24°C (D/N) and 300μmol m-2 s-1 PPF, in a walk-in type growth cabinet equipped with 3-band fluorescent lamps. For 0, 5, 30 or 120 min, blue-lighting at 30 μmol m-2 s-1 in PPF was applied daily just before the 14 h photoperiod (morning twilight) . Growth parameters were measured after 12 and 24 d of treatment. After 13 d of treatment, the stomatal conductance, transpiration rate and net photosynthetic rate were measured under 3-band fluorescent lamps at a PPF of 200 μmol m-2 s-1. At 17-19 d of treatment, changes in net photosynthetic rate affected by blue-light were measured continuously for 30 min. Fresh and dry weight, leaf area, plant height and stem diameter of plants were the greatest with bluelighting for 5 min. The stomatal conductance, transpiration rate and net photosynthetic rate after 13 d of treatment were greatest in the plants grown with supplemental blue-light for 5 min. The net photosynthetic rate for 5 min treatment increased by 60% as compared with that of control plants grown without lighting. Continuous measurements showed net photosynthetic rate to rise and the high level was maintained with 5 min blue-lighting treatment. These results indicate that the promotion of plant growth by blue-lighting during morning twilight is dependent on the lighting time. For cucumber seedlings, blue-lighting for 5 min was more effective for growth than for 30 and 120 min.
  • TOMITA Noriko, HIRANO Takashi, KIYOTA Makoto
    Environmental Control in Biology Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists 36 (3) 177 - 181 0582-4087 1998 [Refereed][Not invited]
     
    In order to know the effect of supplemental UV-A irradiation on the growth of lettuce (Lactuca sativa L. cv. Okayama) and radish (Raphanus sativus L, cv. Comet), these plants were grown under artificial irradiation with 3-band fluorescent lamps and additional UV-A lamps. The UV-A irradiation promoted shoot growth of both plants, and reduced the bitter taste intensity of mature lettuce leaves. However, the UV-A effects varied with stage of vegetative development. Moreover, there was no significant effect of the UV-A on the hypocotyl growth of radish plants.
  • 樹木によるガス状大気汚染物質の時期別収着速度
    重久眞至, 平野高司, 清田信
    環境情報科学論文集 12 35 - 42 1998 [Refereed][Not invited]
  • Monji N, Hamotani K, Hirano T, Yabuki K, Jintana V
    Journal of Agricultural Meteorology 52 489 - 492 1997 [Refereed][Not invited]
  • フィールドチャンバーを用いた樹木のガス状大気汚染物質収着速度の測定法
    重久眞至, 平野高司, 清田信
    環境情報科学論文集 11 1 - 6 1997 [Refereed][Not invited]
  • SUNG Il Kyung, KIYOTA Makoto, HIRANO Takashi
    Shokubutsu Kankyo Kogaku JAPANESE SOCIETY OF AGRICULTURAL, BIOLOGICAL AND ENVIRONMENTAL ENGINEERS AND SCIENTISTS 9 (4) 271 - 277 0918-6638 1997 [Refereed][Not invited]
     
    Cucumber (Cucumis sativus L. cv. Naoyosi) plants were grown hydroponically at air temperatures of 28/24°C (D/N) and 300 μmol m-2 s-1 PPFD, in a walk-in type growth cabinet equipped with 3-band fluorescent lamps. At 10, 30, 100, 200 μmol m-2 s-1 PPFD, supplemental blue-lighting was applied daily for 5min just before the 14h photoperiod (morning twilight).
    Growth parameters were measured after 7 and 14 days of treatment. After 13 days of treatment, the stomatal conductance, transpiration rate and photosynthetic rate were measured under 3-band fluorescent lamps at a PPFD of 300 μmol m-2 s-1. At 12-14 days of treatment, changes in photosynthetic rate were measured continuously for 30 minutes, after the end of supplemental blue-lighting.
    Dry weight, leaf area, stem diameter of plants were the greatest with blue-lighting at 30 μmol m-2 s-1 PPFD. The stomatal conductance, transpiration rate and photosynthetic rate after 13days of treatment were greatest in the plants grown with supplemental blue light at 30 and 100 μmol m-2 s-1 PPFD. The photosynthetic rate at 30 μmol m-2 s-1 PPFD increased by 23% as compared with that of control plants grown without supplemental lighting. Continuous measurements showed photosynthetic rate to rise, and the high level was maintained with 30 μmol m-2 s-1 PPFD blue-lighting treatment.
    These results indicate that the promotion of plant growth by supplemental blue-lighting at morning twilight is dependent on the lighting intensity.
  • T. Hirano, N. Tomita, I. Aiga
    Journal of Agricultural Meteorology 52 (5) 863 - 866 1881-0136 1997 [Refereed][Not invited]
     
    Radish plants were grown in chambers (PPFD 300 μmol m2s-1, day length 14 h, 21°C, 70 %RH) for 10 days, under UV-B irradiation (UV-BBE 0, 6.5 (low) and 8.6 (high) kJ m-2d-1) for 12ha day the plants were exposed to acid mist (pH 3.0 and 5.6) every 2 days. At the end of the treatments, leaf area, dry weights of shoot and hypocotyl, total chlorophyll content, water loss rate and water droplet contact angle (DCA), which is a measure of wettability, on adaxial and abaxial leaf surfaces were determined in each of 9 combinations of treatments, 3 (UV-B)×3 (mist, including no mist). UV-B radiation significantly decreased leaf area and dry weights of shoot and hypocotyl, and increased total chlorophyll content per unit leaf area. Similarly, acid mist of pH 3.0 significantly decreased leaf area and hypocotyl dry weight. However, no combined effect of UV-B and mist on these growth parameters and chlorophyll content was found. On the other hand, there were significant combined effects on DCA on both adaxial and abaxial surfaces at the high UV-B level, DCA on adaxial surfaces of treated leaves with mist decreased, although that of untreated leaves increased. © 1997, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Nobutaka Monji, Ken Hamotani, Takashl Hirano, Kazutoshl Yabuki, Vlpak Jintana
    Journal of Agricultural Meteorology 52 (2) 149 - 154 1881-0136 1996/09/01 [Refereed][Not invited]
     
    An experiment was conducted to find out the characteristics of CO2 flux in a mangrove forest of Thailand during the rainy season. The relaxed eddy accumulation method was applied to the measurement of the CO2 flux over the forest. The CO2 flux increased with solar radiation, and the daytime downward CO2 flux was -0.5~-1.0 mg m-2 s-1 for the global radiation 400~800 Wm-2, which is about the same magnitude as the typical values obtained in other tropical or temperate forests. The soil respiration was an order of magnitude smaller in the mangrove forest compared to other forests. © 1996, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Vegetation in Sakai city, Osaka as a sink of air pollutants
    Hirano T, Kiyota M, Aiga I
    Bulletin of Osaka Prefecture University, Series B 48 55 - 64 1996 [Refereed][Not invited]
  • HIRANO Takashi, MONJI Nobutaka, HAMOTANI Ken, JINTANA Vipak, YABUKI Kazutoshi
    Environmental Control in Biology Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists 34 (4) 285 - 293 0582-4087 1996 [Refereed][Not invited]
     
    In order to investigate the seasonal change of transpiration in mangrove species, the sap flow rates (Fs) in Bruguiera cylindrica were measured in southern Thailand, with a stem heat balance method. From the result, the transpiration rates (Tr) normalized by leaf area in wet and dry seasons were estimated to be 0.50 and 1.04 kg m-2 d-1 on the average, respectively. Tr in the dry season was rather high compared to that in the wet season. This was probably caused by the difference of meteorological conditions, such as solar radiation and air humidity. Moreover, stomatal conductance (gs) in 4 species, Rhizophora apiculata, Ceriops decandra, Xylocarpus moluccensis and B. cylindrica, was measured in the wet season with a porometry to investigate its interspecific difference. In all the species, gs reached a plateau at the PPFD of 200 to 400μmol m-2 s-1. The plateau in R. apiculata was estimated to be between 150 and 250 mmol m-2 s-1 ; the level is similar to that in evergreen trees in Japan. However, gs in the remaining 3 species was rather low.
  • HIRANO Takashi, AIGA Ichiro, MONJI Nobutaka, HAMOTANI Ken, JINTANA Vipak, ISHIKAWA Toshio, YABUKI Kazutoshi
    Environmental Control in Biology Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists 34 (1) 87 - 90 0582-4087 1996 [Refereed][Not invited]
     
    The pneumatophores of Avicennia and Sonneratia species photosynthesize and the photosynthetically generated O2 is used for the respiration in the roots in subsoil. To understand the radiation environment of the pneumatophores, we measured solar radiation on the vertical surface (Rv) in the water with dye films. The Rv averaged over the daytime at a depth of 30 cm was similar to the light compensation points in the pneumatophores. From this result, it can be supposed that the photosynthesis nearly compensated the respiration at a depth of 30 cm and supplied O2 to the roots in subsoil at shallower places, even when the pneumatophores were submerged in the daytime.
  • Hirano Takashi
    関西自然保護機構会報 関西自然保護機構 17 (2) 137 - 143 0919-4657 1995 [Refereed][Not invited]
  • KIYOTA Makoto, TANI Akira, MURAKAMI Katsusuke, HIRANO Takashi, AIGA Ichiro
    CELSS Journal 7 (2) 27 - 34 0915-4353 1995 [Refereed][Not invited]
  • HIRANO Takashi, SEKI Kazuo, AIGA Ichiro, KAWASE Kenji
    Environment control in biology 日本生物環境調節学会 33 (2) 113 - 122 0582-4087 1995 [Refereed][Not invited]
  • T HIRANO, M KIYOTA, AIGA, I
    ENVIRONMENTAL POLLUTION 89 (3) 255 - 261 0269-7491 1995 [Refereed][Not invited]
     
    The physical effects of dust accumulating on leaf surfaces, on leaf physiology, such as photosynthesis, transpiration, stomatal conductance and leaf temperature of cucumber and kidney bean plants were investigated by the use of chemically inert dust. It was found that dust decreased stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting. When dust of smaller particles was applied the effect was greater. However, the effect was negligible when the stomata were closed during dusting. The dust decreased the photosynthetic rate by shading the leaf surface. The dust of smaller particles had a greater shading effect. Moreover, it was found that the additional absorption of incident radiation by the dust increased the leaf temperature, and consequently changed the photosynthetic rate in accordance with its response curve to leaf temperature. The increase in leaf temperature also increased the transpiration rare.
  • HIRANO Takashi, UCHIDA Akio, KIYOTA Makoto, ENOKI Mikio, AIGA Ichiro
    Journal of Japan Society of Air Pollution Japan Society for Atmospheric Environment 30 (5) 327 - 336 1341-4178 1995 [Refereed][Not invited]
     
    The single and combined effects of O3, NO2 and SO2 on net photosynthetic rate (Pn) and leaf diffusive conductance (LDC) in 3-year-old Japanese cedar clones (Cryptomeria japonica D. Don, cv. Shibahara) were investigated. Moreover, the effects of air temperature (15, 25 and 35°C) and humidity (50 and 70% RH) on the response of Pn and LDC in the clones of two cultivars (Shibahara and Nakagen) to the mixture of 0.1 ppm O3 and NO2 were also investigated. At 25°C and 70% RH, the Pn and LDC in Shibahara clones did not reduce when they were exposed to 0.1 ppm O3, NO2 and SO2 alone for three hours. However, the exposure to the mixture of the three gases resulted in the significant reductions in Pn and LDC. The reduction in Pn was caused not only by reduction in stomatal conductance but also by that in mesophyll conductance.
    Although there were no effects of the mixture of 0.1 ppm O3 and NO2 on Pn, the effects on LDC depended on cultivars, air temperature and relative air humidity. By the exposure to the mixture of O3 and NO2, the LDC in Shibahara clones was significantly reduced at 15 and 35°C under the condition of 70% RH, while it was not reduced at 50% RH. On the other hand, no change in the LDC in Nakagen clones simultaneously exposed to O3 and NO2 was detected under all experimental conditions.
  • HIRANO Takashi, AIGA Ichiro
    Journal of Environmental Conservation Engineering 環境技術学会 123 (12) 728 - 732 0388-9459 1994 [Refereed][Not invited]
  • AIGA Ichiro, KIYOTA Makoto, HIRANO Takashi, MURAKAMI Katsusuke, TANI Akira
    Environmental Control in Biology Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists 32 (2) 71 - 78 0582-4087 1994 [Refereed][Not invited]
  • Takashi Hirano, Kazuo Seki, Makoto Kiyota, Ichiro Aiga
    Journal of Agricultural Meteorology 49 (4) 273 - 277 1881-0136 1994 [Refereed][Not invited]
     
    Cucumber plants were grown in the pots cantaining the soil covered with volcanic ash from Mt. Unzen-Fugendake, and the concentration of CO2 and O2 in the soil was measured during the cucumber growth. Diffusion of O2 was also measured in the volcanic ashes from Mt. Unzen-Fugendake and Mt. Sakurajima, and in the soil. The O2 diffusion coefficients were much smaller in the volcanic ashes than in the soil. In the rhizosphere, the concentration of CO2 increased and that of O2 decreased under the soil cover with the volcanic ash. This was attributed to the slower exchanges of CO2 and O2 between the atmosphere and the soil through the volcanic ash layer. The cucumber growth in the pots with the soil cover was slower than in the control pots. The increased CO2 concentration in the rhizosphere may be the cause of the growth reduction. © 1994, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Gen-ichi HlRAI, Masayo Omori, Hiroyoshi Chujo, Osamu Tanaka, Toshikatsu Okumura, Shiro Takeuchi, Takashi HlRANO
    Japanese Journal of Crop Science 62 (3) 395 - 400 1349-0990 1993 [Refereed][Not invited]
     
    The effect of relative humidity (RH) on the dry matter production and nitrogen absorption of rice seedlings (age in leaf mumber of 5) was investigated. Plants were grown for 4 days under 60 or 90% RH at 12 -hr day/12-hr night temperatures of 24/20, 28/24, 32/28 and 36/32°C. 1. Dry matter increase of leaves and roots in the plants grown at 90% RH was higher at 24/20 and 28/24°C, but lower at 32/28 and 36/32°C than that of the plants grown in 60% RH. 2. Nitrogen absorption and content of heavy nitrogen of leaves and roots in the plants grown at 90% RH were also higher at 24/20 and 28/24°C, but lower at 32/28 and 36/32°C than those of the plants grown in 60% RH. These results indicate that dry matter increase and nitrogen absorption of rice seedlings are affected by humidity and temperature, with highly significant correlations. © 1993, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.
  • 植物による都市の熱環境緩和
    清田信, 平野高司, 相賀一郎
    環境情報科学 22 96 - 100 1993 [Refereed][Not invited]
  • 洞口公俊, 森田, 平野高司, 清田信, 相賀一郎
    National Technical Report 松下電器産業技術総務センター技術情報部 38 (1) 114 - 122 0028-0291 1992 [Refereed][Not invited]
  • Gen-Ichi Hirai, Masayo Omori, Hiroyoshi Chujo, Takashi Hirano, Osamu Tanaka
    Japanese Journal of Crop Science 61 (3) 364 - 368 1349-0990 1992 [Refereed][Not invited]
     
    The effect of relative humidity (RH) on the growth and dry matter production of rice seedlings was investigated at the early vegetative stage. Plants were grown for 10 days under 60 or 90% RH at 12-hr day/12-hr night temperatures of 22/18 (low), 28/24 (moderate) and 34/30 (high) °C. Dry matter production of the plants grown at 90% RH was higher at low and moderate temperatures, but much lower at high temperature than that of the plant grown in 60% R.H. The increase of root dry weight was more influenced by RH than that of the top dry weight. Thus, the relative value of top weight to root weight (T-R ratio) of the plant grown under 90% RH decreased at the low temperature, but increased at the high temperature, as compared with that of the plant grown under 60% R.H. At the moderate temperature, T-R ratio of the plant grown in 90% RH was almost the same as that of the plant grown in 60% R.H. These results indicate that the effect of humidity on growth and dry matter production must be considered in association with the temperature. © 1992, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.
  • Takashi Hirano, Makoto Kiyota, Kazuo Seki, Ichiro Aiga
    Journal of Agricultural Meteorology 養賢堂 48 (2) 139 - 145 1881-0136 1992 [Refereed][Not invited]
     
    This study was conducted to infer the effects of volcanic ash accumulating on a leaf surface on its photosynthesis. Particle size distribution and shading ratio were measured on 2 kinds of ash from Mt. Sakurajima (white and black) and 4 kinds from Mt. Unzen-Fugendake. Reflected spectral radiant flux density, temperature and stomatal conductance of cucumber leaves covered with those ashes were also measured. Particle size distribution of ashes were different each other. Particle (< 3 μm) contents of them were 6 to 13%. Shading ratios were 8 to 20% at 5 g m-2 of ash load. The ash with smaller particle size had bigger shading ratio. Integrated radiant flux density (280-2500 nm) of reflection from leaves covered with ashes from Mt. Sakurajima (black and white) and Mt. Unzen-Fugendake at 50 gm-2 were 65, 53 and 106% to control leaves, respectively. Temperature of leaves covered with these ashes at 50 g m-2 increased by 2.4, 2.6 and 1.2°C, respectively, at a solar radiation of 876 Wm-2. The ash from Mt. Unzen-Fugendake, with the smallest particle size, decrease stomatal conductance significantly even after it was washed out from the leaf surface. These results suggest that the volcanic ash with dark color and small particle size reduces photosynthesis through shading, increasing temperature and plugging stomata. © 1992, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • 観葉植物のガス交換と室内ガス環境の改善
    清田信, 平野高司, 石黒武, 三輪, 相賀一郎
    環境情報科学 21 107 - 111 1992 [Refereed][Not invited]
  • 堺市におけるサンゴジュの葉内重金属含有量の20年間の変化
    矢吹万寿, 平野高司, 清田信, 青木正敏, 今村太, 相賀一郎
    環境情報科学 21 102 - 106 1992 [Refereed][Not invited]
  • Gen-ichi Hirai, Noboru Nakayama, Hiroyoshi Chujo, Toichiro Inano, Takashi Hirano, Hiroyuki Shimoda, Osamu Tanaka
    Japanese Journal of Crop Science 61 (1) 41 - 48 1349-0990 1992 [Refereed][Not invited]
     
    The horizontal distribution of leaf temperature in a rice population of 40 X 40 meters was investigated with an infrared scanning thermometer under a high temperature and high solar radiation during the period from late-July to late-August. The results obtained are summarized as follows: 1. Either the west wind blowing from a paved road toward the rice population or the east wind blowing across the field was the predominant wind direction in the examined rice population. These winds formed some belt-like low-temperature areas (rice plant waving) on the surface of the rice population. The leaf temperature in the cross section of the rice plant waving was the lowest at the middle of the rice plant waving and increased with distance from the middle. The temperature at the middle of the rice plant waving decreased gradually from windward to lee side in the case of the west wind, but did not vary in the case of the east wind. 2. In the case of the west wind, leaf temperature increased from the border to inside of the population at the wind speed of less than 1 m/sec, but it decreased with the distance from the bordering area at the wind speed of more than 1 m/sec. In the case of the east wind, the leaf temperature varied little in the rice population irrespective of the wind. speed. © 1992, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.
  • HIRANO Takashi, KIYOTA Makoto, AIGA Ichiro
    Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi Japan Society for Atmospheric Environment 26 (5) 352 - 358 0386-7064 1991 [Refereed][Not invited]
     
    In order to estimate the effect of road dust on photosynthesis by shading, dust load accumulated on leaf surface of satsuma mandarin trees were investigated. Dust load on leaf surface was indicated by the shading ratio, which was the fraction of light intercepted by the dust on the leaf.
    Dust load on lower surface of leaves were much less than that on upper surface. With the increase of distance from the road, the shading ratio decreased. The maximum value of the shading ratio was 30% at 1 m from the road. The shading ratio on leaves of roadside trees changed remarkably with the changes of traffic and precipitation. On inside leaves of the roadside trees' crown, the change of dust load was less than that on outside leaves.
    The effect of shading by road dust on the photosynthesis of satsuma mandarin trees was estimated every month from July to October in 1989 by using the shading ratio, solar radiation and a light curve of net photosyntheticrate of satsuma mandarin leaf. As a result, when the shading ratio was 10, 20 and 30%, it was estimated that the net photosynthesis of satsuma mandarin was decreased by 5, 9-12 and 16-19%, respectively.
  • 水稲における葉温と光合成速度の関係
    平井源一, 中山登, 中條博良, 田中修, 平野高司
    近畿作物育種研究 36 91 - 93 1991 [Refereed][Not invited]
  • Takashi Hirano, Makoto Kiyota, Ichiro Aiga
    Journal of Agricultural Meteorology 46 (4) 215 - 222 1881-0136 1991 [Refereed][Not invited]
     
    The physical effects of dust on gaseous exchange through stomata were investigated by measuring stomatal conductance of dusted and clean leaves. The effects of dust by increasing leaf temperature on net photosynthetic rate and transpiration rate were investigated. Four classes of dust (JIS Z 8901: three classes of Kanto-loam powder and carbon-black), which were different in particle size and were chemically inert to plants, were made to adhere to upper surface of leaves of cucumber plants. In order to except the shading effect of dust, stomatal conductance, net photosynthetic rate and transpiration rate were measured under the condition of fairly high light intensity. The stomatal conductance of upper surface of dusted leaves whose stomata had been open in exposure of dust to leaves decreased in light peoriod and increased in dark peoriod. As particle size of dust became smaller, the changes of stomatal conductance increased both in light peoriod and dark peoriod. There was no change of stomatal conductance of leaves which had been exposed to dust when stomata had been closed. It seemed that dust caused these changes of stomatal conductance by covering and plugging stomata. Temperature of leaves covered with carbon-black were higher than clean leaves by 1.7-3.7°C in 15-40°C of air temperature. The net photosynthetic rates of leaves which had been exposed to carbon-black when stomata had been closed were higher than the rates of clean leaves below 25°C of air temperature, and were lower above 30°C. The transpiration rates of the same dusted leaves were higher than the rates of clean leaves by 0.4-0.6 g • dm-2 • hr-1 in 15-40°C of air temperature. The results suggest that dust affects net photosynthetic rate by covering and plugging stomata, and by increasing leaf temperature. © 1991, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Takashi Hirano, Makoto Kiyota, Yoshiaki Kitaya, Ichiro Aiga
    Journal of Agricultural Meteorology 46 (1) 1 - 7 1881-0136 1990 [Refereed][Not invited]
     
    Dust cover on leaves is considered to affect photosynthesis directly, mainly by shading leaf surface, increasing leaf temperature and plugging stomata. This study was carried out to make clear these physical effects of dust on photosynthesis. Four classes of JIS Z 8901 dust (Carbon-Black and Kanto-loam powder Coarse, Fine, Ultrafine), which were different in particle size and had pH values around neutrality, were applied to upper surfaces of leaves of kidney bean and cucumber plants at various densities. These two species were different in stomatal density. Both net photosynthetic rates and leaf temperatures of dusted leaves and clean leaves were measured at the same time, over a range of light intensities. The following results were obtained both in kidney bean and cucumber plants. (1) Photosynthetic rate was reduced by dust. As dust density on leaf surface increased, it was reduced further. (2) When carbon-black was applied, leaf temperature increased by 3°C at the maximum, but none of three classes of kanto-loam powder increased leaf temperature. (3) Regardless of dust characteristics or dust density, the reduction in photosynthetic rate was nearly equal to the reduction in PPFD incoming to upper surface of leaf by dust accumulation, in all measurments in this study. Therefore it seemed that the shading leaf surface was the most important of the injurious physical effects of dust on photosynthesis. © 1990, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • Ikuo Horiguchi, Takashi Hirano
    Journal of Agricultural Meteorology 養賢堂 43 (4) 295 - 303 1881-0136 1988 [Refereed][Not invited]
     
    Following the previous studies (Horiguchi I., et al, 1983, 1985), a study on fog formation in greenhouses and the characteristics of plastic films was made with regard to the following objectives. 1) Comparison of fog formation or density in the tunnels when using films with different duration of use (Table 1). In addition to fog formation, temperature, humidity and the amount of water flowed down on the film were also measured. 2) Investigation of fog formation or density with regard to the different contents of surface active agent contained in films (Tables 2 & 3). The surface active agent used was a sorbitan group (named Surfactant S). 3) Investigation of fog formation or density through changing the quality of the surface active agents contained in the films (Tables 3 & 4). In this case, two kinds of experiments were conducted as follow: a) adding surfactant F (fluorine group surface active agent) to surfactant S, b) adding surfactant Sb plus surfactant F to surfactant Sa. 4) Investigation of fog formation or density for different types of plastic films. Six different kinds of films, i.e., polyolefin, EVA, PE, none-dropping-type PVC, none-fog formation-type PVC, and dropping-type PVC, were used. Major results of the experiments can be summarized as follows: 1) The less fog formation or density, the larger amount of water flowed down on the film, was observed. 2) Fog formation or density was not related to both the minimum temperature and humidity. 3) With both none-dropping-type and dropping-type PVC films, fog formation or density was reduced with the age of films. 4) In case of none-fog formation-type PVC film, the amount of fog formed increased with duration of use of the films until a certain point, and then was reduced. 5) In both cases of films containing no surface active agents (dropping-type PVC) and films containing only a small amount of surface active agents, fog formation or density was less. 6) Up to around 1.5 phr, work of adhesion increased in proportion to the amount of surface active agents contained in the films. 7) Beyond about 1.5 phr, work of adhesion slightly decreased. However, the relationship between work of adhesion and the amount of active surface agents was not clear. 8) Addition of surfactant F to films containing surfactant Sa and Sb, greatly reduced fog formation and density. 9) Among the samples of six different plastic films which are on the market, the lowest fog formation or density was observed with dropping-type PVC without surface active agents. From these results, it can be concluded that fog formation, density and quality of films are closely related to the easy flow of water adhered to the film and the ease with which vapor adheres to the film. Although these two characteristics are contrary to each other, it is considered that a feature combining allowance of water flowing down and ease of vapor adhesion is developed by adding surfactants F to S. © 1988, The Society of Agricultural Meteorology of Japan. All rights reserved.
  • 海洋性冷気流の農業地帯への影響に関する研究―勇払・石狩平野における気温変化―
    平野高司, 堀口郁夫, 谷宏, 松岡延浩
    北海道の農業気象 37 18 - 20 1985 [Refereed][Not invited]

MISC

Books etc

  • 平野高司 (Joint work異常気象と気候変動，光合成と気象環境)
    文永堂出版 2021/01 (ISBN: 9784830041419) xvi, 301p
  • 持続可能な社会への道 : 環境科学から目指すゴール
    平野高司 (Joint work熱帯における土地利用変化と物質循環)
    日本学術協力財団 2020/10 (ISBN: 9784990997236) 263p
  • 平野高司 (Joint editor地表近くを吹く風，熱と物質の流れ，植物群落の熱・物質収支の測定法)
    朝倉書店 2020/04 (ISBN: 9784254440300) ix, 199p, 図版 [2] 枚
  • 平野高司 (Joint work熱帯林への気候変動および人間活動の影響)
    共立出版 2019/12 (ISBN: 9784320058224) xii, 216p, 図版 [12] p
  • 図説 日本の湿地
    平野 高司 (Contributor二酸化炭素の吸収と蓄積)
    朝倉書店 2017/06
  • 湿地の科学と暮らし 北のウエットランド大全
    HIRANO Takashi (Contributor湿地の炭素固定機能)
    北海道大学出版会 2017/04
  • Tropical Peatland Ecosystems
    Wataru Takeuchi, Takashi Hirano, Orbita Roswintiarti (Joint workEstimation model of graound water table at peatland in Central Kalimantan, Indonesia)
    Springer 2016
  • サロベツ湿原と稚咲内砂丘林帯湖沼群
    平野 高司 (Joint work地表のエネルギー収支と蒸発散)
    北海道大学出版会 2014
  • 北海道の気象と農業（日本農業気象学会北海道支部）
    平野 高司 (Editorはじめに，森林と大気の関係)
    北海道新聞社 2012/11
  • Agricultural Sciences for Human Sustainability
    平野高司 (ContributorCarbon dioxide exchange between the atmosphere and terrestrial ecosystems)
    海青社 2012/06
  • The Biodiveristy Observation Network in the Asia-Pacific Region, Ecological Research Monographs
    Osaki M, Hirano T, Inoue G, Honma T, Takahashi H, Takeuchi W, Kobayashi N, Evri M, Kohyama T, Ito A, Setiadi B, Sekine H, Hirose K (ContributorSensing/monitoring networks on carbon balance and biodiversity in tropical peatland)
    Springer 2012
  • 浦野 慎一, 山川 修治, 文字 信貴, 小林 哲夫, 大槻 恭一, 平野 高司, 町村 尚, 上村 賢治, 鈴木 晴雄, 谷 宏, 蔵田 憲次, 干場 信司, 蓑輪 雅好 (Contributor光合成による生物生産，異常気象と気候変動)
    文永堂出版 2009 (ISBN: 9784830041167)
  • 続・環境負荷を予測する（日本土壌肥料学会監修）
    平野高司, 児玉裕二, 梁 乃申 (Contributor土壌呼吸の自動測定)
    博友社 2005/09
  • 森林の科学（中村太士，小池孝良編著）
    平野 高司 (Contributor北方林と気候との相互作用)
    朝倉書店 2005/09
  • 新農業情報工学（農業情報学会編）
    平野 高司 (Contributor気象予測)
    養賢堂 2004/08
  • 陸域生態系における二酸化炭素等のフラックス観測の実際（AsiaFlux運営委員会編）
    平野高司, 三枝信子 (Contributor渦相関法によるフラックス測定の実際)
    国立環境研究所地球環境研究センター 2004
  • 地球温暖化－世界の動向から対策技術まで－
    藤沼康実, 三枝信子, 平野高司 (Contributor温室効果ガスのモニタリングと森林フラックスの測定)
    裳華房 2003/11
  • 地表面フラックス測定法（気象研究ノート199）
    平野 高司 (Contributor土壌呼吸量)
    日本気象協会 2001/03
  • 文字信貴, 平野高司, 高見晋一, 堀江武, 桜谷哲夫, 文字 信貴, 高見 晋一, 桜谷 哲夫, 平野 高司, 堀江 武 (Joint editor植物の放射環境，地表に接した大気の特徴，熱と物質の流れ，環境汚染と植物)
    丸善 1997/08 (ISBN: 462104351X) 199
  • 新版 生物環境調節ハンドブック（日本生物環境調節学会編）
    平野 高司 (Contributor環境に対する生物の反応（エアロゾル，粉じん）)
    養賢堂 1995/04

Presentations

  • Networking flux researches to assess the carbon balance of tropical peatland ecosystems in SE Asia  [Invited]
    HIRANO Takashi
    9th AsiaFlux Workshop  2011/11
  • Evapotranspiration of peatlands with different vegetation types  [Invited]
    HIRANO Takashi
    Yangling International Agri-Science Forum 2011  2011/11
  • Increasing vulnerability of tropical peat carbon  [Invited]
    HIRANO Takashi
    3rd ASIAHOECs Joint Symposium  2011/10
  • Carbon Flux in Tropical Peat  [Not invited]
    HIRANO Takashi
    5th Technical Roundtable on MRV "Key Workshop on MRV and REDD+"  2010/10
  • 熱帯泥炭林の現状と炭素収支  [Invited]
    平野高司
    SELIS-GCOE合同セミナー  2010/10
  • Effect of drainage on soil respiration in tropical peat swamp forest  [Not invited]
    HIRANO Takashi
    International Workshop on "Wild fire and carbon management in Peat-Forest in Indonesia"  2010/09
  • 熱帯泥炭林の炭素収支  [Invited]
    平野高司
    統合的陸域圏研究連絡会  2009/05
  • Fire, degradation and carbon flux: monitoring and field experiment in East Asia  [Not invited]
    HIRANO Takashi
    IGBPシンポジウム  2009/04
  • 陸上植物はどれだけ二酸化炭素を吸収しているのか？  [Invited]
    平野高司
    北海道芝草研究会講演会  2009/01
  • タワー観測ネットワーク（JapanFlux）の現状  [Invited]
    平野高司
    地球観測連携拠点国内ワークショップ  2008/12
  • 微気象学的方法による陸域生態系の炭素吸収量の推定 －わかることとわからないこと－  [Invited]
    平野高司
    日本農業気象北海道支部・東北支部合同シンポジウム  2008/11
  • フラックス研究の現状と将来像  [Invited]
    平野高司
    日本農業気象学会シンポジウム  2008/11
  • Carbon dioxide balance of tropical and temperate forests  [Invited]
    HIRANO Takashi
    G8関連シンポジウム  2008/07
  • 泥炭と地球環境  [Invited]
    平野高司
    北海道土質試験協同組合技術懇談会  2008/05
  • 熱帯泥炭の炭素収支  [Not invited]
    平野高司
    「熱帯泥炭のCDM化」ワークショップ  2007/08
  • Field manipulative experiments for evaluating disturbance effects on ecosystem carbon exchange  [Invited]
    HIRANO Takashi
    International Symposium on monitoring and predicting the change in the terrestrial human-environment systems  2006/02
  • 空気質と植物生産  [Invited]
    平野高司
    植物工場学会北海道支部講演会  2005/11
  • Three years of flux measurement at Tomakomai FRS  [Invited]
    HIRANO Takashi
    APGC-Post Flux Meeting  2004/10
  • 苫小牧カラマツ林におけるCO2フラックスモニタリング  [Invited]
    平野高司
    IGBP国内シンポジウム  2001/03
  • 植物のガス交換計測  [Invited]
    平野高司
    日本農業気象学会北海道支部講演会  2000/12
  • 都市の大気汚染と植物  [Invited]
    平野高司
    日本農業気象近畿支部50周年記念シンポジウム  1996/11
  • 作物の成長に与える紫外線（UV-B）の影響  [Invited]
    平野高司
    照明学会1996年全国大会  1996/06

Teaching Experience

  • Agricultural MeteorologyAgricultural Meteorology Hokkaido University, Faculty of Agriculture

Association Memberships

  • The Ecological Society of Japan   JpGU   The meteorological Society of Japan   Japanese Society of Agricultural, Biological and Environmental Engineers and Scientists   AsiaFlux   The Society of Agricultural Meteorology of Japan   JapanFlux   

Research Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A)
    Date (from‐to) : 2022/06 -2024/03 
    Author : Takashi Hirano
  • 文部科学省：科学研究費補助金（基盤研究S）
    Date (from‐to) : 2019/07 -2024/03 
    Author : 平野 高司
  • メタン吸収能を含めたアジア域の森林における土壌炭素動態の統括的観測に基づいた気候変動影響の将来予測
    独立行政法人環境再生保全機構：環境省環境研究総合推進費
    Date (from‐to) : 2020/04 -2023/03 
    Author : 梁乃申, 高橋善幸, 高木健太郎, 平野高司, 石田祐宣, 髙木正博, 市井和仁, 近藤俊明, 小嵐淳, 安藤麻里子, 寺本宗正
  • Research Institute for Humanity and Nature：Research Project
    Date (from‐to) : 2013/04 -2022/03
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : 伊藤 雅之, 平田 竜一, 平野 高司, 常田 岳志, 坂部 綾香
     
    インドネシア・中カリマンタン州のサイトにおいては、フラックス観測タワーを用いた生態系スケールのメタンフラックス観測を継続して行っており、気象の年々変動を受けてどのように変動するかについてのデータが蓄積されつつある。新型コロナウィルスの拡大により現地でのデータ回収等が行えなくなったため、カウンターパートとオンライン会議システムを用いることで観測データの回収を継続している。 入荷が遅れていたレーザーメタン計を用いた現地でのチャンバー法によるメタンフラックス観測の準備を整えた。しかしながら新型コロナウィルスの感染症の拡大により海外渡航し現地調査できない状況となっている。そのため過去に採取した様々な土地利用条件下の熱帯泥炭地の地下水中溶存有機態炭素の量と質の分析及びデータ解析を進めた。インドネシア・スマトラ島のリアウ州（未火災の泥炭地二次林・複数回の火災を受けた焼け跡や後に小規模オイルパーム農園化した泥炭地・アカシアプランテーションから流出する排水路の水・天然泥炭湿地林など）とカリマンタン島の中カリマンタン州（未排水の泥炭湿地然林・排水泥炭林・複数回火災を受けた焼け跡）を含む約250個の試料について、燃焼式吸光光度法によるDOC濃度測定、EEMSによるDOMの蛍光特性分析を行った。クラスター解析及び主成分分析を行ったところ、土地利用ごとに個別のクラスターとして分類され、現在、既に得られている水質データと合わせてデータを検討している。これまでの結果から、火災を受けた泥炭地下水のDOCの性質は未火災の泥炭地のものとは異なることなどが示唆された。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2021/03 
    Author : Kumagai Tomo'omi
     
    The original plan was to develop the forest inventory network with numerous plots over Southeast Asian tropical forests and conduct synthesized forest carbon balance analyses. However, we did not complete most of the plan because of the worldwide covid situation. Under such a situation, we (1) were successful in arranging some highland mixed forest plots in Vietnam, (2) clarified that the effects of illegal logging are critical in evaluating the total forest carbon balance in Myanmar, (3) suggested twice more total forest carbon stock than the previous estimation via revisiting the total Japanese forest inventory data, and (4) successfully developed an individual-based forest dynamics model, which can be applied for the global-scale simulation.
  • JSPS：二国間交流事業 オープンパートナーシップ共同研究
    Date (from‐to) : 2018/04 -2020/03 
    Author : HIRANO Takashi
  • 文部科学省：科学研究費補助金（萌芽）
    Date (from‐to) : 2017/07 -2020/03 
    Author : 平野 高司
  • 環境省：環境研究総合推進費
    Date (from‐to) : 2015/06 -2018/03 
    Author : 平野 高司
  • 旭硝子財団：環境研究 近藤次郎グラント
    Date (from‐to) : 2015/04 -2018/03 
    Author : 平野 高司
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : TAKAGI Kentaro, IDE Reiko, HIRAYAMA Kojiro
     
    We examined the feasibility of estimating forest biomass changes using two airborne LiDAR measurements of forest height acquired 10 yr apart (2004 and 2014) over the Teshio Experimental Forest (225 km2) of Hokkaido University in northern Japan, with 1 ha spatial resolution. The average of the decadal net biomass change was 4.18 (±6.64 SD) MgC/ha having large spatial variation. Estimated values were comparable with the results obtained from ground surveys or tower flux observations. Decadal net biomass change was significantly lower at high elevation, north facing slope, steep slope, large tree height variance, and coniferous forest, and significantly higher at south facing slope, deciduous forest, and secondary forest. The photosynthetic biomass increase was linearly correlated with the decadal average of the MODIS NDVI and Green ratio, which implies the application of satellite vegetation indices to further large scale estimation of forest biomass changes
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013/04 -2016/03 
    Author : ICHII Kazuhito, KOBAYASHI Hideki, SATO Hisashi, KATO Tomomichi, UEYAMA Masahito, SASAI Takahiro, KONDO Masayuki, WATANABE Akira, ITOH Akihiko, SAIGUSA Nobuko, HIRANO Takashi
     
    Terrestrial carbon budget in Asia was analyzed using network data of site observation (e.g. AsiaFlux), remote sensing data, and terrestrial ecosystem models. Data-driven terrestrial CO2 fluxes were estimated using AsiaFlux observation and remote sensing data with a machine learning method. The data-driven estimation of CO2 fluxes were further evaluated with outputs from multiple terrestrial biosphere models, and we found consistent interannual variations and gradual increases in CO2 sink in Siberia. We also found large model-data differences in tropical Asia region.
  • 文部科学省：科学研究費補助金（基盤研究（A））
    Date (from‐to) : 2013 -2016 
    Author : 平野 高司
  • 文部科学省：科学研究費補助金（基盤研究（A））
    Date (from‐to) : 2013 -2016 
    Author : 平野 高司
  • 土地利用変化が熱帯泥炭の分解にともなう二酸化炭素排出に与える影響の評価
    住友財団：環境研究助成
    Date (from‐to) : 2014/11 -2015/11 
    Author : 平野 高司
  • 東アジア陸域生態系における炭素動態の定量化のための日中韓研究ネットワークの構築
    日本学術振興会：日中韓フォーサイト事業
    Date (from‐to) : 2007/08 -2012/07 
    Author : 平野 高司
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 2008 -2012 
    Author : Noboru NOGUCHI, 平野 高司, 波多野 隆介, 山田 浩之, 石井 一暢, 海津 裕
     
    (抄録なし)
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2009 -2011 
    Author : HIRANO Takashi, KONDO Hiroaki, MAEDA Takahisa, KOSUGI Yoshiko, TAKANASHI Satoru, TANAKA Nobuaki, TAMAI Koji, KUMAGAI Tomoomi, SAIGUSA Nobuko
     
    We have continuously measured fluxes of CO2 and water vapor above 11 tropical forests in Southeast Asia. Using the long-term monitoring data, gas exchange processes (photosynthesis, respiration and evapotranspiration) were examined. As a result, factors controlling the gas exchange processes were determined, and the effect of a precipitationpattern on the gas exchange processes was elucidated.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2008 -2010 
    Author : HIRANO Takashi, HATANO Ryusuke, INOUE Takashi, FUJITA Hiroko, YAMADA Hiroyuki, TAKADA Masayuki
     
    We compared evapotranspiration and carbon balance between areas dominated by sphagnum species and vascular plats,"sasa" using flux monitoring data. Evapotranspiration during the snow-free season was higher at the sphagnum area than the sasa area, which does not support a hypothesis that the invasion of sasa plants with root systems dries the Sarobetsu Mire. The carbon balance during the snow-free season shows that both the ecosystems functioned as net CO_2 sinks to the atmosphere. In 2010, which had a very hot summer, net CO_2 uptake increased in the sphagnum area, whereas it decreased in the sasa area mainly because of increased ecosystem respiration due to high temperature.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 2007 -2010 
    Author : Takashi INOUE, 大崎 満, 橋床 泰之, 俵谷 圭太郎, 原口 昭, Ryusuke HATANO, Takashi HIRANO, Hiroshi TANI, Hideyuki SAITOU, Yutaka TAMAI, Mitsuru OSAKI, Hiroshi HATA, Yasuyuki HASHIDOKO, Yasumitsu URAKI, Keitaro TAWARAYA, Akira HARAGUCHI, Ryuichiro ABE
     
    Tropical peat land is a huge carbon sink involving an ecosystem that is very fragile but rich in biodiversity. This study deployed on establishment of measures for optimum land use and land management based on the viewpoint of control of carbon flow in tropical peatland. Prevention of peat fire, restoration of devastated land, sustainable bioproduction, and the reduction of environment load are the special interest that is rendered for the approach.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2006 -2008 
    Author : Takashi HIRANO, 谷 宏, 井上 京, 島田 沢彦, 山田 浩之
     
    東南アジアの低平地に分布する熱帯泥炭地は膨大な量の土壌炭素を貯留しているが, 開発による地下水位の低下などにより, 大量のCO_2を大気に放出する危険性が高まっている。そのため, CO_2排出量を抑制するために, 排水路を堰上げする簡易ダムによる環境修復が実施されている。本研究では, 生態系と大気との間のCO_2交換量をモニタリングし, ダムによる環境修復が熱帯泥炭の好気的分解を抑制し, CO_2排出量を低減させることを実証した。また, 衛星リモートセンシングを利用した地下水位の広域評価の可能性を示した。
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2005 -2007 
    Author : Takashi HIRANO, 藤沼 康実, 小熊 宏之, 梁 乃申, 犬飼 孔
     
    A plantation (42°44'N, 141°31'E) of Japanese larch (Larix kaempferi Sarg.) in Tomakomai, Hokkaido, Japan was destroyed by Typhoon Songda in September 2004. About 90% trees were blown down by strong wind. In this study, we compared vegetation properties, biomass and net ecosystem CO_2 uptake (NEP) before and after the typhoon damage. Before the typhoon damage, this forest was a 45-year-old plantation of Japanese larch with some broad-leaved trees. The canopy height was 15 m and the maximum leaf area index (LAI) was 5.6m^2 m^<-2>. After the typhoon, all stems of larch trees were removed from ...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2004 -2006 
    Author : Akira TANI, 高山 真策, 平野 高司, 小池 真
     
    In order to evaluate the contribution that higher plants make to the removal of volatile organic compounds from the atmosphere, a measurement system consisting of a proton transfer reaction mass spectrometer (PTR-MS), CO2 analyzer, diffusion devise and leaf enclosure was established. Methacrolein (MACR), methyl vinyl ketone (MVK), croton aldehyde (CA), methyl ethyl ketone (MEK) and methylisobuthylketone (MIBK) were fumigated. The uptake of VOCs by Epipremnum aureum, Quercus acutissima, Q. myrsinaefolia and Q. phillyraeoides was investigated.The overall error associated with measurements mad...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(S))
    Date (from‐to) : 2002 -2006 
    Author : Masami FUKUDA, 平野 高司, 町村 尚
     
    In the Mid of Siberian Taiga, long term field measurements at disturbed and control sites on Carbon budget, heat and mass transfers were conducted. As to investigation, two observation towers were installed. Before disturbance intact Taiga forest absorbed carbon dioxide by 86mg/m^2.day, but after disturbance carbon dioxide was emitted from the ground by 140 mg/m2.day due to the loss of vegetation and increase of soil respiration. Loss of surface vegetation resulted in the increase of flux heat to the ground by 20% and it caused the large scale thawing of upper permafrost. The long term file...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 2003 -2005 
    Author : Takashi HIRANO, 高橋 英紀, 大崎 満, 谷 宏, 井上 京, 岡田 啓嗣, 兒玉 裕二
     
    Tropical peatlands, which coexist with swamp forests, have accumulated vast amounts of carbon as soil organic matter. Since the 1970s, however, deforestation and drainage have progressed on an enormous scale. In addition, El Nino and Southern Oscillation (ENSO) drought and large-scale fires, which grow larger under the drought condition, are accelerating peatland devastation. That devastation enhances decomposition of soil organic matter and increases the carbon release to the atmosphere as CO_2. This phenomenon suggests that tropical peatlands have already become a large CO_2 source, but r...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2003 -2004 
    Author : Hiroshi TANI, 平野 高司, 王 秀峰, 矢沢 正士, 鮫島 良次
     
    Monitoring crop condition and production estimates on a large scale is important for food supply. The objectives of the study are (1)mapping meteorological values by use of Geostationary Meteorological Satellite data for solar radiation and by routine observation data for meteorological grid data on daily and hourly basis, (2)simulating crop growth by coupling of crop growth model and estimation model for meteorological data, (3)applying estimation technique for meteorological variables by satellite data to a foreign country, and (4)monitoring environmental information for agricultural prod...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2001 -2004 
    Author : Takashi HIRAO, 町村 尚, 鱧谷 憲, 文字 信貴, 岡田 啓嗣, 高木 健太郎
     
    An extremely important objective of long-term observations of CO_2 flux is to improve the understanding of climatic effects on the CO_2 exchange process between terrestrial ecosystems and the atmosphere for predicting net CO_2 ecosystem exchange (NEE). Nevertheless, reports that address NEE remain limited for Asian ecosystems. This paper reports the three-year measurement of NEE over a manmade Japanese larch forest in northern Japan, which is one of the most important forests for forestry in this area, using an eddy covariance technique with an open-path system from 2001 to 2003. Difference...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 2001 -2004 
    Author : Mitsuru OSAKI, 蒲生 稔, 平野 高司, 井上 京, 甲山 隆司, 松原 健司
     
    Huge amount of tropical peat distribute in Kalimantan, Indonesia, which face a crisis of decomposition by frequent fire because of unruly development and irregular logging. As CO_2 by fire and microorganisms are tremendously, it is observed CO_2 increase in atmosphere clearly. Therfore, we have studied here to rehabilitate forestry and to conserve peat soil in devastated peat land. Obtained results are as follows.(1)Estimation of environmental values1)Dynamics of chemical compounds and lignin degradationDynamics of chemical compounds was estimated in peat soil, river, and lake, for which ma...
  • 冬期積雪条件における森林土壌からのCO2発生量の評価
    住友財団：環境研究助成
    Date (from‐to) : 2003 -2003 
    Author : 平野 高司
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2002 -2003 
    Author : Ken HAMATANI, 文字 信貴, 平野 高司
     
    We developed a long-term methane flux measurement system with REA method and conducted a continuous observation in forests. The system operates automatically to make flux measurements with micro-computer. We developed the hardware of sampling system and processing parts and software for the long-term continuous estimation. We adopted a methane analyzer with FID detector. Although the accuracy of the analyzer is 50ppb, REA system requires relative concentration differences of two sampled air which this analyzer can detect down to several ppb.Before we carried out the methane flux measurement...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2001 -2003 
    Author : Nobuyoshi ISHIKAWA, 平野 高司, 石井 吉之, 兒玉 裕二, 知北 和久, 浦野 慎一
     
    For understanding the heat, water and carbon cycles of high latitudes, meteorological and hydrological researches have been carried out at the experimental watershed in Interior Alaska from 2001 to 2004. Observed items were radiation, sensible heat, evapo-transpiration, CO_2 concentration above vegetation floor, soil respiration, soil moisture, soil temperature, runoff and chemical contents of river water, groundwater and precipitation. Underground structure was obtained by geophysical exploration and confirmed by well borings at three different points in the watershed.The main observationa...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2000 -2002 
    Author : Kazuo YABE, 平野 高司, 倉持 寛太, 浦野 慎一, 植村 滋
     
    In order to clarify the reasons of regional differences in shape and size of Sphagnum hummocks throughout Hokkaido, we examined the growth of 3 Sphagnum species growing on hummocks in 4 mires, with controlling the conditions of snow pressure and shading by other plants. Fuhrengawa has cylindrical and extremely raised type, Sarobetsu and Utasai have flat and low type. Utonai has conical and middle height type, The annual growth was larger in Sarobetu and Utasai. Remarkable suppression of the growth of S. papillosum at Sarobetu was observed in June, where hummock surface was desiccated owing ...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1999 -2002 
    Author : Nobuyoshi ISHIKAWA, 兒玉 裕二, 田中 夕美子, 石井 吉之, 平野 高司, 高橋 英紀, 兒玉 裕二, 田中 夕美子
     
    For understanding the effects of forest and snow cover on the water, CO_2 and chemical cycles were examined at two different experimental watersheds from 1999 to 2003 including three snow cover seasons. One watershed located at the northern part of Hokkaido where the annual temperature range was -30℃ to 25℃ and the maximum snow depth was more than 2m. The other was at the southern part of Hokkaido, where the temperature range was -25℃ to 25℃ and the snow depth was below 50cm. Vegetations of both sites are mixed forests of evergreen needle leaf trees and deciduous broad-leaved trees with bam...
  • 熱帯泥炭林の消失にともなう環境劣化機構に関する研究
    昭和シェル石油：環境研究助成
    Date (from‐to) : 2001 -2001 
    Author : 平野 高司
  • 北方森林土壌におけるCO2の動態と発生量に関する研究
    アサヒビール学術振興財団：研究助成
    Date (from‐to) : 2001 -2001 
    Author : 平野 高司
  • 文部科学省：科学研究費補助金(萌芽的研究)
    Date (from‐to) : 2000 -2001 
    Author : 平野 高司
     
    土壌のCO_2濃度,土壌表面からのCO_2放出速度(土壌呼吸速度),および土壌の層別CO_2発生速度を長期・連続測定(モニタリング)する手法を開発し,森林において実証試験を行った(現在も継続中)。開発した手法は,小型の赤外線CO_2分析計を土壌の数深度に埋め込み,土壌CO_2濃度を連続測定し,得られたCO_2の濃度勾配,土壌のCO_2拡散係数,および土壌層でのCO_2貯留変化量を用いて,土壌中のCO_2の輸送速度(フラックス),土壌呼吸速度,CO_2発生速度を連続的に定量評価するものである。現地実験は,北海道大学苫小牧研究林の落葉広葉樹林において,1999年5月から,また隣接する苫小牧国有林のカラマツ林において2001年6月から連続して行っており,現在も継続中である。現地実験の結果,本研究で考案したシステムにより,土壌CO_2濃度および土壌呼吸速度を長期にわたり連続測定できることが実証された。土壌のCO_2濃度を,このような長期にわたって連続測定した例は過去にない。なお,2年間以上にわたる現地実験を通して得られた主要な結果は,1)土壌のCO_2濃度は,基本的には地温の変化にともなって日変化および季節変化するが,降雨にともなう土壌水分の変化にも影響を受ける,2)土壌呼吸速度は,地温の上昇にともなって指数関数的に増大し,7〜9月に最大となった,3)2000年6〜11月の無積雪期の...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1997 -2000 
    Author : Makoto KIYOTA, 平野 高司, 北宅 善昭, 渋谷 俊夫
     
    This study investigated the changes in CO_2 and H_2O gas exchange of woody plants due to increases in CO_2 concentrations. This report contains information obtained from the study on gas exchange of woody plants in ambient and elevated CO_2 concentrations :(1) effects of CO_2 concentration and light intensity on photosynthesis and transpiration rate of young trees,(2) inhibition of water stress in evergreen trees under elevated CO_2 concentration,(3) effects of elevated CO_2 concentration on heat balance and transpiration of tree seedlings,(4) method for measurement of sorption rates of gas...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1997 -1999 
    Author : Shinichi URANO, 堀口 郁夫, 山梨 光訓, 町村 尚, 上田 宏, 高橋 英紀, 平野 高司
     
    In order to study the relationship between landwater and bioproduction, the heat storage and lake effect in Lake Toya, and the characteristics of hydro-meteorology in Zanbeji river flood plain, Zambia, were invesitigated. The results are summarized as follows;In Lake Toya, because of large heat storage in the lake, there was the phase difference of about 6 months between land and water surfaces in the change of effective energy. Such phase difference has coursed the lake effect. The lake effects in Lake Toya were strongly generated in summer than in winter because the cold air on the water ...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(一般研究(C))
    Date (from‐to) : 1994 -1995 
    Author : Takashi HIRANO, 清田 信
     
    NO and NO2 fluxes were measured micrometeorologically from Oct.to Dec.in 1994 above vegetation and from Jul.to Oct.in 1995 above vegetation and bare soil. The experimental sites were a lawn (Zoysia matrella Merr.) trimmed to 1 cm (average LAI 4,2) and uncultivated bare soil, in Osaka Prefecture University. The fluxes were determined using a gradient method, together with those of CO2 and water vapor. Data for calculation were obtained near the surfaces, at heights of 2 and 8 cm. NO and NO2 concentration of the air sampled in shaded Teflon bags was determined with a chemiluminescent analyzer...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(試験研究(B))
    Date (from‐to) : 1993 -1995 
    Author : Ichiro AIGA, 洞口 公俊, 谷 晃, 村上 克介, 平野 高司, 清田 信
     
    This study had started after the success of our former project concerning the growth control of plants by additional far-red (FR) irradiation and 4-band fluorescent lamp for plant growth which has more FR irradiation than normal fluorescent lamp. Our aim in this research was as follows :(I) To get an efficient plant growth control method by modifying the spectral characteristics of 4-band fluorescent lamp.(2) Development of covering materials for greenhouses to control plant growth by changing the spectral distribution of daylight.(3) High speed measurements of spectral characteristics conc...
  • 文部科学省：科学研究費補助金(一般研究(C))
    Date (from‐to) : 1994 -1994 
    Author : 文字 信貴, 鱧谷 憲, 平野 高司
     
    増え続ける温室効果気体が地球の気候環境を変えることが懸念されているが,大気の微量気体がどの程度の量,どの様なメカニズムで,さまざまな地表から出ているか,あるいは植生などによって吸収されているが明確にされていないことは気候変化の予測を困難にする一因となっている.これは,微量気体の動態の測定技術が未開発であることが原因である.微量気体の交換過程は大気乱流の混合がその役割を果たす.したがって,微量気体濃度の乱流変動をさまざまな植被上などではかる必要があるが,現在の技術では分析器の応答性,安定性に限界がある.この点を解決する方法として提案されたのが渦集積法である.渦集積法は気流が上向きの成分と下向きの成分を持つ場合にわけてそれぞれ空気を別々にその成分の大きさに比例して容器に収集し,それぞれの濃度を計測する方法である.しかし,誤差が大きいため,条件を緩和して空気の収納を定速で行う簡易渦集積法が提案されている.本研究ではその方法を実用化するためにサンプリング装置を開発し,森林で試験観測を実施した.観測は滋賀県南部の針葉樹林で行った.この簡易渦集積法では係数を実験によって決定しなければならない.そのために,すでに乱流変動の測定が可能な赤外線の二酸化炭素変動計をもちいて直接的な渦相関法により二酸化炭素のフラックスを求め,その一方でサンプルした二つの容器の二酸化炭素濃度は購入した赤外線分析計を...
  • 文部科学省：科学研究費補助金(奨励研究(A))
    Date (from‐to) : 1993 -1993 
    Author : 平野 高司
     
    本研究では、緑化樹の大気浄化(NO_2吸収)機能と温湿度環境緩和機能を評価するための基礎的な実験データを得ることを目的として、いくつかの条件で植物のNO_2吸収速度、蒸散速度、光合成速度および葉温を同時測定し、それらの相互関係を調べた。実験は現有の人工光型グロースチャンバー内に設置した開放系のガス交換測定システム(同化箱法)を用いて行い、ガス濃度差などの出力データは設備備品として購入したパソコンを用いてガス交換速度に変換した。システムへのNO_2の吸着ができるだけ少なくなるように、配管にはステンレス、あるいはテフロン製のものを用い、また同化箱の壁面をテフロンシートで被覆したが、吸着量は温度条件などにより変化した。そのため、まず植物を入れる前の段階でシステムへのNO_2吸着量に与える測定条件の影響を調べ、測定値を補正する方法を検討した。植物材料には鉢植えのポプラのクローン苗(系統:I-214)を用いた。土壌水分が十分、大気の飽差が一定の条件で気温とひかり強度を変化させて実験を行った結果、NO_2吸収速度、蒸散速度、光合成速度は同様に変化し、気温15〜35℃で光強度500mumolm^<-2>s^<-1>(PPFD)以下では、それぞれのガス交換速度間の関係はほぼ直線となった。これらの関係は、気孔コンダクタンスによって説明できることが認められた。現在、大気湿度を変化させて同様の実験...
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(一般研究(C))
    Date (from‐to) : 1991 -1993 
    Author : Makoto KIYOTA, 平野 高司
     
    The respiration and transpiration rates of many tropical fruits are generally higher than those of other fruits, therefore, the tropical fruits often occur external injury and incidence of decay. This study was aimed at establishing some useful retention method and assessing the quality and storability of tropical fruits in air and CA storage.Papaya (Carica papaya L.), avocado (Persea americana Mill.), banana (Musa paradisiaca L.), and mango (Mangifera indica L.) were evaluated for external appearance, flesh firmness, and internal quality.Storage of several fresh fruits in controlled atmosp...
  • Monitaring of environmental functions of terrestrial ecosystems

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