研究者データベース

杉本 敦子(スギモト アツコ)
北極域研究センター
教授

基本情報

所属

  • 北極域研究センター

職名

  • 教授

ホームページURL

J-Global ID

研究キーワード

  • 4407)   土壌有機物分解   光合成   水利用   炭素窒素安定同位体   水同位体   水蒸気輸送   降水過程   水安定同位体   同位体水文学   温室効果ガス   メタン   生物地球科学   炭素循環   水循環   永久凍土   シベリア   タイガ林   green house gas   methane   Biogeoscience   

研究分野

  • ライフサイエンス / 生態学、環境学
  • 自然科学一般 / 大気水圏科学
  • 自然科学一般 / 宇宙惑星科学
  • 環境・農学 / 環境動態解析

職歴

  • 1996年 - 2003年 京都大学 生態学研究センター 助教授
  • 1996年 - 2003年 Associate Professor,Center for Ecological Research
  • 2003年 - 北海道大学 大学院地球環境科学研究科 教授
  • 2003年 - Professor
  • 1991年 - 1996年 京都大学 生態学研究センター 助手
  • 1991年 - 1996年 Research Associate,Center for Ecological Research
  • 1990年 - 1991年 三菱化成生命科学研究所 特別研究員
  • 1990年 - 1991年 Post Doctral Fellow,Post-doctral fellow (Mitsubishi Kasei Institute for Life Science)

学歴

  •         - 1987年   名古屋大学   理学研究科   研究生
  •         - 1987年   名古屋大学   理学研究科   大気水圏科学専攻後期博士課程満了
  •         - 1987年   名古屋大学
  •         - 1987年   名古屋大学
  •         - 1984年   名古屋大学   理学研究科   大気水圏科学専攻前期博士課程終了
  •         - 1984年   名古屋大学
  •         - 1982年   岡山大学   理学部   地学科
  •         - 1982年   岡山大学

所属学協会

  • 日本地球化学会   日本雪氷学会   日本生態学会   日本気象学会   American Geophysical Union   

研究活動情報

論文

  • Morozumi, T, Shingubara, R, Murase, J, Nagai, S, Kobayashi, H, Takano, S, Tei, S, Fan, R, Maximov, TC, Sugimoto, A
    Morozumi, T; Shingubara, R; Murase, J; Nagai, S; Kobayashi, H; Takano, S; Tei, S; Fan, R; Maximov, TC; Sugimoto, A 21 186 - 194 2019年09月 [査読有り][通常論文]
  • Tei, S, Sugimoto, A, Kotani, A, Ohta, T, Morozumi, T, Saito, S, Hashiguchi, S, Maximov, T
    Tei, S; Sugimoto, A; Kotani, A; Ohta, T; Morozumi, T; Saito, S; Hashiguchi, S; Maximov, T 21 146 - 157 2019年09月 [査読有り][通常論文]
  • Tei, S, Nagai, S, Sugimoto, A
    Tei, S; Nagai, S; Sugimoto, A 21 136 - 145 2019年09月 [査読有り][通常論文]
  • Fujiyoshi, L, Sugimoto, A, Yamashita, Y, Li, XY
    Fujiyoshi, L; Sugimoto, A; Yamashita, Y; Li, XY 101 1086 - 1093 2019年06月 [査読有り][通常論文]
  • Gusyev, MA, Morgenstern, U, Nishihara, T, Hayashi, T, Akata, N, Ichiyanagi, K, Sugimoto, A, Hasegawa, A, Stewart, MK
    Gusyev, MA; Morgenstern, U; Nishihara, T; Hayashi, T; Akata, N; Ichiyanagi, K; Sugimoto, A; Hasegawa, A; Stewart, MK 659 1307 - 1321 2019年04月01日 [査読有り][通常論文]
  • Morozumi, T, Shingubara, R, Suzuki, R, Kobayashi, H, Tei, S, Takano, S, Fan, R, Liang, M, Maximov, TC, Sugimoto, A
    Morozumi, T; Shingubara, R; Suzuki, R; Kobayashi, H; Tei, S; Takano, S; Fan, R; Liang, M; Maximov, TC; Sugimoto, A 71 2019年03月26日 [査読有り][通常論文]
  • Shingubara, R, Sugimoto, A, Murase, J, Iwahana, G, Tei, S, Liang, MC, Takano, S, Morozumi, T, Maximov, TC
    Shingubara, R; Sugimoto, A; Murase, J; Iwahana, G; Tei, S; Liang, MC; Takano, S; Morozumi, T; Maximov, TC 16 3 755 - 768 2019年02月11日 [査読有り][通常論文]
  • Nagai, S, Akitsu, T, Saitoh, TM, Busey, RC, Fukuzawa, K, Honda, Y, Ichie, T, Ide, R, Ikawa, H, Iwasaki, A, Iwao, K, Kajiwara, K, Kang, S, Kim, Y, Khoon, KL, Kononov, AV, Kosugi, Y, Maeda, T, Mamiya, W, Matsuoka, M, Maximov, TC, Menzel, A, Miura, T, Mizunuma, T, Morozumi, T, Motohka, T, Muraoka, H, Nagano, H, Nakai, T, Nakaji, T, Oguma, H, Ohta, T, Ono, K, Pungga, RAS, Petrov, RE, Sakai, R, Schunk, C, Sekikawa, S, Shakhmatov, R, Son, Y, Sugimoto, A, Suzuki, R, Takagi, K, Takanashi, S, Tei, S, Tsuchida, S, Yamamoto, H, Yamasaki, E, Yamashita, M, Yoon, TK, Yoshida, T, Yoshimura, M, Yoshitake, S, Wilkinson, M, Wingate, L, Nasahara, KN
    Nagai, S; Akitsu, T; Saitoh, TM; Busey, RC; Fukuzawa, K; Honda, Y; Ichie, T; Ide, R; Ikawa, H; Iwasaki, A; Iwao, K; Kajiwara, K; Kang, S; Kim, Y; Khoon, KL; Kononov, AV; Kosugi, Y; Maeda, T; Mamiya, W; Matsuoka, M; Maximov, TC; Menzel, A; Miura, T; Mizunu 33 6 1091 - 1092 2018年11月 [査読有り][通常論文]
  • Fan, R, Morozumi, T, Maximov, TC, Sugimoto, A
    Fan, R; Morozumi, T; Maximov, TC; Sugimoto, A 6 2018年09月20日 [査読有り][通常論文]
  • Tei, S, Sugimoto, A
    Tei, S; Sugimoto, A 24 9 4225 - 4237 2018年09月 [査読有り][通常論文]
  • Fang Li, Atsuko Sugimoto
    Isotopes in Environmental and Health Studies 54 1 63 - 77 2018年01月02日 [査読有り][通常論文]
     
    Soil moisture is a major factor controlling carbon isotope discrimination (Δ13C), which has been demonstrated to decrease under dry conditions in many studies however, few studies on Δ13C under waterlogging condition have been conducted. In this study, a pot experiment was conducted with Larix gmelinii, a major larch species in the east Siberian Taiga, to investigate the effect of waterlogging on Δ13C during photosynthesis. Assimilation rate and Δ13CRD (instantaneous Δ13C calculated with Rayleigh distillation equation) decreased drastically soon after waterlogging, followed by recovery in their values, which was caused by a change in stomatal conductance. Thereafter, assimilation rate decreased gradually, whereas Δ13CRD decreased more gently. These results were thought to be caused by the decrease in both stomatal conductance and carboxylation. Our results indicate that extreme wet events may cause a decrease in Δ13C, which is important information for detecting flooding events in the past using tree-ring isotope analyses and for studying impacts of flooding on plants in areas where waterlogging might occur.
  • Shunsuke Tei, Atsuko Sugimoto, Hitoshi Yonenobu, Yojiro Matsuura, Akira Osawa, Hisashi Sato, Junichi Fujinuma, Trofim Maximov
    GLOBAL CHANGE BIOLOGY 23 12 5179 - 5188 2017年12月 [査読有り][通常論文]
     
    Circumboreal forest ecosystems are exposed to a larger magnitude of warming in comparison with the global average, as a result of warming-induced environmental changes. However, it is not clear how tree growth in these ecosystems responds to these changes. In this study, we investigated the sensitivity of forest productivity to climate change using ring width indices (RWI) from a tree-ring width dataset accessed from the International Tree-Ring Data Bank and gridded climate datasets from the Climate Research Unit. A negative relationship of RWI with summer temperature and recent reductions in RWI were typically observed in continental dry regions, such as inner Alaska and Canada, southern Europe, and the southern part of eastern Siberia. We then developed a multiple regression model with regional meteorological parameters to predict RWI, and then applied to these models to predict how tree growth will respond to twenty-first-century climate change (RCP8.5 scenario). The projections showed a spatial variation and future continuous reduction in tree growth in those continental dry regions. The spatial variation, however, could not be reproduced by a dynamic global vegetation model (DGVM). The DGVM projected a generally positive trend in future tree growth all over the circumboreal region. These results indicate that DGVMs may overestimate future wood net primary productivity (NPP) in continental dry regions such as these; this seems to be common feature of current DGVMs. DGVMs should be able to express the negative effect of warming on tree growth, so that they simulate the observed recent reduction in tree growth in continental dry regions.
  • Kumiko Takata, Prabir K. Patra, Ayumi Kotani, Junko Mori, Dmitry Belikov, Kazuhito Ichii, Tazu Saeki, Takeshi Ohta, Kazuyuki Saito, Masahito Ueyama, Akihiko Ito, Shamil Maksyutov, Shin Miyazaki, Eleanor J. Burke, Alexander Ganshin, Yoshihiro Iijima, Takeshi Ise, Hirokazu Machiya, Trofim C. Maximov, Yosuke Niwa, Ryo'ta O'ishi, Hotaek Park, Takahiro Sasai, Hisashi Sato, Shunsuke Tei, Ruslan Zhuravlev, Toshinobu Machida, Atsuko Sugimoto, Shuji Aoki
    ENVIRONMENTAL RESEARCH LETTERS 12 12 2017年12月 [査読有り][通常論文]
     
    Carbon dioxide (CO2) fluxes by different methods vary largely at global, regional and local scales. The net CO2 fluxes by three bottom-up methods (tower observation (TWR), biogeochemical models (GTM), and a data-driven model (SVR)), and an ensemble of atmospheric inversions (top-down method, INV) are compared in Yakutsk, Siberia for 2004-2013. The region is characterized by highly homogeneous larch forest on a flat terrain. The ecosystem around Yakutsk shows a net sink of CO2 by all the methods (means during 2004-2007 were 10.9 gCm(-2) month(-1) by TWR, 4.28 gCm(-2) month(-1) by GTM, 5.62 gCm(-2) month(-1) and 0.863 g Cm-2 month(-1) by SVR at two different scales, and 4.89 g Cm-2 month(-1) by INV). Absorption in summer (June-August) was smaller by three bottom-up methods (ranged from 88.1 to 191.8 g Cm-2 month(-1)) than the top-down method (223.6 gCm(-2) month(-1)). Thus the peak-to-trough amplitude of the seasonal cycle is greater for the inverse models than bottom-up methods. The monthly-mean seasonal cycles agree among the fourmethodswithin the range of inter-model variations. The interannual variability estimated by an ensemble of inverse models and a site-scale data-driven model (the max-min range was 35.8 g Cm-2 month(-1)and 34.2 g Cm-2 month(-1)) is more similar to that of the tower observation (42.4 gCm(-2) month(-1)) than those by the biogeochemical models and the large-scale data-driven model (9.5 gCm(-2) month(-1) and 1.45 gCm(-2) month(-1)). The inverse models and tower observations captured a reduction in CO2 uptake after 2008 due to unusual waterlogging.
  • Shunsuke Tei, Atsuko Sugimoto, Maochang Liang, Hitoshi Yonenobu, Yojiro Matsuura, Akira Osawa, Hisashi Sato, Junichi Fujinuma, Trofim Maximov
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 122 11 2786 - 2803 2017年11月 [査読有り][通常論文]
     
    We describe the physiological responses of boreal conifers to climate change for the past 112years using ring-width and carbon isotope ratio (C-13) chronologies at six forest sites in northern Eurasia and Canada. Responses differed among regions, depending on their climatic and/or geographic characteristics. Tree radial growth decreased over the past 52years in central eastern Siberia with the higher rate of summer temperature increase than other regions, as indicated by the negative correlation between radial growth and summer temperature, but increased in northern Europe and Canada. Changes in tree-ring C-13 indicated that recent climatic conditions have induced stronger drought stress for trees from central eastern Siberia than for those from other regions. The observed tree growth trends were compared to those simulated using a dynamic global vegetation model. Although the modeled annual net primary production (NPP) for trees generally exhibited similar decadal variation to radial growth, simulations did not show a recent decrease in tree growth, even in central eastern Siberia. This was probably due to an overestimation of the sensitivity of modeled tree NPP to precipitation. Our results suggest that the tree NPP forecasted under the expected future increases in temperature and average precipitation might be overestimated, especially in severely dry regions such as central eastern Siberia.
  • Xiaoyang Li, Atsuko Sugimoto, Akihiro Ueta
    HYDROLOGICAL PROCESSES 31 17 3029 - 3044 2017年08月 [査読有り][通常論文]
     
    Spatial and temporal variations of the isotopic composition of precipitation were investigated to better understand their controlling factors. Precipitation was collected from six locations in Hokkaido, Japan, and event-based analyses were conducted for a period from March 2010 to February 2013. Relatively low delta values and a high d-excess for annual averages were observed at three sites located along the Japan Sea compared to the three sites at Pacific Ocean side. Lower delta values in spring and fall and higher d-excess in winter were observed for the region along the Japan Sea. In total, 264 precipitation events were identified. Precipitation originated predominantly from low-pressure system (LPS) events, which were classified as northwest (LPS-NW) and southeast (LPS-SE) events according to the routes of the low-pressure center, that passed northwest and southeast of Hokkaido, respectively. LPS-SE events showed lower delta O-18 than LPS-NW events, which is attributable to the lower delta O-18 of water vapor resulting from heavy rainfalls in the upstream region of the LPS air mass trajectories over the Pacific Ocean. This phenomenon observed in Hokkaido can be found in other midlatitude coastal regions and applied for hydrological, atmospheric, and paleoclimate studies. A characteristic spatial pattern was found in LPS-NW events, in which lower delta O-18 was observed on the Japan Sea side than on the Pacific Ocean side in each season. This is likely due to the location of the sampling sites and their distance from the LPS: Precipitation with lower delta O-18 in the region along the Japan Sea occurs in a well-developed cloud system near the low-pressure center in cold and warm sectors of LPS, whereas precipitation with higher delta O-18 on the Pacific side mainly occurs in a warm sector away from the low-pressure center. Air mass from the north does not always cause low delta in precipitation, and the precipitation process in the upstream region is another important factor controlling the isotopic composition of precipitation, other than the local temperature and precipitation amount.
  • Lei Fujiyoshi, Atsuko Sugimoto, Akemi Tsukuura, Asami Kitayama, M. Larry Lopez Caceres, Byambasuren Mijidsuren, Ariunaa Saraadanbazar, Maki Tsujimura
    ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 53 1 54 - 69 2017年03月 [査読有り][通常論文]
     
    The spatial patterns of plant and soil N-15 and associated processes in the N cycle were investigated at a forest-grassland boundary in northern Mongolia. Needles of Larix sibirica Ledeb. and soils collected from two study areas were analysed to calculate the differences in N-15 between needle and soil (N-15). N-15 showed a clear variation, ranging from -8 parts per thousand in the forest to -2 parts per thousand in the grassland boundary, and corresponded to the accumulation of organic layer. In the forest, the separation of available N produced in the soil with N-15-depleted N uptake by larch and N-15-enriched N immobilization by microorganisms was proposed to cause large N-15, whereas in the grassland boundary, small N-15 was explained by the transport of the most available N into larch. The divergence of available N between larch and microorganisms in the soil, and the accumulation of diverged N in the organic layer control the variation in N-15.
  • Mukesh Singh Boori, Komal Choudhary, Alexander Kupriyanov, Atsuko Sugimoto
    ASIA-PACIFIC CONFERENCE ON FUNDAMENTAL PROBLEMS OF OPTO- AND MICROELECTRONICS 10176 2017年 [査読有り][通常論文]
     
    Eastern Siberia, Russia is physically and socio-economically vulnerable to accelerated Arctic sea level rise due to low topography, high ecological value, harsh climatic conditions, erosion and flooding of coastal area and destruction of harbor constructions and natural coastal hazards. A 1 to 10m inundation land loss scenarios for surface water and sea level rise (SLR) were developed using digital elevation models of study site topography through remote sensing and GIS techniques by ASTER GDEM and Landsat OLI data. Results indicate that 10.82% (8072.70km(2)) and 29.73% (22181.19km(2)) of the area will be lost by flooding at minimum and maximum inundation levels, respectively. The most severely impacted sectors are expected to be the vegetation, wetland and the natural ecosystem. Improved understanding of the extent and response of SLR will help in preparing for mitigation and adaptation.
  • Mukesh Singh Boori, Komal Choudhary, Alexander Kupriyanov, Atsuko Sugimoto, Viktor Kovelskiy
    INFORMATICS, GEOINFORMATICS AND REMOTE SENSING CONFERENCE PROCEEDINGS, SGEM 2016, VOL II 971 - 978 2016年 [査読有り][通常論文]
     
    In landscape studies, land use/cove is very important and useful information for sustainable development and planning. Remote sensing and Geographical Information System (GIS) technology with multi-temporal satellite imagery are widely used for this purpose. The present study applied supervised classification-maximum likelihood algorithm in ArcGIS 10.2 Software to detect land use/cover changes in Eastern Siberia, Russia using multi-spectral satellite data obtained from Landsat 7 and 8 for the years of 2000, 2008 and 2015 respectively. The study area was classified into five major land use/cove classes' viz. settlements, vegetation, water/ice, wasteland and wetland. Change detection analysis shows that in first half (2000-2008) wasteland area was increased from 1015 to 12620 km(2) by 15% and wetland reduced by 13%. In second half from 2008 to 2015 wasteland shrink more than 13% and wetland augmented around 9% but in the same time other classes have minor variation. The results suggest that spatial pattern metrics of land cover changes can provide a good quantitative measurement for better understanding of the spatio-temporal pattern of land use/cover change due to different causes which proposes concrete perspectives and possibilities to benefit from existing commonalities in the construction and application of assessment tools.
  • Mukesh S. Boori, Komal Choudhary, Alexander Kupriyanov, Atsuko Sugimoto, Mariele Evers
    EARTH RESOURCES AND ENVIRONMENTAL REMOTE SENSING/GIS APPLICATIONS VII 10005 2016年 [査読有り][通常論文]
     
    The aim of this research work is to understand natural and environmental vulnerability situation and its cause such as intensity, distribution and socio-economic effect in the Indigirka River basin, Eastern Siberia, Russia. This paper identifies, assess and classify natural and environmental vulnerability using landscape pattern from multidisciplinary approach, based on remote sensing and Geographical Information System (GIS) techniques. A model was developed by following thematic layers: land use/cover, vegetation, wetland, geology, geomorphology and soil in ArcGIS 10.2 software. According to numerical results vulnerability classified into five levels: low, sensible, moderate, high and extreme vulnerability by mean of cluster principal. Results are shows that in natural vulnerability maximum area covered by moderate (29.84%) and sensible (38.61%) vulnerability and environmental vulnerability concentrated by moderate (49.30%) vulnerability. So study area has at medial level vulnerability. The results found that the methodology applied was effective enough in the understanding of the current conservation circumstances of the river basin in relation to their environment with the help of remote sensing and GIS. This study is helpful for decision making for eco-environmental recovering and rebuilding as well as predicting the future development.
  • T. Sueyoshi, K. Saito, S. Miyazaki, J. Mori, T. Ise, H. Arakida, R. Suzuki, A. Sato, Y. Iijima, H. Yabuki, H. Ikawa, T. Ohta, A. Kotani, T. Hajima, H. Sato, T. Yamazaki, A. Sugimoto
    EARTH SYSTEM SCIENCE DATA 8 1 1 - 14 2016年 [査読有り][通常論文]
     
    Here, the authors describe the construction of a forcing data set for land surface models (including both physical and biogeochemical models; LSMs) with eight meteorological variables for the 35-year period from 1979 to 2013. The data set is intended for use in a model intercomparison study, called GTMIP, which is a part of the Japanese-funded Arctic Climate Change Research Project. In order to prepare a set of site-fitted forcing data for LSMs with realistic yet continuous entries (i.e. without missing data), four observational sites across the pan-Arctic region (Fairbanks, Tiksi, Yakutsk, and Kevo) were selected to construct a blended data set using both global reanalysis and observational data. Marked improvements were found in the diurnal cycles of surface air temperature and humidity, wind speed, and precipitation.
  • Shunsuke Tei, Hitoshi Yonenobu, Shinya Suzuki, Motonari Ohyama, Katsuya Gotanda, Takeshi Nakagawa, Atsuko Sugimoto
    PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 435 203 - 209 2015年10月 [査読有り][通常論文]
     
    We present a large-scale dendroclimatic reconstruction of July temperatures from 42-52 degrees N to 140-145 degrees E in the Northwest Pacific region for the period from 1800 to 1996. A multiple regression model with principal components (PCs) of a tree-ring chronology network was used for the reconstruction, which accounted for 31.7% of the temperature variance in the calibration period (1901-1996). The reconstructed spatially-averaged July temperatures show large fluctuations, which are comparable to previously published dendroclimatic reconstruction of spring temperatures in northeast Asia. It also shows stable relationships with other datasets, notably sea surface temperatures (SSTs) in a wide area of the North Pacific and the Pacific Decadal Oscillation (PDO), indicating atmospheric-oceanic interaction in the Northwest Pacific region since AD 1800. (C) 2015 Elsevier B.V. All rights reserved.
  • Shunsuke Tei, Hitoshi Yonenobu, Atsuko Sugimoto, Takeshi Ohta, Trofim C. Maximov
    JOURNAL OF HYDROLOGY 529 442 - 448 2015年10月 [査読有り][通常論文]
     
    We present a tree-ring reconstruction of Palmer Drought Severity Index (PDSI) in Ust-Maya region (60 degrees 00'N, 133 degrees 49'E), central part of eastern Siberia using total ring (TR) widths and latewood (LW) delta C-13 chronologies from larch trees (1850-2008 AD). Summer (JJA) PDSI was correlated positively and negatively with the TR widths and LW delta C-13, respectively. Using a multiple liner regression approach, we reconstructed summer PDSI using the time series of TR widths and LW delta C-13. The reconstruction showed an interannual to decadal wet/dry fluctuation with several moist periods before 1950s and a severe drought event from 1991 to 1993. Comparison of the reconstruction with reconstructed July PDSI for the Yakutsk region, 300 km northwest of Ust-Maya, showed heterogeneous changes in the mean states of soil moisture, but synchronous year-to-year changes. These results indicate that regional studies are quite important to precisely depict the spatio-temporal variability of hydrological changes in the central part of eastern Siberia. (C) 2015 Elsevier B.V. All rights reserved.
  • Yohei Narita, Atsuko Sugimoto, Daisuke Kawashima, Takahiro Watanabe, Teru Kanda, Hiroshi Kimura, Tatsuya Tsurumi, Takayuki Murata
    SCIENTIFIC REPORTS 5 2015年06月 [査読有り][通常論文]
     
    Epstein-Barr virus (EBV) is associated with several malignancies, including Burkitt lymphoma and nasopharyngeal carcinoma. To overcome such disorders, understanding the molecular mechanisms of the EBV replication is important. The EBV DNA polymerase (Pol) is one of the essential factors for viral lytic DNA replication. Although it is well known that its C-terminal half, possessing DNA polymerase and 3'-5' exonuclease activity, is highly conserved among Family B Pols, the NH2-terminal half has yet to be characterized in detail. In this study, we show that a stretch of hydrophobic amino acids within the pre-NH2-terminal domain of EBV Pol plays important role. In addition, we could identify the most essential residue for replication in the motif. These findings will shed light on molecular mechanisms of viral DNA synthesis and will help to develop new herpesviruses treatments.
  • S. Miyazaki, K. Saito, J. Mori, T. Yamazaki, T. Ise, H. Arakida, T. Hajima, Y. Iijima, H. Machiya, T. Sueyoshi, H. Yabuki, E. J. Burke, M. Hosaka, K. Ichii, H. Ikawa, A. Ito, A. Kotani, Y. Matsuura, M. Niwano, T. Nitta, R. O'ishi, T. Ohta, H. Park, T. Sasai, A. Sato, H. Sato, A. Sugimoto, R. Suzuki, K. Tanaka, S. Yamaguchi, K. Yoshimura
    Geoscientific Model Development 8 9 2841 - 2856 2015年 [査読有り][通常論文]
     
    As part of the terrestrial branch of the Japan-funded Arctic Climate Change Research Project (GRENE-TEA), which aims to clarify the role and function of the terrestrial Arctic in the climate system and assess the influence of its changes on a global scale, this model intercomparison project (GTMIP) is designed to (1) enhance communication and understanding between the modelling and field scientists and (2) assess the uncertainty and variations stemming from variability in model implementation/design and in model outputs using climatic and historical conditions in the Arctic terrestrial regions. This paper provides an overview of all GTMIP activity, and the experiment protocol of Stage 1, which is site simulations driven by statistically fitted data created using the GRENE-TEA site observations for the last 3 decades. The target metrics for the model evaluation cover key processes in both physics and biogeochemistry, including energy budgets, snow, permafrost, phenology, and carbon budgets. Exemplary results for distributions of four metrics (annual mean latent heat flux, annual maximum snow depth, gross primary production, and net ecosystem production) and for seasonal transitions are provided to give an outlook of the planned analysis that will delineate the inter-dependence among the key processes and provide clues for improving model performance.
  • Maochang Liang, Atsuko Sugimoto, Shunsuke Tei, Ivan V. Bragin, Shinya Takano, Tomoki Morozumi, Ryo Shingubara, Trofim C. Maximov, Serguei I. Kiyashko, Tatiana A. Velivetskaya, Alexander V. Ignatiev
    POLAR SCIENCE 8 4 327 - 341 2014年12月 [査読有り][通常論文]
     
    To better understand the factors controlling the growth of larch trees in Arctic taiga-tundra boundary ecosystem, we conducted field measurements of photosynthesis, tree size, nitrogen (N) content, and isotopic ratios in larch needles and soil. In addition, we observed various environmental parameters, including topography and soil moisture at four sites in the Indigirka River Basin, near Chokurdakh, northeastern Siberia. Most living larch trees grow on mounds with relatively high elevations and dry soils, indicating intolerance of high soil moisture. We found that needle delta(13)c was positively correlated with needle N content and needle mass, and these parameters showed spatial patterns similar to that of tree size. These results indicate that trees with high needle N content achieved higher rates of photosynthesis, which resulted in larger amounts of C assimilation and larger C allocation to needles and led to larger tree size than trees with lower needle N content. A positive correlation was also found between needle N content and soil NK4+ pool. Thus, soil inorganic N pool may indicate N availability, which is reflected in the needle N content of the larch trees. Microtopography plays a principal role in N availability, through a change in soil moisture. Relatively dryer soil of mounds with higher elevation and larger extent causes higher rates of soil N production, leading to increased N availability for plants, in addition to larger rooting space for trees to uptake more N. (C) 2014 Elsevier B.V. and NIPR. All rights reserved.
  • D. Penna, M. Ahmad, S. J. Birks, L. Bouchaou, M. Brencic, S. Butt, L. Holko, G. Jeelani, D. E. Martinez, G. Melikadze, J. B. Shanley, S. A. Sokratov, T. Stadnyk, A. Sugimoto, P. Vreca
    HYDROLOGICAL PROCESSES 28 22 5637 - 5644 2014年11月 [査読有り][通常論文]
     
    We modified a passive capillary sampler (PCS) to collect snowmelt water for isotopic analysis. Past applications of PCSs have been to sample soil water, but the novel aspect of this study was the placement of the PCSs at the ground-snowpack interface to collect snowmelt. We deployed arrays of PCSs at 11 sites in ten partner countries on five continents representing a range of climate and snow cover worldwide. The PCS reliably collected snowmelt at all sites and caused negligible evaporative fractionation effects in the samples. PCS is low-cost, easy to install, and collects a representative integrated snowmelt sample throughout the melt season or at the melt event scale. Unlike snow cores, the PCS collects the water that would actually infiltrate the soil; thus, its isotopic composition is appropriate to use for tracing snowmelt water through the hydrologic cycle. The purpose of this Briefing is to show the potential advantages of PCSs and recommend guidelines for constructing and installing them based on our preliminary results from two snowmelt seasons. Copyright (C) 2014 John Wiley & Sons, Ltd.
  • Go Iwahana, Shinya Takano, Roman E. Petrov, Shunsuke Tei, Ryo Shingubara, Trofini C. Maximov, Alexander N. Fedorov, Alexey R. Desyatkin, Anatoly N. Nikolaev, Roman V. Desyatkin, Atsuko Sugimoto
    POLAR SCIENCE 8 2 96 - 113 2014年06月 [査読有り][通常論文]
     
    Understanding geocryological characteristics of frozen sediment, such as cryostratigraphy, ice content, and stable isotope ratio of ground ice, is essential to predicting consequences of projected permafrost thaw in response to global warming. These characteristics determine thermokarst extent and controls hydrological regime-and hence vegetation growth-especially in areas of high latitude; it also yields knowledge about the history of changes in the hydrological regime. To obtain these fundamental data, we sampled and analyzed unfrozen and frozen surficial sediments from 18 boreholes down to 1-2.3 m depth at five sites near Chokurdakh, Russia. Profiles of volumetric ice content in upper permafrost excluding wedge ice volume showed large variation, ranging from 40 to 96%, with an average of 75%. This large amount of ground ice was in the form of ice lenses or veins forming well-developed cryostructures, mainly due to freezing of frost-susceptible sediment under water-saturated condition. Our analysis of geocryological characteristics in frozen ground including ice content, cryostratigraphy, soil mechanical characteristics, organic matter content and components, and water stable isotope ratio provided information to reconstruct terrestrial paleo-environments and to estimate the influence of recent maximum thaw depth, microtopography, and flooding upon permafrost development in permafrost regions of NE Russia. (C) 2014 Elsevier B.V. and NIPR. All rights reserved.
  • Shunsuke Tei, Atsuko Sugimoto, Hitoshi Yonenobu, Takeshi Ohta, Trofim C. Maximov
    POLAR SCIENCE 8 2 183 - 195 2014年06月 [査読有り][通常論文]
     
    Tree-ring chronologies of ring width and stable carbon isotope ratios (delta(13)c) over the past 160 years were developed using living larch trees at two forest sites, each with different annual precipitation, in eastern Siberia: Spasskaya Pad (SP) (62 degrees 14'N, 129 degrees 37'E); and Elgeeii (EG) (60 degrees 0'N, 133 degrees 49'E). Intrinsic water-use efficiency (iWUE) was derived from tree-ring delta C-13. The physiological responses of the larch trees to climate varied between these sites and over time. Ring widths correlated negatively with summer temperatures at SP, where summer precipitation is lower than at EG, probably due to temperature-induced water stress. Since the 1990s, however, the negative effect of warming has been more severe at EG, where the productivity of larch trees is higher than at SP. A greater reduction of larch tree growth and higher increase rate of iWUE at EG reflects greater temperature-induced water stress, which is incident to the larger forest biomass. Our results suggest that effect of increase in atmospheric CO2 on larch tree growth is not sufficient to compensate for temperature-induced water stress on larch growth in eastern Siberia and differences in precipitation and forest productivity largely affect the larch tree response to changing climate in eastern Siberia. (C) 2013 Elsevier B.V. and NIPR. All rights reserved.
  • Akihiro Ueta, Atsuko Sugimoto, Yoshihiro Iijima, Hironori Yabuki, Trofim C. Maximov
    ECOHYDROLOGY 7 2 197 - 208 2014年04月 [査読有り][通常論文]
     
    Isotopic composition of atmospheric water vapour (O-18(V)) was observed at a larch forest near Yakutsk in eastern Siberia during the late summer periods of 2006, 2007 and 2008. The O-18(V) [and deuterium excess (d-excess)] values observed in 2006 and 2008 positively (and negatively) correlated with mixing ratio of atmospheric water vapour, whereas, in 2007 when soil was extremely wet and resulted in limitation of plant transpiration, neither correlation was found between mixing ratio and O-18(V) nor d-excess. Observed results were also compared with components of atmospheric water balance calculated for a 500x500km region; however, neither specific relationship between O-18(V) and horizontal advection (direction) nor evapotranspiration was observed. On the other hand, obviously low O-18(V) and high d-excess values were found with low mixing ratio after removal of water vapour from the atmosphere because of the process of rainout in 2006 and 2008. Assuming the O-18(V) under this condition to be a background, and also assuming the O-18 of sap water in larch trees as transpired water vapour, contribution of transpiration to the atmospheric water vapour was calculated. Fraction of transpired water vapour to the atmospheric water vapour was nearly 08 in maximum when plant transpiration was active under warm condition. Our isotope data confirm the importance of recycling of water through transpiration of forest plants in taiga to the hydrologic cycle in eastern Siberia. Copyright (c) 2013 John Wiley & Sons, Ltd.
  • A. Ignatev, T. Velivetckaia, A. Sugimoto, A. Ueta
    JOURNAL OF HYDROLOGY 498 265 - 273 2013年08月 [査読有り][通常論文]
     
    A new method of soil water extraction for oxygen and hydrogen isotopic analysis has been developed; this method uses a helium flow system as an alternative to the conventional vacuum extraction method. The method significantly increases the efficiency of sample preparation and simplifies the extraction. During the water distillation, a helium carrier gas transfers water vaporized at 95 degrees C from the soil sample to a cold trap at liquid nitrogen temperature. An extraction time of 180 min is used to distill the water from the fine-grained soil completely. The proposed He-purging distillation technique makes it possible to distill approximately a dozen samples simultaneously. The method was tested using liquid water samples and clayey soil samples hydrated with water of known isotopic composition. The standard deviations for these tests were 0.08 parts per thousand for delta O-18 and 0.7 parts per thousand for delta D. An intercomparison test was conducted for the helium and vacuum extraction methods using natural soil samples. The correlation coefficients between the methods were 0.9926 and 0.9939 for delta D and delta O-18, respectively. The proposed He-purging distillation method can achieve high precision for clayey soil samples with low water content and has the potential to provide adequate isotopic data in hydrological and ecological studies. The method is relatively fast, efficient, and inexpensive. We also recommend using the method to distill salt solutions (sea water, mineralized water) before determining the delta D and delta O-18 values using a chromium or carbon reduction method to avoid "salt effects". (C) 2013 Elsevier B.V. All rights reserved.
  • Akihiro Ueta, Atsuko Sugimoto, Yoshihiro Iijima, Hironori Yabuki, Trofim C. Maximov, Tatiana A. Velivetskaya, Alexander V. Ignatiev
    Hydrological Processes 27 16 2295 - 2305 2013年07月30日 [査読有り][通常論文]
     
    Deciduous forest covers vast areas of permafrost under severe dry climate in eastern Siberia. Understanding the water cycle in this forest ecosystem is quite important for climate projection. In this study, diurnal variations in isotopic compositions of atmospheric water vapour were observed in eastern Siberia with isotope analyses of precipitation, sap water of larch trees, soil water, and water in surface organic layer during the late summer periods of 2006, 2007, and 2008. In these years, the soil moisture content was considerably high due to unusually large amounts of summer rainfall and winter snowfall. The observed sap water δ18O ranged from -17.9‰ to -13.3‰, which was close to that of summer precipitation and soil water in the shallow layer, and represents that of transpired water vapour. On sunny days, as the air temperature and mixing ratio rose from predawn to morning, the atmospheric water vapour δ18O increased by 1‰ to 5‰ and then decreased by about 2‰ from morning to afternoon with the mixing ratio. On cloudy days, by contrast, the afternoon decrease in δ18O and the mixing ratio was not observed. These results show that water vapour that transpired from plants, with higher δ18O than the atmospheric water vapour, contributes to the increase in δ18O in the morning, whereas water vapour in the free atmosphere, with lower δ18O, contributes to the decrease in the afternoon on sunny days. The observed results reveal the significance of transpired water vapour, with relatively high δ18O, in the water cycle on a short diurnal time scale and confirm the importance of the recycling of precipitation through transpiration in continental forest environments such as the eastern Siberian taiga. © 2012 John Wiley & Sons, Ltd.
  • Tei Shunsuke, Sugimoto Atsuko, Yonenobu Hitoshi, Yamazaki Takeshi, Maximov Trofim C
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 118 3 1256 - 1265 2013年07月 [査読有り][通常論文]
  • Alexandra S. Popova, Naoko Tokuchi, Nobuhito Ohte, Miki U. Ueda, Ken'ichi Osaka, Trofim Ch. Maximov, Atsuko Sugimoto
    Soil Science and Plant Nutrition 59 3 427 - 441 2013年06月 [査読有り][通常論文]
     
    The inorganic nitrogen (N) cycle and its dynamics in the soil were observed in the ecosystem at the Spasskaya Pad experimental forest near Yakutsk in northeastern Siberia in order to estimate the N availability for the larch (Larix cajanderi Mayr.) The soil pool of bulk N in the forest accounted for up to 866 g N m-2 (0-50 cm), whereas up to 1.7% (14.6 g N m-2) was potassium chloride (KCl)-extractable inorganic N. Ammonium was a dominant form of inorganic N. The size of the soil inorganic N pool fluctuated seasonally. It was small in the beginning of the summer and increased rapidly once the cumulative degree day of the soil temperature at 20 cm reached more than 300 (°C days), indicating that active N mineralization began at some point from the middle of July to the beginning of August. This soil pool of inorganic N that had accumulated at the end of the previous summer was consumed by the beginning of the next summer through microbial immobilization, which may have begun in September. Recycling of N in the soil was important because the input of inorganic N by deposition was very small (48 mg N m-2 year-1). A tracer 15N experiment showed that larch did not uptake organic N in the form of amino acid (alanine) rather, it used ammonium and nitrate as N sources. The amount of available N for plants was assessed as water-extractable inorganic N in the soil solution that was transported to the rooting area by mass flow driven by plant transpiration, and it accounted for 1.9 × 103 (1.2 × 103 for trees) mg N m-2 during the growing season-1 (0-50 cm of the mineral soil layer in June, July, and August). Microorganisms in the soil are also expected to be competing for this available N. Our results show that despite a large amount of inorganic N production, N availability for plants is low as the soil pool of inorganic N is built up at the same rate as larch senescence. © 2013 Copyright The Author(s). Published by Taylor & Francis.
  • Shunsuke Tei, Atsuko Sugimoto, Hitoshi Yonenobu, Yasuharu Hoshino, Trofim C. Maximov
    QUATERNARY INTERNATIONAL 290 275 - 281 2013年03月 [査読有り][通常論文]
     
    We present a dendroclimatic reconstruction of Palmer Drought Severity Index (PDSI) in Yakutsk (62 degrees 14'N, 129 degrees 37'E), East Siberia using a larch tree-ring (latewood) delta C-13 chronology (1780-2008 AD). The correlation function analysis showed significant positive correlations between earlywood, latewood and total ring width and July PDSI of the previous summer. On the other hand, tree-ring delta C-13 from earlywood, latewood and total ring showed significant negative correlations with July PDSI in current summer, of which latewood delta C-13 showed highest correlation with PDSI. A moving-window correlation analysis demonstrated that the temporal stability in correlation between tree-ring variables and PDSI was highest when July PDSI was compared with latewood delta C-13. Tree-ring delta C-13 values were corrected by taking account of both the changes in the isotope ratio of atmospheric CO2 (delta C-13(a)) and the plant physiological response to changes in atmospheric CO2 concentration (C-a). This correction significantly improved the sensitivity of larch tree-ring delta C-13 to PDSI, demonstrating that the correction is useful in building a reliable model to estimate past changes in PDSI. Our study shows that larch tree-ring delta C-13 has enough potential to reconstruct July PDSI series. Using a liner regression model, July PDSI was reconstructed from latewood delta C-13 over the last 229 years. The reconstruction showed an interannual to decadal wet/dry fluctuation with a decreasing trend from 1780 to 1960, suggesting that aridification progressed at least after the late Little Ice Age in East Siberia to the modern period of global warming. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.
  • Hiyama Tetsuya, Ohta Takeshi, Sugimoto Atsuko, Yamazaki Takeshi, Oshima Kazuhiro, Yonenobu Hitoshi, Yamamoto Kazukiyo, Kotani Ayumi, Park Hotaek, Kodama Yuji, Hatta Shigemi, Fedorov Alexander N, Maximov Trofim C
    COLD AND MOUNTAIN REGION HYDROLOGICAL SYSTEMS UNDER CLIMATE CHANGE: TOWARDS IMPROVED PROJECTIONS 360 155 - 160 2013年 [査読有り][通常論文]
  • Ryota Murai, Atsuko Sugimoto, Shinsuke Tanabe, Ichiro Takeuchi
    CHEMOSPHERE 73 11 1749 - 1756 2008年12月 [査読有り][通常論文]
     
    The measurement of organotins in the various biotas of coastal food webs with stable nitrogen isotope ratios (delta N-15), which increase 3.4 parts per thousand per trophic level, can provide a biomagnification profile of organotins through food web. In this study, various biological samples were collected from three localities in Western Japan between 2002 and 2003 for analyses. Tributyltin (TBT) and triphenyltin (TPT) were still detected with a maximum of 99.5 and 8.7 ng wet weight g(-1), respectively. Unlike TBT, significant biomagnification of TPT through the food web (expressed by delta N-15) was found in all three localities. The log transformed octanol-water partition coefficient (log K-ow) of TPT of 2.11-3.43 was overlapped by, but was slightly lower than, that of TBT of 3.70-4.70. Thus, this study demonstrates that although these chemicals have a log K-ow lower than 5. at least TPT undergoes significant biomagnification through the food web. (C) 2008 Elsevier Ltd. All rights reserved.
  • Akira Watanabe, Masahiro Kasuya, Ayumi Tsunekawa, Mieko Maeda, Atsuko Sugimoto, Makoto Kimura
    AGRICULTURE ECOSYSTEMS & ENVIRONMENT 127 3-4 207 - 214 2008年09月 [査読有り][通常論文]
     
    It is important to estimate the amount of CH4 released following the use of groundwater and to understand the dynamics of groundwater CH4 from the viewpoints of biogeochemical C cycle and global warming. We determined CH4 concentration in 216 groundwaters used for agriculture in Aichi Prefecture, central Japan, and analyzed the spatial and seasonal variations. The percentage of CH4-detected samples and mean CH4 concentration were high in deltaic regions, 88% and 239 mu mol L-1(n = 24) or 69% and 166 mu mol L-1 (n = 49), low in alluvial fan (0%; n = 12) and mountainous area (35% and 11.7 mu mol L-1 (n = 22)). Methane was more frequently detected in groundwater with >50 m depth (84%; n = 37). Mean CH4 concentration for CH4-detected samples from >50 in depth was also higher than those from <5 m depth, 248 versus 60.2 mu mol L-1. Among groundwater samples with <5 m depth, the probability of CH4 detection was higher tinder paddy fields. Seasonal variations in the concentration and stable C isotopic ratio of CH4 (delta C-13(CH4); -65 to -89 parts per thousand) were generally small in monitored groundwaters with 4-180 in depth, suggesting that CH4 produced mainly by CO2 reduction was preserved through a year. There were also shallow groundwaters (<5 m depth) showing adverse seasonal changes in CH4 concentration and delta C-13 CH4 (up to 20 parts per thousand). Such shallow groundwaters showed significant CH4 production in a 90-day incubation with maximum rates of 3.03-6.43 nmol day(-1). Acetoclastic methanogens were generally absent, while an addition of glucose and especially CO2/H-2 enhanced methanogenesis. CH4 oxidizing potential was also observed in an aerobic incubation. These results suggested that the production/oxidation of CH4 in situ or at the source was responsible for the seasonal variations in CH4 concentration. (C) 2008 Elsevier B.V. All rights reserved.
  • Masayuki Itoh, Nobuhito Ohte, Keisuke Koba, Atsuko Sugimoto, Makoto Tani
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 113 G3 2008年07月 [査読有り][通常論文]
     
    To clarify how hydrological processes affect biogenic methane (CH4) production and emission from soil surfaces, we analyzed the delta C-13 of CH4 and CO2 and chemical constituents dissolved in groundwater at a wetland in the headwater catchment of a temperate forest in Japan. We estimated the contribution of acetate fermentation using the delta C-13 isotope mass balance of dissolved CH4 and CO2. CH4 production pathways (e. g., acetate fermentation and carbonate reduction) changed temporally and spatially with hydrologically controlled redox conditions. The proportion of methanogenesis attributable to acetate fermentation usually decreased with temperature, suggesting that carbonate reduction dominated under conditions of high CO2 concentration. In particular, the groundwater table and summer temperatures were key controlling factors in the interannual and intra- annual changes in CH4 production pathways, controlling oxygen supply and consumption and, therefore, redox conditions in the soil. Under high temperature and high water table conditions during summer, the soil was strongly reduced and the proportion of carbonate reduction increased. Acetate fermentation also increased episodically, resulting in sporadic increases in delta C-13-CH4. The calculated acetate contribution obviously decreased in periods of low water table and high temperature when the soil surface was relatively oxic, implying deactivation of acetoclastic methanogenesis under oxic conditions. Thus, hydrological processes control the supply of these electron donors and acceptors and therefore play an important role in determining the relative proportions of CH4-producing pathways. Our results also indicate that an increase in acetate contribution under highly reducing conditions stimulates CH4 production and emission from the soil surface.
  • Sheng-Gong Li, Maki Tsujimura, Atsuko Sugimoto, Gombo Davaa, Dambaravjaa Oyunbaatar, Michiaki Sugita
    TREES-STRUCTURE AND FUNCTION 21 4 479 - 490 2007年07月 [査読有り][通常論文]
     
    This paper reports the temporal variation (2002-2004) in foliar delta C-13 values, which are indicative of long-term integrated photosynthetic and water use characteristics, of Siberian larch (Larix sibirica Ledeb.) trees in a montane forest at Mongonmorit, NE Mongolia. At the stand, the delta C-13 value for understory shaded leaves was more negative by 2 parts per thousand on average than that for sunlit leaves sampled concurrently from open and sun-exposed environments in a forest gap. The delta C-13 value of both sunlit and shaded leaves showed pronounced intra- but relatively small inter-seasonal variations. The delta C-13 value was more positive for juvenile than mature leaves. We conjecture that juvenile leaves may derive carbon reserves in woody tissues (e.g., stems). Regardless of leaf habitats, the delta C-13 value was also affected by insect herbivores occurred in mid summer of 2003, being more negative in newly emerging leaves from the twigs after defoliation than in non-defoliated mature leaves. This pattern seems to contrast with that for the juvenile leaves in the early growing season. We surmise that the newly emerging leaves used stored organic carbon that was depleted due to fractionation during remobilization and translocation for leaf regrowth. There was also intra- and inter-seasonal variation in the foliar N concentrations and C: N ratios. A good positive (negative) correlation between the foliar delta C-13 values and N concentrations (C:N ratios) was also observed for both sunlit and shaded leaves, suggesting that the relationship between water and nitrogen use is a crucial factor affecting the plant carbon-water relationship in this mid latitude forest with a cold semiarid climate. Our isotopic data demonstrate that the larches in NE Mongolia exhibits relatively higher water use efficiency with a distinct within-season variability.
  • SG Li, M Tsujimura, A Sugimoto, G Davaa, M Sugita
    JOURNAL OF BIOSCIENCES 31 1 85 - 93 2006年03月 [査読有り][通常論文]
     
    Steppe desertification due to vehicle travel is a severe environmental issue in Mongolia. We studied natural vegetation recovery on abandoned vehicle tracks in the central Mongolia steppe through vegetation surveys and stable isotopic techniques. The following issues were addressed: (i) invasion of pioneering plant species, (ii) alteration of soil surface features, and (iii) contribution of revegetated plants to soil organic matter (SOM). The pioneering plant species that firstly invaded the abandoned tracks are those that could germinate, root and survive in the compacted track surface. Salsola collina is one of these candidate plants. Due to revegetation, soil surface hardness was reduced. With the improvement of surface microenvironmental conditions, other plants began to colonize and establish; concomitantly species richness and species diversity increased. Carbon isotope ratios of SOM at the top surface layer indicated that C-4-derived carbon contributed more to SOM in the early phase of recovery and decreased with further recovery.
  • SG Li, M Tsujimura, A Sugimoto, L Sasaki, T Yamanaka, G Davaa, D Oyunbaatar, M Sugita
    TREES-STRUCTURE AND FUNCTION 20 1 122 - 130 2006年01月 [査読有り][通常論文]
     
    Measurements of water oxygen isotopic composition were conducted in the 2003 growing season for a montane larch (Larix sibirica Ledeb.) forest in northern Mongolia, a transitional area from the south Siberian taiga to the Asian steppe. Oxygen isotopic composition of foliar water and its daily variability were found to be sensitive to atmospheric evaporative demand. During most of the growing season, water sources used by larch trees were from the upper 30-cm surface layer of the soil when precipitation input was large, and were from the deeper layer when the water supply at the upper soil layer was limited. The Keeling plot method suggested that the forest returned soil water to the atmosphere predominantly by means of canopy transpiration during the peak growth period (in August).
  • N Kurita, A Sugimoto, Y Fujii, T Fukazawa, VN Makarov, O Watanabe, K Ichiyanagi, A Numaguti, N Yoshida
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 110 D13 2005年07月 [査読有り][通常論文]
     
    The spatial isotopic distribution of the snowpack over Siberia, where winter temperatures are as cold as those of the polar regions, was observed by the Trans-Siberian Snow Survey (TSSS) and Trans-Verkhoyansk Snow Survey Expedition (TVSSE) in March 2000 and March 2001. The results show inland delta D depletion and a slightly increasing deuterium excess value, d, in the snowpack over Siberia. To explore the relationship between source region variability and the isotopic composition of snow, a model simulation was performed that reproduced the observed isotopic composition of snow. Moisture sources for Siberian precipitation were estimated using the Center for Climate System Research/National Institute for Environmental Studies (CCSR/NIES) atmospheric general circulation model (AGCM). A simple isotopic model was used to evaluate the total isotopic changes during transport from the designated source region to the region of precipitation. The results showed that the variability of the contribution of each source to the snow results in large isotopic variability, and the fact that the model reproduced the observed inland depletion of dD in snowpack suggests that GCM-predicted source contributions were verified by observed values. However, the modeled d values did not match observed d values over Siberia. Observations of d values in precipitation show an increase during autumn toward a maximum in late autumn and then a decrease during winter; however, the modeled d value reached a maximum in early autumn and decreased toward a minimum in winter. The simple isotope model does not consider additional moisture evaporation joining an airmass moving from a source region. Therefore the disagreement between the modeled and observed d values of snow suggests that moisture supplied from the land surface during transportation significantly contributes to autumn snow. The increased d values of Siberian snow show that evaporation from open water or from the soil surface, which are accompanied by isotopic fractionation, are more important than transpiration flux, which does not change the isotopic content. The contribution of land-derived moisture that has evaporated from open water plays an important role in eastern Siberian snow.
  • A Yamada, T Inoue, D Wiwatwitaya, M Ohkuma, T Kudo, T Abe, A Sugimoto
    ECOLOGICAL RESEARCH 20 4 453 - 460 2005年07月 [査読有り][通常論文]
     
    A role of termites in decomposition processes was quantitatively evaluated in a dry evergreen forest (DEF) in Thailand, using respiration rates and biomasses of fungus combs as well as of termites themselves. The termite Population and fungus combs mineralized 11.2% of carbon (C) in the annual above-ground litterfall (AAL) by their respiration. Fungus combs were responsible for a major part (7.2% of the AAL) of the C mineralization mediated by termites. For comparison, fractions of AAL mineralized by respiration from termite populations and fungus combs were estimated for tropical forests and savannas where termites have been Well Studied, assuming that there is the same ratio as for the DEF between biomass of fungus combs and abundance of fungus growers. Termites in dry tropical forests (annual rainfall <2,000 min) are shown to mineralize about 10% of C in the AAL by respiration from their populations and fungus combs, and their ecological impact in savannahs is comparable in this aspect. A significant negative correlation between fraction of AAL and annual rainfall demonstrates that the importance of termites in decomposition processes is greater in dry tropical forests than in moist tropical forests. Considering that fungus combs contributed significantly to AAL mineralization in most of the tropical forests and savannas, fungus growers are a much more influential group than previously expected in tropical ecosystems.
  • J Murase, Y Sakai, A Kametani, A Sugimoto
    ECOLOGICAL RESEARCH 20 3 377 - 385 2005年05月 [査読有り][通常論文]
     
    As a part of a core project of IGBP (International Geosphere-Biosphere Programme), distribution, production, oxidation and transport processes of methane in bottom sediments and lake water in a mesotrophic lake (Lake Biwa) have been studied with special reference to the spatial heterogeneity of each process. In this study, we attempted to synthesize previously reported results with newly obtained ones to depict the methane dynamics in the entire lake. The pelagic water column exhibited subsurface maxima of dissolved methane during a stratified period. Transect observation at the littoral zone suggested that horizontal transportation may be a reason for the high methane concentration in epilimnion and thermocline at the offshore area. Tributary rivers and littoral sediments were suggested to be the source. Observations also showed that the internal wave caused resuspension of the bottom sediment and release of methane from the sediment into the lake water. The impact of the internal waves was pronounced in the late stage of a stratified period. The littoral sediment showed much higher methanogenic activity than the profundal sediments, and the bottom water of the littoral sediments had little methanotrophic activity. In the profundal sediment, most of the methane that diffused up from the deeper part was oxidized when it passed through the oxic layer. Active methane oxidation was also observed in the hypolimnetic water, while the lake water in the epilimnion and thermocline showed very low methane oxidation, probably due to the inhibitory effect of light. These results mean a longer residence time for methane in the epilimnion than in the hypolimnion. Horizontal inflow of dissolved methane from the river and/or littoral sediment, together with the longer residence time in the surface water, may cause the subsurface maxima, which have also been observed in other lakes and in the ocean.
  • M Katoh, J Murase, A Sugimoto, M Kimura
    ORGANIC GEOCHEMISTRY 36 5 803 - 811 2005年 [査読有り][通常論文]
     
    A flooded soil column experiment was conducted in which C-13-enriched rice straw (RS, 7.0 g kg(-1) dry weight soil) was added to evaluate the effects of RS application on the leaching of cationic nutrients (Ca, Mg, and Fe), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and CH4 from the plow layer of rice paddies by water percolation. The origins of these nutrients in rice paddy soil were studied by comparing their content in the soil before and after the percolation experiment. The proportion of total cationic nutrients in percolating water to the content of exchangeable Ca, Mg and amorphous Fe in the soil during the I I I d experiment increased from 21% to 46% for Ca, 34-61% for Mg, and 4.5-14% for Fe as a result of RS application at 25 degrees C. The decrease in exchangeable Ca, Mg and amorphous Fe after the experiment were comparable to the total amounts detected in the percolating water, suggesting that these cationic nutrients in the water were derived from exchangeable Ca, Mg and amorphous Fe in the soil. The application of RS increased DIC and CH4 leaching more than twofold compared to a control experiment in which C-13-enriched RS was not applied. The contribution of RS carbon to DIC, DOC and CH4 in percolating water was 80, 23 and 70%, respectively. The application of RS was shown to suppress the decomposition of soil organic matter, based upon measurement of a low C-12 content of DIC in the percolating water. (C) 2005 Elsevier Ltd. All rights reserved.
  • J Dan, T Kumai, A Sugimoto, J Murase
    LIMNOLOGY 5 3 149 - 154 2004年12月 [査読有り][通常論文]
     
    To determine the rate and mechanism of CH, production in Lake Biwa sediment, slurry was prepared and incubated. Surface sediment (sed) slurry (1.5-6cm) showed a CH4 release rate (4.9-9.5nmolg-dry-sed(-1) day(-1)) higher than that observed in the 5(-1) to 10(-1)cm sediment slurry (0.22nmolg-dry-sed(-1) day(-1)). Methane release from the surface (1.5-6cm) sediment slurry was biotic and was inhibited by addition of 2-bromoethanesulfonate (BES, an inhibitor of CH, production), whereas that from 5- to 10-cm sediment slurry was abiotic. The addition of BES, HNO3, and O-2 showed no effect on the CH4 release rate from the 5- to 10-cm sediment slurry. In addition, tracers ((NaHCO3)-C-13, 13 CH,COONa) were not incorporated into the released CH4 However, delta(13)C of CH4 released from the 5- to 10-cm sediment slurry (-74.0 +/- 0.6%.) indicated that this CH4 was produced by bacterial metabolism in the past, stored by adsorption on the surface of clay minerals in the sediment, and then released abiotically by desorption from the sediment slurry as a result of a decrease in hydraulic pressure and CH4 concentration in the pore water. This CH4 stored by adsorption could be extracted by autoclaving. In the sediment below 5cm, bacterial activity for CH4 production ceased, possibly because of the limitated availability of H-2 To clarify the mechanism of CH4 production in the sedi- ment, biotic CH4 production and the abiotic CH4 release found here should be estimated separately.
  • T Uchida, N Kaneko, MT Ito, K Futagami, T Sasaki, A Sugimoto
    APPLIED SOIL ECOLOGY 27 2 153 - 163 2004年10月 [査読有り][通常論文]
     
    Differences in food resource use by earthworms (Megascolecidae) were studied at three Japanese forest sites with different latitude in cool-temperate (TOEF), temperate (MFF) and subtropical (Yona) zones. The vertical distribution and the fractionation of gut contents of earthworms were analysed to determine ecological categories. At TOEF and MFF, earthworm communities were composed of species living mainly in litter and topsoil layers. At TOEF, Amynthas vittatus (Goto and Hatai, 1898), Metaphire hilgendorfi (Michaelsen, 1892) and Eisenia japonica (Michaelsen, 1891) (Lumbricidae) were dominant, the former two species being mainly observed in the litter layer whereas the latter was in soil layers. At MFF, `Metaphire' soulensis (Kobayashi, 1938), Amynthas purpuratus (Ishizuka, 1999), A. vittatus and Amynthas distichus (Ishizuka, 2000) were dominant and the former three species were observed in the litter layer whereas the latter one occurred in soil. The gut contents of those living in the litter layer had more organic fractions, whereas the latter had more inorganic fractions. Therefore these species were regarded as epigeic species and polyhumic-endogeic species, respectively. At Yona, Amynthas yambarliensis (Ishizuka and Azama, 2000) had burrows through 20 cm depth with casts and middens on the forest floor, and their fraction ratio of gut content was intermediate between the epigeic and endogeic earthworms at TOEF and MFF. Therefore. A. yambaritensis was classified as anecic. In addition, at Yona, there were two unidentified Amynthas spp.; one epigeic species in the midden of A. yalnbaruenesis, and one endogeic species found in B-layer soil. Natural abundances of the stable isotope pairs t'C/1-'C and 15N/14N (8"C and &15 N) were measured in soil organic matter and earthworm tissue. 815N values showed epigeic < polyhumic-endogeic at TOEF and MFF, whereas at Yona, 815N values were in the order anecic < epigeic < endogeic. The observed 15N enrichments thus appear to indicate that the functional niches of earthworm species are due to resources available to them in the decomposition process from fresh litter to humus. delta13C values showed similar trends. but the differences between ecological group was smaller compared to delta15 N. 2004 Elsevier B.V. All rights reserved.
  • YH Lu, J Murase, A Watanabe, A Sugimoto, M Kimura
    FEMS MICROBIOLOGY ECOLOGY 48 2 179 - 186 2004年05月 [査読有り][通常論文]
     
    Photosynthesis by terrestrial vegetation is the driving force of carbon cycling between soil and the atmosphere. The soil microbiota, the decomposers of organic matter, is the second player carrying out carbon cycling. Numerous efforts have been made to quantify rhizodeposition and soil respiration to understand and predict the carbon cycling between the soil and atmosphere. However, there have been few attempts to link directly the soil microbial community to plant photosynthesis. We carried out a pulse-chase labeling experiment in a wetland rice system in which rice plants of various ages were labeled with (CO2)-C-13 for 6 h and the distribution of the assimilated C-13 to soil microorganisms was estimated by analyzing the C-13 profile of microbial phospholipid fatty acids (PLFAs). The results showed that total PLFA increased with plant growth, indicating an increase of microbial biomass. But the mono-unsaturated PLFAs increased faster than the branched chain fatty acids. The C-13 was incorporated into PLFAs immediately after the plant (CO2)-C-13 assimilation, proving the tight coupling of microbial activity to plant photosynthesis. In line with the finding of seasonal change in total PLFAs, more of C-13 was distributed to the straight chain fatty acids (16:0, 16:1omega7, 18:1omega7 and 18:1omega9) than to the branched chain fatty acids. The total plant carbon incorporation estimated from C-13 labeling roughly corresponded to the increase in total PLFAs over the growing season of plants. Our study suggests that microbial populations in rice soil differ greatly in their responses to plant photosynthate input. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
  • A Yamada, T Inoue, A Sugimoto, Y Takematsu, T Kumai, F Hyodo, A Fujita, Tayasu, I, C Klangkaew, N Kirtibutr, T Kudo, T Abe
    SOCIOBIOLOGY 43 2 231 - 232 2004年 [査読有り][通常論文]
  • A Sugimoto, J Dan, T Kumai, J Murase
    GEOPHYSICAL RESEARCH LETTERS 30 21 2003年11月 [査読有り][通常論文]
     
    Methane stored in a natural lake sediment was investigated. Fresh sediment (8-25 cm in sediment depth) taken from Lake Biwa, Japan, contains 2.6 mumol/g d.s. (dry sediment) of CH4 on average. The sediment retained 0.31 mumol/g <LF>d.s. of CH4 even after air drying, which is 12% of the total CH4 in the fresh sediment. The higher the temperature for drying of the sediment, the smaller the amount of CH4 retained. The result of an adsorption experiment indicated that dried and completely degassed lake sediment adsorbs CH4. Clay particles in the sediment are possibly responsible for the adsorption of CH4. Methane observed in the fresh lake sediment was probably produced by bacteria in the past, then adsorbed on the sediment particles. Adsorption is another form of storage of CH4 in lake and ocean sediments, in addition to the well known forms of dissolved, bubble, and hydrate CH4.
  • Contribution of rice straw carbon to IC, DOC, and methane in percolation water from a submerged paddy soil: A microcosm experiment using C-13-enriched rice straw
    Kimura, A, Kato, A, Murase, J, Sugimoto, A
    Kimura, A; Kato, A; Murase, J; Sugimoto, A 67 18 A217 - A217 2003年09月 [査読有り][通常論文]
  • J Murase, Y Sakai, A Sugimoto, K Okubo, M Sakamoto
    LIMNOLOGY 4 2 91 - 99 2003年08月 [査読有り][通常論文]
     
    The spatial distribution and seasonal variation in the concentration and carbon isotopic composition of dissolved methane in a river-lake ecosystem were studied in Lake Biwa, Japan, and its tributary rivers. Methane concentrations in all subsystems examined were supersaturated with respect to the atmosphere. The epilimnion showed higher concentrations of dissolved methane than the hypolimnion in the pelagic zone. Peak methane concentrations were observed at the thermocline. The largest amount of methane in the pelagic water column was recorded at the end of a stagnant period, at which the bottom water of the sublittoral zone (30m in depth) exhibited increased methane concentration. Transect observation of dissolved methane revealed three methane peaks at different water depths in the lake, and river water and the sediments in littoral and sublittoral zones were suggested to be the corresponding sources. Water at the river mouth was replete with dissolved oxygen but also contained a high concentration of methane. The present results suggest that river water and littoral sediment are potential sources of dissolved methane in Lake Biwa, and other sources, such as internal waves, are responsible for increased methane in the pelagic zone at the end of stagnant periods. Carbon stable isotope analysis indicated that there were different sources of dissolved methane, although it was difficult to identify the origins due to high variation of the isotopic composition of methane from different sources.
  • A Kagawa, D Naito, A Sugimoto, TC Maximov
    JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 108 D16 2003年08月 [査読有り][通常論文]
     
    We studied the relationships between earlywood/latewood width, stable carbon isotope ratio (delta(13)C) of cellulose, and soil moisture at a dry and a wet site in Yakutsk, eastern Siberia, which differed considerably in soil water conditions. Recharge of soil water by snowmelt in spring and subsequent drought in summer provided a marked seasonal contrast in soil water conditions between the earlywood and latewood formation period. Ring index was calculated by dividing each earlywood/latewood width by the 5-year averaged width for each individual. In order to determine whether drought influenced the ring index-delta(13)C relation, the ring index time series were compared with delta(13)C time series. We collected wood samples from eight Larix gmelinii (Rupr.) Rupr. and four Pinus sylvestris L. trees from the two sites and measured the earlywood and latewood widths and delta(13)C of earlywood and latewood formed during the years 1996-2000. At the dry site, seasonal soil water content variation corresponded to seasonal delta(13)C variation of tree rings. We found negative ring index-delta(13)C correlations in latewood for both species at the dry site mainly dominated by Pinus but not in latewood of Larix at the wet site dominated by Larix. Decrease and/or early cessation of latewood growth and increase in delta(13)C under drought conditions possibly explain this negative correlation. This suggests the growth limitation of trees in this region by drought and the prospects of reconstructing past drought with latewood delta(13)C of the dry site.
  • Kurita, N, Numaguti, A, Sugimoto, A, Ichiyanagi, K, Yoshida, N
    Kurita, N; Numaguti, A; Sugimoto, A; Ichiyanagi, K; Yoshida, N 108 D11 2003年06月07日 [査読有り][通常論文]
  • R Tateno, S Katagiri, H Kawaguchi, Y Nagayama, CH Li, A Sugimoto, K Koba
    ECOLOGICAL RESEARCH 18 3 279 - 286 2003年05月 [査読有り][通常論文]
     
    We compared the foliar delta(15)N and delta(13)C values of Pinus massoniana growing on soils with and without microbiotic crust to examine the influence of the microbiotic crust on N and water use in plants in deteriorated watersheds in southern China. At our study site, litterfall and undergrowth had been intensively removed for fuel and soil N concentration was extremely low. Microbiotic crust covered the lower slope within the watersheds and pine trees were taller here than on the middle and upper slopes, although the crust reduced the amount of rainfall that could penetrate the soil. The foliar delta(15)N values were greater (closer to zero) in pine trees growing on soil covered with microbiotic crust on the lower slope than on the middle and upper slopes, which lacked the microbiotic crust. These data suggest that P. massoniana may depend on N fixed by the microbiotic crust on the lower slope, and on N carried by precipitation on the middle and upper slopes. The microbiotic crust did not influence foliar delta(13)C, an index for water use efficiency, in P. massoniana . The fact that P. massoniana biomass was greater on the lower slope, which is less permeable to rainfall, suggests that P. massoniana growth may be limited by the amount of available N rather than by water. The microbiotic crust may improve plant productivity by increasing N availability, despite its negative effect on water availability.
  • A Kohzu, K Matsui, T Yamada, A Sugimoto, N Fujita
    ECOLOGICAL RESEARCH 18 3 257 - 266 2003年05月 [査読有り][通常論文]
     
    Variation in stable nitrogen isotope ratios (delta(15)N) was assessed for plants comprising two wetland communities, a bog-fen system and a flood plain, in central Japan. delta(15)N of 12 species from the bog-fen system and six species from the flood plain were remarkably variable, ranging from -5.9 to +1.1parts per thousand and from +3.1 to +8.7parts per thousand, respectively. Phragmites australis exhibited the highest delta(15)N value at both sites. Rooting depth also differed greatly with plant species, ranging from 5 cm to over 200 cm in the bog-fen system. There was a tendency for plants having deeper root systems to exhibit higher delta(15)N values; plant delta(15)N was positively associated with rooting depth. Moreover, an increasing gradient of peat delta(15)N was found along with depth. This evidence, together with the fact that inorganic nitrogen was depleted under a deep-rooted Phragmites australis stand, strongly suggests that deep-rooted plants actually absorb nitrogen from the deep peat layer. Thus, we successfully demonstrated the diverse traits of nitrogen nutrition among mire plants using stable isotope analysis. The ecological significance of deep rooting in mire plants is that it enables those plants to monopolize nutrients in deep substratum layers. This advantage should compensate for any consequential structural and/or physiological costs. Good evidence of the benefits of deep rooting is provided by the fact that Phragmites australis dominates as a tall mire grass.
  • A. Sugimoto, D. Naito, N. Yanagisawa, K. Ichiyanagi, N. Kurita, J. Kubota, T. Kotake, T. Ohata, T. C. Maximov, A. N. Fedorov
    Hydrological Processes 17 6 1073 - 1092 2003年04月30日 [査読有り][通常論文]
     
    Soil moisture and its isotopic composition were observed at Spasskaya Pad experimental forest near Yakutsk, Russia, during summer in 1998, 1999, and 2000. The amount of soil water (plus ice) was estimated from volumetric soil water content obtained with time domain reflectometry. Soil moisture and its δ18O showed large interannual variation depending on the amount of summer rainfall. The soil water δ18O decreased with soil moisture during a dry summer (1998), indicating that ice meltwater from a deeper soil layer was transported upward. On the other hand, during a wet summer (1999), the δ18O of soil water increased due to percolation of summer rain with high δ18O values. Infiltration after spring snowmelt can be traced down to 15 cm by the increase in the amount of soil water and decrease in the δ18O because of the low δ18O of deposited snow. About half of the snow water equivalent (about 50 mm) recharged the surface soil. The pulse of the snow meltwater was, however, less important than the amount of summer rainfall for intra-annual variation of soil moisture. Excess water at the time just before soil freezing, which is controlled by the amount of summer rainfall, was stored as ice during winter. This water storage stabilizes the rate of evapotranspiration. Soil water stored in the upper part of the active layer (surface to about 120 cm) can be a water source for transpiration in the following summer. On the other hand, once water was stored in the lower part of the active layer (deeper than about 120 cm), it would not be used by plants in the following summer, because the lower part of the active layer thaws in late summer after the plant growing season is over. Copyright © 2002 John Wiley and Sons, Ltd.
  • N Ohte, K Koba, K Yoshikawa, A Sugimoto, N Matsuo, N Kabeya, LH Wang
    ECOLOGICAL APPLICATIONS 13 2 337 - 351 2003年04月 [査読有り][通常論文]
     
    We used stable isotope techniques to investigate water utilization of two native trees, Sabina vulgaris Ant. and Artemisia ordosica Krasch., and one introduced tree, Salix matsudana Koidz., in the semiarid Mu-Us desert, Inner Mongolia, China. The study site was in a region where there has been a decline in agricultural productivity, caused by severe desertification over the past several decades. S. matsudana is used extensively for reforestation to protect farms and cultivated lands from shifting sand dunes. We identified water sources for each tree species by comparing the stable isotopes deltaD and delta(18)O in water in stems, soil, and groundwater. We also measured delta(13)C levels in leaves to evaluate the intrinsic water-use efficiency (WUE) of each plant. Comparison of isotopes showed that S. vulgaris and S. matsudana consume relatively deep soil water as well as groundwater, whereas A. ordosica uses only shallow soil water. The delta(13)C measurements indicated that S. vulgaris has exclusively high WUE, whereas that of the other species was typical of temperate-region C, plants. The water source data plus WUE data suggest that planted S. matsudana uses groundwater freely, whereas native plants conserve water. Thus, reforestation with S. matsudana might cause irreversible groundwater shortages.
  • Y Takematsu, T Inoue, F Hyodo, A Sugimoto, N Kirtebutr, T Abe
    SOCIOBIOLOGY 42 3 587 - 596 2003年 [査読有り][通常論文]
     
    In a dry evergreen forest of Sakaerat, Thailand, five types of nests (arboreal, epigeal, hypogeal, inquiline and nests within wood) which were built by the genus Microcerotermes were observed. Morphologically, all samples collected from five nest types belonged to the same species and were identified as Microcerotermes crassus. This indicates that a single species can build different nest types in the same locality. Furthermore, the density of nests and the relative abundance were investigated. At 99 nests per plot area (165 nests per hectare), the nest abundance and the relative abundance was very much higher than in other Southeast Asian forests.
  • A Yamada, T Inoue, A Sugimoto, Y Takematsu, T Kumai, F Hyodo, A Fujita, Tayasu, I, C Klangkaew, N Kirtibutr, T Kudo, T Abe
    SOCIOBIOLOGY 42 3 569 - 585 2003年 [査読有り][通常論文]
     
    The abundance and biomass of termites in dead wood were estimated in a dry evergreen forest in Thailand. Litter and dead wood were collected within ten 2 x 2 m quadrats on a 100 m transect, and then all termites in the litter and dead wood (= termites in dead wood) were dislodged. The biomass of litter and dead wood was 2.50 kg (dry weight) m(-2), of which 76% was represented by dead wood with a diameter of ! 1 cm. A total of 239 pieces of dead wood (diameter ! I cm) were collected, and 38 of them contained termites. The frequency of termites in dead wood was significantly different between pieces with a diameter of 1-5 cm and pieces with a diameter of greater than or equal to5 cm. The abundance and biomass of termites in dead wood were 1269 termites m(-2) and 3.53 g m(-2), respectively. A total of I I species, comprising Kalotermitidae, Rhinotermitidae and Termitidae, were collected; all of them belonged to the wood/litter-feeding group. Using our previous estimation for termites in the soil and data from other studies, the abundance and biomass of termites in the dry evergreen forest were estimated to be 7794 termites m(-2) and 16.7 g m(-2), of which 16 and 21%, respectively, were represented by termites in dead wood. Our study confirmed the importance of termites in dead wood in tropical seasonal forests.
  • K Ichiyanagi, A Sugimoto, A Numaguti, N Kurita, Y Ishii, T Ohata
    GEOCHEMICAL JOURNAL 37 4 519 - 530 2003年 [査読有り][通常論文]
     
    Detailed measurements of temporal variations in the stable isotopic composition of precipitation and lake water were conducted in the permafrost region near Yakutsk, eastern Siberia. The delta(18)O ranged from approximately -30 to -5parts per thousand in precipitation and from -25 to -5parts per thousand in lake water were observed from April to August, 2000. Temporal changes in delta(18)O of precipitation observed weekly at 12 sites all showed the same trend. The temporal variation of delta(18)O in lakes classified into two groups: isotopically steady-state lakes with less than 5parts per thousand variation, and non-steady-state lakes with variation exceeding 10parts per thousand. In non-steady-state lakes, the water originated from snowmelt, and the delta(18)O of lake water gradually enriched as a result of evaporation during the summer. In steady-state lakes, the water originated predominantly from O-18-enriched lake water that had evaporated in the previous summer. The temporal volumetric and isotopic variations in alas lakes are accurately depicted by an isotope mass-balance model using Rayleigh fractionation over daily time steps. The inflow of soil water (subsurface flow) was estimated to be constant (200 m(3)/day) from May to August, based on the difference between observed and simulated lake volumes. Taking the isotopic mass-balance into consideration, the soil water in lower part of the active layer is inferred as a major component of inflow which has a delta(18)O of about -23parts per thousand.
  • F Nakagawa, N Yoshida, A Sugimoto, E Wada, T Yoshioka, S Ueda, P Vijarnsorn
    BIOGEOCHEMISTRY 61 1 1 - 19 2002年10月 [査読有り][通常論文]
     
    Stable isotopes (delta(13)C, deltaD) and radiocarbon were measured in methane bubbles emitted from rice paddies and swamps in southern Thailand. Methane emitted from the Thai rice paddies was enriched in (13)C (mean delta(13)C; -51.5 +/- 7.1parts per thousand and -56.5 +/- 4.6parts per thousand for mineral soil and peat soil paddies, respectively) relative to the reported mean value of methane from temperate rice paddies (- 63 +/- 5parts per thousand). Large seasonal variation was observed in delta(13)C(similar to32parts per thousand) in the rice paddies, whereas variation in deltaD was much more smaller (similar to20parts per thousand), indicating that variation in delta(13)C is due mainly to changes in methane production pathways. Values of delta(13)C were lower in swamps (-66.1 +/- 5.1parts per thousand) than in rice paddies. The calculated contribution of acetate fermentation from delta(13)C value was greater in rice paddies (mineral soils: 62-81%, peat soils: 57-73%) than in swamps (27-42%). deltaD in methane from Thai rice paddies (-324 +/- 7parts per thousand (n=46)) is relatively higher than those from 14 stations in Japanese rice paddies ranging from -362 +/- 5parts per thousand (Mito: n=2) to -322 +/- 8parts per thousand (Okinawa: n=3), due to higher deltaD in floodwaters. (14)C content in methane produced from Thai rice paddies (127 +/- 1 pMC) show higher (14)C activity compared with previous work in paddy fields and those from Thai swamps (110 +/- 2 pMC).
  • A Sugimoto, N Yanagisawa, D Naito, N Fujita, TC Maximov
    ECOLOGICAL RESEARCH 17 4 493 - 503 2002年07月 [査読有り][通常論文]
     
    Stable oxygen isotope ratios of plant water (sap water) were observed at Spasskaya Pad experimental forest near Yakutsk, Russia in 1997-1999. The delta(18)O of sap water in larch trees (Larix gmelinii ) decreased soon after leaf unfolding every year, indicating that snowmelt water was used in the beginning of summer. During mid to late summer, a clear difference in the water source used by plants was observed between wet summers and severe drought summers. The delta(18) O values of water in larch trees were high (-17.8 to -16.1parts per thousand) in August 1999 (wet summer), but low (-20.4 to -19.7parts per thousand) in August 1998 (drought summer). These results indicated that plants used rainwater during a wet summer, but meltwater from permafrost was used by plants during a drought summer. One important role of permafrost is to provide a direct source of water for plants in a severe drought summer; another role is to keep surplus water in the soil until the next summer. If this permafrost system is disturbed by future global warming, unique monotypic stands of deciduous larch trees in east Siberia might be seriously damaged in a severe drought summer.
  • Tsujimura, M, Numaguti, A, Tian, L, Hashimoto, S, Sugimoto, A, Nakawo, M
    Tsujimura, M; Numaguti, A; Tian, L; Hashimoto, S; Sugimoto, A; Nakawo, M 79 1B 599 - 605 2001年05月 [査読有り][通常論文]
  • T Inoue, Y Takematsu, F Hyodo, A Sugimoto, A Yamada, C Klangkaew, N Kirtibutr, T Abe
    SOCIOBIOLOGY 37 1 41 - 52 2001年 [査読有り][通常論文]
     
    The abundance and biomass of subterranean termites were assessed in the dry evergreen forest within the Sakaerat Environmental Research Station, northeast Thailand. The samplings were carried out by pit-digging in November 1998 (during rainy season) and February 1999 (during dry season). A total of 23 species of termites, comprising 17 genera were identified. Estimated abundance was 6450 tesmites/m(2) in November and 2526 termites/m(2) in February and biomass was 10.74g/m(2) (fresh mass) in November and 5.35g/m(2) in February, although no significant difference was detected in termite abundance and biomass between rainy and dry season. In 30cm depth pit-digging, we found more than 93% of individual termites and more than 94% of total biomass within the top 20cm of soil layer in both samplings. The termite abundance and biomass within the surficial soil layer (0-10cm layer) showed no significant difference between in November and February sampling.
  • J Murase, A Sugimoto
    GEOCHEMICAL JOURNAL 35 4 257 - 263 2001年 [査読有り][通常論文]
     
    The spatial variation of methane contents and its stable carbon isotopic composition of sediments from a mesotrophic lake (Lake Biwa) were determined. Methane concentrations in the sediments (0-10 cm), ranging from 0.04 to 2.41 mu mol ml(-1), were weakly correlated with the amounts of organic carbon in the surface sediments (0-2 cm), but were poorly correlated with the nitrogen isotopic composition of the bulk sediments used as an indicator of the origin of the organic matter (autochthonous vs. allochthonous). The carbon isotopic composition of methane ranged from -61 to -80 parts per thousand and exhibited positive correlation with methane concentration and the carbon isotopic composition of total carbonate (Sigma CO2). The apparent fractionation factor (alpha cCH(4)-CO2) between methane and Sigma CO2 was in the range between 1.07 and 1.085, which were rather high compared to previously reported values in freshwater sediments. The results suggested that major parts of methane were produced via CO2-H-2 in the Lake Biwa sediments.
  • S Ueda, CSU Go, T Yoshioka, N Yoshida, E Wada, T Miyajima, A Sugimoto, N Boontanon, P Vijarnsorn, S Boonprakub
    BIOGEOCHEMISTRY 49 3 191 - 215 2000年06月 [査読有り][通常論文]
     
    We studied the distribution of dissolved O-2, CO2, CH4, and N2O in a coastal swamp system in Thailand with the goal to characterize the dynamics of these gases within the system. The gas concentrations varied spatially and seasonally in both surface and ground waters. The entire system was a strong source for CO2 and CH4, and a possible sink for atmospheric N2O. Seasonal variation in precipitation primarily regulated the redox conditions in the system. However, distributions of CO2, CH4, and N2O in the river that received swamp waters were not always in agreement with redox conditions indicated by dissolved O-2 concentrations. Sulfate production through pyrite oxidation occurred in the swamp with thin peat layer under aerobic conditions and was reflected by elevated SO42-/Cl- in the river water. When SO42-/Cl- was high, CO2 and CH4 concentrations decreased, whereas the N2O concentration increased. The excess SO42- in the river water was thus identified as a potential indicator for gas dynamics in this coastal swamp system.
  • Tayasu, I, F Hyodo, Y Takematsu, A Sugimoto, T Inoue, N Kirtibutr, T Abe
    ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 36 3 259 - 272 2000年 [査読有り][通常論文]
     
    Nitrogen and carbon stable isotope ratios and uric acid concentrations in termites sampled from a dry evergreen forest in Thailand, were determined across three kinds of feeding habits. Feeding habits of Microcerotermes crassus, which is an abundant wood-feeder, and Dicuspiditermes makhamensis, a common soil-feeding termite, were confirmed by isotopic signatures. Lichen feeding termites (Hospitalitermes birmanicus, H. bicolor and H. ataramensis) were characterized by low delta N-15 values, suggesting that they assimilated nitrogen deposited from the atmosphere. There was also a significant difference in uric acid concentrations between termites representing different feeding habits. No significant relationships were found between uric acid concentrations and delta N-15 or delta C-13 in Hospitalitermes. However, delta N-15 values were correlated with C/N ratios in H. birmanicus, except in one colony of H. ataramensis. delta C-13 values in both species were negatively correlated with C/N ratios.
  • A Sugimoto, T Inoue, N Kirtibutr, T Abe
    GLOBAL BIOGEOCHEMICAL CYCLES 12 4 595 - 605 1998年12月 [査読有り][通常論文]
     
    Emission rates and carbon isotope ratios of CH4, emitted by workers of termites, and of CH4, emitted from their mounds, were observed in a dry evergreen forest in Thailand to estimate the proportion of CH4 oxidized during emission through the mound. The delta(13)C of CH4 emitted from a termite mound (-70.9 to -82.4 parts per thousand) was higher than that of CH4 emit-red by workers in the mound (-85.4 to -97.1 parts per thousand). Using a fractionation factor (alpha = 0.987) for oxidation of CH4 which was obtained in the incubation experiment, an emission factor defined as (CH4 emitted from a termite mound/CH4 produced by termites) was calculated. The emission factor obtained in each termite mound was nearly zero for Macrotermes (fungus-growing termites), of which the nest has a thick soil wall and subterrannean termites, and 0.17 to 0.47 for Termitinae (small-mound-making termites). Global CH4 emission by termites was estimated on the basis of the CH4 emission rates by workers and termite biomass with the emission factors. The calculated result was 1.5 to 7.4 Tg/y (0.3 to 1.3% of total source), which is considerably smaller than the estimate by the IPCC[1994].
  • Tayasu, I, T Inoue, LR Miller, A Sugimoto, S Takeichi, T Abe
    FUNCTIONAL ECOLOGY 12 4 536 - 542 1998年08月 [査読有り][通常論文]
     
    1. Carbon (delta(13)C) and nitrogen (delta(15)N) Stable isotope ratios of termites (Isoptera) were examined in Darwin, northern Australia. It is suggested that the stable isotope technique, together with phylogenetics, is a useful tool to understand the evolution of functional groups in detritivores. 2. A high delta(15)N value was observed in the Termes-Capritermes branch of the subfamily Termitinae and the genus Amitermes, two distinct taxonomic groups that evolved from wood-feeding to soil-feeding in Australia. Among eight Termes-Capritermes branch species, only two species (Xylochomitermes melvillensis and Ephelotermes melachoma) were discernible as wood/soil interface feeders, the remaining six species analysed were soil-feeders, where the diet preference was identified by using delta(15)N Of workers. 3. The Termes-Capritermes group in Australia contains both wood/soil interface feeders and soil-feeders, whereas wood/soil interface feeders in Cameroon are from the Termes-Capritermes branch while soil-feeders are from Cubitermes group. The result confirmed that soil-feeding forms evolved both in Australia and Africa, but from different phylogenetic groups.
  • A Sugimoto, T Inoue, Tayasu, I, L Miller, S Takeichi, T Abe
    ECOLOGICAL RESEARCH 13 2 241 - 257 1998年08月 [査読有り][通常論文]
     
    Methane and hydrogen emission rates and the delta(13)C Of CH4 were observed for various termites in Australia, Thailand and Japan. Combined with the already reported emission rates of CH4 in the literature, the phylogenetic trend was examined. Emission rates of the observed termites were categorized into five groups: group I with high CH4 and low H-2 emission rates with a CH4/H-2 ratio of typically 10/1; group II with high CH4 and high H-2 emissions with a CH4/H-2 ratio of 4/1-1/2; group III with low emission rates of CH4 and H-2; group TV with high H-2 and insignificant CH4 emissions; and group V with insignificant emissions for both CH4 and H-2. In lower termites, there are both colonies infected and uninfected with methanogens even in the same species, and no specific trend in CH4 and H-2 emissions was observed within a genus. Whether protozoa in the hindgut of termites are infected with methanogens or not and the differences in species compositions of protozoa are possibly responsible for the inter-colonial variations. The proportions of infected colonies were possibly small for the family Kalotermitidae (dry wood feeders), and relatively large for families of wet or damp wood feeders. The hydrogen emission rate possibly depends on the locality of methanogens: namely, whether they are intracellular symbionts of protozoa or whether they are attached to the hindgut wall. Emission rates of higher termites were classified into groups according to genera and the diet. Most species of soil or wood/soil interface feeders classified into group I, while the soil feeders Dicuspiditermes in Thailand and Amitermes in Australia were classified into groups with high H-2 emission rates. Typical wood-feeding termites and fungus-growing termites were classified into group III. The results indicate that higher termites tend to increase the CH4 emission rate during dietary evolution from wood- to soil feeding, and two types of the system with different efficiencies of interspecies transfer of H-2 have been formed. The delta(13)C Of CH4 was discernible with a difference in the decomposition process in the termite-symbiont system among lower termites, fungus-growing termites and other higher termites.
  • A Sugimoto, N Fujita
    TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY 49 4 382 - 392 1997年09月 [査読有り][通常論文]
     
    Methane flux was observed on a floating mat of temperate sphagnum bog, Mizorogaike, Japan, during the period April to October in 1993, to investigate the factors controlling CH4 emission, especially differences in vegetation and variation of water level. Comparing the CH4 flux among reed dominant site, marsh trefoil (a broad-leaved perennial aquatic herb) dominant site and sphagnum dominant site, the largest CH4 flux was observed at the marsh trefoil site and the smallest flux was at the sphagnum site, reflecting the difference in decomposability of organic matter. Namely, the decomposition rate of marsh trefoil was high, while that of sphagnum was extremely low. At the marsh trefoil site, lowering of the water table below the surface during summer caused an increase of surface soil temperature due to direct exposure to solar radiation. Consequently, it caused a low Eh and enhanced methane production which was supported by the supply of organic matters with high decomposition rate derived from marsh trefoil. At the reed site, CH4 flux increased in late summer. Such a delayed CH4 emission at the reed site was possibly caused by decomposition of roots growing during the summer and delay of soil temperature increase due to the waterlogging. Average CH4 fluxes for seven months were 450, 290, and 70 mgC/m(2)/day for the marsh trefoil, reed and sphagnum sites respectively. The delta(13)C of dissolved CH4, higher than that of bubbles, suggested CH4 oxidation in the soil water. However, oxidation was not a deterministic process controlling CH4 Bur at the observed temperate wetland where CH4 production rate was high because of high soil temperature. Sphagnum can only grow in oligotrophic (limited amount of nutrients) water, and its domination suppresses growth of other plants because of low concentration or low availability of nutrients. However, sphagnum can be easily replaced by other wetland plants, if the water in a sphagnum bog becomes rich in nutrients due to water pollution or change in the water circulation in the area. Such a vegetation change from a sphagnum dominant bog to a fen dominated by other wetland plants can accelerate CH4 emission to the atmosphere.
  • T. Inoue, K. Murashima, J. I. Azuma, A. Sugimoto, M. Slaytor
    Journal of Insect Physiology 43 3 235 - 242 1997年 [査読有り][通常論文]
     
    The distribution of the enzymes of cellulose and xylan metabolism namely endo-β-1,4-glucanase, β-glucosidase, endo-β-1,4-xylanase and β-xylosidase activities, in Reticulitermes speratus (Kolbe) was measured both in the salivary glands and in the major gut sections and along the length of the gut in freshly collected termites. The majority of the endo-β-1,4-glucanase activity (77.8%) was found in the salivary glands which also contained 23.9% of the β-glucosidase activity. At least 70% of the remaining activity was located in the anterior section of the hindgut. A small amount of endo-β-1,4-xylanase activity (2.4%), but no β-xylosidase activity, was present in the salivary glands. The majority of these activities were in the anterior section of the hindgut. The RQ of freshly collected termites at 25°C was 1.03±0.01. Maintaining termites for 16 days on wood, cellulose and xylan showed that the RQ values of termites fed on wood or xylan were not significantly different from those of freshly collected termites but significantly increased when maintained on cellulose. The RQ of starved termites after 11 days was 0.81±0.02. There were three effects on protozoan populations of feeding termites xylan for 20 days. One species, Dinenympha parva was not affected, while five others, Pyrsonympha grandis, Holomastigotes elongatum, Dinenympha rugosa, Dinenympha leidy and Dinenympha porteri survived for 20 days but slowly decreased in numbers. The numbers of P. grandis and D. leidy surviving for 20 days were significantly different from those in starved termites. The third group comprising the two large species, Teratonympha mirabilis and Trichonympha agilis and three small species, Pyrsonympha modesta, Dinenympha exilis and Dinenympha nobilis disappeared within 15 days as in starved termites. It is suggested that protozoa in the first two groups are xylanolytic. Protozoan populations on wood and cellulose diets were not markedly affected. Selective removal of the protozoa by u.v. irradiation led to the loss of xylanolytic activity and a life span comparable to starved termites.
  • A Sugimoto
    GEOCHEMICAL JOURNAL 30 3 195 - 200 1996年 [査読有り][通常論文]
     
    A flow-through system, GC/GC/C/IRMS (gas chromatograph/gas chromatograph/combustion/isotope ratio mass spectrometer) was developed for carbon isotope analysis of methane in a sample of low level concentration. In this system, methane was roughly separated from a large amount of N-2 and O-2 in the first GC with packed column, then introduced into GC/C/IRMS and carbon isotopic composition was measured. The delta(13)C of methane in a sample of 92 ml in volume with concentration of 11 ppm was successfully obtained with a standard deviation of +/-0.4 parts per thousand.
  • A SUGIMOTO, E WADA
    GEOCHIMICA ET COSMOCHIMICA ACTA 59 7 1329 - 1337 1995年04月 [査読有り][通常論文]
     
    In order to discern the delta D-water-delta D-CH4 relationship between CO2/H-2 reduction and acetate fermentation in freshwater environments where CH4 is produced from both CO2/H-2 and acetate, incubation experiments of a paddy soil were made, using water with four different delta D values. From the observed delta D-water-delta D-CH4 relationships and a fractional contribution of acetate estimated from delta(13)C of CH4, delta D-water-delta D-CH4 relationships were obtained for CO2/H-2 reduction and for acetate fermentation, respectively. The relationships were expressed as follows; delta D-CH4(CO2) = (0.683 +/- 0.020)delta D-water - (317 +/- 20) delta D-CH4(Ac) = (0.437 +/- 0.045)delta D-water - (302 +/- 15). The obtained difference in delta D between freshwater and CH4 from CO2/H-2 (317 parts per thousand) was much larger than that reported in marine sediments (180 parts per thousand). Accordingly, no significant difference in delta D of CH4 between CO2/H-2 reduction and acetate fermentation is expected when the delta D of water is close to SMOW, and delta D of CH4 from CO2/H-2 is lower than that from acetate when the delta D of water is low. The large fractionation obtained for CO2/H-2 reduction may be caused by a high H-2 concentration in the freshwater soil which is rich in easily decomposable organic matters. The estimated slope (0.437) of the delta D-water-delta D-CH4 relationship for acetate fermentation indicates that some of the hydrogen atoms in the methyl group of acetate exchanged with water during the acetate production. On the basis of the experimental results, the range of delta D-delta(13)C for CH4 from CO2/H-2 reduction and that for acetate fermentation were calculated for the freshwater environments. Although only a negative correlation between delta D and delta(13)C of CH4 has been expected, our results indicate the possibility of a positive correlation between them in freshwater areas.
  • TAYASU, I, A SUGIMOTO, E WADA, T ABE
    NATURWISSENSCHAFTEN 81 5 229 - 231 1994年05月 [査読有り][通常論文]
  • Tei, S, Sugimoto, A, Yonenobu, H, Kotani, A, Maximov, TC
    Tei, S; Sugimoto, A; Yonenobu, H; Kotani, A; Maximov, TC [査読有り][通常論文]
  • Tei, S, Morozumi, T, Nagai, S, Takano, S, Sugimoto, A, Shingubara, R, Fan, R, Fedorov, A, Gavrilyeva, T, Tananaev, N, Maximov, T
    Tei, S; Morozumi, T; Nagai, S; Takano, S; Sugimoto, A; Shingubara, R; Fan, R; Fedorov, A; Gavrilyeva, T; Tananaev, N; Maximov, T [査読有り][通常論文]
  • Mori, T, Goto-Azuma, K, Kondo, Y, Ogawa-Tsukagawa, Y, Miura, K, Hirabayashi, M, Oshima, N, Koike, M, Kupiainen, K, Moteki, N, Ohata, S, Sinha, PR, Sugiura, K, Aoki, T, Schneebeli, M, Steffen, K, Sato, A, Tsushima, A, Makarov, V, Omiya, S, Sugimoto, A, Takano, S, Nagatsuka, N
    Mori, T; Goto-Azuma, K; Kondo, Y; Ogawa-Tsukagawa, Y; Miura, K; Hirabayashi, M; Oshima, N; Koike, M; Kupiainen, K; Moteki, N; Ohata, S; Sinha, PR; Sugiura, K; Aoki, T; Schneebeli, M; Steffen, K; Sato, A; Tsushima, A; Makarov, V; Omiya, S; Sugimoto, A; Tak [査読有り][通常論文]

書籍

  • 地球環境と生態系
    共立出版 2006年

その他活動・業績

  • 土壌・植物の水同位体比
    気象研究ノート 気象学における水安定同位体比の利用 (220号) 45 -59 2009年 [査読無し][通常論文]
  • H. Fudeyasu, K. Ichiyanagi, A. Sugimoto, K. Yoshimura, A. Ueta, M. D. Yamanaka, K. Ozawa Jounal of Geophysical Research 113 (D12) doi:10.1029/2007JD009313 2008年06月 [査読無し][通常論文]
     
    Isotope ratios of precipitation and water vapor were observed during the passage of Typhoon Shanshan at Ishigaki Island, southwestern Japan, on 15-16 September 2006. Such high-resolution isotopic observations allow for qualitative understanding of atmospheric moisture cycling; they revealed that isotope ratios of both the precipitation and water vapor decreased radially inward in the cyclone's outer region; anomalously high isotope ratios appeared in the cyclone's inner region; and d-excess tended to decrease in the cyclone's inner region. In the cyclone's outer region, the water vapor was isotopically depleted due to the rainout effect which involves both condensation efficiency as reflected in inwardly increasing cloud thickness and isotopic exchange between falling droplets and the ambient water vapor. In contrast, water vapor in the cyclone's inner region was isotopically enriched due to weak rainout effect in conjunction with intensive isotopic recharge from the sea spray and sea surface with heavy isotope ratios. Since water vapor mainly acts as a source of precipitation, the isotope ratios of precipitation also had systematic variation. A unique circumstance is the intensity of isotopic exchange with almost saturated surface air and high winds, causing anomalously high isotope ratios and low d-excess values in the cyclone's inner region.
  • a
    a 113 (D12113) doi:10.1029/2007JD009313 2008年 [査読無し][通常論文]
  • a
    a 113 (D12113) doi:10.1029/2007JD009313 2008年 [査読無し][通常論文]
  • Tomonori Sato, Maki Tsujimura, Tsutomu Yamanaka, Hiroyuki Iwasaki, Atsuko Sugimoto, Michiaki Sugita, Fujio Kimura, Gombo Davaa, Dambaravjaa Oyunbaatar JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 (D17) doi:10.1029/2006JD008321 2007年09月 [査読無し][通常論文]
     
    Origin of water vapor, which falls as precipitation over arid/ semiarid area in northeast Asia, is investigated by modeling and observational approaches. The regional climate model evaluates the spatiotemporal variations of precipitation and water vapor budget, which are used to drive the single- layer isotope circulation model. Intraseasonal variations of delta(18) O in precipitation are well simulated during June- July- August of 2003. The delta(18) O in water vapor experiences rapid decreases according to the passage of synoptic- scale disturbances. The rapid decreases of delta(18) O are attributed to two processes. ( 1) The delta(18) O in air mass locally decreases over the western mountains associated with the mountain precipitation; the light vapor is advected to eastern Mongolia by the prevailing westerly wind. ( 2) Convective systems pass by in the vicinity of the observation site, which persistently keep the lower delta(18) O in the air mass. Origin of the water vapor during June-July- August in 2003 is evaluated by the colored moisture analysis in which the tracers are assigned depending on the region where the water vapor finally evaporated. Seasonal mean result indicates that the regions contributing to precipitation in Mongolia are not low- latitude regions but central Asia and western Siberia located to the northwest of Mongolia. Observed multilevel isotopic composition supports the model estimation. The moisture transport along the southwesterly wind of the Asian summer monsoon has difficulty reaching Mongolia as a monthly/ seasonal mean perspective. However, eastern Mongolia and northeast China are situated on the border area between westerly wind moisture transport ( by midlatitude synoptic cyclones) and southerly wind moisture transport ( by Asian summer monsoon).
  • Naoki Kabeya, Masanori Katsuyama, Masatoshi Kawasaki, Nobuhito Ohte, Atsuko Sugimoto HYDROLOGICAL PROCESSES 21 (3) 308 -322 2007年01月 [査読無し][通常論文]
     
    We measured deuterium excess (d = delta D - 8 delta(18)O) in throughfall, groundwater, soil water, spring water, and stream water for 3 years in a small headwater catchment (Matsuzawa, 0.68 ha) in the Kiryu Experimental Watershed in Japan. The d value represents a kinetic effect produced when water evaporates. The d value of the throughfall showed a sinusoidal change (amplitude: 6.9 parts per thousand relative to Vienna standard mean ocean water (V-SMOW)) derived from seasonal changes in the source of water vapour. The amplitude of this sinusoidal change was attenuated to 1.3-6.9 parts per thousand V-SMOW in soil water, groundwater, spring water, and stream water. It is thought that these attenuations derive from hydrodynamic transport processes in the subsurface and mixing processes at an outflow point (stream or spring) or a well. The mean residence time (MRT) of water was estimated from d value variations using an exponential-piston flow model and a dispersion model. MRTs for soil water were 0-5 months and were not necessarily proportional to the depth. This may imply the existence of bypass flow in the soil. Groundwater in the hillslope zone had short residence times, similar to those of the soil water. For groundwater in the saturated zone near the spring outflow point, the MRTs differed between shallow and deeper groundwater; shallow groundwater had a shorter residence time (5-8 months) than deeper groundwater (more than 9 months). The MRT of stream water (8-9 months) was between that of shallow groundwater near the spring and deeper groundwater near the spring. The seasonal variation in the d value of precipitation arises from changes in isotopic water vapour composition associated with seasonal activity of the Asian monsoon mechanism. The d value is probably an effective tracer for estimating the MRT of subsurface water not only in Japan, but also in other East Asian countries influenced by the Asian monsoon. Copyright (c) 2006 John Wiley & Sons. Ltd.
  • Sheng-Gong Li, Hugo Romero-Saltos, Maki Tsujimura, Atsuko Sugimoto, Lisa Sasaki, Gombo Davaa, Dambaravjaa Oyunbaatar JOURNAL OF HYDROLOGY 333 (1) 109 -117 2007年01月 [査読無し][通常論文]
     
    In the cold semiarid region of northeastern Mongolia, we used stable isotopes (180 and D) to determine potential plant water sources during the 2003 growing season (June to September) in two habitats: montane forest and an elevation gradient from the forest to Kherten river bank. The forest is dominated by larch (Larix sibirica) with patches of cinquefoil shrubs (Potentilla fruticosa). The latter also grow throughout the elevation gradient, while the Larch grows only on the top slope. Poplar (Populus spp.) and willow (Salix spp.) trees grow only on the river bank. All plant and soil samples showed isotopic signatures similar to summer precipitation, which is isotopically heavier in summer than winter. In July and August, [arch trees in the forest tended to shift their water uptake to shallow depths in response to recent rainfall, but during the remaining months (June and September), depths of water uptake were unclear. Further, both the larch trees and cinquefoil shrubs in the forest used water at similar depths, suggesting potential competition for water. Plants along the elevation gradient showed different patterns of water use: (1) in July, larch used recent rainfall only, but in other months, the pattern was unclear; (2) cinquefoil depended on rainfall from recent weeks (as in August), but sometimes used antecedent rainwater from one month prior; and (3) poplar and willow seemed to use water from the river (as in August) or from precipitation that felt a few weeks prior (as in September), but the factors controlling this unusual shift are unknown. This study contributes to our understanding of plant water use strategies in cold semiarid ecosystems, and provides baseline data for models designed to understand large-scale hydrological effects of global climate change. (c) 2006 Elsevier B.V. All rights reserved.
  • Maki Tsujimura, Lisa Sasaki, Tsutomu Yamanaka, Atsuko Sugimoto, Sheng-Gong Li, Dai Matsushima, Ayumi Kotani, Mijiddorj Saandar JOURNAL OF HYDROLOGY 333 (1) 35 -46 2007年01月 [査読無し][通常論文]
     
    The stable isotopes of deuterium and oxygen 18 in precipitation, atmospheric water vapor and subsurface water were investigated at forest and grassland sites in Kherten River basin, eastern Mongolia. Atmospheric water vapor was sampled at heights of 0.5-1000 m from the ground surface using an aircraft and aboveground observations, and soil water was sampted at depths of 0.1-1.5 m by digging a trench and using suction lysimeters from June to October 2003. The isotopic ratios of deuterium and oxygen-18, delta D and delta(18)O, of 230 water samples were determined. The delta(18)O of precipitation in the forest and grassland sites showed clear seasonal variation from October 2002 to September 2003, with higher values in summer and lower values in winter. The delta(18)O values in the atmospheric water vapor decreased from June to October 2003, parallel to those of precipitation. The vertical profile of delta(18)O in the water vapor tended to show a gentle decrease with attitude in the atmospheric boundary layer at both the forest and grassland sites. This was caused by evapotranspiration and mixing with air in the free atmosphere over the atmospheric boundary layer. We separated evaporation and transpiration components by Keeling plots analysis using the delta(18)O of atmospheric water vapor and soit water. Accordingly, the ratio of transpiration rate to evapotranspiration rate was estimated to be 60-73% at the forest site and 35-59% at the grassland site. (c) 2006 Elsevier B.V. AR rights reserved.
  • Jun Murase, Yuri Matsui, Masahiko Katoh, Atsuko Sugimoto, Makoto Kimura SOIL BIOLOGY & BIOCHEMISTRY 38 (12) 3483 -3491 2006年12月 [査読無し][通常論文]
     
    Rice straw is a major organic material applied to rice fields. The microorganisms growing on rice-straw-derived carbon have not been well studied. Here, we applied C-13-labeled rice straw to submerged rice soil microcosms and analyzed phospholipid fatty acids (PLFAs) in the soil and percolating water to trace the assimilation of rice- straw-derived carbon into microorganisms. PLFAs in the soil and water were markedly enriched with C-13 during the first 3 days of incubation, which indicated immediate incorporation of rice- straw-derived carbon into microbial biomass. The enrichment of PLFAs in the percolating water with C-13 Suggested that microorganisms other than the population colonizing rice straw also assimilated rice-straw-derived carbon or that some bacterial groups were selectively released from the straw. The microbial populations could be categorized into two communities based on the carbon isotope data of the PLFAs: those derived from rice straw and those derived from soil organic matter (SOM). The composition of the PLFAs from the two communities differed, which indicated the assimilation of rice-straw-derived carbon by a subset of microbial populations. The composition of rice-straw-derived PLFAs in the percolating water was also distinct from that in the soil. (c) 2006 Elsevier Ltd. All rights reserved.
  • Atsuko Sugimoto, Noboru Fujita BIOGEOCHEMISTRY 81 (1) 33 -44 2006年10月 [査読無し][通常論文]
     
    Bubble gas samples were collected at three different vegetation sites and two different depths (surface and 40 cm) in a natural wetland, Mizorogaike in Kyoto city, to investigate hydrogen concentration and delta D and delta C-13 values of CH4. Hydrogen concentration in bubble gas varied from 1 to 205 ppm, and that collected during summer was higher than that during winter. Bubble samples collected at 40 cm at sphagnum site usually showed the lowest H-2 concentration among the samples collected at the three sites and two depths on the same day. The lowest H-2 concentration observed at 40 cm at sphagnum site was similar to that expected for environmental water in which H-2 producer and consumer need to assemble for free energy requirement. Low delta C-13 and high dD (relatively small hydrogen fractionation; Delta delta Dwater-CH4 congruent to 220%) were observed in CH4 collected at a deeper (40 cm) layer of sphagnum site during winter, when H-2 concentration was low (typically 2-4 ppm). On the other hand, CH4 in the bubble samples collected during summer showed high delta C-13 and low delta D (relatively large hydrogen fractionation; Delta delta Dwater-CH4 congruent to 300 parts per thousand), when H-2 concentration was high. Carbon and hydrogen isotope fractionation during CH4 production were variable, possibly depending on the H-2 concentration and the production rate. Difference in enzymatic reaction and magnitude of hydrogen isotope exchange among water, CH4, and H-2 may cause the variation in isotope fractionation during CH4 production.
  • A Kagawa, A Sugimoto, TC Maximov PLANT CELL AND ENVIRONMENT 29 (8) 1571 -1584 2006年08月 [査読無し][通常論文]
     
    Post-photosynthetic fractionation processes during translocation, storage and remobilization of photoassimilate are closely related to intra-annual delta C-13 of tree rings, and understanding how these processes affect tree-ring delta C-13 is therefore indispensable for improving the quality of climate reconstruction. Our first objective was to study the relationship between translocation path and phloem grain. We pulse-labelled a branch of Larix gmelinii (Rupr.) Rupr. and later analysed the delta C-13 distribution in the stem. A C-13 spiral translocation path closely related to the spiral grain was observed. Our second objective was to study the use of remobilized storage material for earlywood formation in spring, which is a suspected cause of the autocorrelation (correlation of ring parameters to the climate in the previous year) observed in (isotope) dendroclimatology. We pulse-labelled whole trees to study how spring, summer and autumn photoassimilate is later used for both earlywood and latewood formation. Analysis of intra-annual delta C-13 of the tree rings formed after the labelling revealed that earlywood contained photoassimilate from the previous summer and autumn as well as from the current spring. Latewood was mainly composed of photoassimilate from the current year's summer/autumn, although it also relied on stored material in some cases. These results emphasize the need for separating earlywood and latewood for climate reconstruction work with narrow boreal tree rings.
  • Toshiyuki Takai, Yoshimichi Fukuta, Atsuko Sugimoto, Tatsuhiko Shiraiwa, Takeshi Horie PLANT PRODUCTION SCIENCE 9 (3) 271 -280 2006年07月 [査読無し][通常論文]
     
    Carbon isotope discrimination (Delta) occuring in the process of photosynthesis, shows variation among rice (Oryza sativa L.) cultivars. Elucidation of specific traits associated with the extent of this discrimination under irrigated conditions may be useful to improve photosynthetic ability in rice plants. We measured leaf photosynthesis and Delta in Milyang 23 and Akihikari, and conducted quantitative trait loci (QTL) analysis on Delta at heading stage using a population of 126 recombinant inbred lines (RILs), derived from a cross between the two cultivars. While the two parental cultivars showed a similar Delta, the RILs showed a wide variation in Delta including transgressive segregation. Seven QTLs were detected for Delta; four on chromosomes 2 (two regions), 7, and 11 were those for Delta that is increased by the Milyang 23 allele, whereas the other three on chromosomes 1, 2, and 6 were those for Delta that is increased by the Akihikari allele. These results suggest that G in Milyang 23 may be discriminated through a photosynthetic process different from that in Akihikari. Milyang 23 showed a higher stomatal conductance and a higher ratio of intercellular to ambient CO2 concentration (Ci/Ca), while Akihikari showed a higher carboxylation efficiency but a lower Ci/Ca. According to the theory that a higher Ci/Ca leads to a higher Delta, the QTLs for Delta that is increased by the Milyang 23 allele might be related to a higher stomatal conductance. However, the theory provided no persuasive factors to explain the QTLs for Delta that is increased by the Akihikari allele. Plausible factors associated with these QTLs are discussed.
  • A Yamada, T Inoue, D Wiwatwitaya, M Ohkuma, T Kudo, A Sugimoto ECOSYSTEMS 9 (1) 75 -83 2006年02月 [査読無し][通常論文]
     
    Nitrogen (N) fixed by termites was evaluated as a N input to decomposition processes in two tropical forests, a dry deciduous forest (DDF) and the neighboring dry evergreen forest (DEF), Thailand. A diverse group of termite species were assayed by acetylene reduction method and only the wood/litter-feeding termites were found to fix N. More intensive samplings of two abundant species, Microcerotermes crassus and Globitermes sulphureus, were done across several seasons, suggesting N fixation rates of 0.21 and 0.28 kg ha(-1) y(-1) by termites in the DDF and DEF, respectively. Also, estimates of asymbiotic N fixation rates were 0.75 and 3.95 kg ha(-1) y(-1). N fixed by termites and by asymbiotic fixers is directly supplied to decomposers breaking down dead plant material and could be a major source of their N. N fixed by termites was 7-22% of that fixed by termites and asymbiotic fixers. Although N fixed by termites is a small input compared to other inputs, this N is likely important for decomposition processes.
  • Akira Kagawa, Atsuko Sugimoto, Trofim C. Maximov NEW PHYTOLOGIST 171 (4) 793 -804 2006年 [査読無し][通常論文]
     
    Autocorrelation - correlation of tree-ring parameters such as ring width, density and isotope ratios to the environmental conditions of the previous year(s) - is associated with the use of previous photoassimilate for current year's tree ring formation. To clarify the seasonal course of carbon allocation patterns among needles, branches, stem and roots, we pulse-labeled 10 Larix gmelinii growing in a continuous permafrost zone with (CO2)-C-13. Photoassimilate incorporated in June was allocated mainly to above-ground parts, indicating active above-ground growth in spring. Very little was allocated to below-ground parts (2.6-7.9%), probably because root growth is inhibited by low soil temperatures in spring. Conversely, a higher proportion of July and August photoassimilate was allocated to below-ground parts (32-44 and 12-24%, respectively). About half the carbon in new needles was derived from stored material. The starch pool in non-needle parts, which can be used for xylem formation, drew approx. 43% of its carbon from the previous year's photoassimilate, indicating that carbon storage is a key mechanism behind autocorrelation in (isotope) dendroclimatology.
  • J Murase, A Sugimoto LIMNOLOGY AND OCEANOGRAPHY 50 (4) 1339 -1343 2005年07月 [査読無し][通常論文]
     
    Methane oxidation was studied in mesotrophic lake water (Lake Biwa, Japan) under thermally stratified conditions. Methane oxidation rates at in situ concentrations were very low in lake water from the epilimnion and thermocline but were high in hypolimnetic water. Incubation under light conditions ranging from 4.1 to 57 mu mol photons m(-2) s(-1) resulted in decreased methane oxidation in hypolimnetic water. This inhibition was more severe as the light intensity increased. Addition of inorganic nitrogen (ammonium and nitrate) did not promote methane oxidation in the thermocline but inhibited it in the hypolimnion. Methane oxidation activity in the thermocline was observed after I month of incubation under dark conditions. Our results suggest that the inhibitory effect of light was bacteriostatic for the methanotrophic population. The different rates of methane oxidation between the hypolimnion and epilimnion/thermocline may explain the surface maximum of dissolved methane during the period of thermal stratification.
  • A Kagawa, A Sugimoto, K Yamashita, H Abe PLANT CELL AND ENVIRONMENT 28 (7) 906 -915 2005年07月 [査読無し][通常論文]
     
    Using a combined method of pulse-labelling trees and analysing detailed distribution of C-13 tracer within tree rings, we studied how photo-assimilates incorporated on a given day are then distributed in a tree ring. A branch of a 4-year-old Cryptomeria japonica D.Don tree growing in Tsukuba, Japan was pulse-labelled with non-radioactive (CO2)-C-13 on two occasions: 29 May 2001 and 18 September 2001. Two discs were cut from the stem on 4 March 2002, one immediately under and the other 0.5 m below the branch and put through high-resolution delta C-13 analysis. delta C-13 peaks were observed in both the earlywood and latewood of the concerned tree ring, corresponding to each pulse-labelling date. The earlywood peaks was broader than the latewood peaks, possibly reflecting seasonal variation of the width of wood developing zone. Half-widths of the peaks were measured and used as indicators for the potential time resolution of tree-ring isotope analysis. The half-widths of the peaks indicated a time resolution no finer than 8.7-28 and 33-42 d in the early and latewood, respectively. Holocellulose extraction yielded only a slight change to the shape of the delta C-13 peaks. C-13 tracer pulse-labelled in May and September reached tangentially different locations in the lower disc, suggesting a seasonal change in the pathway of carbohydrates. Local consumption of spring assimilates and long-distance downward transport of autumn assimilates were also suggested.
  • Murase, J., Sakai, Y., Kametani, A., Sugimoto, A. (2005) Dynamics of methane in a mesotrophic Lake Biwa, Japan. Ecol Res. 20, 377-385*
    2005年 [査読無し][通常論文]
  • Yamada, A., Inoue, T., Wiwatwitaya, D., Ohkuma, M., Kudo, T., Abe, T., and Sugimoto, A. (2005) Carbon mineralization by termites in tropical forests, with emphasis on fungus-combs, Ecological Research 20, 453-460.*
    2005年 [査読無し][通常論文]
  • Katoh, M., Murase, J., Sugimoto, A., and Kimura, M. (2005) Effect of rice straw amendment on dissolved organic and inorganic carbon and cationic nutrients in percolatinhg water from a flooded paddy soil: A microcosm ecperiment using 13C-enriched rice s・・・
    2005年 [査読無し][通常論文]
     
    Katoh, M., Murase, J., Sugimoto, A., and Kimura, M. (2005) Effect of rice straw amendment on dissolved organic and inorganic carbon and cationic nutrients in percolatinhg water from a flooded paddy soil: A microcosm ecperiment using 13C-enriched rice straw. Org Geochem, 36, 803-811.*
  • Li, S-G, Tsujimura, M., Sugimoto, A., Sasaki, L., Yamanaka, T., Davaa, G., Oyunbaatar, O., Sugita, M. (2005) Seasonal variation in oxygen isotope composition of waters for a montane larch forest in Mongolia. Trees DOI: 10.1007/s00468-005-0019-1*
    2005年 [査読無し][通常論文]
  • Hoonibrook, E., and Sugimoto, A. (Ed) Stable isotope applications in methane cycle studies. Organic Geochemistry,36, (5) Pages 679-825
    2005年 [査読無し][通常論文]
  • Uchida, T., Kaneko, N., M. T. Ito, Futagami, K., Sasaki, T., and A Sugimoto: "Analysis of the feeding ecology of earthworms (Megascolecidae) in Japanese forests using gut content fractionation and d15N and d13C stable isotope natural abundances", Appli・・・
    2004年 [査読無し][通常論文]
     
    Uchida, T., Kaneko, N., M. T. Ito, Futagami, K., Sasaki, T., and A Sugimoto: "Analysis of the feeding ecology of earthworms (Megascolecidae) in Japanese forests using gut content fractionation and d15N and d13C stable isotope natural abundances", Applied Soil Ecology, 27: 153-163 (2004)*
  • Lu, Y., Murase, J., Watanabe, A., Sugimoto, A., and Kimura, M: "Linking microbial community dynamics to rhizosphere carbon flow in a wetland rice soil", FEMS Microbial Ecol 48: 179-186 (2004)*
    2004年 [査読無し][通常論文]
  • Dan, J., Kumai, T., Sugimoto, A., and Murase, J:"Biotic and abiotic methane release from Lake Biwa sediment slurry", Limnology, 5: 149-154 (2004)*
    2004年 [査読無し][通常論文]
  • Tateno, R., Katagiri, S., Kawaguchi, H., Nagayama, Y., Changhua, L., Sugimoto, A., Koba, K. The use of foliar 15N and 13C abundance to evaluate effects of microbiotic crust on nitrogen and water utilization of Pinus massoniana in deteriorated pine stan・・・
    2003年 [査読無し][通常論文]
     
    Tateno, R., Katagiri, S., Kawaguchi, H., Nagayama, Y., Changhua, L., Sugimoto, A., Koba, K. The use of foliar 15N and 13C abundance to evaluate effects of microbiotic crust on nitrogen and water utilization of Pinus massoniana in deteriorated pine stands of south China. Ecological Research, 18, 279-286.*
  • Kohzu,A., Matsui, K., Yamada, T., Sugimoto, A., Fujita, N. Significance of rooting depth in mire plants: evidence from natural 15N abundance. Ecological Research, 18, 257-266
    2003年 [査読無し][通常論文]
  • Murase J., Sakai, Y., Sugimoto, A., Okubo, K., Sakamoto, M. Sources of dissolved methane in Lake Biwa. Limnology, 4:91-99 (DOI:10.1007/210201-003-0095-0)*
    2003年 [査読無し][通常論文]
  • Sugimoto, A., Dan, J., Kumai, T., and Murase, T. (2003) Adsorption as a methane storage process in natural lake sediment. Geophys. Res. Lett. Doi:10.1029/2003GL018162
    2003年 [査読無し][通常論文]
  • Sugimoto, A., Dan, J., Kumai, T., and Murase, T. (2003) Adsorption as a methane storage process in natural lake sediment. Geophys. Res. Lett. Doi:10.1029/2003GL018162*
    2003年 [査読無し][通常論文]
  • Kagawa, A., Naito, D., Sugimoto, A., and Maximov, T. C. Effects of spatial and temporal variability in soil moisture on widths and delta13C values of Eastern Siberian tree rings. Journal of Geophysical Research, doi:10.1029/2002JD003019*
    2003年 [査読無し][通常論文]
  • Ichiyanagi, K., Sugimoto, A., Numaguti, A., Kurita, N., Ishii, Y., Ohata, T. Seasonal variation of stable isotopic composition of alas lake water near Yakutsk, Eastern Siberia. Geochemical Journal, 37, 519-530*
    2003年 [査読無し][通常論文]
  • Sugimoto, A., Naito, D., Yanagisawa, N., Ichiyanagi, K., Kurita, N., Kubota, J., Kotake, T., Ohata, T., Maximov, T. C., and Fedorov, A. N. Characteristics of soil moisture in permafrost observed in East Siberian Taiga with stable isotopes of water. Hy・・・
    2003年 [査読無し][通常論文]
     
    Sugimoto, A., Naito, D., Yanagisawa, N., Ichiyanagi, K., Kurita, N., Kubota, J., Kotake, T., Ohata, T., Maximov, T. C., and Fedorov, A. N. Characteristics of soil moisture in permafrost observed in East Siberian Taiga with stable isotopes of water. Hydrological Processes, 17, 1073-1092.*
  • Ohte, N., Koba, K., Yoshikawa, K., Sugimoto, A., Mtsuo, N., Kabeya, N., Wang, L. Water utilizatioin of natural and planted trees in semi-arid desert in inner Mongolia, Chaina Ecological Applications, 13, 337-351.*
    2003年 [査読無し][通常論文]
  • Kurita, N., Numaguchi, A., Sugimoto, A., Ichiyanagi, K., Yoshida, N. Relationship between the variation of isotopic ratios and the source of summer precipitation in eastern Siberia. Jounal of Geophysical Research, 108, doi:10.1029/2001JD001359*
    2003年 [査読無し][通常論文]
  • Yamada, A., Inoue, T., Sugimoto, A., Takematsu, Y., Kumai, T., Hyodo, F., Tayasu, I., Kulangkeaw, C., Kirtibutr, N., Kudo, T., and Abe, T. Abandance and biomass of termites (Insecta:Isoptera) in dead wood in a dry evergreen forest of Thailand. Sociobio・・・
    2003年 [査読無し][通常論文]
     
    Yamada, A., Inoue, T., Sugimoto, A., Takematsu, Y., Kumai, T., Hyodo, F., Tayasu, I., Kulangkeaw, C., Kirtibutr, N., Kudo, T., and Abe, T. Abandance and biomass of termites (Insecta:Isoptera) in dead wood in a dry evergreen forest of Thailand. Sociobiology, 42, 569-585.*

共同研究・競争的資金等の研究課題

  • シベリアタイガ林の水・炭素循環、生物圏における温室効果ガス代謝、永久凍土の水循環、降水の安定同位体比と雲物理
  • Water and carbon cycles in Siberian Taiga, Gas metabolism from biosphere,

教育活動情報

主要な担当授業

  • 大学院共通授業科目(教育プログラム):RJE3
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 環境評価、文化的多様性、土壌と生産、地域資源開発、防災管理
  • 大学院共通授業科目(教育プログラム):RJE3
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 環境評価、文化的多様性、防災管理
  • 大学院共通授業科目(一般科目):自然科学・応用科学
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 北極、地球観測、衛星リモートセンシング
  • 水循環学特論
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 水循環, 気候学, 気象学, 水文学, 人間活動 Hydrological cycle, Climatology, Meteorology, Hydrology, Human activities
  • 大学院共通授業科目(一般科目):自然科学・応用科学
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 安定同位体比、質量分析
  • 大学院共通授業科目(教育プログラム):RJE3
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 野外観測、タイガ、永久凍土、環境、文化
  • 生物地球科学特論
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 生態系、水循環、炭素循環、安定同位体、地球環境、地球システム ecosystem, water cycle, carbon cycle, stable isotopes, global environment, earth system
  • 陸圏物質循環学特論
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : ecosystem, water cycle, carbon cycle, stable isotopes, global environment, earth system
  • 環境分析化学特論
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 化学分析、データ解析 Chemical analysis, Data analysis
  • 地球環境学
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 気候変化、炭素循環、古環境、氷期・間氷期、人類環境、生物圏


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