研究者データベース

吉田 俊也(ヨシダ トシヤ)
北方生物圏フィールド科学センター 森林圏ステーション 北管理部
教授

基本情報

所属

  • 北方生物圏フィールド科学センター 森林圏ステーション 北管理部

職名

  • 教授

学位

  • 博士(農学)(新潟大学)

ホームページURL

科研費研究者番号

  • 60312401

J-Global ID

研究キーワード

  • 森林動態   ササ   個体群動態   針広混交林   環境要因   植生回復   森林伐採   影響評価   人工裸地   造林施業   掻き起し   地域間比較   資源管理モデル   植物種多様性   種多様性   北方林   物質循環   林学   森林流域   土壌学   河川水質   山火事撹乱   常緑性・落葉性   更新   野外操作実験   ブラックプルース   準水域   肥大成長   炭素   遷移   地域資源管理学   造林学   森林生態学   Regional Resources Management   Silviculture   Forest Ecology   

研究分野

  • 環境・農学 / 生物資源保全学
  • ライフサイエンス / 森林科学

職歴

  • 2012年 - 現在 北海道大学北方生物圏フィールド科学センター 教授
  • 2009年 - 2012年 北海道大学北方生物圏フィールド科学センター 准教授
  • 2011年 北海道大学 准教授
  • 2002年 - 2009年 - 北海道大学北方生物圏フィールド科学センター 助教
  • 1999年 - 2002年 北海道大学助手(農学部附属演習林) 助手
  • 1999年 - 2001年 Research Associate
  • 2001年 - Research Associate,Field Science Center for Northern Biosphere, Hokkaido University

学歴

  • 1995年 - 1998年   新潟大学大学院   自然科学研究科
  • 1993年 - 1995年   新潟大学大学院   農学研究科
  • 1985年 - 1989年   新潟大学   農学部   林学科

所属学協会

  • 日本生態学会   日本森林学会   The Japanese Forestry SocietyThe Ecological Society of JapanInternational Association of Vegetation Science   

研究活動情報

論文

  • Kobayashi Makoto, Elizaveta Susloparova, Ikutaro Tsuyama, Takuya Shimase, Satoshi Nakaba, Naoki Takahashi, Toshiya Yoshida
    JOURNAL OF WOOD SCIENCE 67 1 2021年12月 [査読有り]
     
    Heartwood colour is often an important factor in determining timber prices. However, the determinants of intraspecific variation in heartwood colour, which is useful information for sustainable wood marketing, are little understood, especially at the local scale in cool temperate forests. Because heartwood is produced as a secondary compound and photosynthesis is regulated by nitrogen (N) in cool temperate forests, we hypothesized that (1) soil conditions determine heartwood colour even at a local scale within a tree species and (2) N, specifically, can be an important driver of the intraspecific variation in heartwood colour in the trees of cool temperate forests. To test these hypotheses, we investigated the relationship between the colour values (luminescence, redness, and yellowness) of heartwood from Juglans mandshurica var. sachalinensis and the soil parameters in a cool temperate forest. Among the soil properties, not soil N but soil magnesium (Mg) contents alone had a significant influence on the redness and yellowness of the heartwood. Higher soil Mg contents resulted in increased redness and yellowness of the heartwood in our study, probably due to the increase in phenolics and the colouring of the tannins in the heartwood with Mg. Our results indicate that even at a local scale, soil condition can determine the intraspecific variation in heartwood colour and that forest managers can utilize edaphic information to predict heartwood colour for timber marketing.
  • Aye Myat Myat Paing, Shufen Chen, Yoshihiko Tsumura, Nobuhiro Tomaru, Kousuke Homma, Masahiko Kadomatsu, Toshiya Yoshida, Hajime Kobayashi, Atsuhiro Iio, Katsuhiro Osumi, Haruhiko Taneda, Yoko Hisamoto, Susumu Goto
    JOURNAL OF FOREST RESEARCH 2021年08月 [査読有り]
     
    Habitat loss of forest tree species distributed in cold temperate and alpine zones is a serious issue in the context of global warming. Considering that intraspecific variation is essential for adaptation to changing environments, intraspecific variation in seed weight, leaf traits, and sapling size of a sub-alpine broad-leaved tree species, Betula ermanii, was examined in this study using seeds collected from 11 populations across its natural distribution. Seeds were sown in seed beds, and containerized seedlings were grown in a greenhouse with a uniform environment (a common garden experiment). The effects of four climate variables, i.e. warmth index (WI), minimum temperature of the coldest month (TMC), summer precipitation (PRS), and maximum snow depth (MSD) were evaluated on seed weight, leaf functional traits, and sapling size using a generalized linear mixed model (GLMM). Positive latitudinal clines were detected for seed weight, whereas negative clines were detected for both specific leaf area and leaf nitrogen. These clines were not consistent with the general trends observed in previous studies. The reasons might be partly explained by geographic variation in climatic variables and nutrient availability. The findings obtained from this study should be useful for conservation of mountainous forest ecosystems in the age of climate change.
  • Toshiya Yoshida
    FORESTS 12 8 2021年08月 [査読有り]
     
    The treefall mounds and pits resulting from uprooting caused by strong winds is an indispensable microtopography for the regeneration of many tree species through improved light conditions and mineral soil exposure. These microtopographies are expected to become more important because global warming is predicted to increase windstorm frequency. This study aimed to clarify the characteristics of mounds and pits that contribute to the early establishment of major tree species in a natural mixed forest of northern Japan. The 39 tip-up mounds caused simultaneously by a strong typhoon in September 2004 were selected. In 2006, light intensity and soil moisture contents were measured in each mound and pit. Seedlings of all tree species were counted, and in 2014, the height of saplings was measured. The initial seedling density, regardless of tree species, was significantly higher in the pits than on the mound, but the density at the 10-th growing season decreased significantly in the pits and was comparable between the two locations. Intense light conditions favor regeneration of Betula sp. (Betula platyphylla and B. ermanii). In contrast, for Abies sachalinensis and Picea glehnii, the light intensity had a negative effect, so it was concluded that regeneration of conifers would be limited under the condition where strong winds form large gaps.
  • Nanami Suzuki, Toshiya Yoshida, Toshizumi Miyamoto, Karibu Fukuzawa, Takeshi Taniguchi, Haruka Yamazaki
    SCANDINAVIAN JOURNAL OF FOREST RESEARCH 36 2-3 126 - 134 2021年04月 [査読有り]
     
    To examine the potential for natural regeneration of Picea glehnii, seeds and current-year seedlings were evaluated at a scarification site. Three surface-soil treatments of different scarification intensity were used: removed, organic soil was mostly removed from the site; remained, some soil remained at the site; and replaced, the soil was removed but replaced. Seeds were sown in the fall, and samples were collected in the following spring to examine the rot rate by fungi. Germination, mortality, growth, and mycorrhiza formation rate of the seedlings were recorded in the first growing season. The seed rot rate was generally low, and no significant differences among surface-soil treatments were observed. The germination rate was higher in the removed treatment than in the other treatments, but seedling survival was lower, and the final seedling density was similar to that in the replaced treatment. Seedling total weight and ectomycorrhizal formation rate were higher in the replaced treatment than in the removed treatment, suggesting that the higher amount of organic soil at the site led to better growth at least in the first growing season. Correlation analysis indicated that a high soil moisture content associated with the presence of organic soil contributed to survival and growth.
  • Yoshiyuki Umatani, Atsushi Okuda, Eishi Fujito, Toshiya Yoshida, Fuyuki Satoh, Koji Maekawa, Masahiro Nakamura
    ECOLOGICAL RESEARCH 35 6 986 - 993 2020年11月 [査読有り]
     
    Nakagawa experimental forest of Hokkaido University is located in the middle Teshio River and some tributaries flow through the forest. The construction of Otoineppu bypass route started in 2007. This bypass route will pass through the forest. In order to evaluate the impacts of the road construction on stream ecosystem, a long-term monitoring of fish community and stream environmental characteristics have been conducted including before, during and after the road construction. The survey has been implemented on five streams in Teshio River (three streams inside the bypass construction zone and two streams outside the zone). Here, we report the data of species, body size and weight of fish sampled using an electrofishing unit and the data of stream environmental characteristics such as water temperature, water surface area, pH and EC. The three-pass removal method for fish sampling and measurement of stream environmental characteristics was conducted three times a year (mainly June, August and October) from 1999 to 2018. A total of 57,203 individuals were observed, belonging to 11 species in seven families. After bypass road construction started (2007), the number of fishes gradually increased at both bypass road construction and control sites. Occasionally, the number of fishes at the bypass construction site tended to be lower than at the control site, but there was not always noticeable difference between them. The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at .
  • Karibu Fukuzawa, Fuyuki Satoh, Hideaki Shibata, Tatsuya Kamiura, Chikara Kozuka, Toshikazu Takanishi, Shintaro Hayakashi, Yuya Hirano, Wataru Mamiya, Yuri Yabuhara, Rei Sakai, Hiroshi Sugiyama, Hiroshi Masumoto, Naoko Fukuzawa, Tetsuji Takeda, Hideaki Morita, Makoto Yamanouchi, Junko Hasegawa, Toshiya Yoshida
    ECOLOGICAL RESEARCH 35 5 742 - 749 2020年09月 [査読有り]
     
    The water chemistry of a stream reflects the biogeochemical processes occurring in upstream forests. Anthropogenic disturbances in forests, such as cutting trees, altering the nitrogen (N) cycle, and increase in N leaching from the soil to streams, potentially cause acidification or eutrophication downstream. In forests with dense understory vegetation, mechanical site preparation following tree cutting is commonly used to improve the early establishment of tree seedlings. In cool-temperate forests in northern Hokkaido, Japan, dense understory vegetation (mainly comprising Sasa dwarf bamboo) inhibits forest regeneration after tree cutting. Soil scarification is a common site preparation technique for eliminating Sasa bamboo and improving forest regeneration. Long-term data are useful for examining the temporal changes in stream water chemistry exposed to different specific forest management practices under changing environment (e.g., climate change and atmospheric N deposition). For 14 years (2003-2016), we observed the stream water chemistry in naturally forested watersheds and at one point after the confluence of all streams in Uryu Experimental Forest of Hokkaido University (North Hokkaido Experimental Forests Site of JaLTER) in northern Japan. We also monitored stream discharge, water level and stream water temperature in each watershed. Water samples were collected from the outlets of 10 watersheds. The forest management practice in each watershed includes clear-cutting, soil scarification in sparse forest with dense understory Sasa, and clear-cutting and soil scarification followed by soil replacement. Long-term data in the six unmanaged watersheds are also valuable as a background information to analyze the effect of long-term climate, environment and vegetation changes on stream water chemistry. The measured water quality data of 1,873 water samples include the ion concentrations (Cl-, NO3-, SO42-, Na+, NH4+, K+, Mg2+, and Ca2+), pH, and electrical conductivity (EC) in the stream water. The range of the concentrations of Cl-, NO3-, SO42-, Mg2+, and Ca2+ in the stream water across all the watersheds throughout the observed periods (minimum to maximum) were 3.35-23.67, 0.01-8.68, 0.83-4.01, 0.45-2.55 and 0.72-6.16 mg L-1, respectively. Similarly, the stream pH and EC ranged from 6.04 to 7.53 and 3.14 to 9.47 mS m(-1), respectively.
  • Tomoko K. Akitsu, Tatsuro Nakaji, Toshiya Yoshida, Rei Sakai, Wataru Mamiya, Terigele, Kentaro Takagi, Yoshiaki Honda, Koji Kajiwara, Kenlo N. Nasahara
    ECOLOGICAL RESEARCH 35 5 750 - 764 2020年09月 [査読有り][通常論文]
     
    To validate and to improve ecological products obtained from satellites, such as a leaf area index (LAI), above-ground biomass (AGB), and a fraction of photosynthetically active radiation (fAPAR), in-situ accurate data are indispensable. They must be not a single point-data but an areal data representing the satellite footprint. Their accuracy needs to be much higher than the required accuracy for the satellite products. The quantitative assessment of their error is necessary for evaluating the satellite products' error from the discrepancy between the satellite products and the in-situ data. However, such data had not been available. In particular, there had been few data of LAI in a sparse evergreen needle-leaved forest, because of difficulty of accuracy control of in-situ observation in such a forest. To overcome the difficulty and to obtain the representative LAI, we made an allometric equation to estimate the leaf mass of Picea glehnii in northern Hokkaido. We report the allometric equations of leaf mass and AGB of P. glehnii, its leaf mass per area (LMA), its leaf life span, its leaf distribution, its crown shapes, its wood specific gravity, and tree locations. We also report LAI, AGB, and fAPAR within the 500 m x 500 m area, which is the footprint scale of the Global Change Observation Mission-Climate satellite, in a pure and sparse forest of P. glehnii in northern Hokkaido. These precise data are useful for validation of other satellite data, especially with higher spatial resolution, and forest structure modeling.
  • 山崎遥, 間宮渉, 吉田俊也
    日本森林学会誌 102 3 2020年 [査読有り]
  • Haruka Yamazaki, Toshiya Yoshida
    JOURNAL OF FOREST RESEARCH 25 1 41 - 50 2020年01月 [査読有り]
     
    Soil scarification removed surface layers including nutrients and buried seeds. The purpose of this study was to evaluate the success of alternative practices that intentionally leave the surface soil (screening and replacing) along with the standard scarification. We focused on soil properties, the density of buried seeds, the invasion of competitive vegetation, and the regeneration of tree species. There were significant differences in soil properties among the treatments. Soils that were treated with the replacing treatment had the highest water contents from the surface layer to the deep layer in the lower slope in particular. On the other hand, there were higher densities of tall forb germinated from rhizomes, which are likely to shade tree species, with the replacing in the lower slope locations. The residual buried seed densities in the soil were estimated to be significantly higher in the screening than the replacing. Phellodendron amurense, producing seed bank and having dry tolerance, exhibited the greatest seedling density with the screening. However, there was no significant difference between screening and replacing in Betula species which has higher water demands. In conclusion, it is important that screening and replacing should be used properly according to the site condition and target tree species. The replacement had the advantage of retaining higher water content, but it is suggested that the screening is a better option when intended for regeneration from buried seeds and when many tall forb species grow alongside dwarf bamboo prior to treatment.
  • 井上華央, 柴田英昭, 吉田俊也, 中路達郎, 小花和宏之, 加藤顕
    森林立地 61 1 1 - 13 2019年06月 [査読有り][通常論文]
  • Motomu Toda, Karibu Fukuzawa, Masahiro Nakamura, Rie Miyata, Xin Wang, Kazuki Doi, Azusa Tabata, Hideaki Shibata, Toshiya Yoshida, Toshihiko Hara
    TREES-STRUCTURE AND FUNCTION 32 6 1789 - 1799 2018年12月 [査読有り][通常論文]
     
    Key messageThe recovery of leaf photosynthetic rate of an early successional tree, Betula ermanii, to its pre-disturbance state following a defoliating disturbance was brought about by its fast leaf morphological response (LMA, leaf mass per area) but not physiological one (leaf N) as a resilience mechanism.AbstractClimate extremes possibly impair terrestrial vegetation and alter carbon cycles. Meanwhile, large uncertainty remains for evaluating the climatic impact on the vegetational function and structure and ecosystem CO2 exchange. We manipulated a defoliating disturbance experimentally in early September 2011 to simulate an extreme typhoon that actually hit a cool-temperate forest in Japan and ripped away a tremendous amount of foliage of early-successional B. ermanii trees in early September 2004, which corresponded to a decrease in plant area index (PAI) by 1.7m(2)m(-2) from 3.3m(2)m(-2) of the maximum PAI during the plant growth period. Over the 4-year observations in 2011-2016, we measured leaf-level photosynthesis following the manipulated disturbance. The highest maximum photosynthetic rate of leaves (A(max)) occurred in 2014 among the observational period, which was the third year after the disturbance, and the subsequent A(max) returned to the pre-disturbance state. We examined what biotic factors regulated A(max) following the disturbance and found that the increase in the morphological attribute of leaf mass per area (LMA) enhanced A(max) with a significant positive slope between LMA and A(max) (R-2=0.14 and p<0.1). Meanwhile, A(max) was hardly affected by the physiological attribute of leaf nitrogen (N) as indicated by a nonsignificant slope of the leaf N-A(max) relationship (R-2=0.04 and p=0.281) throughout the observational period. This study would be a first challenge of a stand-scale defoliation experiment and provides a possible ecological inference regarding the functional and structural responses of early-successional trees following such disturbances.
  • Shin Nagai, Tomoko Akitsu, Taku M. Saitoh, Robert C. Busey, Karibu Fukuzawa, Yoshiaki Honda, Tomoaki Ichie, Reiko Ide, Hiroki Ikawa, Akira Iwasaki, Koki Iwao, Koji Kajiwara, Sinkyu Kang, Yongwon Kim, Kho Lip Khoon, Alexander V. Kononov, Yoshiko Kosugi, Takahisa Maeda, Wataru Mamiya, Masayuki Matsuoka, Trofim C. Maximov, Annette Menzel, Tomoaki Miura, Toshie Mizunuma, Tomoki Morozumi, Takeshi Motohka, Hiroyuki Muraoka, Hirohiko Nagano, Taro Nakai, Tatsuro Nakaji, Hiroyuki Oguma, Takeshi Ohta, Keisuke Ono, Runi Anak Sylvester Pungga, Roman E. Petrov, Rei Sakai, Christian Schunk, Seikoh Sekikawa, Ruslan Shakhmatov, Yowhan Son, Atsuko Sugimoto, Rikie Suzuki, Kentaro Takagi, Satoru Takanashi, Shunsuke Tei, Satoshi Tsuchida, Hirokazu Yamamoto, Eri Yamasaki, Megumi Yamashita, Tae Kyung Yoon, Toshiya Yoshida, Mitsunori Yoshimura, Shinpei Yoshitake, Matthew Wilkinson, Lisa Wingate, Kenlo Nishida Nasahara
    ECOLOGICAL RESEARCH 33 6 1091 - 1092 2018年11月 [査読有り][通常論文]
     
    We report long-term continuous phenological and sky images taken by time-lapse cameras through the Phenological Eyes Network (http://www.pheno-eye.org. Accessed 29 May 2018) in various ecosystems from the Arctic to the tropics. Phenological images are useful in recording the year-to-year variability in the timing of flowering, leaf-flush, leaf-coloring, and leaf-fall and detecting the characteristics of phenological patterns and timing sensitivity among species and ecosystems. They can also help interpret variations in carbon, water, and heat cycling in terrestrial ecosystems, and be used to obtain ground-truth data for the validation of satellite-observed products. Sky images are useful in continuously recording atmospheric conditions and obtaining ground-truth data for the validation of cloud contamination and atmospheric noise present in satellite remote-sensing data. We have taken sky, forest canopy, forest floor, and shoot images of a range of tree species and landscapes, using time-lapse cameras installed on forest floors, towers, and rooftops. In total, 84 time-lapse cameras at 29 sites have taken 8 million images since 1999. Our images provide (1) long-term, continuous detailed records of plant phenology that are more quantitative than in situ visual phenological observations of index trees; (2) basic information to explain the responsiveness, vulnerability, and resilience of ecosystem canopies and their functions and services to changes in climate; and (3) ground-truthing for the validation of satellite remote-sensing observations.
  • Haruka Yamazaki, Toshiya Yoshida
    JOURNAL OF FOREST RESEARCH 23 3 166 - 172 2018年05月04日 [査読有り][通常論文]
     
    We compared early establishment of B. maximowicziana, a commercially valuable tree species producing buried seeds, among the standard scarification and three alternative treatments in which surface soil was retained (soil replacing, screening, and plowing). We found the efficiencies of the soil retention for the seedling emergence were clearly different among the treatments the replacing and plowing caused significantly richer seedling emergence, whereas the screening resulted in lower emergence than the standard treatment. In total, the most abundant seedling emergence was estimated to have occurred in the case of higher soil water content with lower soil hardness. These seemed to be attributed to soil properties, induced differently by each treatment, and relatively high water demand characteristics of B. maxomowicziana. On the other hand, plowing showed low seedling density at the end of the second growing season despite its greater emergence, probably because of suppression from understory vegetation recovered from undisturbed root system. We conclude that replacing would be a best alternative for regeneration of B. maxomowicziana. The scarification treatments in which surface soil is retained can be evaluated to be positive or negative according to the site conditions, physiological characteristics of the target tree species, and recovery of other vegetation.
  • Hadsuki Abe, Toshiya Yoshida
    JOURNAL OF FOREST RESEARCH 23 5 279 - 286 2018年 [査読有り]
     
    We examined the incidence of heart rot (butt rot and trunk rot) in stems of each main tree species, with regard to the effects of individual and site characteristics, in the northern Japanese natural mixed forest. We addressed the hypotheses that incidences of rot are influenced by species identification, individual size, local vegetation, and topographic conditions. The proportions of tree individuals with heart rot (totally 36.7%) varied with tree species, with trunk rot having a significantly higher incidence in two broadleaved species (Quercus crispula and Betula ermanii) than coniferous species (Abies sachalinensis). However, butt rot incidence was similar among tree species, suggesting that each rot type appeared differently by species. The random forest classifications did not necessarily show high accuracy; it was suggested that heart rot incidence in stems of Acer mono and A. sachalinensis occurs randomly. However, in the models for both rot types of B. ermanii and trunk rot of Q. crispula, we revealed that diameter at breast height was highly important factor. Another important variable was sum of basal area of the neighboring trees, in which the incidence of both rot types tended to increase at low and high tree basal area. In addition, it was appeared that the butt rot incidence in B. ermanii was sensitive to steep slope.
  • Tsuyoshi Sato, Haruka Yamazaki, Toshiya Yoshida
    JOURNAL OF FOREST RESEARCH 22 6 336 - 342 2017年11月02日 [査読有り][通常論文]
     
    Strong wind constitutes the major force behind disturbance of northern Japanese forests. Canopy gaps induced by disturbance are responsible for subsequent recovery of the stand (i.e. enhancement of growth and recruitment). There is also a possibility that a sudden change in stand structure, involving significant microclimatic alterations, results in further stand degradation. We therefore examined a hypothesis proposing that wind disturbance causes indirect and delayed negative effects on the demography of Abies sachalinensis, a dominant conifer species of northern Japanese natural mixed forests. Data for all trees in a 3-ha study stand with diameter at breast height ≥10 cm were recorded for over 10 years, including the period of severe wind disturbance induced by Typhoon Songda in 2004. We found that the total amount of dead A. sachalinensis in the post-disturbance period was equivalent to that in the wind disturbance. The mortality of the species was generally high in larger trees. Within 1–2 years immediately after the disturbance, dead trees frequently presented the uprooted form despite there being no record of strong winds, suggesting that the physical influence of the disturbance persisted. Moreover, these dead trees showed spatial association with trees in the surrounding trees that died due to strong wind. In contrast, most A. sachalinensis trees that died 3–8 years later showed growth reduction after the disturbance. We conclude that a strong wind disturbance can have long-term influence on the stand dynamics, during which the possible cause of tree deaths changes gradually from physical damage to physiological stress.
  • Toshiya Yoshida, Sayoko Naito, Misato Nagumo, Natsumi Hyodo, Taiki Inoue, Hiromitsu Umegane, Haruka Yamazaki, Hisashi Miya, Futoshi Nakamura
    SUSTAINABILITY 9 11 2017年11月 [査読有り][通常論文]
     
    The objective of forest management has become broader, and it is essential to harmonize timber production with conservation of the forest ecosystem. Selection cutting is recognized as a major alternative of clear-cutting, because it can maintain the complexity and heterogeneity of a natural forest; however, its long-term evaluations are limited. This study compared various attributes of stand structures, which are indicators of biodiversity and ecosystem carbon stock between managed and unmanaged blocks (12.6 ha area in total) in a natural mixed forest in Hokkaido, the northernmost island of Japan. We found that 30 years' implementation of single-tree selection did not affect the volume, size structure, species diversity nor spatial distribution of overstory trees in the managed stands. Also, the total carbon stock in the managed stands was almost equal to that of the unmanaged stands. In contrast, several structural attributes and indicator elements that are significant for biodiversity (such as large-diameter live trees, dead trees, cavities, epiphytic bryophytes, and some avian guilds) showed marked decrease in the managed stands. We conclude that it is required to leave these structures and elements to some extent for deriving the merit of the management as an alternative silvicultural regime in the region.
  • Ippei Asada, Haruka Yamazaki, Toshiya Yoshida
    FOREST ECOLOGY AND MANAGEMENT 393 81 - 88 2017年06月 [査読有り][通常論文]
     
    Spatial patterns have been a major topic regarding natural regeneration of oak species, but the effects may differ considerably in sites subjected to intense forestry practices, which greatly alter many aspects of site conditions. We examined the hypothesis that the regeneration of oak (Quercus crispula Blume) following scarification (displacement of inhibiting vegetation and surface soil using machinery) is enhanced at a certain distance from a conspecific overstory tree, depending on the stage of development. We conducted both field surveys in scarification sites with different stand ages (1-16 year-old) and a laboratory seeding experiment to clarify factors contributing to its early establishment. The results demonstrate that the spatial relationship between the regeneration of oak and the conspecific overstory tree at scarification sites changes considerably among stages of the establishment. In the initial stage (0-1 years after the scarification), a location beneath the crown provided favorable conditions, whereas at subsequent stages (2-4 years), the distance-dependent effects were unclear, until eventually (8-16 years) a location outside the crown became more favorable. The condition produced by the scarification was basically competition-free and resource-rich, but it can also be harsh for acorns and small seedlings, imposing a requirement for shading to moderate the environment in the initial stage. Such an effect of facilitation was found also in the later (sapling) stage via the existence of neighbors of the other regenerated fast-growing species. The current findings supported the effectivity of a shelter-wood system, in which the regeneration starts from shaded condition followed by a gap status created by a successive felling. The area away from the conspecific crown would have a potential if acorns are plentifully supplied (e.g. by direct seeding) and they withstand the initial negative factors at the initial stage of development. (C) 2017 Elsevier B.V. All rights reserved.
  • Takahiro Inoue, Karibu Fukuzawa, Tsunehiro Watanabe, Toshiya Yoshida, Hideaki Shibata
    ECOLOGICAL RESEARCH 32 2 227 - 241 2017年03月 [査読有り][通常論文]
     
    Natural disturbances create spatial patterns of the ecosystem processes and functions in natural forests. However, how dynamics and the spatial structure of forests relate to soil nitrogen dynamics is not well understood. We examined the spatial relationship between the distributions of canopy and understory species, and soil nitrogen dynamics in a natural coniferous-broadleaved mixed forest with a dense understory of Sasa dwarf bamboo in northern Japan. The O horizon was thick where coniferous litter predominated, and it was thin where broadleaved litter predominated. The soil water content was low in areas with a thick O horizon and a high abundance of coniferous trees. The soil nitrate content was low where the soil water content was low, and the soil nitrate content increased linearly with increasing net nitrification potential. These results suggest that the soil nitrate content under the coniferous canopy was lower because of the low nitrification potential of soil microbes in soils with low water contents. The soil nitrate content and nitrification potential were higher in the canopy gap than under the canopy. Our results suggest that forest structure, specifically the thickness of the forest floor, significantly affects the spatial pattern of the soil water content, thereby creating a spatial pattern of soil nitrogen availability at a relatively small scale with flat topography. The higher nitrification potential under the canopy gap could pose a long-term risk of nitrate leaching because of the suppression of the natural regeneration of canopy species by dense Sasa dwarf bamboo in this forest ecosystem.
  • Shigeru Niwa, Ayu Toyota, Toshio Kishimoto, Kji Sasakawa, Shin Abe, Takeshi Chishima, Motoki Higa, Tsutom Hiura, Kosuke Homma, Daisuke Hoshino, Hideyuki Ida, Naoto Kamata, Yohei Kaneko, Motohiro Kawanishi, Kazutaka Kobayashi, Kaname Kubota, Koichiro Kuraji, Takashi Masaki, Kaoru Niiyama, Mahoko Noguchi, Haruto Nomiya, Satoshi Saito, Michinori Sakimoto, Hitoshi Sakio, Shigeho Sato, Mitsue Shibata, Atsushi Takashima, Hiroshi Tanaka, Naoaki Tashiro, Naoko Tokuchi, Hisahiro Torikai, Toshiya Yoshida
    ECOLOGICAL RESEARCH 31 5 607 - 608 2016年09月 [査読有り][通常論文]
     
    This data paper reports census data of ground-dwelling beetle and other fauna of the forest floor environment; collections were made from a network of 22 forest sites in Japan. To our knowledge, this represents the largest dataset for long-term monitoring of a ground-dwelling beetle community and other taxa in a ground environment in forests, which covers a broad climatic range in the temperate zone and is freely available. The network forms part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subalpine, cool- and warm-temperate and subtropical climatic zones and the four major forest types of Japan. Thirty-three permanent plots usually 1 ha in size were established in old-growth, secondary natural and a few plantation forests. Censuses of the ground-dwelling beetle community were conducted using pitfall trapping and forest floor environment monitoring every year from 2004 to the present. During the initial 9 years of the census (2004-2012), 59,762 beetle individuals (including 3182 larvae) of more than 314 species were recorded. This dataset includes taxonomy and biomass of each beetle individual and each taxonomic group of other invertebrates coincidently captured in pitfall trapping. The dataset also includes data related to ground coverage by forest floor vegetation, dry mass of the accumulated organic litter layer, and carbon and nitrogen contents and cellulose decomposition rate in organic layer and surface mineral soil. The data could be used to investigate geographical patterns and intra- and inter-annual dynamics of individual body mass, populations and community structures of ground-dwelling beetles, and their relationships with the forest floor environment. Furthermore, the data could be analyzed with other open datasets related to tree community dynamics and litter fall continuously measured in the same study plots. This dataset also provides information related to the distribution and average body mass of each beetle species.
  • 吉田俊也
    北方林業 67 1 29‐32  2016年04月01日 [査読無し][通常論文]
  • 吉田 俊也
    日本森林学会大会発表データベース 127 530 - 530 日本森林学会 2016年 
    ヤチダモは、広葉樹の中で代表的な造林樹種である。高齢級の林分も存在するが、施業履歴が定かな事例が限られており、管理のための情報が不足している。ここでは、長期データを用いて、林分動態に及ぼす局所的な混み合いの効果を解析し、とくに間伐の影響について考察した。小渓流に沿った緩斜地に1920年台に植栽(植栽密度2740本/ha)されたヤチダモ造林地を対象とした。この造林地では、54-57年生時に、本数比17%、胸高断面積比10%程度の間伐が行なわれた。間伐以降の30年間、6箇所の標準地(合計面積2.0ha)において10年間隔で毎木調査を実施した。蓄積(胸高断面積合計)の増加率は、調査期間全体では1%/年未満にとどまっていた。期間別にみると、間伐直後の10年間は、成長率・生残率ともに低い傾向が見られ、間伐の局所的な負の効果が見積もられた。蓄積は、その後の10年間は顕著な増加に転じたが、続く期間には、とくに生存率が低下したために増加率はふたたび鈍化していた。ヤチダモ人工林において間伐の必要性は明らかであったが、その実施にあたっては、直後の成長率・生残率の低下を避ける方策が必要といえた。
  • 田村太壱, 加藤顕, 小花和宏之, 吉田俊也
    日本緑化工学会誌 41 1 163 - 168 日本緑化工学会 2015年08月31日 [査読無し][通常論文]
     
    森林の管理には簡易なモニタリング技術が必要である。これまでの3次元データの取得は,レーザーによるデータの取得が行われてきたが,近年Structure from Motion(以下SfM)という技術が利用可能となった。SfMは写真測量の技術であり,小型UAVを用いることで3次元データを簡易的に取得できる。本研究では,北海道大学雨龍研究林において,小型UAVによる空撮画像とSfMを適用することで森林の3次元データを取得し,樹種の違い,季節変化,地形が樹高計測に与える影響について検討した。その結果,季節変化が樹高計測に影響を与えること,展葉時期において高い精度で樹高を計測できることがわかった。
  • Takeshi Motohka, Toshiya Yoshida, Hideaki Shibata, Takeo Tadono, Masanobu Shimada
    IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 53 4 1683 - 1691 2015年04月 [査読有り][通常論文]
     
    We tested the performance of the stereo observations of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS) in the mapping of forest aboveground biomass (AGB) in Japan. Digital canopy height models (DCHMs), which are differences between PRISM digital surface models and surveying-based digital terrain models (DTMs), were compared to in situ AGB measurements of several forest types (number of stands: 28; average stand size: 0.54 ha; stand size range: 0.25-3.00 ha). DCHM values exhibited a significant correlation with AGB (r = 0.66-0.87; five different DCHMs), and the root-mean-square error and bias of the regression model evaluated by the leave-one-out cross validation were 37.2-57.8 t/ha(22.1%-32.6%) and -0.11-1.89 t/ha, respectively. There was no saturation in the relationship between DCHM and AGB (AGB range: 19-332 t/ha). The correlations between DCHM and mean canopy height (r = 0.17-0.52) and between DCHM and Lorey's height (r = 0.26-0.66) were weaker than the correlation between DCHM and AGB. The PRISM AGB distribution estimated by the regression model was consistent with a tree density map produced from aerial photos. Comparison to Phased Array-type L-band Synthetic Aperture Radar (PALSAR) data showed that the PRISM DCHMs can estimate high AGB over the saturation level of PALSAR backscattering coefficient, i.e., 100-200 t/ha. The results described here demonstrate that the PRISM DCHMs are capable of wall-to-wall AGB estimation at 50-m resolution. This approach will be useful for improving the performance of satellite-based AGB estimation when an accurate DTM is available.
  • Klaus J. Puettmann, Scott McG Wilson, Susan C. Baker, Pablo J. Donoso, Lars Droessler, Girma Amente, Brian D. Harvey, Thomas Knoke, Yuanchang Lu, Susanna Nocentini, Francis E. Putz, Toshiya Yoshida, Juergen Bauhus
    FOREST ECOSYSTEMS 2 8  2015年04月 [査読有り][通常論文]
     
    Background: The development of forestry as a scientific and management discipline over the last two centuries has mainly emphasized intensive management operations focused on increased commodity production, mostly wood. This "conventional" forest management approach has typically favored production of even-aged, single-species stands. While alternative management regimes have generally received less attention, this has been changing over the last three decades, especially in countries with developed economies. Reasons for this change include a combination of new information and concerns about the ecological consequences of intensive forestry practices and a willingness on the part of many forest owners and society to embrace a wider set of management objectives. Alternative silvicultural approaches are characterized by a set of fundamental principles, including avoidance of clearcutting, an emphasis on structural diversity and small-scale variability, deployment of mixed species with natural regeneration, and avoidance of intensive site-preparation methods.Methods: Our compilation of the authors' experiences and perspectives from various parts of the world aims to initiate a larger discussion concerning the constraints to and the potential of adopting alternative silvicultural practices.Results: The results suggest that a wider adoption of alternative silvicultural practices is currently hindered by a suite of ecological, economic, logistical, informational, cultural, and historical constraints. Individual contexts display their own unique combinations and relative significance of these constraints, and accordingly, targeted efforts, such as regulations and incentives, may help to overcome specific challenges.Conclusions: In a broader context, we propose that less emphases on strict applications of principles and on stand structures might provide additional flexibility and facilitate the adoption of alternative silvicultural regimes in a broader set of circumstances. At the same time, the acceptance of alternative silvicultural systems as the "preferred or default mode of management" will necessitate and benefit from the continued development of the scientific basis and valuation of a variety of ecosystem goods and services. This publication is aimed to further the discussion in this context.
  • Takeshi Motohka, Toshiya Yoshida, Hideaki Shibata, Takeo Tadono, Masanobu Shimada
    IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 53 4 1683 - 1691 2015年04月 [査読有り][通常論文]
     
    We tested the performance of the stereo observations of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS) in the mapping of forest aboveground biomass (AGB) in Japan. Digital canopy height models (DCHMs), which are differences between PRISM digital surface models and surveying-based digital terrain models (DTMs), were compared to in situ AGB measurements of several forest types (number of stands: 28; average stand size: 0.54 ha; stand size range: 0.25-3.00 ha). DCHM values exhibited a significant correlation with AGB (r = 0.66-0.87; five different DCHMs), and the root-mean-square error and bias of the regression model evaluated by the leave-one-out cross validation were 37.2-57.8 t/ha(22.1%-32.6%) and -0.11-1.89 t/ha, respectively. There was no saturation in the relationship between DCHM and AGB (AGB range: 19-332 t/ha). The correlations between DCHM and mean canopy height (r = 0.17-0.52) and between DCHM and Lorey's height (r = 0.26-0.66) were weaker than the correlation between DCHM and AGB. The PRISM AGB distribution estimated by the regression model was consistent with a tree density map produced from aerial photos. Comparison to Phased Array-type L-band Synthetic Aperture Radar (PALSAR) data showed that the PRISM DCHMs can estimate high AGB over the saturation level of PALSAR backscattering coefficient, i.e., 100-200 t/ha. The results described here demonstrate that the PRISM DCHMs are capable of wall-to-wall AGB estimation at 50-m resolution. This approach will be useful for improving the performance of satellite-based AGB estimation when an accurate DTM is available.
  • 戸田求, 福澤加里部, 中村誠宏, 田中幹展, 吉田俊也, 柴田英昭, WANG Xin, 石田祐宣, 宮田理恵
    低温科学 73 21 - 29 北海道大学低温科学研究所 = Institute of Low Temperature Science, Hokkaido University 2015年03月31日 [査読無し][通常論文]
     
    北海道北部の森林生態系が台風による撹乱をうけた状況を想定し, 撹乱以後の生態系および炭素動態の回復過程を定量的に評価することを目的とした撹乱操作実験が実施された. 本実験に際し, 遷移初期段階にあるダケカンバ二次林を対象に葉群の完全切除が実施された. 撹乱処理の結果, 葉群は撹乱以前の状態への回復の兆候を示すものの, 撹乱から3年経過した段階においても未だに完全な回復に至っていない. 一方で, 同一光条件下での個葉レベルの最大光合成速度は撹乱以前と比べて高まる傾向を示した. また, 撹乱による林冠構造の変化は林床の微気象環境を変化させ, 林床植生であるササの被度を高めた. 本結果から, 葉群撹乱による生態系炭素動態への影響として, 短期的には樹木の光合成機能が高まることで直後にみられる生産性の低下が補償されるが, 一方で長期的にはササの被度を増加させ遷移の進行を妨げることで炭素動態を大きく変化させる可能性のあることが考えられる. したがって, 今後の気候変化に伴い同域に強い勢力の台風が到来する頻度が高まると, 長期的にはササの優占度がさらに高まることで, 従来とは異なる植生状態やそれに伴う生態系炭素動態へ移行する可能性が示唆される.To assess the effects of typhoon-induced disturbance on vegetation state, foliage, and ecosystem carbondynamics, we conducted a manipulation experiment to simulate typhoon disturbance in a northern forest inJapan. The experiment simulated a less intensive disturbance than one that would cause stand replacement,forcing the vegetation to form an alternative stable state. We ripped away most of the foliage from theoverstory trees in an established plot. Three years after this disturbance,the foliage had recovered to one-thirdof its original state before the disturbance occurred,whereas the photosynthetic rate was markedly higher thanthat before the disturbance. The structural changes in the foliage of the overstory trees after the disturbanceresulted in a brighter light environment at the forest floor,which favored the growth of understory vegetation.These results suggest that from a long-term viewpoint,widespread understory Sasa vegetation may disturb theregeneration of tree seedlings,creating an alternative stable state in which Sasa dominates in the next generation of the forested area.
  • 來住牧, 宮久史, 吉田俊也, 植村滋
    低温科学 73 125 - 132 北海道大学低温科学研究所 = Institute of Low Temperature Science, Hokkaido University 2015年03月31日 [査読無し][通常論文]
     
    北海道北部の天然林に生育するミズナラ種子生産量の年次変動の特徴を明らかにし, 種子の豊凶現象に関する至近要因仮説の適合性をGLM 解析により評価した. 各モデルのAIC 値から, 豊凶の変動には気象要因よりも個体の資源動態が強く影響することが示唆された. 各モデルで選択された説明変数のΔAIC 値から, 前年の種子生産量が不作を誘発する負の方向への強い影響と, 花芽形成期の降水量と生育期の気温の弱い影響が認められ, 個体の内的条件が整った上で外的因子が作用することにより個体間で豊凶が同調すると考えられた.We explored models for mast-seeding by using a set of long-term data for acorn crop from 1984 to 2011 and tree-ring records of 47 labeled trees of Mongolian oak Quercus crispula Blume growing in the Uryu Research Forest of Hokkaido University,northern Japan. We verified three dominant models for a proximate approach to mast-seeding:the weather dependence model,the resource balance model,and the combined weather-resourcemodel. Annual acorn crop has intensely fluctuated synchronously among individuals and sites, and there was a trend towards biennial reciprocal masts, except in the consecutive extremely lean years from 1988 to 1993. The models were subjected to GLM analyses,and the AIC values indicated that the obvious fluctuations in acorncrop was strongly influenced by the inner resource dynamics of the trees, rather than the seasonal weather conditions neither in anthogenesis, fecundation, nor maturation. However, the AIC value was higher for theweather model than for the complex model, suggesting that the influence of the weather conditions was not negligible. Among the explanatory variables adopted in each model,acorn crop was the most strongly influencedby the previous crop size,and subsequently by rainfall in the previous June corresponding to the anthogenetic season negatively, and then by the current mid-summer temperature promoting maturation after fecundation.The negative correlation between acorn crop and rainfall in the previous June for the period from 1981 to 1993 was insignificant, suggesting that the phenological schedule for reproduction in this species may have changed over recent decades, possibly because of drastic changes in climate such as global warming.
  • Kentaro Takagi, Yasumichi Yone, Hiroyuki Takahashi, Rei Sakai, Hajime Hojyo, Tatsuya Kamiura, Mutsumi Nomura, Naishen Liang, Tatsuya Fukazawa, Hisashi Miya, Toshiya Yoshida, Kaichiro Sasa, Yasumi Fujinuma, Takeshi Murayama, Hiroyuki Oguma
    ECOLOGICAL INFORMATICS 26 3 54 - 60 2015年03月 [査読有り][通常論文]
     
    Trees are recognized as a carbon reservoir, and precise and convenient methods for forest biomass estimation are required for adequate carbon management Airborne light detection and ranging (LiDAR) is considered to be one of the solutions for large-scale forest biomass evaluation. To clarify the relationship between mean canopy height determined by airborne LiDAR and forest timber volume and biomass of cool-temperate forests in northern Hokkaido, Japan, we conducted LiDAR observations covering the total area of the Teshio Experimental Forest (225 km(2)) of Hokkaido University and compared the results with ground surveys and previous studies. Timber volume and aboveground tree carbon content of the studied forest stands ranged from 101.43 to 480.40 m(3) ha(-1) and from 30.78 to 180.54 MgC ha-1, respectively. The LiDAR mean canopy height explained the variation among stands well (volume: r(2) = 0.80, RMSE = 55.04 m(3) ha(-1); aboveground tree carbon content: = 0.78, RMSE = 19.10 MgC ha(-1)) when one simple linear regression equation was used for all types (hardwood, coniferous, and mixed) of forest stands. The determination of a regression equation for each forest type did not improve the prediction power for hardwood (volume: r(2) = 0.84, RMSE = 62.66 m(3) ha(-1); aboveground tree carbon content: r(2) = 0.76, RMSE = 27.05 MgC ha(-1)) or coniferous forests (volume: r(2) = 0.75, RMSE = 51.07 m(3) ha(-1); aboveground tree carbon content: r(2) = 0.58, RMSE = 19.00 MgC ha(-1)). Thus, the combined regression equation that includes three forest types appears to be adequate for practical application to large-scale forest biomass estimation. (C) 2015 Elsevier B.V. All rights reserved.
  • Kentaro Takagi, Yasumichi Yone, Hiroyuki Takahashi, Rei Sakai, Hajime Hojyo, Tatsuya Kamiura, Mutsumi Nomura, Naishen Liang, Tatsuya Fukazawa, Hisashi Miya, Toshiya Yoshida, Kaichiro Sasa, Yasumi Fujinuma, Takeshi Murayama, Hiroyuki Oguma
    ECOLOGICAL INFORMATICS 26 54 - 60 2015年03月 [査読有り][通常論文]
     
    Trees are recognized as a carbon reservoir, and precise and convenient methods for forest biomass estimation are required for adequate carbon management Airborne light detection and ranging (LiDAR) is considered to be one of the solutions for large-scale forest biomass evaluation. To clarify the relationship between mean canopy height determined by airborne LiDAR and forest timber volume and biomass of cool-temperate forests in northern Hokkaido, Japan, we conducted LiDAR observations covering the total area of the Teshio Experimental Forest (225 km(2)) of Hokkaido University and compared the results with ground surveys and previous studies. Timber volume and aboveground tree carbon content of the studied forest stands ranged from 101.43 to 480.40 m(3) ha(-1) and from 30.78 to 180.54 MgC ha-1, respectively. The LiDAR mean canopy height explained the variation among stands well (volume: r(2) = 0.80, RMSE = 55.04 m(3) ha(-1); aboveground tree carbon content: = 0.78, RMSE = 19.10 MgC ha(-1)) when one simple linear regression equation was used for all types (hardwood, coniferous, and mixed) of forest stands. The determination of a regression equation for each forest type did not improve the prediction power for hardwood (volume: r(2) = 0.84, RMSE = 62.66 m(3) ha(-1); aboveground tree carbon content: r(2) = 0.76, RMSE = 27.05 MgC ha(-1)) or coniferous forests (volume: r(2) = 0.75, RMSE = 51.07 m(3) ha(-1); aboveground tree carbon content: r(2) = 0.58, RMSE = 19.00 MgC ha(-1)). Thus, the combined regression equation that includes three forest types appears to be adequate for practical application to large-scale forest biomass estimation. (C) 2015 Elsevier B.V. All rights reserved.
  • 加藤顕, 安藤祐樹, 吉田俊也, 梶原康司, 本多嘉明, 小林達明
    日本緑化工学会誌 40 1 136 - 141 日本緑化工学会 2014年08月20日 [査読無し][通常論文]
     
    レーザースキャナーが身近に利用できるようになり,3 次元レーザーデータから樹木調査ができるようになってきた。本研究では北海道大学中川研究林において,様々な樹種構成のある22 箇所のプロットで簡易型地上レーザーを用いて3 次元データを取得し,得られたデータから森林簿作成に必要な樹高,胸高直径,枝下高,毎木位置図を作成した。本研究に用いた簡易型地上レーザーは半径50 m まで照射できるSICK LMS511 であり,市販されているレーザーセンサーの中で安価な製品の一つである。安価で可搬性に富む簡易型地上レーザーを用いた毎木調査法を確立するために,樹木測定精度を明らかにした。
  • 吉田俊也
    ランドスケープ研究 78 2 87 - 88 2014年07月31日 [査読無し][通常論文]
  • 加藤顕, 阿部葉月, 安藤祐樹, 吉田俊也
    ランドスケープ研究 78 1 54 - 55 2014年04月25日 [査読無し][通常論文]
  • Akira Yasuda, Toshiya Yoshida, Hisashi Miya, Brian D. Harvey
    JOURNAL OF FOREST RESEARCH 18 5 398 - 406 2013年10月 [査読有り][通常論文]
     
    In uneven-aged conifer-broadleaved mixed forests in Hokkaido, northern Japan, single-tree selection cutting has been a common management practice since the early twentieth century. This practice is expected to produce timber without major changes in stand structure or tree species composition. The demographic response of forests to this practice has often been unexpected, and degradation of stand properties has been widely observed. We propose here a sustainable management regime of selection cutting, based on an individual-based forest dynamics simulation model, SORTIE-ND. Our simulations, based on demographic data from 15 long-term monitoring stands, suggest that selection cutting using a lower cutting intensity together with a longer rotation period and reduced removal of small trees and conifer species is more appropriate than traditional systems in terms of maintaining stand structure and tree species composition, as well as being profitable financially. Supplemental regeneration practices, which can counter accidental mortality incurred during harvesting operations, would also be necessary to ensure tree recruitment.
  • Takeshi Motohka, Toshiya Yoshida, Hideaki Shibata, Takeo Tadono, Masanobu Shimada
    2013 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS) 968 - 971 2013年 [査読有り][通常論文]
     
    In this study, we examine the applicability of digital surface model (DSM) generated from ALOS PRISM data for mapping forest above ground biomass (AGB). We obtained the digital canopy height model (DCHM) by calculating the differences between the PRISM DSM and surveying-based digital elevation model (DEM), and investigated the relationship between the DCHM values and field measured mean tree height and AGB in Northern Hokkaido, Japan. The results show a strong linear relationship between the field measured AGB and PRISM-DCHM (R = 0.872, n = 25). The RMSE and bias of the regression model, which were evaluated by the leave-one-out cross validation, are 38.1 t/ha (22 %) and -0.2 t/ha, respectively. Saturation at high AGB is not shown. We also demonstrate the wall-to-wall AGB mapping by using the regression model and the PRISM DCHM image. A pan-sharpen image generated from PRISM and AVNIR-2 images is utilized for forest cover mapping. The PRISM-based AGB values are generally reasonable except for high mountain areas. The relationship between the PRISM AGB and backscattering coefficient measured by L-band synthetic aperture radar (PALSAR) is consistent with the regression models discovered by the previous researches.
  • 吉田俊也
    北方林業 64 11 341-343  2012年11月01日 [査読無し][通常論文]
  • Satoshi N. Suzuki, Masae I. Ishihara, Masahiro Nakamura, Shin Abe, Tsutom Hiura, Kosuke Homma, Motoki Higa, Daisuke Hoshino, Kazuhiko Hoshizaki, Hideyuki Ida, Ken Ishida, Motohiro Kawanishi, Kazutaka Kobayashi, Koichiro Kuraji, Shigeo Kuramoto, Takashi Masaki, Kaoru Niiyama, Mahoko Noguchi, Haruto Nomiya, Satoshi Saito, Takeshi Sakai, Michinori Sakimoto, Hitoshi Sakio, Tamotsu Sato, Hirofumi Shibano, Mitsue Shibata, Maki Suzuki, Atsushi Takashima, Hiroshi Tanaka, Masahiro Takagi, Naoaki Tashiro, Naoko Tokuchi, Toshiya Yoshida, Yumiko Yoshida
    ECOLOGICAL RESEARCH 27 6 989 - 990 2012年11月 [査読有り][通常論文]
  • 長谷川幹夫, 中島春樹, 吉田俊也
    植物地理・分類研究 59 1 31-34  2011年12月01日 [査読無し][通常論文]
  • 井上太樹, 南雲未智, 伊村智, 吉田俊也
    せん苔類研究 10 6 173-174  2011年11月 [査読無し][通常論文]
  • Masae I. Ishihara, Satoshi N. Suzuki, Masahiro Nakamura, Tsutomu Enoki, Akio Fujiwara, Tsutom Hiura, Kosuke Homma, Daisuke Hoshino, Kazuhiko Hoshizaki, Hideyuki Ida, Ken Ishida, Akira Itoh, Takayuki Kaneko, Kaname Kubota, Koichiro Kuraji, Shigeo Kuramoto, Akifumi Makita, Takashi Masaki, Kanji Namikawa, Kaoru Niiyama, Mahoko Noguchi, Haruto Nomiya, Tatsuhiro Ohkubo, Satoshi Saito, Takeshi Sakai, Michinori Sakimoto, Hitoshi Sakio, Hirofumi Shibano, Hisashi Sugita, Mitsuo Suzuki, Atsushi Takashima, Nobuyuki Tanaka, Naoaki Tashiro, Naoko Tokuchi, Toshiya Yoshida, Yumiko Yoshida
    ECOLOGICAL RESEARCH 26 6 1007 - 1008 2011年11月 [査読無し][通常論文]
     
    This data paper reports tree census data collected in a network of 34 forest sites in Japan. This is the largest forest data set freely available in Japan to date. The network is a part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subarctic to subtropical climate zones and the four major forest types in Japan. Forty-two permanent plots, usually 1 ha in size, were established in old-growth or secondary natural forests. Censuses of woody species a parts per thousand yen15 cm girth at breast height were conducted every year or once during 2004 to 2009. The data provide species abundance, survivorship and stem girth growth of 52,534 individuals of 334 tree and liana species. The censuses adopted common census protocol, which provide good opportunities for meta-analyses and comparative studies among forests. The data have been used for ecological studies as well as for the biodiversity reports published by the Ministry of the Environment.
  • Toshiya Yoshida, Mahoko Noguchi, Shigeru Uemura, Satoshi Yanaba, Hisashi Miya, Tsutom Hiura
    JOURNAL OF FOREST RESEARCH 16 3 215 - 222 2011年06月 [査読有り][通常論文]
     
    Windthrow is recognized as an extremely significant disturbance in many forests. Its effects are increased by stand fragmentation, which exposes the stand to strong winds. In this study, we investigated the change in tree mortality in fragmented stands with the distance from the stand edge, in a conifer-broadleaved mixed forest in northern Japan. We set out experimental plots having three stand sizes (400, 1,600, 6,400 m 2) and examined the stand dynamics over 10 years. Tree mortality tended to be higher in smaller stands, although an effect of stand size was found only in the first 5 years of the study. Distance-dependent individual mortality was obvious in Abies sachalinensis, the most vulnerable major tree species, again in the first 5 years, suggesting that wind-risk management should emphasize the area within ca. 20 m from the stand edge. No distant-dependent effect was found, however, in the latter 5 years, in which there was a strong typhoon; tree deaths occurred throughout the stand (irrespective of distance within) as a result of this event. We conclude that the severity of wind can cause the features of wind-induced damage to differ; stand edge effects peculiar to a small forest are unlikely to occur with particularly strong winds, and the effect of fragmentation might therefore be clear only in weaker disturbances.
  • Floortje Vodde, Kalev Jogiste, Yasuhiro Kubota, Timo Kuuluvainen, Kajar Koester, Aljona Lukjanova, Marek Metslaid, Toshiya Yoshida
    JOURNAL OF FOREST RESEARCH 16 3 155 - 167 2011年06月 [査読有り][通常論文]
     
    We reviewed studies dealing with regeneration under variable conditions in boreal and hemiboreal forests as affected by different microsite types by tree species functional groups. Generally, the importance of storm-induced microsites for regeneration dynamics in boreal forests depends on several factors: (1) distribution and type of microsites (generated by storm characteristics and stand conditions); (2) viable seed supply (stand history, species dispersal traits and status of surviving trees) and their species' life history strategy; (3) climatic and site conditions (pre-storm conditions and storm-induced changes); and (4) delayed storm effects, such as retarded falling of trees, favoured vegetation growth, etc. Studies acknowledging the significance of microsites were mostly related to intermediate or severe events, causing sufficient changes in resource levels and growth conditions, and influencing extrinsic factors such as frost heaving, erosion and browsing. Also, the dispersal traits of available tree species, including sprouting and response of surviving trees, such as canopy expansion, should be considered in evaluating microsite importance in individual cases. In intermediate to severe windstorm events, pioneer species are generally profiting most from the additional offer in microsites, requiring bare mineral soil and elevated locations for their establishment and growth. Under gap dynamics, shade-tolerant species benefit from dead wood and elevated locations as these offer safe sites in stands with abundant understorey vegetation.
  • Ahto Kangur, Toshiya Yoshida, Yasuhiro Kubota, Marek Metslaid
    JOURNAL OF FOREST RESEARCH 16 3 153 - 154 2011年06月 [査読有り][通常論文]
  • Motomu Toda, Pasi Kolari, Taro Nakai, Yuji Kodama, Hideaki Shibata, Toshiya Yoshida, Shigeru Uemura, Akihiro Sumida, Kyoko Kato, Kiyomi Ono, Toshihiko Hara
    JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 116 G02006-45  2011年04月 [査読有り][通常論文]
     
    The effects of wind disturbance on forest dynamics and ecosystem CO2 exchange were examined in cool temperate forests of northern Japan during 2004-2008 using eddy covariance (EC) measurements. One site was a young, even-aged, monoculture, deciduous forest; the other was an uneven-aged mixed forest of evergreen and deciduous overstory tree species, including some over 200 years old. On 8 September 2004, a strong typhoon struck the forests, after which leaf and branch amounts decreased in young growth forest, but foliage showed little change in old growth forest. By 2006, foliage at the young-growth forest had recovered to the 2004 pretyphoon state. Average daily accumulated gross primary production (GPP(d)), terrestrial ecosystem respiration (TERd), and net ecosystem exchange (NEEd) were assessed for six growth stages annually. After the typhoon, large increases in GPP(d) were found during the growing stage of overstory tree species with high photosynthetic rates compared to that before the typhoon. Pronounced increases in GPP(d) and corresponding large reductions in NEEd were detected at the young-growth forest, indicating that NEEd was largely regulated by GPP(d) throughout the growing stages. Although EC measurements contain uncertainty, our continuous EC measurements revealed that interannual variability in meteorological variables and structural changes in foliage have only small impacts on GPP and NEE, while photosynthetic recovery of foliage from typhoon damage has high potential to increase GPP and enhance NEE as compared with those under nondamage conditions.
  • 清水池 義治, 神沼 公三郎, 佐藤 信, 吉田 俊也, 奈須 憲一郎, 三島 徳三
    地域と住民 : 道北地域研究所年報 0 29 73 - 88 名寄市立大学 2011年03月 [査読無し][通常論文]
  • 柴田 英昭, 高木 健太郎, 吉田 俊也
    水利科学 54 6 30 - 42 日本治山治水協会 2011年02月01日 [査読無し][通常論文]
  • Keiichi Aoyama, Toshiya Yoshida, Akane Harada, Mahoko Noguchi, Hisashi Miya, Hideaki Shibata
    JOURNAL OF FOREST RESEARCH 16 1 35 - 45 2011年02月 [査読有り][通常論文]
     
    To restore non-wooded stands dominated by dwarf bamboo species (Sasa kurilensis or S. senanensis) into forests, mechanical soil scarification has been applied in northern Japan since the 1960s. The treatment is followed both by natural regeneration and artificial planting. In this study, we quantified the total carbon stock (plants plus 0.3 m depth of soil) of these stands over 35-year age-sequences. The natural regeneration stands were gradually dominated by Betula ermanii. The carbon stock increased linearly to 215.1 +/- A 35.2 Mg C ha(-1) for a 37-year-old stand formerly dominated by S. kurilensis, and 181.1 +/- A 29.8 Mg C ha(-1) for a 34-year-old stand formerly dominated by S. senanensis. The latter was similar to that of a Picea glehnii plantation, formerly dominated by S. senanensis, with comparable stand age (160.3 +/- A 6.7 Mg C ha(-1) for 35-year-old stands). Although the carbon stock in plants quickly offset the untreated level, that in the soil remained depressed even in the older stands. This resulted in small differences in carbon stock of these stands with untreated dwarf bamboo stands. We conclude that natural regeneration following scarification could be a prime option for carbon sink management in the region. However, we should take a long rotation period (i.e., > 50 years) to ensure a carbon sink state. A potential of further improvements of the practice, including that reduce intensity of soil disturbance, was presented.
  • 吉田 俊也
    北方林業 63 1 6 - 9 北方林業会 2011年01月01日 [査読無し][通常論文]
  • Takagi Kentaro, Kotsuka Chikara, Fukuzawa Karibu, Kayama Masazumi, Makoto Kobayashi, Watanabe Tsunehiro, Nomura Mutsumi, Fukazawa Tatsuya, Takahashi Hiroyuki, Hojyo Hajime, Ashiya Daitaro, Naniwa Akihiko, Sugata Sadao, Kamiura Tatsuya, Sugishita Yoshiyuki, Sakai Rei, Ito Kinya, Kobayashi Makoto, Maebayashi Mamoru, Mizuno Masato, Murayama Takeshi, Kinoshita Koji, Fujiwara Daisaku, Hashida Shukichi, Shibata Hideaki, Yoshida Toshiya, Sasa Kaichiro, Saigusa Nobuko, Fujinuma Yasumi, Akibayashi Yukio
    Eurasian Journal of Forest Research 13 1 1 - 7 Hokkaido University Forests, EFRC 2010年08月 [査読有り][通常論文]
     
    To evaluate the biomass of conifer-broadleaf mixed forests in northern Hokkaido, Japan, the relationships between tree dry masses (including belowground roots) and diameter at breast height (DBH) and tree height (H) for major three tree species (Quercus crispula Blume, Betula ermanii Cham., and Abies sachalinensis (F. Schmidt) Mast.) were calculated. In addition, carbon and nitrogen contents of each tree organ were measured for an accurate estimation of the carbon and nitrogen stocks in the trees. For all three species, one allometric equation explained the relationship between DBH (or DBH2...
  • Hiromi Mizunaga, Takuo Nagaike, Toshiya Yoshida, Sauli Valkonen
    JOURNAL OF FOREST RESEARCH 15 1 1 - 2 2010年02月 [査読有り][通常論文]
  • 石原 正恵, 酒井 武, 齋藤 哲, 崎尾 均, 嵜元 道徳, 芝野 博文, 杉田 久志, 鈴木 三男, 高木 正博, 高嶋 敦史, 武生 雅明, 石田 健, 田代 直明, 田中 信行, 徳地 直子, 並川 寛司, 新山 馨, 西村 尚之, 野口 麻穂子, 野宮 治人, 日浦 勉, 藤原 章雄, 井田 秀行, 星野 大介, 本間 航介, 蒔田 明史, 正木 隆, 吉岡 崇仁, 吉田 俊也, 伊東 明, 榎木 勉, 大久保 達弘, 金子 隆之, 金子 信博, 倉本 惠生
    日本生態学会誌 60 1 111 - 123 日本生態学会暫定事務局 2010年 [査読無し][通常論文]
     
    モニタリングサイト1000は環境省生物多様性センターの事業であり、そのうち森林・草原調査では、樹木、地表徘徊性甲虫、鳥類を指標生物群として定め、2004年よりモニタリング調査を行っている。本稿では、コアサイト・準コアサイトで取られた樹木に関するデータ(毎木調査データ)が研究・教育・保全政策などに広く活用されるよう、その概要を紹介し、データの活用方法について提案する。
  • Toshiya Yoshida, Mahoko Noguchi
    LANDSCAPE AND ECOLOGICAL ENGINEERING 6 1 37 - 42 2010年01月 [査読有り][通常論文]
     
    Previous studies have indicated that recruitment of Abies sachalinensis, a representative conifer species of northern Japan, decreased following single-tree selection harvesting in stands with dense dwarf bamboo understory. We tested the hypothesis that growth and survival of A. sachalinensis seedlings are reduced by canopy opening in that type of stand. A 0.75 ha study plot was examined, and all the seedlings (defined as trees with height 0.5-2 m) were identified and their shoot extensions measured for three years after single-tree selection harvesting (26% intensity in terms of basal area). The leader extensions of A. sachalinensis seedlings that experienced canopy opening were greatly improved. However, a negative effect on survival was also apparent; nearly 40% of seedlings died at the sites that experienced canopy opening. These results were supported by generalized linear models that examined variations of local harvesting intensity for individual seedlings. Despite the ability of A. sachalinensis to respond rapidly to exposure, some physiological stresses may have appeared, and presumably were amplified by co-occurring dwarf bamboos. With regard to the low seedling density (156 stems ha(-1)), common in this type of stands, local harvesting intensity in the selection system should be reduced to maintain survival of advanced regeneration, thus sustaining stand structure and composition.
  • 石原 正恵, 酒井 武, 齋藤 哲, 崎尾 均, 嵜元 道徳, 芝野 博文, 杉田 久志, 鈴木 三男, 高木 正博, 高嶋 敦史, 武生 雅明, 石田 健, 田代 直明, 田中 信行, 徳地 直子, 並川 寛司, 新山 馨, 西村 尚之, 野口 麻穂子, 野宮 治人, 日浦 勉, 藤原 章雄, 井田 秀行, 星野 大介, 本間 航介, 蒔田 明史, 正木 隆, 吉岡 崇仁, 吉田 俊也, 伊東 明, 榎木 勉, 大久保 達弘, 金子 隆之, 金子 信博, 倉本 惠生
    日本生態学会誌 60 1 111 - 123 日本生態学会暫定事務局 2010年 [査読無し][通常論文]
     
    モニタリングサイト1000は環境省生物多様性センターの事業であり、そのうち森林・草原調査では、樹木、地表徘徊性甲虫、鳥類を指標生物群として定め、2004年よりモニタリング調査を行っている。本稿では、コアサイト・準コアサイトで取られた樹木に関するデータ(毎木調査データ)が研究・教育・保全政策などに広く活用されるよう、その概要を紹介し、データの活用方法について提案する。
  • 柴田 英昭, 戸田 浩人, 福島 慶太郎, 谷尾 陽一, 高橋 輝昌, 吉田 俊也
    日本森林学会誌 = Journal of the Japanese Forest Society 91 6 408 - 420 日本森林学会 2009年12月01日 [査読無し][通常論文]
     
    日本の森林生態系における物質循環と森林施業の関わりについて, 既往研究をレビューした。これまで, 森林伐採が物質循環や水質形成に及ぼす影響については, 伐採後に樹木の養分吸収が低下することによって, 河川へ硝酸態窒素が溶脱することが示されてきた。一方, 北海道北部における伐採後の林床植生による窒素養分吸収や, 関東北部での火山灰土壌における硝酸吸着, 流域水文過程に伴う河川水質変化など, 日本における特色あるプロセスについて報告されている。また, 急傾斜地における森林施業の結果として斜面崩壊が生じることで, 流域生態系の水文・水質形成過程が影響されることも示唆された。さらに, 河畔緩衝域での窒素除去, 河川流路内での栄養塩スパイラル, 里山における森林管理と物質循環変化など, 生態系境界域での研究が重要であることが指摘されている。今後は, 地域ごとの特性を考慮に入るとともに, 施業影響下での物質循環モデルのパラメタリゼーションなどをさらに推し進めることが重要である。
  • Hisashi Miya, Toshiya Yoshida, Mahoko Noguchi, Futoshi Nakamura
    JOURNAL OF FOREST RESEARCH 14 5 302 - 310 2009年10月 [査読有り][通常論文]
     
    We analyzed temporal patterns in diameter growth of saplings following selection harvesting in an uneven-aged mixed stand dominated by Abies sachalinensis, Acer mono, Quercus crispula, and Betula ermanii in Hokkaido, northern Japan. We examined interspecific differences in growth responses to local growing conditions including harvesting intensity, crowding, stem size, and past duration of the small growth period. Consistent with expectations based on shade tolerance of the species, the age at which the individual reached a diameter at breast height (DBH) of 12.5 cm was highest for A. sachalinensis and lowest for B. ermanii. The interspecific growth differences between saplings that had or had not experienced local harvesting increased gradually for A. sachalinensis and B. ermanii, but peaked at around 4-6 years after harvesting for Q. crispula. Generalized linear mixed model analysis clearly suggested that individual growth conditions required to enhance diameter growth of saplings differed considerably among species. For Q. crispula and B. ermanii, local harvesting intensity was most strongly and positively associated with diameter growth rate, whereas for A. sachalinensis and A. mono, stem size had the strongest negative effect. Abies sachalinensis saplings responded more to surrounding harvesting when they were relatively small, whereas A. mono showed a weak opposite response. The duration of the small growth period before harvesting had negative effect for A. sachalinensis, but not for the other species. Our study indicated that the influence of selection harvesting on growth of shade-tolerant species depends upon pre- and post-harvest growing conditions.
  • Mahoko Noguchi, Toshiya Yoshida
    JOURNAL OF FOREST RESEARCH 14 5 311 - 320 2009年10月 [査読有り][通常論文]
     
    We investigated the individual-scale responses of five dominant species (Abies sachalinensis, Acer mono, Tilia japonica, Quercus crispula, and Betula ermanii) to single-tree selection harvesting in a conifer-broadleaved mixed forest in Hokkaido, northern Japan. Using data from stems with a diameter at breast height of a parts per thousand yen12.5 cm, collected during 20 years of monitoring a 6.7-ha stand, we analyzed the effects of harvesting in the neighborhood on tree recruitment and the growth (diameter class transition) and mortality of the residual trees. The effects of harvesting varied considerably among tree sizes and species. Harvesting improved the recruitment of A. mono and B. ermanii, and moderated the negative effect of the initial basal area of the surrounding canopy trees on the recruitment of Q. crispula. Conversely, harvesting limited the recruitment of A. sachalinensis by offsetting the positive effect of the initial basal area of the surrounding canopy trees. The growth of A. sachalinensis and Q. crispula decreased with the initial basal area of the surrounding canopy trees. Harvesting in the neighborhood resulted in an improvement in the growth of the trees of these species only in the smaller size classes. With increasing local harvesting intensity, the mortality of smaller A. sachalinensis trees decreased, whereas the mortality of larger trees increased. These results suggest that differences in the local harvesting intensity, spatial patterns of harvesting, and initial stand structures influence the stand-scale dynamics in response to partial harvesting in the mixed forests of this region.
  • M. Katsuyama, H. Shibata, T. Yoshioka, T. Yoshida, A. Ogawa, N. Ohte
    SUSTAINABILITY SCIENCE 4 2 179 - 188 2009年10月 [査読無し][通常論文]
     
    We simulated hydrological and biogeochemical responses to logging in a forested watershed to determine the vulnerability and/or resiliency of the forest ecosystems in the Lake Shumarinai Basin in northern Hokkaido, Japan. We used a biogeochemical model (PnET-CN) and a rainfall-runoff model (HYCYMODEL) to predict ecosystem responses. The PnET-CN model simulated well the observed NO3 (-) concentrations in streamwater, particularly at high concentrations during snowmelt; however, the model could not simulate small increases in NO3 (-) during the summer. By considering hydrological processes within the watershed and combining the model with the HYCYMODEL (PnET + HYCYMODEL), the seasonality of streamwater NO3 (-) concentrations was better simulated. Using these models, the long-term effects of logging were simulated for coniferous, deciduous, and mixed forests. NO3 (-) concentrations in streamwater increased in response to the logging disturbance in both coniferous and deciduous forests. In the coniferous forest, NO3 (-) concentrations reached a maximum 10 years after logging, and high concentrations persisted for 30 years. In contrast, NO3 (-) concentrations in the deciduous forest reached a maximum within 3-4 years and recovered to pre-disturbance levels after 15 years. We also used the models to determine the effects of different sizes and types (coniferous, deciduous, and mixed forest) of logging areas on Lake Shumarinai. The model results indicated that large areas of cutting require more than 100 years for complete lake recovery. Whereas the annual discharge to the lake minimally increased, the annual NO3 (-) load greatly increased. Our simulation results elucidate the vulnerability and resiliency of forest ecosystems and provide valuable information for ecosystem management.
  • Toshiya Yoshida, Mahoko Noguchi
    ECOLOGICAL RESEARCH 24 4 909 - 919 2009年07月 [査読有り][通常論文]
     
    This study examined historical census data to evaluate the vulnerability of major tall-tree species in northern Japan to strong winds. Intensive data, which measured more than 20,000 damaged trees (defined as trees that were killed or lost their major crown) in > 500 ha of a natural mixed forest, were collected immediately after a severe typhoon in 1954. More than half of the damaged trees had been uprooted, and the negative size-dependency was found for the proportion of uprooting throughout species. Simple correlation analyses with respect to the averaged species-specific characteristics suggested that tree species with a high crown-depth/height tended to uproot (against to stem breakage) in a size-class with diameter at breast height 30-50 cm. Although the census data had yielded no information about non-damaged trees, the estimation of pre-disturbed stand (based on 63 1-ha plot data together with aerial photographs and GIS) revealed that the observed damage reached ca. 25% in terms of basal area. The proportion of damaged trees seemed to be doubled among species (15-42% in basal area). A higher proportion of uprooting, which indicates a large supply of tip-up mounds, and mixture of less vulnerable species, might contribute to recovery process after a wind disturbance in this type of mixed forests.
  • Keiichi Aoyama, Toshiya Yoshida, Tomohiko Kamitani
    JOURNAL OF FOREST RESEARCH 14 1 58 - 62 2009年02月 [査読有り][通常論文]
     
    We examined an alternative natural regeneration practice with a scarification treatment, in which removed soil is replaced on the scarified area, in northern Japan. The effect of the soil replacement on tree establishment was quite obvious; the basal area of trees, composed mostly of Betula ermanii, in the soil-replaced site was about 150-fold greater than that of the normally treated site. The greater growth rates together with higher density, both of which seemed to be enhanced by improved (i.e., deeper, tender, and nutrient-rich) soil properties, produced the marked difference to the normally treated site. The expected enhancement of species diversity owing to utilizing buried seeds in the replaced soil was not found. The current study revealed that the soil replacement could substantially improve forest restoration management with emphasis on biomass production for large nonwooded sites.
  • 長谷川 幹夫, 相浦 英春, 高橋 由佳, 吉田 俊也
    日本森林学会誌 90 6 372 - 377 一般社団法人日本森林学会 2008年12月01日 [査読無し][通常論文]
     
    ミヤマカワラハンノキの治山植物としての可能性を探るため,成長と樹形を使用頻度の高いミヤマハンノキ・ヤマハンノキと比較しつつ検討した。豪雪地の山腹工施工地において,3種の植栽木の樹高・樹冠直径を9〜18年間,ミヤマカワラハンノキとミヤマハンノキの萌芽幹の樹幹長と根元直径を18年間にわたって調査した。ミヤマカワラハンノキは他種に比較して樹高成長より樹冠の拡張を優先する傾向が強く,植栽から3年後で樹高130cmに対し,樹冠直径は110cmに達した。ヤマハンノキが9年後までに雪圧害を受け衰退したのに対し,ミヤマカワラハンノキは被害が少なく施工地で優占していた。この違いは,ミヤマカワラハンノキが多くの萌芽幹をもち,雪圧害を受けにくい樹形を形成することによるものと考えられた。ミヤマハンノキは両種の中間的な樹形であった。以上のことから,ミヤマカワラハンノキは豪雪地での治山植物として有用であると判断した。
  • 原田 茜, 吉田 俊也, Resco de Dios Victor, 野口 麻穂子, 河原 輝彦
    日本森林学会誌 90 6 397 - 403 一般社団法人日本森林学会 2008年12月01日 [査読無し][通常論文]
     
    北海道北部の森林では,ササ地を森林化させるために掻き起こし施業が広く行われてきた。施業から6〜8年が経過した樹冠下の掻き起こし地を対象に,9種の高木性樹種を対象として樹高成長量と生存率を調べ,それらに影響する要因(植生間の競争・促進効果)を明らかにした。成長量と生存率が高かったのはキハダとナナカマド,ともに低かったのはアカエゾマツであった。多くの樹種の成長は,周囲の広葉樹または稚樹以外の下層植生の量から促進効果を受けていた。ただし,シラカンバについては,施業後3〜5年目の時点では促進効果が認められていたものの,今回の結果では競争効果に転じていた。一方,生存率については,多くの樹種について周囲の針葉樹による負の影響のみが認められた。密度または生存率の低かった多くの樹種に対して,周囲のシラカンバやササの回復が負の要因として働いていないことから,多様な樹種の定着を図るうえで,除伐や下刈りの実行は,少なくともこの段階では有効ではないと考えられた。
  • Mahoko Noguchi, Toshiya Yoshida
    CANADIAN JOURNAL OF FOREST RESEARCH 37 9 1554 - 1562 2007年09月 [査読有り][通常論文]
     
    The objective of this study was to assess the effects of fine-scale canopy disturbances induced by selection harvesting and its associated practices (artificial planting and machinery skidding) on the successful regeneration of tree species in a northern Japanese mixed forest. We set up 163 plots in a 6.7 ha permanent study stand where trees have been partially harvested at approximately 10-year intervals since 1974. The regeneration of trees (4324 stems center dot ha(-1)) occurred more frequently under closed canopies than under canopy gaps, except for a typical shade-intolerant species, Betula ermanii Cham. In particular, small canopy openings that tend to close quickly displayed higher understory tree regeneration densities likely due to the suppression of competition from dwarf bamboos. The surface soil disturbances that occurred during planting and harvesting even further enhanced understory regeneration. The results shown here should be generalized carefully because we have investigated only one stand. Nevertheless, our findings clearly indicated that the creation of small canopy gaps associated with site preparation that contains soil disturbances should be examined in management practices to maintain the community structure in this type of mixed forest.
  • 長谷川 幹夫, 平 英彰, 吉田 俊也
    日本森林学会誌 89 1 14 - 20 一般社団法人日本森林学会 2007年02月01日 [査読無し][通常論文]
     
    積雪寒冷地のスギ不成績造林地の修復を目的に当地の極相種であるブナを植栽した林分において,下刈り期間を変えた試験区(10年間継続した部分を下刈り区,3年間で中止した部分を放置区とする)を設定し,処理の違いが植栽木と侵入した広葉樹の消長に与える影響を検討した。ブナは放置区では侵入木等によって庇陰されていたが,その死亡率は下刈り区より低かった。植栽後8年を経たブナの胸高直径,樹冠直径は下刈り区で大きく,樹高は放置区で大きかった。ブナの雪圧による被害率は下刈り区で高かった。侵入木についてみると下刈り区では萌芽力の小さいウダイカンバ,ダケカンバは試験期間中に消失したが,萌芽力の大きいウワミズザクラは下層で生存していた。放置区では植栽木に侵入木などが加わって林冠が閉鎖し,階層構造を形成していた。このような修復施業では,下刈り期間を短縮することで,植栽木と侵入広葉樹が混交する周辺の自然植生に近い森林を育成できると考えられた。
  • 小林 真, ネミロスティフ ユーリ パブロビッチ, 鷹西 俊和, 小塚 力, 上浦 達也, 小宮 圭司, 梶本 卓也, 松浦 陽次郎, 吉田 俊哉, 佐藤 冬樹, 笹 賀一郎, 小池 孝良
    日本森林学会大会発表データベース 118 326 - 326 日本森林学会 2007年
  • Toshiya Yoshida, Mahoko Noguchi, Yukio Akibayashi, Masato Noda, Masahiko Kadomatsu, Kaichiro Sasa
    CANADIAN JOURNAL OF FOREST RESEARCH 36 6 1363 - 1375 2006年06月 [査読有り][通常論文]
     
    Single-tree selection has been employed widely in northern Japanese mixed forests, but management-induced changes in forests are not well understood. This study examined demographic parameters of major tree species during a 20-year study of a 68 ha stand in which single-tree selection has been conducted since 1971. Results showed that growth and survival of conifers (mostly Abies sachalinensis (Fr. Schm.) Masters) was the most strongly positively affected by the treatment. Nevertheless, recruitment of conifers was not sufficiently improved, suggesting their decreased dominance over the longer term. Instead, shade-intolerant broad-leaved species (mainly Betula ermanii Cham.) will gradually increase because of their higher recruitment rates after the treatment. Shade-tolerant broad-leaved species (mainly Acer mono Maxim. and Tilia japonica (Miq.) Simonkai) appeared to experience the most distinct negative effects, especially on survival. These trends differed markedly from those reported in previous papers concerning partial harvesting systems, which predicted an increase in dominance of shade-tolerant species. The results shown here should be generalized carefully because we have investigated only one stand without repetition of the control area. Nevertheless, trends described in this large-scale, long-term study could provide a basis for simulating stand dynamics. We discussed possible reasons for the observed patterns and provided implications for sustainable management in the region.
  • M Nagai, T Yoshida
    JOURNAL OF FOREST RESEARCH 11 1 1 - 10 2006年02月 [査読無し][通常論文]
     
    We investigated effects of silvicultural treatments (planting and subsequent treatments) on understory structure and plant species diversity in managed Picea glehnii plantations (21-26 years old) in northern Japan. We evaluated the importance of each treatment (machinery site preparation, planting, weeding, and thinning) in 19 plantations, with considerable variation among treatments overall. The understory had 98 vascular plant species; the most dominant species was a dwarf bamboo Sasa senanensis, followed by tree species Abies sachalinensis and Betula ermanii. Multiple regression analyses showed that thinning negatively influenced plant species diversity. Planting density showed a strong positive correlation with density of seedlings (height <20 cm), but few independent variables were correlated with density of saplings (height >= 20 cm and diameter at breast height <1 cm). The negative effect of thinning and the positive effect of planting density seem to be related to the existence or reinitiation of dense cover of Sasa senanensis. We present possible mechanisms of response to treatments to generalize the results. We then suggest ways to improve current treatments to meet the goals of wood production and biodiversity conservation in the region.
  • T Yoshida, M Hasegawa, H Taira, M Noguchi
    JOURNAL OF FOREST RESEARCH 10 5 351 - 358 2005年10月 [査読無し][通常論文]
     
    Tree retention is understood as a key practice in creating complexity, leading to heterogeneity in resources and habitats in managed stands. In this article, we clarify the long-term effects of tr e retention on stand structure and tree-species composition in a 60-year-old Larix kaempferi plantation in central Japan. In our study plot (1.5ba) there were 18 stems/ha of retained trees (determined by tree-ring analysis), mostly Quercus crispula. We conducted spatial analyses and tested the hypothesis that tree abundance, size structure, and species composition and diversity change with distance from the retained trees. Near the retained trees, L. kaempferi showed a reduction of 40%-60% in basal area, due presumably to the shading effect. In contrast, the nearby area showed greater species diversity in the canopy layer. The retained trees created patches of different species composition in the understory. The spatial gradient of shade and colonization opportunity provided by retained trees greatly affect the distribution of the colonized species, according to their shade tolerance and seed-dispersal ability, which resulted in the stand structure with a heterogeneous shrub-layer vegetation. Retention proved particularly important for the enhancement and long-term maintenance of structural and compositional complexity in L. kaempferi plantations.
  • VR de Dios, T Yoshida, Y Iga
    FOREST ECOLOGY AND MANAGEMENT 215 1-3 138 - 148 2005年08月 [査読有り][通常論文]
     
    Dwarf bamboo creates a dense carpet that prevents forest regeneration in mixed forests of Japan. Soil-scarification has been used widely to regenerate such forests. However, no study has specifically addressed the effects of soil-scarification on regeneration dynamics following such perturbation. This study analyzed the demography and community structure of the most abundant species 6 years after soil-scarification in a mixed forest stand of Northern Japan. We used canonical correspondence analysis (CCA) to analyze environmental factors effects on species distribution. Using multiple regression analysis, we determined the net balance of competition and facilitation. Abies sachalinensis and Picea glehnii are the most abundant species; Betula sp. and Salix bakko are the largest ones. Increasing distance to the edge of the scarified area is generally concomitant with decreasing seedling density, but changes in extension growth show idiosyncratic responses. These results, together with those of CCA, suggest that light is the main factor directly affecting (with high levels of irradiance) and indirectly affecting (by changing volumetric soil water content) seedling demography and structure. Multiple regression analyses show that facilitation is the most important interaction affecting seedling growth, probably by reducing excess levels of irradiance. (c) 2005 Elsevier B.V. All rights reserved.
  • 秋林幸男, 高木健太郎, 野村睦, 北条元, 菅田定雄, 柴田英昭, 福沢加里部, 吉田俊也, 小池孝良, 笹賀一郎, 藤沼康実, 前林衛
    北方林業 57 8 176 - 179 2005年08月01日 [査読無し][通常論文]
  • 吉田慎一, 吉田俊也, 富岡輝男, 早柏慎太郎, 秦寛
    日本草地学会誌 51 16 - 17 2005年03月26日 [査読無し][通常論文]
  • M Noguchi, T Yoshida
    ECOLOGICAL RESEARCH 20 1 25 - 30 2005年01月 [査読無し][通常論文]
     
    We have investigated the factors influencing the distribution of co-occurring two dwarf bamboo species, Sasa kurilensis (Ruprecht) Makino et Shibata and S. senanensis (Franchet et Savatier) Rehder, within a conifer-broadleaved mixed stand managed with selection cutting in northern Japan. We first sought the possible determinant factors (physical environment and overstory conditions based on 30 years' tree census data) deciding the dominant species in the plots (1683.14 m(2) area). We then examined the effects of these factors on the culm density and height of the dominant species. Linear discriminant analysis indicated that physical environmental conditions are important in determining the distribution; S. kurilensis tended to dominate plots with steep slope, convex shape and deep snow in early spring. Multiple regression analyses showed that culm density and height decreased significantly on steep slopes for both species. Also, the sum of the basal area (BA) of surrounding conifers (7.5 m radius around the plot), as well as the change in BA over the previous 30 years, had a negative influence on the culm height of both species. A reduction in overstory trees, caused by natural or artificial canopy disturbances, would increase the dwarf bamboo biomass. The effects of physical environment and overstory conditions, working through the dominance of the two dwarf bamboo species, should be taken into account in understanding the dynamics of natural forests in this region.
  • T Yoshida, Y Iga, M Ozawa, M Noguchi, H Shibata
    CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE 35 1 175 - 188 2005年01月 [査読無し][通常論文]
     
    Scarification is widely conducted in northern Japan to remove understory dwarf bamboo species in degraded forests for replacement with tree species. To explore ways to enhance species diversity and restoration of mixed forest at the treated site, we clarified the mechanisms that lead to compositional heterogeneity of plant species. We evaluated the relative importance of environmental factors (scarification properties, soil properties, light conditions, litter cover, and presence of canopy trees) for the demography of tall tree species (emergence, mortality, and growth) and whole vegetation structure (species diversity and composition) over the two growing seasons immediately following scarification. Of tall tree species, Betula spp. were dominant (60% in total density), followed by Abies sachalinensis (Fr. Schm.) Masters, Acer mono Maxim., and Phellodendron amurense Rupr. Light intensity was an important factor, having mostly negative effects on the demography of these species. Soil factors (e.g., nitrogen content, moisture) affected the demography mainly of shade-intolerant or hygrophilous species. In general, extreme environmental conditions led to the dominance of grasses, forbs, and lianas rather than tall trees. Maintenance of canopy cover, which limits light and supplies seeds as well as litter, proved to be most important in promoting plant species diversification on the scarification site.
  • 吉田 俊也, 野口 麻穂子
    北方林業 56 7 162 - 165 北方林業会 2004年07月 [査読無し][通常論文]
  • 吉田俊也, 野口麻穂子
    北方林業 56 7 162 - 165 2004年07月01日 [査読無し][通常論文]
  • M Noguchi, T Yoshida
    FOREST ECOLOGY AND MANAGEMENT 190 2-3 335 - 344 2004年03月 [査読無し][通常論文]
     
    We assessed the relationship of the regeneration (seedling and sapling) densities of seven representative tall-tree species to the past partial cutting and current stand structure. We also determined if differences in tree regeneration were associated to establishment substrates (coarse woody debris (CWD) and root throws) and understory inhibitor vegetation (the dwarf bamboo species: Sasa senanensis). The study was conducted in 17 conifer-hardwood mixed stands in a heavy snowfall region in Hokkaido, northern Japan. The results suggest that stand structure, rather than logging intensity, is the primary factor influencing regeneration densities. Total conifer basal area was positively correlated with the regeneration density of individual tree species, including two conifers and three hardwoods. These patterns differ from those observed in old-growth stands in the region. A negative correlation between total conifer basal area and dwarf bamboo coverage suggests that the presence of dense conifer canopies causes an increase in regeneration density of tall-tree species by preventing domination of dwarf bamboo. Picea glehnii, a species that depends for its establishment strongly on CWD, has lower seedling and sapling density in stands with higher logging intensity. This seems to be a result of the decrease in the volume of CWD with increasing logging intensity in these stands. We suggest that both reducing logging intensity and retaining overstory conifers should be considered to develop a sustainable silvicultural system in this region. Providing sufficient CWD and root throws may also be important to ensure natural regeneration of tree species that require these as an establishment substrate. (C) 2003 Elsevier B.V. All rights reserved.
  • 秦 寛, 富岡 輝男, 尾島 徳介, 吉田 俊也, 植村 滋, 竹田 哲二
    日本草地学会誌 49 0 208 - 209 日本草地学会 2003年03月24日 [査読無し][通常論文]
  • 秦寛, 富岡輝男, 尾島徳介, 吉田俊也, 植村滋, 竹田哲二
    Grassl Sci 49 208 - 209 日本草地学会 2003年03月24日 [査読無し][通常論文]
  • H Kurokawa, T Yoshida, T Nakamura, JH Lai, T Nakashizuka
    JOURNAL OF TROPICAL ECOLOGY 19 1 - 7 2003年01月 [査読無し][通常論文]
     
    Using C-14 dating, the life span and growth rate of Borneo ironwood (Eusideroxylon zwageri, Lauraceae), which is a canopy tree species with extremely durable and decay-resistant wood distributed in tropical rain forests of South-East Asia, were studied. Timber segments collected from 15 logged stumps in Kubah National Park, Sarawak, Malaysia, were analysed by accelerator mass spectrometry and the obtained data were calibrated to determine the age of individuals. The C-14 dating turned out to be an effective method for estimating ages of long-lived trees, such as E. zwageri, in the aseasonal tropics because the estimated error was small compared with estimated age. We found that E. zwageri can live more than 1000 y and that the growth rate of this species was very slow, with a mean radial growth rate of 0.058 cm y(-1). The life span was much greater and the growth rate was much slower than those observed or estimated for trees of Dipterocarpaccae, the dominant family in this tropical forest. The long life span of this species may be caused by wood durability with a high specific gravity and abundant defensive compounds; Given equal carbon allocation, the high density and carbon-based defensive compounds may result in a reduced growth rate.
  • 鷹西 俊和, 吉田 俊也, 竹田 哲二
    北方林業 54 5 97 - 99 北方林業会 2002年05月01日 [査読無し][通常論文]
  • Stem growth and interspecific competition in a broadleaved secondary forest, central Japan.
    Eurasian Journal of Forest Research 4 51 - 84 2002年 [査読無し][通常論文]
  • T Yoshida, T Kamitani
    FOREST ECOLOGY AND MANAGEMENT 137 1-3 221 - 230 2000年10月 [査読無し][通常論文]
     
    We investigated causes and consequences of interspecific competition among canopy-tree species with different shade-tolerance. The shading effects caused by neighbors were determined fur three tree species, shade-tolerant Fagus crenata, and intermediate tolerant Quercus crispula and Magnolia obovata, in six even-aged stands containing different proportions of each species. The competitive attributes (sensitivity to suppression and intensity of shading) varied considerably among species. Shade-tolerant F. crenata caused most intensive shading effects probably because of its deeper crown depth. Less-tolerant Q. crispula decreased its stem growth and crown depth markedly in association with the presence of shade-tolerant F. crenata. In contrast, F. crenata and M. obovata were less influenced by their neighbors; it may be due to its own higher shade-tolerance in the case of F. crenata and larger initial growth rates in ill. obovata. We suppose that differences in initial species composition may lead a species to have different dominance in stand development. When shade-tolerant species are absent in mixture, less shade-tolerant species could maintain their dominance for a long period. In contrast, mixture with tolerant species would reduce the dominance of less-tolerant species, unless they had growth advantage in early stage in development. (C) 2000 Elsevier Science B.V. All rights reserved.
  • Yanagisawa Yukiko, Yoshida Toshiya, Kamitani Tomohiko
    Journal of forest research 4 1 53 - 56 一般社団法人日本森林学会 1999年02月16日 [査読無し][通常論文]
     
    A new method for predicting understory light levels around an artificial canopy gap prior to the selective cutting is presented. In two even-aged coppice stands, hemispherical photographs were taken at a height of 1.3 m, and crowns of each canopy stem on the photographs were identified by field observations. To predict light levels after cutting, we used computerized images of the hemispherical photographs, in which we digitally erased all crowns to be cut (named 'erasing method'). Light levels were calculated by an analyzing program; HEMIPHOT. Light levels predicted by the 'erasing method'...
  • T Yoshida, T Kamitani
    FOREST ECOLOGY AND MANAGEMENT 113 1 57 - 65 1999年01月 [査読有り][通常論文]
     
    A generally accepted trend in secondary succession - the decline in dominance of shade-intolerant species was examined. We dealt with a shade-intolerant species, Phellodendron amurense Rupr. in a 38 ha mixed-species coppice forest. There were 45 stems of P. amurense with dbh (diameter at breast height) greater than or equal to 10 cm in the forest. P. amurense had smaller means of stem sizes (dbh, height, and crown ratio) and basal area increments than those of their neighbors. Analysis on choosing cores indicated that most of P. amurense had already been under a suppressed condition at 20 years after their establishment, and obviously showed decline in growth during the following stages. Although they could grow faster without any suppression, their sensitivity to shading effects was greater than other more tolerant species. It seemed that suppression by species with deep crowns was particularly prominent. Such extreme responses to suppression seemed to cause decrease in growth rate after the onset of suppression in the actual forest. We conclude that two factors: the relative growth rates in the initial stage, and the species composition in the following stage are considered to be definitive in the declining process of P. amurense. (C) 1999 Elsevier Science B.V. All rights reserved.
  • T Yoshida, Y Yanagisawa, T Kamitani
    FOREST ECOLOGY AND MANAGEMENT 109 1-3 85 - 89 1998年09月 [査読有り][通常論文]
     
    An empirical model for predicting light levels under a canopy gap in an even-aged oak stand is presented. The effects of gap size, distance from the gap, and directional position (noah-south) within the gap on gap light index (GLI) [sensu Canham, C.D. 1988. An index for understory light levels in and around canopy gaps. Ecology 69, 1634-1638] are quantified by multiple regression analysis. Data were obtained by the 'erasing method' (Yanagisawa et al., in preparation') which predicts the GLI from computerized images of hemispherical photographs. Forty-five 'virtual canopy gaps' were assumed, and at 945 points, light levels were calculated using HEMIPHOT [ter Steege, H. 1993. HEMIPHOT, A Programme to Analyze Vegetation Indices, Light and Light Quality from Hemispherical Photographs. The Tropenbos Foundation, Wageningen, The Netherlands]. The model presented in this study has the advantage that the indices needed for the prediction can be measured easily in field survey. The applicability of the model is discussed. (C) 1998 Elsevier Science B.V.
  • Yoshida Toshiya, Kamitani Tomohiko
    Journal of forest research 3 3 181 - 184 一般社団法人日本森林学会 1998年08月16日 [査読無し][通常論文]
     
    We compare three or four years effects of crown release on stem growth rates among four deciduous broad-leaved tree species, Fagus crenata, Quercus crispula, Magnolia obovata and Acer mono, in an e\"en-aged coppice forest, central Japan. The crown release significantly improved relative growth rates for basal-area (RGR<BA>) of the four species. However the effects of neighboring gap area (GAPA) on the RGR<BA> differed among the species. The effects were slgnificant for Q. crispula and M. obovata, indicating that growth rates of these two species increase with intensity of the crown release....
  • T Yoshida, T Kamitani
    FOREST ECOLOGY AND MANAGEMENT 95 1 35 - 43 1997年07月 [査読有り][通常論文]
     
    We investigated stand dynamics of a mixed coppice Forest of shade-tolerant and intermediate species, Fagus crenata Bl. and Quercus crispula Bl., in five stands with canopy-stem densities from 420 to 1320 ha(-1) (estimated stand age: 37-62 years). The mean basal area (BA), exposed-crown area (ECA) and crown depth (CD) per stem were significantly larger in F. crenata in the three lower density plots. Also Q. crispula had considerably less overtopped stems in the two lower density plots. The mean annual BA increments of the two species were similar in the earlier 20 years; however, in the most recent 5 years, F. crenata had a higher relative growth rate for basal area (RGR(BA)) than Q. crispula. The most critical variable of the RGR(BA) was the ECA for F. crenata and the relative height (RH) for Q. crispula. We predict that dominance of F. crenata will gradually increase over that of Q. crispula as stands mature. This seems to be caused by lower shade-tolerance despite the similar initial growth rates of Q. crispula compared with F. crenata. (C) 1997 Elsevier Science B.V.
  • 紙谷 智彦, 吉田 俊也
    日本林學會誌 73 2 154 - 157 一般社団法人日本森林学会 1991年03月01日 [査読無し][通常論文]

書籍

  • 森への働きかけ-森林美学の新体系構築に向けて
    海青社 2010年
  • Management for forests
    Kaiseisha 2010年
  • 北の森づくりQ&A
    北方林業会 2009年
  • 北海道北部の地域社会-分析と提言
    筑波書房 2008年
  • 吉田 俊也 
    [北海道大学北方生物圏フィールド科学センター] 2008年
  • 森林の科学-森林生態系科学入門-
    朝倉書店 2005年
  • Restoration of Boreal and Temperate Forests.
    CRC Press 2005年

講演・口頭発表等

その他活動・業績

受賞

  • 2008年 日本森林学会奨励賞

共同研究・競争的資金等の研究課題

  • 天然林施業を組み入れた地域の森林管理オプションの提示 研究課題
    文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2014年04月 -2017年03月 
    代表者 : 吉田 俊也
     
    木材の利用と生態系の保全とのバランスを考慮した天然林の管理について、北海道北部をモデル地域として考察した。択伐施業試験地における長期データから得られた主要樹種の個体群動態パラメータ、および樹種による伐採に対する反応の違い、天然更新補助作業等の効果を反映させた森林動態シミュレーションを実施した。森林の蓄積や、生物多様性の維持に寄与する構造を長期にわたって維持する森林施業の要件を、経済的な持続可能性も考慮して提示した。
  • 北方林における攪乱後の主要樹種の成長と死亡:長期ストレスとしての個体間競争の影響
    文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2014年04月 -2017年03月 
    代表者 : 大野 泰之
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2010年 -2012年 
    代表者 : 久保田 康裕, 吉田 俊也, 榎木 勉
     
    北方域の気候変動や森林施業による人為インパクトは、将来的な北方林の資源動態に大きな影響を及ぼしつつある。本研究では、北方域の針葉樹林帯における山火事撹乱の強度・頻度の変化が、木材資源動態に及ぼす影響を、実データに基づいた空間点過程モデルと個体ベースの森林動態シミュレータで分析しようとしている。本研究は、従来の地域限定型の資源保全研究とは一線を画し、環北方域の森林動態に共通した生態プロセスを解明する。今年度は研究初年であるため、フィンランドの共同研究者を相手国のマッチングファンドで招聘し、研究計画全体について会議を行い、調査計画と論文執筆計画を策定した。この会議では、山火事撹乱が変化した場合、北方林が低密度林やヒースに劣化するメカニズムを明らかにし、環境変動に適応し汎用性のある持続的森林施業のオプションを提示することを確認した。北方林の山火事撹乱は、その頻度と燃焼強度に負の相関がある。燃焼強度の高い山火事が稀に発生する場合、高密度の針葉樹林が更新し、次の山火事までに複数世代の樹木が共存する異齢林が発達する。山火事の頻度が高く燃焼強度も弱くなるに伴い、針葉樹の更新密度は低下し、同齢の低密度林からヒースへと衰退する。フィンランド北部の森林構造の空間変異や更新様式の差異は、このような山火事撹乱の頻度と強度の変異に対応していると考えられる。以上のプロセスを分析するため、本年度は、山火事...
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2010年 -2012年 
    代表者 : 長池 卓男, 吉田 俊也
     
    社会的背景を考慮した新たな人工林施業を考えるために、複数の樹種を植栽した混交植栽人工林において、(1)炭素固定機能を地上部の蓄積量・成長量および成長経過から明らかにし、(2)立木の個体間距離や立木密度から、混交植栽人工林における林分構造・林内光環境・土壌養分が相互作用的に及ぼす炭素固定機能(生産性)への影響を定量化し、単一植栽人工林と比較する。このことによって、混交植栽人工林において生産性を損なわないための間伐指針を明らかにする。山梨県有林内のすべての混交植栽人工林のリストアップを行った。樹下植栽による複層林や混植された広葉樹造林地を含めて、6142小班が混交植栽人工林であった。森林簿から、単一植栽人工林と混交植栽人工林での材積の比較を行った。山梨県鳴沢村内の列状伐採された41年生のカラマツ-シラベ人工林において、100×80mの調査区を設定した。胸高直径3cm以上の立木を対象として毎木調査を行った。調査区あたりの立木密度はカラマツ260本、シラベ285本で、全体の47%、51%をそれぞれ占めていた。しかしながら胸高面積合計でみるとカラマツ33%、シラベ65%と、シラベの割合が増大していた。平均胸高直径でみても、カラマツ19.7cmに対しシラベ26.4cmと、シラベの方が優勢な成長をしていた。樹高・樹冠体積においてもシラベの方が優勢で、常緑樹であるシラベが落葉樹であるカラマツ...
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2011年 -2011年 
    代表者 : 吉田 俊也
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2009年 -2011年 
    代表者 : 笹 賀一郎, 佐藤 冬樹, 柴田 英昭, 吉田 俊也, 野村 睦, 高木 健太郎
     
    本研究は、北海道大学北方生物圏フィールド科学センターの雨竜研究林と天塩研究林の操作実験流域を主な対象として、原生林状態から森林伐採・表土除去・樹木の植栽などの炭素や窒素などの物質循環への影響を地下部・根茎の状況もふくめて明らかにしようとするものである。平成21年度の主な成果は、以下のようである。1.天塩研究林の実験流域において、原生林伐採後に植栽したカラマツのバイオマスについて、根茎もふくめた測定をおこなった。また、前年度におこなった15m×15m林分の地下部調査については、根茎等の分析用サンプルの乾燥をすすめるとともに、樹種ごとの根茎量等についてのデータをとりまとめた。2.雨竜研究林・天塩研究林の実験流域においては、炭素・窒素の動態変化に加えて、水分や炭素・窒素以外の物質、および土砂・浮遊砂等に関する観測を継続した。とくに、下流域に対する溶存鉄の供給については、北方針広混交林は供給が少ないという特徴をもちながらも、森林は持続的な溶存鉄生成と供給の役割を果たしていることを明らかにした。さらに、冬季間の観測から、積雪期においても窒素の無機化や硝化は進行し、降雪前にはアンモニアの生成が進行し、融雪期には硝酸の生成か進行すること、積雪量の減少によって融雪期のアンモニア正味生成量の増加と硝酸の正味生成量が減少することなどを明らかにした。3.原生林伐採とカラマツ植栽によるCO2フラック...
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2006年 -2007年 
    代表者 : 久保田 康裕, 榎木 勉, 吉田 俊也
     
    本研究において、我々は以下の仮説を設定し、そのメカニズムを統計モデルによって検証しようとしている。"北方林では、近年の環境変動に対応した撹乱体制(強度・頻度)の変化が土壌特性を変質させ、森林の更新・遷移過程に作用し、従来の潜在的極相林とは異なる代替的定常状態を創出し、森林の生産量衰退を引き起こす。"この仮説における重要な生態現象は"paludification"と呼ばれる土壌表層における滞水および未分解リターの蓄積である。"paludification"は土壌の理化学特性を変化させ、従来の植生遷移とは異なる代替的な定常状態を創出すると予想される。上記仮説を検証するため、テラノバ国立公園において森林構造と土壌条件の2傾度のサンプリングデザインを設定した。この地域の北方林は、自然撹乱の強度・頻度に応じて、同齢針葉樹林、パッチ状針葉樹林、針葉樹散在のヒースヘ至る衰退過程をたどると考えれられる。この過程を時系列化するために、これら3タイプの林分の森林構造と土壌特性の調査を行なった。その結果、山火事の強度に応じて土壌表層の有機物量が異なり、そのことが針葉樹の更新様式に影響を及ぼすことが明らかとなった。
  • 文部科学省:科学研究費補助金(基盤研究(C))
    研究期間 : 2005年 -2007年 
    代表者 : 吉田 俊也, 久保田 康裕, 長池 卓男, 野口 麻穂子
     
    北海道内に点在するモニタリングサイトを活用して、既存の長期観測データと野外調査の結果を組み合わせ、北方林生態系、とりわけ樹木群集の動態に及ぼす森林伐採の影響を明らかにした。まず、北海道の北部における研究では、概して伐採の影響がネガティブであり(Yoshida et al. 2006)、とりわけ若木の新規加入の制限が大きな問題であることがわかった(Noguchi and Yoshida 2007)。このような傾向を詳細に把握するために、樹種間の比較や、特定の樹種に焦点をあてた解析)を進めた。また、土壌の攪乱も稚幼樹の定着にとって重要であり、そのような攪乱を施業の中に位置づける方策について検討した(Nagai and Yoshida 2006)。一方、北海道東部地域の択伐林においては、伐採後の回復が全体的に顕著であり、北部の結果とは対照的であった。また、北海道中央部の高標高域に分布する針葉樹林において、周辺の原生林(Kubota et al. 2006)と比較して、択伐跡地の林分構造は大きく異なっているが、樹種によって反応に差があることが示された。このように、同様の伐採方法であってもその影響の顕在化が地域によって全く異なることが示された。これらのデータをもとにした資源管理を可能にするために、シミュレーションモデル化の検討を進めた。実用に資するモデルの構築にむけてはなお検討が必要で...
  • 文部科学省:科学研究費補助金(基盤研究(A))
    研究期間 : 2005年 -2007年 
    代表者 : 佐藤 冬樹, 笹 賀一郎, 小池 孝良, 柴田 英昭, 吉田 俊也, 高木 健太郎
     
    極東アジアの永久凍土南限域(中国・東北地方およびロシア・アムール州)を対象に長期モニタリングのための流域試験地を設定し、この地域の優先樹種であるカラマツ林をはじめとする森林のバイオマス量の把握および成長・推移過程の解析、水分や炭素および物質の動態把握をおこなった。設定したカラマツ林の固定調査地は、a)ハルビン近郊の東北林業大学老山演習林(季節的凍土地帯)、b)大興安嶺の中心部・加格達寄周辺、c)中国最北部、ロシア国境付近の漠河周辺、d)ロシア・アムール州北部のブラガベシェンスク周辺(不連続的永久凍土地帯でc・dは繰り返し山火事被害を受けている)地域である。加えて、連続的永久凍土地帯最南限のアムール州北部山岳地帯のカラマツ林についても毎木調査をおこなった。調査の結果、永久凍土南限地域においてカラマツ林の分布は永久凍土層の存在と密接に関連し、しかもその永久凍土層は森林や湿原の存在によりかろうじて保存されていることがわかった。したがって、地球温暖化あるいは大規模な山火事により森林被覆がなくなると、永久凍土は容易に崩壊して森林はより温暖域のものに遷移し、凍土上にあるいは凍土内に蓄積された有機態炭素は温暖気下で容易にCO2に分解され、メタンとともに大気中に放出されるシナリオが考えられた。また、大興安嶺地域では炭素の蓄積はおもに永久凍土のある湿原部に偏在していると推定され、この地域におけ...
  • 文部科学省:科学研究費補助金(若手研究(B))
    研究期間 : 2002年 -2004年 
    代表者 : 吉田 俊也
     
    A.北海道大学雨龍研究林内に設定した人口裸地プロット(造成後4年目,重機による「掻き起し」施業地)における調査を継続して行った。2年目までの光・土壌・生物環境の変化と,出現する植生との関係はすでに明らかになっている(Yoshida et al.2005)。今年度は,植生の発達に伴って発言すると考えられる植物種内・種間の競争関係を解析に加えるため,1.96ha(140×140m)の調査プロットに設置された60ヶ所の調査区において,植生センサス(2回/年:高木性樹種の雅樹は固体識別),土壌資料の採取および窒素濃度の測定を行なった。B.「掻き起し」施業後の8年が経過したプロットにおいて,施業後に発生した高木性樹種の雅樹の動態を明らかにした。この段階では,雅樹間の競争関係は少なく,高い周辺密度はむしろ成長を促進していることがわかった。また,他の下層植生・周辺の上層木の存在も,生長にポジティブな効果を与えていた。一方,同じ施行年で,掻き起し施業1年後に,取り除いた表土を再び施業地に戻したプロットでも調査を行った。表土を戻した箇所では,通常の施工地に比べて数十倍以上の生長が見られた。また雅樹の発生も多いことから,このような施工方法は,森林の回復速度を高め,また森林の階層構造のすばやい発達にも寄与することが示唆された。C.この地域の森林の林床優占種であるササ類と,他の林床植生との関係を調査...
  • 文部科学省:科学研究費補助金(基盤研究(B))
    研究期間 : 2001年 -2003年 
    代表者 : 柴田 英昭, 植村 滋, 吉岡 崇仁, 大手 信人, 高木 健太郎, 吉田 俊也
     
    陸上生態系における植生や土地利用の違いが陸域から湖沼にかけての溶存成分動態に及ぼす影響を調べるために、北海道北部に位置する朱鞠内湖集水域において、異なる特性を持つ実験流域における植生環境や水質環境に関する研究を行った。自然生態系における植生の分布は、地形の違いに原因する土壌水分環境と密接な関係にあり、河川中流から河畔にかけて存在する湿地林は土壌から河川にかけての水質形成に重要な役割を果たしていることが明らかとなった。湿地を通過した地下水や河川水には有機物の分解過程で生じる溶存有機炭素や溶存有機窒素が豊富に含まれるのに対し、無機態窒素である硝酸態イオンは湿地における微生物や植生の働きで除去される傾向にあった。また、酪農を主体とする農地流域では施肥や家畜糞尿に由来する窒素やリンが多量に河川へと流出し、森林や湿原といった自然生態系流域からの負荷よりも明らかに多量な栄養塩類が湖へと流入している実態が明らかとなった。湖内では降水や融雪といった流入河川の水文化学的プロセスと湖内での生物地球化学的プロセスの影響によって溶存成分濃度に特有の鉛直プロファイルが認められた。既往の植生分布データやGIS解析および現地水文水質観測を組み合わせることによって実現した本研究の成果は、さまざまな生態系を含有する広域複合集水域系における溶存成分動態を明らかにするためのモデル研究として位置づけることができ、今...
  • 生態系の保全を考慮した森林の施業方法に関する研究
    研究期間 : 1999年
  • Forestry management with considering ecosystem sustainability in Japan
    研究期間 : 1999年

教育活動情報

主要な担当授業

  • 生物生産学基礎論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 生物生産、植物栽培、畜産業、林業、養殖、餌、生態系、持続的生産、バイオテクノロジー、フィールド管理 animal products, aquaculture, biotechnology, crop production, ecosystem, field management, fish-seed, forestry, livestock, stockbreeding, sustainable production
  • 森林圏科学特論Ⅳ
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 地域資源、地域資源管理、森林管理、森林資源の多様な利用、リモートセンシング regional resources, regional resource management, forest management, diverse use of forest resources, remote-sensing
  • フィールド科学基礎論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 生物資源創成、共生生態系保全、持続的生物生産、生物多様性、生態系機能、生物群集生態 Bio-resources development, Ecosystem conservation, Sustainable bio-production, Biodiversity, Ecosystem function, Population and community ecology
  • 森林動態実習
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 農学部
    キーワード : 森林動態、攪乱、樹木、更新、森林再生
  • 森林空間機能学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 農学部
    キーワード : 森林、環境保全機能、生物多様性保全、野生生物保全、土地利用、流域保全、森林利用
  • 森林空間機能学演習
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 農学部
    キーワード : 森林の種類と分布、森林空間、環境保全機能、森林保全、資料作成方法、発表方法、ディスカッション
  • 森林保全実習
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 農学部
    キーワード : 流域保全、資源利用、森林と地域社会、自然災害の軽減・修復
  • 環境と人間
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 生物資源創成、共生生態系保全、持続的生物生産、生物多様性、生態系機能、生物群集生態


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