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Kudo Gaku

Faculty of Environmental Earth Science　Environmental Biology　Terrestrial EcologySpecially Appointed Associate Professor

Researcher basic information

■ Degree
  • 博士（環境科学）, 北海道大学
■ URL
researchmap URLホームページURL■ Various IDs
Researcher number
  • 30221930
J-Global ID■ Research Keywords and Fields
Research Keyword
  • Alpine ecosystem
  • phenology
  • Global Change Ecology
  • 繁殖生態学
  • 植物生態学
  • Reproductive Ecology
  • Plant Ecology
Research Field
  • Life Science, Ecology and environment
■ Educational Organization

Career

■ Career
Career
  • 1994 - 2000
    北海道大学大学院地球環境科学研究科助手 助手
  • 1994 - 2000
    Research Associate
  • 2000
    - 北海道大学大学院地球環境科学研究科助教授 助教授
  • 2000
    - Associate Professor
Committee Memberships
  • 2009 - 2013
    日本生態学会, 全国委員, Society
  • 2007
    日本生態学会, 英文誌編集員, Society

Research activity information

■ Awards
  • Mar. 2020, Ecological Society of Japan, Ecological Society of Japan (ESJ) Prize
    Gaku Kudo
  • Mar. 1997, Ecological Society of Japan, Miyadi Award of the Ecological Society of Japan (ESJ Miyadi Award)
    Gaku Kudo
■ Papers
■ Other Activities and Achievements
■ Books and other publications
  • Structure and Function of Mountain Ecosystems in Japan
    KUDO Gaku
    Springer, 2016, [Joint editor]
  • 高山植物学 高山環境と植物の総合科学
    共立出版, 2009
  • 登山道の保全と管理
    古今書院, 2008
  • 生態系と群集をむすぶ
    京都大学学術出版会, 2008
  • Ecology and Evolution of Flowers
    Oxford University Press, 2006, [Joint work]
  • 森林の科学—森林生態系科学入門—
    朝倉出版, 2005
  • 高山植物の自然史：お花畑の生態学
    北海道大学図書刊行会, 2000
  • 大雪山のお花畑が語ること：高山植物と雪渓の生態学
    京都大学学術出版会, 2000
■ Syllabus
  • 植物生態・多様性生物学特論Ⅱ, 2024年, 修士課程, 環境科学院
  • 大学院共通授業科目（一般科目）：自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 北方生態系の生物多様性基礎論, 2024年, 修士課程, 環境科学院
■ Affiliated academic society
  • 日本生態学会
  • 種生物学会
  • The Society for the Study of Species Biology
■ Research Themes
  • 地域集団の遺伝的多様性と気候変動へのレジリエンス：高山植物を用いた地域間比較
    科学研究費助成事業
    01 Apr. 2022 - 31 Mar. 2026
    工藤 岳; 和久井 彬実; 和田 直也; 甲山 哲生; 矢吹 哲夫
    大雪山サイトでは、ウスユキトウヒレン、ハクサンボウフウ、ヨツバシオガマ、コガネギクの開花時期とパフォーマンス（花茎高、花序サイズなど）、結実率、種子食害率のモニタリングを行った。また、対象種の花粉媒介昆虫の観察を行った。立山サイトでは、ハクサンボウフウ、ヨツバシオガマ、コガネギクについて同じくパフォーマンス、結実率、種子食害率の計測を行った。
    立山室堂周辺で、50 m x 50 mグリッドごとに遺伝解析用の葉のサンプリングを行い、5種合計620個体のサンプルを得た（前年度からの累計は1095個体）。これにより、設定した調査区の約2/3の区画でサンプリングを完了した。また、これまでにシーケンスデータが得られていた大雪山の5種合計2555個体についてジェノタイピングを完了し解析を行った。その結果、複数種で共通する空間遺伝構造が確認され、高山植物の遺伝的多様性が雪解け時期とポリネーターの季節活性によって形成される可能性が強く示唆された。
    約100 haの調査地を対象に、22年及び23年の無積雪期（10月）に撮影したドローンRTK空撮画像より地表面のデジタル標高モデル（DEM）を、23年の積雪期（4月）に撮影したRTK画像より積雪面のDEMを作成し、調査地の積雪深を推定した。さらに、人工衛星画像（PlanetScope）を用いた解析により、23年における消雪日の推定や調査地において優占するハイマツの被覆度を明らかにした。
    22年度に大雪山5個体群、立山4個体群で採取したハクサンボウフウの種子について、発芽試験を行った。大雪山の個体群については、冷暗所で2か月程度置くと発芽した。一方で、立山の個体群の種子は、冷暗所で2か月置いてもほとんど発芽せず、明環境に移した後に順次発芽した。大雪山と立山間で、ハクサンボウフウの発芽特性が異なっている可能性が考えられた。
    日本学術振興会, 基盤研究(B), 北海道大学, 23K23958
  • 地域集団の遺伝的多様性と気候変動へのレジリエンス：高山植物を用いた地域間比較
    科学研究費助成事業
    01 Apr. 2022 - 31 Mar. 2026
    工藤 岳; 和久井 彬実; 和田 直也; 甲山 哲生
    日本学術振興会, 基盤研究(B), 北海道大学, 22H02695
  • Effects of intra-specific variation on the coexistence of sessile organisms evaluated by long-term observation
    Grants-in-Aid for Scientific Research
    01 Apr. 2018 - 31 Mar. 2021
    Kohyama Takashi
    Large within-species variation is observed in sessile organisms, such as forest trees, shrubs and intertidal barnacleｓ. Dealing with those systems consisted of multiple species, this study examined the relationship between within-species, among-individual variations of life-history measures (in particular, size-dependent growth) and among- species coexistence. We quantified within-species variation using long-term repeated census records, applying bias-free new methods. Life-long integration of variation characterized species-level turnover rates. The fast-slow trade-off among species facilitated the equitability mechanism of coexistence.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 18H02504
  • Occurrence of phenological mismatch and its impacts on the function of pollination systems
    KAKENHI
    Apr. 2017 - Mar. 2020
    KUDO Gaku
    JSPS, Principal investigator, Competitive research funding
  • A Model Analysis for the Regime Shift under climate change
    Grants-in-Aid for Scientific Research
    01 Apr. 2015 - 31 Mar. 2019
    YABUKI TETSUO; Hara Toshihiko; Tanaka Shigenori; Ebina Kuniyoshi; Tanaka Ayumi
    To propose how to recover already degraded alpine vegetation through the regime shift under climate change especially global warming, we have performed model analyzing based on the state structure quantitative analysis in terms of several dimensionless parameters, referring to field measurement data and recovery experiment data in our research field. It has been found that the plausible values of the parameters in our model can explain the degraded alpine vegetation in our field as a regime shift, and the initial soil water content increased by cutting dwarf bamboo on the ground can recover the favorable stable state structure, and as a result our degraded alpine vegetation can be recovered within a reasonable value of dimensionless parameters in our model.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), 15K00524
  • Clarification of ecosystem functions of bee-pollination system: flowering structure of plant communities and evolution of floral traits
    KAKENHI
    Apr. 2015 - Mar. 2019
    KUDO Gaku
    JSPS, Principal investigator, Competitive research funding
  • Ecological function of dipteran pollinators in plant community: from the perspective of pollinators behavior and pollen flow.
    Grants-in-Aid for Scientific Research
    01 Apr. 2015 - 31 Mar. 2018
    Ishii Hiroshi; KUDO Gaku; USHIMARU Atsushi
    To investigate the ecological significance of dipteran pollinators at a community scale, we compared plant-pollinator communities where the proportion of dipteran pollinators differs. In general, diversity of flower colors, as well as the diversity of flower morphology, appeared to decrease as the rate of dipteran pollinators in pollinator community increase. Differences in the composition of flower color and morphology between communities are due to differences in the pollinator fauna in these communities. We also found that color preference of dipterans differed between species. Our survey further revealed that rate of conspecific pollen grains to the total pollen grains on the stigma of the dipteran pollinated plants was large as much as those of the hymenopteran pollinated plants. Our results suggest that dipteran pollinators play a significant role in maintenance of plant community.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), University of Toyama, 15K07216
  • Mechanism of vegetation change in alpine snowmeadow under climate change
    KAKENHI
    Mar. 2012 - Mar. 2016
    KUDO Gaku
    JSPS, Principal investigator, Competitive research funding
  • A network analysis of plant-pollinator interactions in alpine ecosystems in japan.
    Grants-in-Aid for Scientific Research
    28 Apr. 2011 - 31 Mar. 2015
    ISHII Hiroshi; KUDO Gaku; USHIMARU Atsushi
    We analyzed the pollination network structure of alpine ecosystem in Tateyama Mountains, central Japan. The pollination community was significantly nested and modular. However, significant nestedness resulted mainly from the bias of species abundance. In the modular matrix model, on the other hand, there existed many links outside the modules. We then categorized plants and flower visitors into several groups in accord with quantitative data of the flower visitation pattern, assumed the groups as units, and constructed model in which a single pollination group may use one to a few plant groups. In the new model, number of exceptional links was small, which implies that the model could adequately mentioned the structure of pollination network.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), University of Toyama, 23770017
  • Mechanisms of flowering-phenology formation in plant communities: functional evaluation of plant-pollinator interactions
    KAKENHI
    Apr. 2011 - Mar. 2015
    KUDO Gaku
    JSPS, Principal investigator, Competitive research funding
  • Current situation of biodiversity crisis in the forest-alpine ecotone and its mechanism under global change
    環境研究特別推進費
    Apr. 2009 - Mar. 2012
    KUDO Gaku
    環境省, Principal investigator, Competitive research funding
  • Climate change impacts on the dynamics of alpine plant communities and clarification of its mechanisms
    KAKENHI
    Apr. 2009 - Mar. 2012
    KUDO Gaku
    We aimed to evaluate the climate change impacts on the vegetation dynamics in alpine ecosystem and to clarify the changing mechanisms. Expansion of dwarf bamboo and drought stress caused the rapid decrease in species diversity and declining alpine vegetation. We developed new methods to quantify the vegetation changes using air-photographs and to evaluate the changes in soil moisture conditions using remote sensing data. Furthermore, we developed theoretical model to predict a drastic vegetation change caused by climate change.
    JSPS, Grant-in-Aid for Scientific Research (B), Hokkaido University, Principal investigator, Competitive research funding, 21370005
  • Plant mating success and gene flow in alpine ecosystems : effects of selfing, hybridization and pollinator behaviors
    Grants-in-Aid for Scientific Research
    2007 - 2008
    KAMEYAMA Yoshiaki; KUDO Gaku
    高山生態系では雪解け時期を反映した連続的な開花現象が認められ、傾度に沿って花粉媒介者や近縁他種との関係が変化する。北海道大雪山系におけるツガザクラ属植物では、雪解け傾度に沿って雑種第一代が優占する広大な交雑帯が形成されており、雑種と親種の間で花粉媒介者を巡る競争が生じていた。親種の受粉成功は開花時期や年によって大きく変動し、繁殖成功(他殖率)に多大な影響を及ぼしていた。
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), 19770009
  • 電熱線大規模埋設実験による落葉広葉樹林生態系の温暖化に対する応答の解明
    科学研究費助成事業
    2007 - 2008
    日浦 勉; 工藤 岳; 笠原 康裕; 彦坂 幸毅
    1、ミズナラの最大光合成速度は温暖化処理によって変化しなかったが、窒素含量は低下したため窒素利用効率は上昇した。イオン交換樹脂法によって土壌中の無機体窒素量がどのように変化したかは現3定量中である。
    2、葉中の窒素含量の低下と硬さの指標が上昇したため、植食性昆虫による食害は低下した。
    3、ミズナラの堅果生産量は枝の温暖化処理によって3〜5倍に上昇した。そのメカニズムは今のところ不明である。
    4、土壌中のバクテリアの量や組成は2年間の実験では変化が見られなかった。
    5、林床植物の総植被率は、林冠閉鎖が完了する6月中旬に最大となり、その後低い値で安定する傾向が見られた。林床に到達する光エネルギーとの対応関係が示された。夏緑性植物の地上部生育開始時期は、温暖化により早まる傾向が見られたが、その程度は種により異なっていた。一方で、秋の生育終了時期には明瞭な違いが認められなかった。すなわち、生育初期に温暖化の効果が大きいことが示された。半常緑性植物のオシダの越冬葉は、温暖区ではほとんどが冬の間に枯死していた。これは、温暖区では積雪がほとんどないため凍害による損傷が強かったためと考えられた。さらに、当年シュートの伸長は温暖区で遅くなる傾向が見られた。越冬葉の損失により、新葉生産のための養分や資源転流がなくなったことが影響していると予測される。土壌温暖化による積雪環境の変化は、冬期の越冬環境を変化させ、植物の生育にマイナスの効果をもたらす可能性が示唆された。
    以上の結果より、温暖化が植物にもたらす影響は、種や生活形により多様であることが示された。温暖化の影響予想には、個々の植物が有する生理特性を考慮する重要性が示された。
    日本学術振興会, 萌芽研究, 北海道大学, 19657007
  • 鮮苔類の地球環境変化に対する応答について
    科学研究費助成事業
    2007 - 2008
    工藤 岳; JAGERBRAND Annika K.; JAGERBRAND AnnikaK.
    北海道の亜高山帯から高山帯にかけて分布する鮮体類(シモフリゴケ・タチハイゴケ・イワダレゴケ)を指標にし、生育環境や標高の違いに対する成長応答と生理活性を現地調査ならびに室内実験により計測した。2年間に及ぶ野外での成長解析の結果、温度変化に対する成長の感受性は、種間・個体群間で大きく異なっていた。例えば、森林帯に主な分布域を持つタチハイゴケは、温度増加に対して伸長生長を増加させる傾向があった。一方で、高山帯に主な分布域を持つシモフリゴケは、高温域で生長の低下が見られた。また、北海道内に広く分布するタチハイゴケを6つの山域で比較した結果、成長速度、分枝パターン、蛍光光合成活性(Fv/Fm比)、窒素含有量いずれにも地域間で違いが見られたが、標高変化に対する感受性は様々であり、明瞭な傾向は認められなかった。室内実験により同一環境で生育させても、鮮体類の温度応答は山域により異なり、遺伝的な差異の存在が示唆された。冷温帯から寒帯地域にかけて広く分布する鮮体類の成長応答を詳細に計測した研究例は、これまでに非常に少ない。本研究成果は、気候変動に対する鮮苔類の応答を予測する際に、個体群あるいは地域固有の応答を考慮する重要性を示唆するものである。以上の研究成果は、現在3つの学術論文として投稿準備中である。また、気候変動に対する鮮苔類の応答についての総説を投稿中である。
    日本学術振興会, 特別研究員奨励費, 北海道大学, 07F07727
  • Comparative life history studies on Arcto-Tertiary elements of Liliaceae(sensu lato)between Japan and north America
    Grants-in-Aid for Scientific Research
    2006 - 2008
    OHARA Masashi; HAYASHI Kazuhiko; KUDO Gaku; KUDO Hiroshi; KITAMURA KEIKO
    日本と北米大陸に現在隔離分する広義のユリ科植物の中でも、日本の近縁種に関して、これまで詳細な生活史研究が行われてきた生態的背景がわかっている種群を対象に、繁殖様式ならびに個体群構造に関する、詳細な野外調査と分子マーカーを活用した遺伝解析を行った。その結果、さまざまな種群について有益なデータを得ることが出来た。特に、カタクリ属(Erythronium)、スズラン属(Convallaria)、バイケイソウ属(Veratrum)に関しては、繁殖特性に関わる集団間ならびに集団内の他殖率の変異性、および個体群統計遺伝学の側面から、種子繁殖と栄養繁殖の寄与に関して、環境と生活史形質の変異の関係を明らかにすることが出来た。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 18405010
  • Studies on plant population viability by long-term monitoring and demographic genetics and conservation
    Grants-in-Aid for Scientific Research
    2004 - 2006
    OHARA Masashi; KUDO Gaku; TAKADA Takenori; WADA Naoya
    In 1996, IUCN proposed new categories for the Red list. In the new criteria defined by IUCN, 'threatened' species are classified into the three categories. These categories are based largely on population biology principles. For defining endangerment, each category requires assessment of the probability of extinction and the generation time of focal species and populations. To assess the persistence of different populations, it is essential to understand integrated aspects of demography, reproductive biology and genetics, that is, life history features. Although the amount of scientific information on the conservation of threatened plants has increased enormously, we are still lacking essential data to enable us to assess the consequence of changing both genetic and demographic processes for population viability.
    In the present project, we focused on the impact of demographic vital rates to understand the importance of genetics and reproductive biology, using long-tem demographic data. Long-term demographic studies is essential for making a realistic simulation model of population dynamics, preferably including information on levels of environmental stochasticity.
    We concluded that integration of data on demographic, reproductive biology and genetic approaches is essential for plant conservation, and we emphasize that it is important to have basic life history data, such as long-tem demographic data and variation in breeding system.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 16370007
  • Reevaluation of reproductive strategies and mating system of insect-pollinated plants from the viewpoint of pollen dispersal patterns
    Grants-in-Aid for Scientific Research
    2003 - 2005
    KUDO Gaku; OHARA Masashi
    To test the hypothesis that diverse floral structures and flowering patterns of animal-pollinated plants may have developed to enhance the reproductive success through male function, i.e. pollination process, we investigated the relationships between floral traits and pollinator mediated pollen flow, and the relationships between pollination efficiency and breeding system of insect-pollinated plants. The pollination experiment using artificial inflorescences under controlled conditions revealed that nectar distribution within inflorescences, inflorescence structure, and floral (and inflorescence) densities effectively influence the pollinator behavior, resulting in pollination efficiency of plants. Observation and manipulations of the pollination situation and breeding systems of various insect-pollinated species under natural conditions revealed that (1) floral color change can be a pollination strategy to reduce the geitonogamous pollination by controlling the number of successive flower visits within plants, (2) floral sex allocation of hermaphrodite flowers varies among flowers within inflorescences differently between populations depending on the type of pollinators having different pollination efficiencies, (3) variations in flowering phenology sometimes cause different pollination efficiency and genetic diversity of progenies due to the seasonal variations in pollinator activity, (4) bee-pollinated species may have higher spatiotemporal fluctuations in seed-set success than fly-pollinated species, because bees usually more susceptible to the climatic conditions than flies, and (5) clonal growth may decrease the outcrossing seed production due to acceleration of geitonogamous pollination among ramets within same genet, indicating a trade-off between clonal growth and sexual reproduction. These results indicate the importance of pollination process for reproductive success and population growth of insect-pollinated plants.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 15370006
  • Tradeoff and diversity of leaf/shoot traits among plant life forms in nonseasonal environment
    Grants-in-Aid for Scientific Research
    2002 - 2004
    KOHYAMA Takashi; TERASHIMA Ichiro; KUDO Gaku; TAKAHASHI Koichi; SUZUKI Eizi; HIGASHI Seigo
    Tropical mountains provide ideal environments for plants without thermal and desiccation stresses, and where we observe a wide variation of within-and across-life form diversity of plants. This study aimed to examine ecophysiological differentiation of leaf and shoot function, based on the hypothesis that such module-level tradeoffs accelerate the differentiation in such environment. Main site was set at Mount Halimun National Park in West Java, and a comparative site at warm-temperate rain forests in Yakushima Island, southern Japan.
    In Mount Halimun, three-year census of leaf demography for 110 species was carried out. Leaf samples were divided into cell-wall and protoplasm components, to test the hypothesis that cell-wall protein increases with leaf longevity, which violates simple explanation of leaf-longevity vs. nitrogen content negative correlation. Several unique life forms such as large epiphytic fern and palm climbers were analyzed their growth and allometry in detail. Water potential change during new leaf flushing, plastic control of among-shoot allocation pattern within a plant crown, and allocation regulation between radial stem growth and shoot growth, were carried out.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 14255003
  • Spatio-temporal dynamics of alpine herbs along snowmelt gradient and prediction of change in global environment
    Grants-in-Aid for Scientific Research
    2001 - 2003
    OHARA Masashi; TAKADA Takenori; WADA Naoya; KUDO Gaku
    Genetic structure of natural plant populations is determined by spatio-temporal heterogeneity and interactions of various biotic as well as abiotic environmental factors. In alpine environments, with heavy snowfall, the occurrence of plants within snow-patches (snowbed plants) can have a strong impact on gene flow via pollen flow among patches. To examine the relationship between landscape features and spatial pattern of genetic variation in alpine environments, we conducted field observations such as differentiation of flowering phenology, behavior of pollinators and also examined population genetic structures using allozyme electrophoresis. This study project was conducted at three mountain ranges, i.e., the central part of the Taisetsu Mountains in Hokkaido, Japan, Tateyama Mountains in Toyama, Japan and Rocky Mountains, Colorado, USA.
    We examined various plant taxa (Peucedanum multivittatum, Veronica stelleri, Gentiana nipponica, Phyllodoce caerulea, P.aleuticca, Dryas octopetala, Japonolirion ozense, Sieversia pentapetala, Erythronium grandiflorum) in this study project. In general, we found that phonologically asynchronous populations are packed within a local area in alpine snowbeds because flowering season of alpine plants highly depends on the timing of snowmelt. The interaction through pollination between the sympatric species is strong enough to cause a phenotypic change in mating system even within a local area. Restriction of gene flow due to phonological separation and possible differential selection along snowmelt gradient may produce genetic clines at microgeographic scale. Furthermore, to forecast the future population structure under stochastically varying environment, plant population dynamics were investigated by application of the transition matrix model. As a result, eigenvalue sensitivity analysis of a population projection matrix that is revealed near equilibrium can give useful information about the sensitivity of the equilibrium population.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 13440226
  • Function of pollination network in a cool-temperate deciduous broad-leaved forest
    Grants-in-Aid for Scientific Research
    1999 - 2002
    TODA Masanori j.; KUDO Gaku; HIURA Tsutom
    In order to examine the hypothesis that annual fluctuation of floral resources of canopy trees generates that of pollinator population, then that of reproductive success of understory plant, that shars the pollinator, flowering in later seasons, we investigated following three components :
    (1) Floral resource amount of entomophilous trees : we quantitatively assessed about twenty entomophilous trees including eight species frequently visited by bumblebees. Reproduction system of Fraxinus lanuginosa with high fluctuation in the number of flower was revealed. As for another masting tree Styrax obbasia, it was revealed that trasport of photosynthetic substrates from the non-reproductive shoot to reproductive shoot played an important role for determination of the number of flower by the tracing such substrates.
    (2) Abundance of bumblebees : In forest site the number of queens (estimated by mark-recapture method) and the number of workers correlated with the number of inflorescences of trees in the year and that in the previous year, respectively. Seasonal change in vertical distribution of bumblebees and trees implied that bumblebee change the flight height associated with the floral resource amount of canopy trees. From the seasonal patterns of workers in forest and open sites indicated that Bombus ardens showed similar seasonal patterns in both habitats while B. hypocrita tended to change main habitats between forest and open site. This suggest that B. hypocita could utilize more effectively the floral resource in open habitats for the population growth than B. ardens.
    (3) Reproductive success of an understory plant : Assessment of reproduction system and seed production of ten species of understory plants for four years documented the general patterns in the reproduction system of understory plants including Corydalis ambigua, a spring ephemeral herb pollinated by bumblebees. Then, relative influence of resource limitation and pollen limitation on seed set of understory plants by comparing seed set between places in different light condition, understory and forest margin.
    These studies quantitatively assessed annual fluctuation of pollination system in temperate forest for the first time, and our hypothesis was supported in general. These suggest that long-term monitoring of reproduction of flower and pollinator abundance is essential to assess the dynamic aspects of pollination system.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 11440223
  • 森林における炭素バランス
    科学研究費助成事業
    1999 - 2001
    甲山 隆司; 田中 教幸; 東 正剛; 岩熊 敏夫; 工藤 岳; 大崎 満
    2001年度には,既設の森林プロットの再測を実施した.3年間の樹高・幹直径関係の推移を測定している幌内川河畔林では,まだ明瞭な方向的推移を得るには至っていない.18年生と45年生の二次林での初期生長を,ミズナラ・イタヤカエデとカラマツ(植林樹)について,樹幹解析によって比較解析したところ,種間で応答挙動が違うことが示唆された.落葉分解観測については,ミズナラがすでに終了しているが,イタヤカエデとオオイタドリ(遷移初期種)について,幌内川河畔林内および有珠山の遷移初期植生で比較観測を実施した.
    森林土壌から放出される二酸化炭素の空間的なばらつきや時間的な変動の詳細を明らかにすることを目的として空間スケールの異なる4つのサイトを設営し,内部に等間隔の100個の格子点上でチャンバー法による土壌CO_2フラックスの季節変化を2001年6月から11月まで毎月観測した.その結果,大きくばらつくフラックスの値は正規分布で近似できることがわかった.CO_2フラックスの季節変動の大きさは全ての観測点で一定の傾向を持っているとは限らず,また観測地点によって最大10〜40倍の差が見られた.季節変動から求めた温度係数Q10は約2〜9,平均値約5.2という値を示した.
    土壌分解系の機能を探る目的で,冷温帯、温帯、暖温帯の広葉樹林と針葉樹林において,落葉・土壌・土壌動物のδ15Nとδ13Cを求めた.安定同位体比には,落葉<土壌<土壌動物の関係が見られ,土壌動物の中でも落葉食者よりも肉食者で大きな値を示した.土壌中の安定同位体比は,δ15Nとδ13Cのいずれも南方ほど高く,有機物の分解速度植物を介した炭素や窒素の流れが速いことを反映していた.
    モデル研究では,既存モデルの適用と,シュートモジュール機能モデルの定量化を実施した.米国モンタナ大学テラダイナミクスシュミレーション研究グループの開発したBIOME-BGCモデルを苫小牧タワーサイトに導入し,水・炭素・窒素の循環と貯蔵を日間隔でシュミレートした.ほぼ妥当な純一次生産速度に対して,現存量が実測推定に対して過少に出る傾向があった.葉・シュートレベルの生態生理過程から,個体と個体群の挙動を記述するモデル(PipeTree)は,北方性モミ属個体群を想定したデータマッチングを行い,今まで報告されてきた自己間引きにともなう変化など個体群過程を再現するのに成功した.
    日本学術振興会, 特定領域研究(B), 北海道大学, 11213203
  • Response of Asian Rainforest Ecosystems to Global Change
    Grants-in-Aid for Scientific Research
    1998 - 2000
    KOHYAMA Takashi; KUDO Gaku; NAKASHIZUKA Toru; SUZUKI Eizi; OSAKI Mitsuru; KOBAYASHI Shigeo
    Tropical rain forests in Borneo Island support amazing amount of biomass with fast turnover of phytoproduction and tree species diversity. This type of forest ecosystem is experiencing the immense human impact, responding quickly to changing climate and land use. It is thus particularly important to monitor the changing process of tropical rain forests along the purpose of projecting ecosystem change in response to climatic change. This program monitored typical foothill dipterocarp mixed forest, lowland heath forest, and lowland freshwater peat swamp forest in West and Central Kalimantan, and Brunei. Demographic and ecosystem processes were intensively monitored in permanent research plots set across these forest types.
    Based on demographic data of mixed dipterocarp forest in Serimbu, West Kalimantan, we proposed a simulation model describing forest structure dynamics in gap-mosaic landscape, that satisfactorily projected the present landscape architecture of forests. Similar model was applied to describe different forest types. The monitored heath forest in Lahei, Central Kalimantan, showed that dense bole-class layer of the forest compared to mixed dipetrocarp forest was not due to the depression of growth at this stage but high upgrowth and rapid recruitment, because the depression by poor nutrient was only for canopy stage trees. As a result, the biomass turnover(biomass divided by net primary production)was just the same between heath forest and mixed dipterocarp forest, which has two times larger biomass. Repeated recensuses of tree trunk girth efficiently recorded temporary variation of production. Reduction of biomass increment after 1997 El Nino was particularly obvious. Further continuation will give us essential information to relate forest ecosystem functioning and environmental change.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A)., HOKKAIDO UNIVERSITY, 10041152
  • 生存戦略としての高山植物の種子発芽特性の評価
    科学研究費助成事業
    1998 - 1999
    工藤 岳
    北海道大雪山系の高山帯で,高山植物実生の発生時期と生存パターンについての調査を2年間行った。また,現地で採取した10数種の種子を用いて実験室内で発芽試験を行い,発芽の温度特性を比較した。野外での観察の結果,雪解けの早い風衝地植物群落では生育シーズンを通しての発芽が認められたのに対して,雪解けの遅い雪田植物群落では雪解け直後に発芽が集中していた。風衝地では生育シーズン初期の乾燥による死亡と越冬期の死亡が高かったが,雪田環境では発芽実生の死亡率は低かった。実験室での様々な温度制御下での発芽試験の結果、風衝地植物の発芽は種内においても様々な温度特性を示したのに対して,雪田植物の発芽はある温度域に集中していた。また,一般に風衝地植物の発芽開始積算温度は雪田植物に比べて低い傾向が認められた。これらの傾向は,風衝地から雪田まで広い分布域をもつミヤマキンバイの個体群間でも認められた。以上の結果より,風衝地は植物にとって変動環境にあり,生育シーズン初期の乾燥や冬季の死亡率が実生の定着を制限していることが推測された。早く発芽した実生は乾燥による死亡の危険性が高いが,長い生育期間を確保できるために根茎の発達がよく,冬季の死亡の危険性が低いというトレードオフの関係が認められた。このような環境では,発芽時期に変異を持たせる危険分散によって,実生集団の絶滅確率を低くするような発芽パターンが適応的であると考えられる。異なる積雪環境にある個体群間では,発芽特性に作用する選択圧が異なっていることが本研究によって示唆された。
    日本学術振興会, 奨励研究(A), 北海道大学, 10740355
  • Response of Bornean rainforest ecosystems to global change
    Grants-in-Aid for Scientific Research
    1997 - 1997
    KOHYAMA Takashi; KUDO Gaku; TANAKA Noriyuki; TAKAHASHI Hideki; HIGASHI Seigo; IWAKUMA Toshio
    This research was organized to establish the monitoring systems and stations in tropical rainforest ecosystems, to contribute to a core-research program "Global change impact on terrestrial ecosystems in Monsoon Asia "(TEMA) of IGBP-GCTE.TEMA monitoring network across East-Asian forest belt is accomplished by the establishment of lowland tropical rainforest sites in Borneo Island. This research was carried out under the collaboration with Indonesian and Malaysian counterparts' full support.
    One site in Central Kalimantan, Indonesian Borneo, was characterized by regionally nutrient poor systems, i.e.heath forest and peat-swamp forest. We established four permanent plots and one research hut on these ecosystems in Lahei site, 20-km NE from PalangkaRaya, where we carried out tree census and set litter traps and litter bags. Monitoring of the emission of greenhouse gasses was regularly carried out. To examine a lager-area characteristics of terrestrial ecosystems, preliminary land water survey was also conducted.
    For coastal ecosystems, research station was established in Tabin National Park in Sabah, Malaysian Borneo, and high-altitude forest systems were monitored in Mount Kinabalu National Park in Sabah.
    One symposium held in Sapporo early in February covered present activities in relation to TEMA,and four members participated in the GCTE-LUCC Conference in Barcelona in mid March, reporting the present activities.
    Japan Society for the Promotion of Science, Grant-in-Aid for International Scientific Research., HOKKAIDO UNIVERSITY, 09041196
  • Life-history syndromes promoting the diversity of perennial herbaceous communities on the forest floor of northern deciduous forests
    Grants-in-Aid for Scientific Research
    1996 - 1997
    KOHYAMA Takashi; KUDO Gaku; UEMURA Shigeru; OHARA Masashi; SATO Toshiyuki
    Northern mixed forests in lowland Hokkaido is characterized by relatively high plant species diversity in forest floor herbaceous communities for their latitude of distribution. This study aimed to clarify the maintenance mechanisms of the species diversity of these forest ecosystems through comparative monitoring of morphological and phenological performance among co-occurring species.
    Main research sites were set at Tomakomai Experimental Forest at Tomakomai City and Nopporo Forest Park at Sapporo City. Due to the difference in winter snowfall, seasonal performance of plants at Tomakomai forest was delayd for ca, 1 month from Nopporo forest.Remarkable high alpha-diversity was recorded for forest-floor communities without dwarf bamboo cover. We monitored seasonal performance of the floor perennial herbs and ferns. Allometric characteristics showed convergent similarity among species, characterized by the dominance of foliage allocation throughout seasons. To quantify the fine-scale vertical structure of foliage, a new technique of'disc-contact method'was designed and applied to a floor community at Tomakomai forest. Reproductive performance was monitored with special reference to dynamic spatial pattern of monocarpic species Cardicrinum cordatum(Liliaceae). The effect of grazing on herbaceous communities was recorded for the summer pasture system of horses in forest. Regional scaling-up of community structure was recorded in detail around Nopporo forest for ferns.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 08454247
  • 訪花昆虫と植食性昆虫の季節性が高山植物の繁殖成功に及ぼす効果について
    科学研究費助成事業
    1995 - 1995
    工藤 岳
    高山植物の開花・結実フェノロジーと繁殖成功との関係を,訪花昆虫や種子食害昆虫の季節性の効果に着目し調査した.北海道大雪山系の雪田で,雪解け時期の異なる4箇所に20×20mの調査プロットを設定し,セリ科多年生草本のハクサンボウフウの開花・結実状況を,5月下旬から10月上旬まで定期的に観察した.プロット間で雪解け時期は6月上旬から8月下旬と大きく異なり,ハクサンボウフウの開花時期も7月中旬から9月中旬までと大きく異なっていた.
    雪解け時期の早い場所では,開花時期の気温が低く,訪花昆虫の活性が低くために結実が花粉不足によって制限されていた.また,双翅目昆虫の幼虫による果実の食害が頻繁に観察された.雪解けが中程度の場所では,開花期の訪花昆虫の活性が高く,種子の食害も非常に低いために,高い種子生産を示していた.一方,雪解けの遅い場所では,受粉成功は高いが種子成熟期間が制限されているために,ほとんど結実できなかった.以上の結果より,雪解け時期の違いによって引き起こされた開花フェノロジーの変異は,種子生産成功度に大きく影響することが示された.
    ハクサンボウフウは,同一個体上に雄花と両性花を持つ雄性両全同株(andromonoecy)である.プロット間で各個体の両性花と雄性花の構成比を比較したところ,雪解けの遅いプロットほど両性花の割合が高くなっていた.このような性表現の変異は,それぞれのハビタットにおける訪花昆虫の活性や生育期間の制限に起因していると考えられる.雄器官・雌器官を通しての繁殖成功度が変化するときの最適両性/雄性花生産比を求めるESSモデルを作り,実際の野外データに当てはめたところ,モデルを支持する傾向が得られた.
    以上得られた成果のうち,野外データについてはOpera Botanicaに掲載予定であり,モデルの当てはめについて現在論文作成中である.
    日本学術振興会, 奨励研究(A), 北海道大学, 07740591
  • 高山植物の積雪に対する反応と適応
    科学研究費助成事業
    1990 - 1990
    工藤 岳
    日本学術振興会, 奨励研究(特別研究員), 北海道大学, 02954013