旭硝子財団助成研究成果報告2018

64/82

60梅木　清76Kiyoshi UMEKI三宅　克英77Katsuhide MIYAKEシカによる摂食圧力を受けた森林における鳥類群集の景観レベルの動態と回復に関する研究(2015採択)Study on landscape-level dynamics and resilience of bird communities in forests affected by deer browsing(Project 2015)生物多様性保全に向けた北陸海岸林のアカテガニの生態と有用性の検討(2016採択)Studies on the ecology and usefulness of land crabs in long-protected forests near the coast in Hokuriku area for biodiversity conservation(Project 2016)旭硝子財団　助成研究成果報告（2018）understand the role of tropical peatlands in the regional and global carbon balances. Thus, we measured soil CO2 efflux in six tropical peat ecosystems with different disturbance levels and quantified annual CO2 emis-sions through oxidative peat decomposition. Its inter-site difference and its relationship with groundwater level were investigated. In addition, subsidence rates were measured and the contribution of oxidative peat decomposition to the subsidence was quantified on an annual basis.1980年代以降，ニホンジカの個体密度が増加し，森林生物群集に様々な影響を与えている．その一つとして鳥類群集に対する影響があるが，十分理解されていない．本研究では，ニホンジカ摂食圧下にある天然林で，摂食圧の効果を直接・間接に受ける可能性のある生物群集（樹木・飛翔性昆虫・鳥類）を調査し，鳥類群集に対する影響を把握することを目指した．調査対象地とした東京大学秩父演習林では，ニホンジカの密度は高く，ササの稈密度を激減させていた．また，ニホンジカ摂食は，樹木実生の死亡率を増加させていた．さらに，飛翔性昆虫の分類群組成と鳥類の種組成はササの密度の影響を強く受けていた．これらの結果から，ニホンジカ摂食圧が間接的に鳥類群集に影響を与えていることが把握できた．Since 1980's, natural populations of sika deer (Cervus nippon) have been increasing in various forested areas in Japan, and have been giving various impact on biological communities in forests. The bird communities in forests can be influenced, but they are not fully understood. In this study, we monitored biological communi-ties (trees, flying insects, birds), which can be influenced directly or indirectly by high grazing pressure by sika deer, in a forested area, and tried to understand the effects of high grazing pressure on bird communities. In the University of Tokyo Chichibu Forest, the research area of this study, the population density of sika deer was high enough to drastically reduce the culm density of dwarf bamboo. The high grazing pressure of sika deer increased the mortality of tree seedlings. Moreover, taxonomic components of flying insect communities and bird communities were influenced by dwarf bamboo density. From these findings, we concluded that the high grazing pressure of sika deer have indirect influences on bird communities in forest ecosystems.アカテガニやクロベンケイガニなどの陸ガニ類は，日本沿岸の海岸原生林に生息し，太平洋岸から日本海岸までの多くの場所で，森と海の間の物質循環に大きな役割を果たしている．本研究では，石川県沿岸の陸ガニ類の生態解明と有効活用を目的としたバイオマス分解能力の解析と海岸原生林の生態系保全のためのアカテガニ人工繁殖技術の確立を試みた．本研究の結果，陸ガニ類の食性と関係したバイオマス分解活性の特性が明らかになり，また陸ガニの個体数維持や増強に役立つ幼生期の生態研究のための人工繁殖技術の確立にも成功した．前者では植食性の強さとリグニン分解に関連する酵素活性とされるグアイアコール酸化活性の強い相関を見出し，後者では実験室レベルでのアカテガニのゾエアから稚ガニへの生育技術を開発した．The land crabs, Chiromantes haematocheir(Akate-gani) and C. dehaani(Kurobenkei-gani) inhabit seaside for-