森林の炭素貯蔵に関する新たな発見(Time Is Not the Driving Influence of Forest Carbon Storage, U-M Study Finds)

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2025-03-18 ミシガン大学

森林の炭素貯蔵に関する新たな発見(Time Is Not the Driving Influence of Forest Carbon Storage, U-M Study Finds)
Illustration by study coauthor Jennifer Kalejs shows synthesis of ecosystem changes over successional time. Image courtesy: Jennifer Kalejs​

ミシガン大学生物学研究所(UMBS)を拠点とする研究チームは、森林の炭素蓄積が単に時間経過によるものではなく、森林の構造、樹木や菌類の構成、土壌の生物地球化学的プロセスなどの要因がより大きな影響を及ぼすことを明らかにしました。 この研究では、UMBSの1万エーカー以上の敷地内にある19世紀に設立された古い森林、20世紀初頭に伐採されその後放置された森林、そしてその後も伐採や焼失を経験した森林など、多様な森林群落を対象に、数十年にわたるデータを統合しました。その結果、森林の炭素循環は時間そのものではなく、樹冠構造、樹木や微生物の群集構成、土壌の窒素利用可能性などの要因によって制御されていることが示されました。これらの要因は、森林管理や自然のプロセスを通じて変化し、炭素の蓄積パターンに影響を与えます。この発見は、森林の炭素蓄積を促進するための管理戦略を策定する際に、これらの要因を考慮する必要性を示唆しています。

<関連情報>

北温帯林における生態系遷移に伴う炭素循環: その制御と管理への影響 Carbon cycling across ecosystem succession in a north temperate forest: Controls and management implications

Lucas E. Nave, Christopher M. Gough, Cameron Clay, Fernanda Santos, Jeff W. Atkins, Sonja E. Benjamins-Carey, Gil Bohrer, Buck T. Castillo, Robert T. Fahey …
Ecological Applications  Published: 24 February 2025
DOI:https://doi.org/10.1002/eap.70001

Abstract

Despite decades of progress, much remains unknown about successional trajectories of carbon (C) cycling in north temperate forests. Drivers and mechanisms of these changes, including the role of different types of disturbances, are particularly elusive. To address this gap, we synthesized decades of data from experimental chronosequences and long-term monitoring at a well-studied, regionally representative field site in northern Michigan, USA. Our study provides a comprehensive assessment of changes in above- and belowground ecosystem components over two centuries of succession, links temporal dynamics in C pools and fluxes with underlying drivers, and offers several conceptual insights to the field of forest ecology. Our first advance shows how temporal dynamics in some ecosystem components are consistent across severe disturbances that reset succession and partial disturbances that slightly modify it: both of these disturbance types increase soil N availability, alter fungal community composition, and alter growth and competitive interactions between short-lived pioneer and longer-lived tree taxa. These changes in turn affect soil C stocks, respiratory emissions, and other belowground processes. Second, we show that some other ecosystem components have effects on C cycling that are not consistent over the course of succession. For example, canopy structure does not influence C uptake early in succession but becomes important as stands develop, and the importance of individual structural properties changes over the course of two centuries of stand development. Third, we show that in recent decades, climate change is masking or overriding the influence of community composition on C uptake, while respiratory emissions are sensitive to both climatic and compositional change. In synthesis, we emphasize that time is not a driver of C cycling; it is a dimension within which ecosystem drivers such as canopy structure, tree and microbial community composition change. Changes in those drivers, not in forest age, are what control forest C trajectories, and those changes can happen quickly or slowly, through natural processes or deliberate intervention. Stemming from this view and a whole-ecosystem perspective on forest succession, we offer management applications from this work and assess its broader relevance to understanding long-term change in other north temperate forest ecosystems.

1304森林環境
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