世界的な鳥類研究が生態系の回復力低下を明らかに(Global bird study reveals declining ecosystem resilience)

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2025-11-27 インペリアル・カレッジ・ロンドン(ICL)

Imperial College London などの国際研究チームは、世界約1,200カ所・3,700種近くの鳥類群集を対象にした統合解析を行い、人為的な土地利用変化(都市化や農地拡大など)が、鳥類の「機能的多様性」と「冗長性」を著しく損なっていることを報告した。これにより、花粉媒介、種子散布、害虫捕食といった生態系サービスを担う複数の機能を複数種で支えるという生態系の“保険(冗長性)”が失われつつあり、将来的な環境変動や生物多様性の減少に対して脆弱になっている。研究のシミュレーションでは、機能冗長性が減少することで生態系の回復力(レジリエンス)が大きく低下する可能性が示された。これらの変化は、生態系全体の安定性と持続性に深刻な警鐘を鳴らすものである。

<関連情報>

土地利用の変化は鳥類の機能的多様性の安定性を損なう Land-use change undermines the stability of avian functional diversity

Thomas L. Weeks,Patrick A. Walkden,David P. Edwards,Alexander C. Lees,Alexander L. Pigot,Andy Purvis & Joseph A. Tobias
Nature  Published:26 November 2025
DOI:https://doi.org/10.1038/s41586-025-09788-0

世界的な鳥類研究が生態系の回復力低下を明らかに(Global bird study reveals declining ecosystem resilience)

Abstract

Land-use change causes widespread shifts in the composition and functional diversity of species assemblages. However, its impact on ecosystem resilience remains uncertain. The stability of ecosystem functioning may increase after land-use change because the most sensitive species are removed, which leaves more resilient survivors1,2,3. Alternatively, ecosystems may be destabilized if land-use change reduces functional redundancy, which accentuates the ecological impacts of further species loss4,5. Current evidence is inconclusive, partly because trait data have not been available to quantify functional stability at sufficient scale. Here we use morphological measurements of 3,696 bird species to estimate shifts in functional redundancy after recent anthropogenic land-use change at 1,281 sites worldwide. We then use extinction simulations to assess the sensitivity of these altered assemblages to future species loss. Although the proportion of disturbance-tolerant species increases after land-use change, we show that this does not increase stability because functional redundancy is reduced. This decline in redundancy destabilizes ecosystem function because relatively few additional extinctions lead to accelerated losses of functional diversity, particularly in trophic groups that deliver important ecological services such as seed dispersal and insect predation. Our analyses indicate that land-use change may have major undetected impacts on the resilience of key ecological functions, hindering the capacity of natural ecosystems to absorb further reductions in functionality caused by ongoing perturbations.

生物環境工学
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