| 要旨トップ | 本企画の概要 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

シンポジウム S22-2 （Presentation in Symposium）

#### Species loss scenarios shape distinct stabilizing mechanisms in plant communities across scales【E】

*Shun NONAKA（Yokohama National Univ.）, Yu YOSHIHARA（Mie Univ.）, Dashzeveg NYAMBAYAR（National Univ. of Mongolia）, Yoshihisa SUYAMA（Tohoku Univ.）, Takehiro SASAKI（Yokohama National Univ.）

Environmental stressors such as grazing and climate variability often drive non-random plant species loss. However, their effects on the temporal stability of plant communities remain unclear.
We conducted a manipulative experiment in a semi-arid grassland using four ecologically realistic species-loss scenarios defined by the order of species removal along local abundance ranks: removal starting from the most abundant species, removal starting from the least abundant species, simultaneous removal from both ends of the abundance rank, and loss of random species. We evaluated the consequences of these scenarios for community stability at the local community scale by (1) testing for overall differences in community stability, (2) identifying pathways linking species loss to community stability, and (3) quantifying the relative contributions of key stabilizing mechanisms.
Community stability showed no apparent decline under any species loss scenario, suggesting the short-term robustness of grassland communities to species loss. However, the mechanisms underpinning stability differed markedly among scenarios. The loss of dominant species, or of both dominant and rare species, reduced stability by decreasing functional diversity and/or compensatory dynamics. Rare species loss alone had minimal effects, whereas random loss unexpectedly increased community stability by enhancing species-level stability. The consequences of species loss for community stability therefore depended on which species were removed, with losses of dominant species causing the most pronounced reductions in stability.
Overall, our results indicate that short-term community stability can be maintained despite substantial species loss, but the stabilizing mechanisms depend strongly on the order in which species are lost. This finding highlights that realistic, non-random extinction pathways can reorganize functional diversity, compensatory dynamics, and species-level stability in ways that are not captured by random-loss assumptions. We therefore argue that predicting and managing grassland stability under global change requires explicit consideration of species’ functional roles and the drivers shaping extinction sequences.

日本生態学会