Resilience and diversity in aquatic metacommunities: Effects of dispersal and the spatial scale of disturbance

近年来，在元群落概念中，物种共存是由局部相互作用和区域扩散介导的，在空间生态动力学分析方面取得了严格的进展。然而，我们缺乏关于元群落动态如何改变多样性和恢复力对干扰和环境波动的反应的信息，特别是如果这些干扰在空间范围上不同。为了验证这一想法，我们将建立由浮游植物（及其消费者）居住的连接微观世界组成的实验性元群落。元群落在扩散速率（影响区域和局部多样性）和共存机制（斑块动态与源汇动态）上存在差异。在这些群落中，我们将通过在局部或区域范围内去除生物量来改变死亡率，并测量这种干扰后群落组成和重要生态系统功能（初级生产、养分保留）的恢复。我们认为恢复力是扩散率、局部丰富度和区域丰富度的函数，但我们预计这些因素在不同的死亡率空间尺度上的相对重要性是不同的。在第二组实验中，我们将探讨在不受干扰但波动的环境条件下，空间共存对于生态系统过程随时间稳定的重要性。该项目的结果将有助于解决在栖息地破坏情况下破碎景观中空间保险机制的重要性，这被认为是未来环境中生物多样性丧失的主要原因。

Recent years have seen stringent advances in the analysis of spatial ecological dynamics embedded in the concept of metacommunities, in which species coexistence is mediated by local interactions and regional dispersal. However, we lack information on how metacommunity dynamics alter responses of diversity and resilience to disturbance and environmental fluctuations, especially if these disturbances differ in their spatial extent. To test this idea, we will establish experimental metacommunities consisting of connected microcosms inhabited by phytoplankton (and their consumers). The metacommunities differ in their dispersal rates (which affect regional and local diversity) and their coexistence mechanism (patch dynamics versus source-sink dynamics). In these communities, we will alter mortality by removing biomass in local or regional extent and measure the recovery of community composition and important ecosystem functions (primary production, nutrient retention) after this disturbance. We except resilience to be a function of dispersal rate, local richness and regional richness, but we expect different relative importance of these factors at different spatial scales of mortality. In a second set of experiments, we will address the importance of spatial coexistence for the stability of ecosystem processes over time under undisturbed but fluctuating environmental conditions. The results from this project will allow addressing the importance of spatial insurance mechanisms in fragmented landscapes in cases of habitat destruction, which are considered to be major causes of biodiversity loss in future environments.