Biological legacies: Direct early ecosystem recovery and food web reorganization after a volcanic eruption in Alaska

摘要

Attempts to understand how communities assemble following a disturbance arc challenged by the difficulty of determining the relative importance of stochastic and deterministic processes. Biological legacies, which result from organisms that survive adisturbance, can favour deterministic processes in community assembly and improve predictions of succcssional trajectories. Recently disturbed ecosystems arc often so rapidly colonized by propagulcs that the role of biological legacies is obscured. We studied biological legacies on a remote volcanic island in Alaska following a devastating eruption where the role of colonization from adjacent communities was minimized. The role of biological legacies in the near shore environment was not clear, becausealthough some kelp survived, they were presumably overwhelmed by the many vagile propagulcs in a marine environment. The legacy concept was most applicable to terrestrial invertebrates and plants that survived in remnants of buried soil that were exposedby post-eruption erosion. If the legacy concept is extended to include ex situ survival by transient organisms, then it was also applicable to the island's thousands of scabirds, because the scabirds survived the eruption by leaving the island and havebegun to return and rebuild their nests as local conditions improve. Our multi-trophic examination of biological legacies in a succcssional context suggests that the relative importance of biological legacies varies with the degree of destruction, the availability of colonizing propagulcs, the spatial and temporal scales under consideration, and species interactions. Understanding the role of biological legacies in community assembly following disturbances can help elucidate the relative importance of colonists versus survivors, the role of priority effects among the colonists, convergence versus divergence of succcssional trajectories, the influence of spatial heterogeneity, and the role of island biogcographical concepts.