| 英文摘要: | Climate warming is expected to intensify drought in many regions of the world. However, the determinants of ecological sensitivity to changing drought dynamics are unclear in many cases. In particular, the role of species interactions in modulating ecological responses to drought remains underexplored. Qiang He from Beijing Normal University, China, and co-workers test whether grazers can lower a natural ecosystem's resistance to, and recovery from, drought using a series of salt marsh grazer exclusion experiments in a protected area in temperate China. They find that in salt marshes experiencing a severe drought, grazers (the crab Helice tientsinensis) eliminated drought-stressed vegetation (Suaeda salsa L.) that could otherwise survive and recover in plots where grazers were excluded. In combination, drought and grazing led to the conversion of previously lush vegetation into persistent salt barrens. These results demonstrate how grazing pressure can make an ecosystem more vulnerable to drought than would be expected based on plant physiological tolerances alone. |