Natural enemies govern ecosystem resilience in the face of extreme droughts

Severe droughts are on the rise in many regions. But thus far, attempts to predict when drought will cause a major regime shift or when ecosystems are resilient, often using plant drought tolerance models, have been frustrated. Here we show that pressure from natural enemies regulates an ecosystem’s resilience to severe droughts. Field experiments revealed that in protected salt marshes experiencing a severe drought, planting-eating grazers eliminated drought-stressed vegetation that could otherwise survive and recover from the climate extreme, transforming once lush marshes into persistent salt barrens. These results provide an explicit experimental demonstration for the obligatory role of natural enemies across the initiation, expansion and recovery stages of a natural ecosystem’s collapse. Our study highlights that natural enemies can hasten an ecosystem’s resilience to drought to much lower levels than currently predicted, calling for integration into climate change predictions and ...全球诸多区域的严重干旱事件正呈愈发频发之势。迄今为止，依托植物耐旱模型开展的、旨在预测干旱引发重大生态系统状态转变（regime shift）时机，或是判定生态系统干旱恢复力的各类研究尝试，均以失败告终。本研究表明，自然天敌（natural enemies）施加的调控压力可调节生态系统对严重干旱的恢复力。野外实验证实，在遭遇严重干旱的受保护盐沼（salt marshes）中，植食性牧食动物会清除受干旱胁迫的植被——而这类植被本可在此次气候极端事件中存活并完成恢复，最终将原本繁茂的盐沼转变为持续存在的盐渍荒漠。本研究结果通过实验明确证实，自然天敌在自然生态系统崩溃的起始、扩张与恢复各阶段均发挥着不可或缺的核心作用。本研究揭示，自然天敌可将生态系统的干旱恢复力削弱至远低于当前预测的水平，呼吁将天敌作用纳入气候变化预测模型及……