Data from: Tree diversity enhances predation by birds but not by arthropods across climate gradients

Tree diversity can promote both predator abundance and diversity. However, whether this translates into increased predation and top-down control of herbivores across predator taxonomic groups and contrasting environmental conditions remains unresolved. We used a global network of tree diversity experiments (www.treedivnet.ugent.be; TreeDivNet) spread across three continents and three biomes to test the effects of tree species richness on predation across varying climatic conditions of temperature and precipitation. We recorded bird and arthropod predation attempts on plasticine caterpillars in monocultures and tree species mixtures. Both tree species richness and temperature increased predation by birds, but not by arthropods. Furthermore, the effects of tree species richness on predation were consistent across the studied climatic gradient. Our findings provide evidence that tree diversity strengthens top-down control of insect herbivores by birds, underscoring the need of implementing conservation strategies that safeguard tree diversity to sustain ecosystem services provided by natural enemies in forests.

树木多样性可同时提升捕食者的丰度与多样性。然而，在不同捕食者类群与迥异环境条件下，这种效应是否能转化为捕食压力提升与植食动物的下行控制（top-down control），目前仍未明确。本研究依托覆盖三大洲、三种生物群区的全球树木多样性试验网络（www.treedivnet.ugent.be；TreeDivNet），旨在检验树木物种丰富度在不同温湿气候条件下对捕食作用的影响。我们在单作林与树木混交林中，记录了针对橡皮泥模拟毛虫的鸟类与节肢动物捕食尝试。研究发现，树木物种丰富度与温度均可提升鸟类的捕食压力，但对节肢动物的捕食无显著影响。此外，在本研究覆盖的气候梯度范围内，树木物种丰富度对捕食作用的影响保持一致。本研究结果证实，树木多样性可通过鸟类强化对昆虫植食者的下行控制，这凸显了制定保护策略以维护树木多样性、进而维持森林中天敌所提供的生态系统服务的必要性。