Spatially heterogeneous perturbations homogenize the regulation of insect herbivores

Anthropogenic influences on resources and consumers can affect food web regulation, with impacts on trophic structure and ecosystem processes. Identifying how these impacts unfold is challenging because alterations to one or both resources and consumers can similarly transform community structure, especially for intermediate consumers. To date, empirical testing of perturbations on trophic regulation has been limited by the difficulty in separating the direct effect of perturbations on species composition and diversity from those unfolding indirectly via altered feeding pathways. Moreover, disentangling the independent and interactive impacts of covarying stressors that characterize human-altered systems has been an ongoing analytical challenge. We used a large-scale metacommunity experiment in grasslands to test how resource inputs, stand perturbation, and spatial factors affect regulation of insect herbivores in tritrophic grassland food webs. Using path-model comparisons, we observed...人为活动对资源与消费者的影响可干扰食物网调控，进而对营养结构（trophic structure）与生态系统过程造成影响。厘清此类影响的发生路径颇具挑战，因为无论是改变资源、消费者其一，还是同时改变二者，均可能类似地重塑群落结构，对于中间消费者而言尤为如此。迄今为止，针对营养调控扰动的实证检验一直受限，其难点在于难以区分扰动对物种组成与多样性的直接效应，以及通过摄食路径改变而间接产生的间接效应。此外，厘清人类干扰系统中普遍存在的协同胁迫因子的独立效应与交互效应，一直是一项长期存在的分析难题。本研究依托草地生态系统中的大型元群落（metacommunity）实验，探究资源输入、样地扰动（stand perturbation）与空间因子对三营养级（tritrophic）草地食物网中昆虫植食者调控过程的影响。通过路径模型（path-model）比较分析，本研究发现……