Data from: Ecosystem engineering strengthens bottom-up and weakens top-down effects via trait-mediated indirect interactions

Trophic interactions and ecosystem engineering are ubiquitous and powerful forces structuring ecosystems, yet how these processes interact to shape natural systems is poorly understood. Moreover, trophic effects can be driven by both density- and trait-mediated interactions. Microcosm studies demonstrate that trait-mediated interactions may be as strong as density-mediated interactions, but the relative importance of these pathways at natural spatial and temporal scales is underexplored. Here, we integrate large-scale field experiments and microcosms to examine the effects of ecosystem engineering on trophic interactions while also exploring how ecological scale influences density- and trait-mediated interaction pathways. We demonstrate that (i) ecosystem engineering can shift the balance between top-down and bottom-up interactions, (ii) such effects can be driven by cryptic trait-mediated interactions, and (iii) the relative importance of density- versus trait-mediated interaction pathways can be scale dependent. Our findings reveal the complex interplay between ecosystem engineering, trophic interactions, and ecological scale in structuring natural systems.

营养级互作（trophic interactions）与生态系统工程（ecosystem engineering）是构建生态系统的普遍存在且作用强效的驱动力，但目前学界对这两类过程如何协同塑造自然生态系统的机制仍缺乏足够了解。此外，营养级效应可由密度介导的互作（density-mediated interactions）与性状介导的互作（trait-mediated interactions）共同驱动。微宇宙实验（microcosm studies）表明，性状介导的互作的强度或许可与密度介导的互作相媲美，但目前学界对这两类互作路径在自然空间与时间尺度下的相对重要性仍探索不足。本研究将大规模野外实验与微宇宙实验相结合，既探究生态系统工程对营养级互作的影响，同时也解析生态尺度如何调控密度介导与性状介导的互作路径。本研究证实：其一，生态系统工程可改变下行控制（top-down）与上行控制（bottom-up）之间的平衡；其二，此类效应可由隐蔽的性状介导互作所驱动；其三，密度介导与性状介导互作路径的相对重要性具有尺度依赖性。本研究结果揭示了生态系统工程、营养级互作与生态尺度在塑造自然生态系统过程中的复杂相互作用。