Data from: Incorporating anthropogenic effects into trophic ecology: predator-prey interactions in a human-dominated landscape

Apex predators perform important functions that regulate ecosystems worldwide. However, little is known about how ecosystem regulation by predators is influenced by human activities. In particular, how important are top-down effects of predators relative to direct and indirect human-mediated bottom-up and top-down processes? Combining data on species’ occurrence from camera traps and hunting records, we aimed to quantify the relative effects of top-down and bottom-up processes in shaping predator and prey distributions in a human-dominated landscape in Transylvania, Romania. By global standards this system is diverse, including apex predators (brown bear and wolf), mesopredators (red fox) and large herbivores (roe and red deer). Humans and free-ranging dogs represent additional predators in the system. Using structural equation modelling, we found that apex predators suppress lower trophic levels, especially herbivores. However, direct and indirect top-down effects of humans affected the ecosystem more strongly, influencing species at all trophic levels. Our study highlights the need to explicitly embed humans and their influences within trophic cascade theory. This will greatly expand our understanding of species interactions in human-modified landscapes, which compose the majority of Earth’s terrestrial surface.

顶级捕食者（apex predators）在全球范围内发挥着调控生态系统的关键功能。然而，目前学界对捕食者的生态系统调控作用如何受人类活动影响的认知仍较为匮乏。具体而言，相较于人类介导的直接与间接上行（bottom-up）、下行（top-down）过程，捕食者的下行效应究竟占据何等重要的地位？
本研究结合相机陷阱与狩猎记录获取的物种出现数据，旨在量化罗马尼亚特兰西瓦尼亚这片人类主导景观中，调控捕食者与猎物分布格局的下行与上行过程的相对效应强度。
从全球标准来看，该研究区域的物种多样性丰富，涵盖顶级捕食者（棕熊与灰狼）、中型捕食者（赤狐）以及大型植食动物（狍与马鹿）；人类与散养犬只亦是该系统中的额外捕食者类群。
本研究借助结构方程模型（structural equation modelling）分析发现，顶级捕食者能够抑制低营养级类群，尤其是植食动物。
然而，人类活动的直接与间接下行效应对生态系统的影响更为强烈，能够作用于所有营养级的物种。
本研究强调，需将人类及其影响明确纳入营养级联理论的框架之中。
这一举措将极大拓展我们对人类改造的景观中物种互作关系的认知，而此类景观占据了地球陆地表面的绝大多数区域。