Scaling biodiversity-stability relationships from populations to meta-communities across trophic levels.

Ecological stability is essential for maintaining ecosystem functioning, but may be imperiled by biodiversity loss. Although the scaling of diversity-stability relationships from populations to communities and metacommunities has been studied within single trophic levels, it remains poorly understood when considering interactions between trophic levels. Here, we utilize data collected from a large-scale forest biodiversity experiment to investigate the scaling of temporal stability from populations, to communities, and meta-communities in a plant-herbivore system, allowing us to disentangle the relative role of top-down and bottom-up regulation. We observe that biodiversity has generally stabilizing effects within and between trophic levels. Specifically, species diversity of herbivores shows strong stabilizing top-down effects by enhancing species stability and asynchrony of plants that cascade to higher levels of organization. In contrast, bottom-up effects play a much smaller role. Our study therefore highlights the importance of top-down processes in safeguarding plant stability across levels of organization, while simultaneously providing a framework that allows the investigation of the multi-layered nature of stability mechanisms that needs to be considered for a successful and sustainable ecosystem management.