Can plant–soil feedbacks scale up from individual species to communities: tests of the richness and biomass‐ratio hypotheses
Mengyue Li, Yan Sun, Evan Siemann, Paul Kardol, Nianxun Xi, Xinmin LuSummary
Plant–soil feedbacks (PSFs) play an important role in maintaining biodiversity and ecosystem functioning. In nature, multiple plant species collectively shape soil biotic and abiotic properties, thereby influencing subsequent plants (hereafter: community‐level PSFs). However, how plant species richness and composition determine community‐level PSFs remains poorly explored. We performed a two‐phase PSF experiment, in which soil was conditioned by one, two, four, six, or 12 species from a pool of 28 species. PSF effects of these conditioned soils were subsequently tested on an identical six‐species assemblage. In our experiment, community‐level PSFs were consistently negative, strengthened with increasing conditioning community biomass, but did not vary with conditioning species richness. While both mean and biomass‐weighted PSFs of individual component species predicted community‐level PSFs, incorporating species identity substantially increased predictive power. Our findings demonstrate that species differ in their contributions to community‐level PSFs, underscoring the need to shift PSF research from a species‐level focus toward a community‐level perspective.