Land-use driven changes in elemental stoichiometry decouple the positive soil biodiversity-stability relationship

Abstract

Land-use intensification often reduces aboveground biodiversity and ecosystem stability, but its effects on belowground biodiversity across multiple trophic levels and spatial scales, as well as their links to ecosystem stability, remain poorly understood. In this study, we conducted a field survey to assess the α-, β-, and γ-diversity of soil biota (bacteria, fungi, and nematodes) and estimated the temporal ecosystem stability using normalized difference vegetation index (NDVI) along a land-use intensity (forests, orchards, croplands) across 44 sites in subtropical regions. Agricultural land conversion significantly reduced α-, β-, and γ-diversity of soil biota across trophic levels, with higher trophic levels (e.g., microbivorous and omnivorous-predaceous nematodes) more affected than lower ones (e.g., microbes). Soil biodiversity, defined as the average diversity of all soil biota groups, was positively related to the temporal stability of plant productivity, with the higher trophic levels playing a greater role at all scales. However, land-use intensification decoupled the positive relationships between soil biodiversity and the temporal stability at both local and regional scales. Further analyses revealed that changes in soil elemental stoichiometry, particularly the carbon to phosphorus ratio, were a predominant driver of soil biodiversity loss at both local and regional scales, as well as its relationship with the temporal stability. These findings highlight the importance of elemental stoichiometry in shaping biodiversity-stability relationships and provide insights into the impacts of land-use intensification on soil communities and ecosystem resilience.