Soil microbiomes in degraded grasslands: Assembly, function, and application

Abstract

Grassland ecosystems are pivotal to sustaining multiple ecosystem functions and services like climate regulation, carbon sequestration, and grass production. However, the global degradation of grasslands is intensifying under the combined impacts of climate change (e.g., extreme drought) and anthropogenic activities (e.g., overgrazing). The exploration of microorganism presence and roles in degraded grasslands has achieved substantial progress. Here, we review the literature on soil microbes in degraded grasslands over the past decade, with emphasis on community response, microbial-mediated nutrient cycling processes, and potential application for restoration. Grassland degradation diminishes soil microbial diversity by reducing resource availability, resulting in the homogenization of microbial communities. However, these effects remain controversial in the context of patchy degradation. Meanwhile, degradation typically triggers the loss of key microbial species or some functional genes, coupled with suppressed activity of nutrient cycling-related enzymes, and may also promote certain processes like the decomposition of complex organic matter (e.g., lignin). We further evaluate current advances and limitations in microbial inoculant applications for grassland restoration. Some future directions in degraded grasslands are advocated, including plant–soil–microbe interaction analysis, degradation trend prediction using microbial dynamic data, and microbial multifunctional inoculant application. Promising restoration strategies, integrating metabolite identification and targeted microbiome modification, offer valuable pathways for future research and practical implementation under global change scenarios.

Keywords

degraded grasslands / microbial inoculants / near-natural restoration / nutrient cycling / soil microbiomes

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