Effects of Climatic Factors and Disturbance on Plant Above-Ground Biomass and Species Diversity of Chinese Grasslands: A Meta-Analysis.

Grassland ecosystems provide substantial social and cultural value but are vulnerable to climate change and human activities. Large-scale evidence on how climate and disturbance jointly affect above-ground biomass (AGB), species richness, and their relationship remains limited. We conducted a meta-analysis by compiling and standardizing plot-level observations from 226 studies of Chinese grasslands. The final database contained 1192 records from 378 sites surveyed between 1982 and 2019, with matched climatic variables (mean annual temperature, annual precipitation, and radiation) and disturbance categories (grazing, mowing, and fencing). Random-forest models identified disturbance, precipitation, and radiation as the strongest predictors of AGB, whereas temperature was the strongest predictor of species richness. AGB was higher under mowing and fencing than under grazing and declined with increasing grazing intensity; it also increased with local precipitation. Species richness was highest under mowing, followed by fencing and grazing, and was greatest under wetter conditions and moderate temperatures. Across the national dataset, AGB and species richness were linearly and positively related overall, although several plant formations showed a unimodal pattern. Heavy grazing weakened the linear relationship, whereas moderate grazing strengthened it. Our study provides a scientific basis for the management of grassland ecosystems under the influence of climate change and human activities.