Plant biodiversity responds more strongly to climate warming and anthropogenic activities than microbial biodiversity in the Qinghai–Tibetan alpine grasslands

Abstract

Abstract Biodiversity serves as the fundamental underpinning for ecosystem functions and services. As a result of human‐induced global change, there is a growing awareness of the substantial alterations in terrestrial above‐ground biodiversity, particularly within alpine regions. However, it remains uncertain whether below‐ground biodiversity will exhibit similar responses, both in terms of magnitude and manner, to anthropogenic global changes as above‐ground biodiversity. Here, we conducted a meta‐analysis to assess the impacts of warming, nutrient addition and grazing on plant and soil microbial biodiversity in alpine grasslands on the Qinghai–Tibetan Plateau, which are known to be climate‐sensitive and vulnerable. The analysis included 819 experimental observations from 152 studies, focussing on species richness, Shannon diversity and Pielou's evenness. We found that plant biodiversity exhibited greater sensitivity to climate warming and anthropogenic activities compared with soil microbial biodiversity. Specifically, plant richness and Shannon diversity were reduced by warming and nutrient addition, while plant evenness was increased by grazing. However, only microbial richness was increased by grazing and microbial evenness was increased by warming slightly. The responses of biodiversity to climate warming and anthropogenic activities were modulated by multiple factors. Specifically, the negative effects of warming on plant biodiversity were more pronounced in long‐term experiments under warmer or drier environmental conditions. The negative effects of nitrogen addition on biodiversity were enhanced by the intensity and duration of nitrogen treatment. Appropriate intensity and frequency of grazing were beneficial to sustaining plant biodiversity. Soil microbial biodiversity was weakly regulated, where bacterial Shannon diversity was more sensitive to nutrient addition, while fungal species richness was sensitive to grazing. Synthesis. Our findings reveal a mismatch between above‐ground plant and below‐ground microbial biodiversity in response to climate warming and anthropogenic activities in alpine grasslands, with plant biodiversity being more sensitive. In the context of future global change, plant biodiversity may be at greater risk than soil microbial biodiversity. In addition, biodiversity responses of different experimental and environmental conditions should be distinguished, and more attention is needed on biodiversity conservation in alpine steppe, or areas with warmer and drier environmental conditions, high‐intensity fertilization or heavy grazing.