Beyond diversity: the functional mechanisms of microbial adapations under climate change in alpine deserts.
BACKGROUND The functional responses of soil microbiomes to concurrent warming and altered precipitation in alpine deserts remain poorly understood, hindering predictions of these fragile ecosystem to climate change. Specifically, the mechanisms by which microbial communities maintain ecosystem function potential despite climate-induced biodiversity changes are unclear. RESULTS A three-year field manipulation experiment in an alpine desert grassland on the Qinghai-Xizang Plateau showed that warming and watering acted as distinct ecological drivers. Warming restructured prokaryotic and fungal communities, favored stress-associated taxa, and increasing interkingdom network complexity, indicating tighter microbial associations under climate stress. Although warming reduced microbial richness and diversity, it did not diminish the overall potential for soil nutrient cycling. Instead, functional stability was associated with sustained microbial abundance, network reorganization, and selective changes in nutrient-cycling genes, particularly those involved in nitrogen and phosphorus transformation hosted by specific bacterial phyla. In contrast, watering did not significantly increase mean soil moisture, but altered soil nutrient availability, affecting key microbial groups and their functions, showing an indirect regulation pathway. CONCLUSIONS Functional stability in alpine deserts under climate change was maintained not by taxonomic diversity alone, but through abundance-based compensation, community reorganization, and pathway-specific functional shifts. This study provides a mechanistic framework linking climate drivers to microbial community structure and nutrient-cycling potential, offering predictive insights into the responses of cold-arid ecosystems to future climate change.