Plant-mediated effects of long-term warming on soil microorganisms on the Qinghai-Tibet Plateau

• Long-term warming experiment showed the changes in environmental contexts. • Soil microbes of two ecosystems responded differently to warming. • Plants mediated the effect of global warming on microbial responses. Exploring the feedback of the soil microbial community and associated processes to global warming represents a major global challenge. To date, the focus has been placed on the direct effects of warming on soil microbial communities, overlooking how concurrent changes in plant communities may mediate these effects. Additionally, few studies have examined long-term effects of warming in more than one environmental context. In the present study, we conducted a long-term simulated warming experiment to investigate how changes to the plant community within two different environmental contexts affect the responses of soil microorganisms and their respiration to warming. We analyzed the abundance, diversity, and community composition of plants and soil microbes, in addition to soil microbial interaction networks and soil microbial respiration, in two typical ecosystems of the Qinghai–Tibet Plateau. Following long-term warming, the soil microbial composition, structure, and interactions changed, and the shifts depended on the aboveground plant type. Specifically, the co-occurring networks containing different microbial communities tended to be more complex in a shrubland than in a grassland after warming, leading to higher carbon use efficiency. Additionally, long-term warming changed the structure of soil microbial communities, increasing the relative abundances of oligotrophic taxa in the shrubland but not in the grassland. The shifts in community structure and interaction patterns could be explained by vegetation community attributes, highlighting the strong effect of plants on soil microbial responses. These plant-mediated effects on community structure and interactions subsequently could explain changes in soil microbial respiration rates. Microbial respiration showed a positive response to elevated temperature in the grassland but no response to temperature in the shrubland. These results indicate that interactions between soil microbial communities and plant communities determine how soil microbes respond to global warming. Therefore, future research on soil microbial community composition and associated carbon feedbacks to the climate change should include plant-mediated effects, which can provide a scientific basis for effectively mitigating global warming.