Climate change globally affects soil microbial community assembly across ecosystems. However, little is known about the impact of warming on the structure of soil microbial communities or underlying mechanisms that shape microbial community composition in subtropical forest ecosystems. To address this gap, we utilized natural variation in temperature via an altitudinal gradient to simulate ecosystem warming. The study was conducted at an existing experimental warming platform in the Dinghu Mountain Biosphere Reserve (established in 2012), Guangdong, China, where there is a typical tropical monsoon climate.

After 6 years, microbial co-occurrence network complexity increased with warming, and changes in their taxonomic composition were asynchronous, likely due to contrasting community assembly processes. We found that while stochastic processes were drivers of bacterial community composition, warming led to a shift from stochastic to deterministic drivers in dry season (Fig 1). Structural equation modelling highlighted that multiple factors regulate microbial community composition, with temperature being a principal driver in both dry and wet seasons (Fig 2). Although there may be seasonal shifts in soil microbe assembly between convergent and divergent processes, we found that overall, there were positive effects of warming over a 6-year period on microbial community structure. Thus, prediction of successional responses of soil microbial communities to shifts in temperature may improve understanding of climate warming impacts on ecosystem function in subtropical forests.

The study was published in the journal Global Change Biology (https://onlinelibrary.wiley.com/doi/10.1111/gcb.16541) under the title "Distinct patterns of soil bacterial and fungal community assemblages in subtropical forest ecosystems under warming”. Postdoctoral fellow Shu-Yi-Dan Zhou is the first author of the paper and Professor Juxiu Liu is the corresponding author. The study was funded by the National Natural Science Foundation of China, the Key Research and Development Program of Guangdong Province and the China Postdoctoral Science Foundation.

Figure 1. Effects of warming on microbial community assembly processes

Figure 2. Environmental drivers of microbial community composition under warming