Responses of soil bacterial community and enzyme activity to experimental warming of an alpine meadow

Summary Soil microbes and enzymes play vital roles in the decomposition and transformation of soil material, nutrient cycling, energy flow and physicochemical properties. However, the responses of soil microbes and enzymes to warming remains poorly understood, which limits our ability to predict the consequences of future climate warming. To understand better how climate warming will alter the activity of soil microbes and enzymes, we established a field experiment to manipulate temperature in an alpine meadow in northwestern Sichuan, China. After 5 years of experimental warming, soil bacterial communities were assessed by MiSeq sequencing of 16S rRNA gene amplicons. The results showed that the experimental warming treatments increased the soil acid phosphatase, invertase and urease activity, and available nutrients, but decreased the catalase activity and soil organic matter (SOM) at the 0–10‐cm soil depth. However, the warming treatment increased catalase activity, SOM, available nitrogen (AN) and available potassium (AK), but decreased invertase activity at the 10–20‐cm soil depth. Warming significantly increased the relative abundance of Chloroflexi at the 0–10‐cm depth, whereas it significantly increased the relative abundance of Cyanobacteria and decreased the relative abundance of Firmicutes at the 10–20‐cm depth. Similarly, warming altered the relative abundance of bacterial genera, for example Candidatus Solibacter increased, whereas Pseudomonas and Janthinobacterium decreased. Warming did not significantly affect diversity or structure of the soil bacterial community. The soil acid phosphatase and urease activity, and SOM, total potassium (TK), AK and total phosphorus (TP) contents were strongly correlated with the soil bacterial community. Overall, despite the pronounced changes in soil enzyme activity and plant nutrient contents under warming, composition and diversity of the soil bacterial community were not changed. This study helps to elucidate soil responses in grasslands to climate warming. Highlights Warming promoted nutrient mineralization and altered soil enzyme activity. Warming decreased diversity of the soil bacterial community. Specific taxa responded differentially to experimental warming. Soil microorganisms regulated plant nutrient cycling under continuous climate warming.