Effects of warming on the bacterial community and its function in a temperate steppe

Highlights: • Warming significantly increased the complexity and stability of the soil bacterial community network. • The interactions between bacterial taxa could be a major driver of the bacterial community network. • Warming increased the ability of bacteria to decompose organic matter and accelerated the soil carbon cycle. As a significant environmental issue, global warming will have a significant impact on soil microorganisms, especially soil bacteria. However, the effects of warming on the network structure of bacterial communities and the function of ecosystems remain unclear. Therefore, we examined the effects of three-year simulated field warming on the complexity of soil bacterial communities and predicted functions in a temperate steppe of Inner Mongolia. Warming significantly increased the α-diversity of bacteria in 2018 but did not affect it in 2019 and 2020. Warming increased network complexity and stability and keystone taxa, and these bacterial taxa also associated more closely with each other, indicating that the protection of interactions between bacterial taxa is very important for the conservation of biodiversity. Warming significantly increased aerobic chemoheterotrophy, ureolysis, and chemoheterotrophy, suggesting that warming increased the ability of bacteria to decompose organic matter and the emission of greenhouse gases, such as CO₂ and CH₄. Collectively, warming will alter soil bacterial community structure and its potential functions, further affecting key functions in grassland belowground ecosystems.