Review of the Effects of Climate Change on Soil Microbial Necromass Carbon

Soil microorganisms serve as the core driving force of the carbon (C) cycle in terrestrial ecosystems, and the necromass formed after their death constitutes a key component of the organic C pool in terrestrial ecosystems. A series of current climate change factors, such as frequent droughts and warming, may affect the transformation of microbial necromass C and its contribution to soil C pools. Based on this, this study systematically reviewed the response mechanisms and research progress of soil microbial necromass C accumulation to four key climate factors: temperature rise, drought, extreme precipitation, and low temperature. The results showed that climate change factors regulated the accumulation and decomposition processes of microbial necromass C mainly by affecting microbial metabolic activity, plant C source substrate supply, and microbial predator predation efficiency. Although the accumulation of microbial necromass C showed an increasing trend under high-temperature and low-temperature stresses, the comprehensive impact of these four stress factors on necromass C accumulation was still dominated by the adverse stress effect. By disturbing the composition and metabolic activities of the microbial community, the generation and transformation of necromass C were inhibited, ultimately leading to a reduction in its contribution to the soil organic C pool. This discussion on the response of soil microbial necromass C accumulation to climate change factors helps to deepen readers' understanding of the C cycle process mediated by soil microorganisms and the accumulation mechanism of their necromass C, and also to provide a relevant theoretical basis for predicting the dynamic evolution of the global C cycle in the future.