Conservative roots confer a larger microbial carbon pump efficacy than acquisitive roots by regulating microbial life‐history strategy

Abstract Root activity creates unique microbial hotspots in the rhizosphere by influencing the metabolic activities of surrounding soil microorganisms, profoundly regulating the dynamics of soil organic carbon (SOC). However, how root economic strategies affect the formation and accumulation of microbial‐derived C (i.e. microbial C pump, MCP) in the rhizosphere by altering the microbial life‐history strategies currently remain unclear. We assessed the microbial necromass C contribution to SOC (MCP efficacy) in the rhizosphere and examined the impacts of root economic strategies and microbial metabolic traits on the MCP efficacy of 12 coexisting tree species in a subtropical forest. The results showed that conservative roots drive a larger soil MCP efficacy than acquisitive roots. This observation was mainly attributed to the synchronous relationship between the conservation gradient of root economic strategies and the microbial high‐yield strategies. Specifically, soil microbes in the rhizosphere associated with conservative roots feature higher C use efficiency, more rapid growth and turnover rates, lower biomass‐specific enzyme activity than those associated with acquisitive roots, indicating that conservative roots support greater microbial necromass production and subsequently higher rhizosphere MCP efficacy. Our findings demonstrated that different tree species could affect the microbial metabolic traits through their unique root strategies, and this extends to the regulation of soil C dynamics. This highlights the importance of integrating tree root function traits into soil C models in order to accurately assess the soil C sequestration potential. Read the free Plain Language Summary for this article on the Journal blog.