Mycorrhizal associations differentiate soil respiration in five temperate monocultures in Northeast China

Tree species associated with different mycorrhizal fungi play a crucial role in the carbon (C) cycling of forest ecosystems, while their effects on soil respiration (RS) and the underlying mechanisms remain uncertain. In this study, we used a common garden experiment that included five monocultures (two arbuscular mycorrhizal - (AM) and three ectomycorrhizal-associated (ECM) temperate tree species) to explore the effects of mycorrhizal associations on the RS and the driving factors. Our specific objectives were to (1) compare the RS between the AM and ECM stands, and (2) explore the driving factors of the RS. We found that the RS in the AM stands was significantly greater (34.3%) than that in the ECM stands. The RS was significantly and positively correlated with microbial biomass C (Cmic), fine roots biomass (Broot), or soil water content (W5), but negatively with forest floor mass (Fmass) or soil dissolved organic C content (Cdis). The best-fitted models of RS explained 46.3%, 38.3%, and 45.4% of the variations in the RS for the AM stands, the ECM stands, and the combined dataset, respectively. However, the factors contributing to the RS varied with mycorrhizal groups. The RS of the AM stands was mainly influenced by Cmic, Broot, root C/N ratio, Fmass, and Cdis, whereas the RS of the ECM stands was mainly affected by litter C/N ratio, Cdis, soil dissolved nitrogen content, soil temperature and W5. These findings highlight the significance of shifts in AM or ECM tree abundance due to forest management and global change in forest C cycling.