While tree species associating with arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi are known to alter the soil carbon (C) cycling in distinct ways, the underlying mechanisms remain uncertain. In this study, we assessed how tree species with AM and ECM affected metabolic activity of soil microbes.We examined differences in the metabolic activity of soil microbes and related factors of five monocultures (two AM versus three ECM temperate tree species) in a common garden in Northeast, China.
Results/Conclusions
We found that the allocation to microbial production of extracellular enzymes in the AM monocultures was significantly less than that in the ECM ones, and the enzyme stoichiometry in the latter invested more in extracellular enzymes needed for N-acquisition relative to those for C-acquisition. The microbial metabolic quotient (qCO2) in the ECM monocultures was significantly greater than that in the AM ones, suggesting that ECM tree species may reduce the formation of stable soil organic matter. Tree species with different mycorrhizal types altered the extracellular enzyme activity mainly by changing soil physicochemical properties or microbial community, whereas they affected the qCO2 mainly due to differences in root traits. Our results support the resource allocation theory and highlight the importance and necessity to consider mycorrhizal associations when predicting the ecosystem biogeochemical cycling and this response to global change.