Variations of belowground C and N cycling between arbuscular mycorrhizal and ectomycorrhizal forests across China

Forests associating with arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi may have distinct belowground carbon (C) and nitrogen (N) cycle processes. However, there are little available data providing evidence for the effects of trees associating with mycorrhizal type on belowground C and N cycling in forest ecosystems in China. Here, we collected a database of 26 variables related to belowground C and N cycling from 207 studies covering 209 sampling sites in China, to better understand the variations in belowground C and N cycling between the two mycorrhizal types in forest ecosystems along a climatic gradient. The AM forests had significantly lower soil total C and N contents, and soil microbial biomass C and N, than ECM forests, probably due to differences in litter quality (N and C/N) between AM and ECM forest types. In contrast, AM forests had significantly higher litter input, litter decomposition and soil respiration than ECM forests. Temperature and precipitation had significant positive effects on litter input and decomposition, soil total C and N contents, and soil respiration in AM and ECM forests. Overall, our results indicated that mycorrhizal type strongly affected belowground C and N cycle processes in forest ecosystems. Moreover, AM forests are likely more sensitive and ECM forests have a greater ability to adapt to global climate change.