Mycorrhizal association controls soil carbon-degrading enzyme activities under nitrogen addition: Implications for soil carbon dynamics

Abstract

Abstract Increasing atmospheric nitrogen (N) deposition affects soil carbon (C) dynamics in terrestrial ecosystems. Recent evidence suggests that changes in C-degrading extracellular enzyme activities (C-EEAs) largely explain the responses of soil C dynamics to N deposition. However, the factors that control C-EEA variations under N addition remain unclear, impeding the inclusion of microbial mechanisms in global C cycle models. Using a global meta-analysis, we show that across a wide range of experimental and environmental factors, the response of C-EEAs to N addition is best predicted by mycorrhizal association. In ecosystems dominated by ectomycorrhizal plants, N addition stimulated cellulase activity by 24.4%, suppressed ligninase activity by 13.8%, and increased soil C stock by 5.8% on average. Nitrogen addition did not affect C-EEAs and soil C pool in ecosystems dominated by arbuscular mycorrhizal plants. Incorporating mycorrhizae in global C cycle models could improve predictions of soil C storage and stabilization under N enrichment.