Differential response of soil CO2, CH4, and N2O emissions to edaphic properties and microbial attributes following afforestation in central China

Land use change specially affects greenhouse gases (GHGs) emissions, and it can act as a sink/source of GHGs. Alterations in edaphic properties and microbial attributes induced by land use change can individually/interactively contribute to GHGs emission, but how they predictably affect soil CO₂, CH₄, and N₂O emissions remain unclear. Here, we investigated the direct and indirect controls of edaphic properties [i.e. dissolved organic C (DOC), soil organic C (SOC), total N (TN), C: N ratio, NH₄⁺-N, NO₃^－-N, soil temperature (ST), soil moisture (SM), pH, bulk density (BD)] and microbial attributes [i.e. total PLFAs (Phospholipid fatty acids), 18:1ω7c, nitrifying genes (ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB)), and denitrifying genes (nirS, nirK, and nosZ)] over the annual soil CO₂, CH₄, and N₂O emissions from the woodland, shrubland, and abandoned land in subtropical China. Soil CO₂ and N₂O emissions were higher in the afforested lands (woodland and shrubland) than in the abandoned land, but the annual cumulative CH₄ uptake did not significantly differ among all land use types. The CO₂ emission was positively associated with microbial activities (e.g., total PLFAs), while the CH₄ uptake was tightly correlated with soil environments (i.e. ST, SM) and chemical properties (i.e. DOC, C:N ratio, NH₄⁺-N concentration), but not significantly related to the methanotrophic bacteria (i.e. 18:1ω7c). Whereas, soil N₂O emission was positively associated with nitrifying genes, but negatively correlated with denitrifying genes especially nosZ. Overall, our results suggested that soil CO₂ and N₂O emissions were directly dependent on microbial attributes, and soil CH₄ uptake was more directly related to edaphic properties rather than microbial attributes. Thus, different patterns of soil CO₂, CH₄, and N₂O emissions and associated controls following land use change provided novel insights into predicting the effects of afforestation on climate change mitigation outcomes.