Land-use legacy effects shape microbial contribution to N2O production in three tropical forests

Abstract

Soil microbes play a key role in regulating nitrous oxide (N2O) production, and land-use history can alter soil microbial communities. However, it remains unclear how land-use legacy effects shape soil nitrogen (N) transformation processes and microbial contribution to N2O production after long-term ecosystem recovery. To address this question, we measured soil N transformation processes and quantified the contribution of soil microbes to N2O production in three tropical forests with different land-use histories (primary, rehabilitated and disturbed forests) in South China. Results showed that soil N2O production was positively correlated with the abundances of ammonia-oxidizing archaea (AOA amoA) and nirS- and nirK-denitrifiers in the three forests, suggesting that these microbial groups can contribute greatly to N2O production in tropical forests, regardless of land-use legacy effects. However, the primary forest had higher microbial biomass, net N transformation rates and N2O production, and greater abundances of AOA and denitrifiers (nirS, nirK and nosZ) than those of both the disturbed and rehabilitated forests. These results suggest that land-use legacy effects can greatly alter N-cycling functional genes and N transformation processes, shaping soil N cycling in tropical forests.