Land use intensification significantly reduced CH4 emissions while increasing N2O emissions: Taihu Lake region, China

Land use intensification is becoming increasingly common in China’s Taihu Lake region because of economic interests. Frequent intensification is the conversion from natural wetlands (NW) to conventional rice-wheat rotation fields (RW), and from conventional RW to greenhouse vegetable fields (GH). However, the impact of land use intensification on greenhouse gas emissions in this area is still unknown. In our study, we chose typical NW, RW, and GH to compare and measure methane (CH4) and nitrous oxide (N2O) emissions from the three land use types through two-year in-situ field experiments. The results showed that land use intensification significantly reduced CH4 emissions, and NW, RW, and GH emissions were 970.66 ± 100.09, 896.71 ± 300.44, and −71.23 ± 63.62 kg C ha-1. Land use intensification significantly increased N2O emissions, and NW, RW, and GH emissions were 3.35 ± 0.44, 14.38 ± 4.09, and 81.62 ± 4.89 kg N ha-1. The global warming potential of CH4 and N2O under different land use types was in the order of RW (28,137.98 ± 9077.12 kg eq-CO2 ha-1) > NW (27,123.76 ± 2703.34 kg eq-CO2 ha-1) > GH (20,360.44 ± 2651.51 kg eq-CO2 ha-1). Overall, we observed that the comprehensive greenhouse effect of CH4 and N2O was enhanced by conversion from NW to RW and weakened by conversion from RW to GH. Our study provides a predictive understanding of how land use intensification changes greenhouse gas emissions in the Taihu Lake region and in regions with similar land use types.