Characterizing Spatiotemporal Dynamics of CH(4) Fluxes from Rice Paddies of Cold Region in Heilongjiang Province under Climate Change

Paddy fields have become a major global anthropogenic CH(4) emission source, and climate change affects CH(4) emissions from paddy ecosystems by changing crop growth and the soil environment. It has been recognized that Heilongjiang Province has become an important source of CH(4) emission due to its dramatically increased rice planting area, while less attention has been paid to characterize the effects of climate change on the spatiotemporal dynamics of CH(4) fluxes. In this study, we used the calibrated and validated Long Ashton Research Station Weather Generator (LARS-WG) model and DeNitrification-DeComposition (DNDC) model to simulate historical and future CH(4) fluxes under RCP 4.5 and RCP 8.5 of four global climate models (GCMs) in Heilongjiang Province. During 1960–2015, the average CH(4) fluxes and climatic tendencies were 145.56 kg C/ha and 11.88 kg C/ha/(10a), respectively. Spatially, the CH(4) fluxes showed a decreasing trend from west to east, and the climatic tendencies in the northern and western parts were higher. During 2021–2080, the annual average CH(4) fluxes under RCP 4.5 and RCP 8.5 were predicted to be 213.46 kg C/ha and 252.19 kg C/ha, respectively, and their spatial distributions were similar to the historical distribution. The average climatic tendencies were 13.40 kg C/ha/(10a) and 29.86 kg C/ha/(10a), respectively, which decreased from west to east. The simulation scenario analysis showed that atmospheric CO(2) concentration and temperature affected CH(4) fluxes by changing soil organic carbon (SOC) content and plant biomass. This study indicated that a paddy ecosystem in a cold region is an important part of China’s greenhouse gas emission inventory in future scenarios.