Simulating Spatial-Temporal Dynamics of Greenhouse Gas Emission From Rice Paddy Field in Liaodong Coastal Region, China

【Objective】Integration of remote sensing technique and DNDC model was applied to simulate and estimate quantitatively the flux of greenhouse gas emission from rice paddy field, and the temporal-spatial pattern of emission flux was analyzed in this study 【Method】The Landsat TM and CBRES remote sensing images which were acquired in 1988 and 2005 were used for classifying the Land Use/Cover in Dawa county, Liaoning province. The purpose is to extract the temporal-spatial distribution of rice paddy field and compute its area. The DNDC model was driven to simulate the flux of gas (Carbon dioxide, nitrous oxide, methane) emission in two periods, and the spatial-temporal dynamics of greenhouse gas (GHG) emission from rice paddy field in Liaodong coastal region was analyzed.【Result】By comparing area of rice paddy field, there were more 7 066.2 hectares in 2005 than in 1988. The total emission of three GHG (CO2, N2O and CH4) were-1.20Tg C, 2.57×10-4Tg N, 1.4×10-2Tg C in 1988, and -0.72Tg C, 2.69×10-4Tg N, 1.7×10-2Tg C in 2005, respectively. The spatial distribution of GHG flux rate showed that CO2 high absorb region was in the east and south of the studied area, low absorb region was in the mid-north, low N2O emission was in the mid-east and west, its high emission was in the north, high CH4 emission was in the mid-east and the southwest and low emission was in the north and the southeast, respectively. For the net global warming potential (GWP), the spatial difference in 2005 were smaller than that in 1988【.Conclusion】Demographic and economic benefit are key factors of driving area change of rice paddyfield. The rice paddy field is the sink of CO2, source of N2O and CH4. And the temporal-spatial difference of their emission flux is significant.