Estimation of vegetation net primary productivity and carbon sink in western Jilin province based on CASA model

The net primary productivity(NPP) and heterotrophic respiration(RH) net ecosystem productivity(NEP) in western Jilin province were calculated by using MODIS,meteorological data and vegetation type map,along with combination of CASA model and soil microbial respiration model.The NPP and RH were used to estimate the net ecosystem productivity(NEP) and vegetation carbon sink.By analyzing the variation rule and reason of the NPP and NEP,it was found that NPP in this area showed an increasing tendency from west to east.The regions of carbon source were distributed in the Tongyu,Zhenlai and Daan countries owed to the alkali soil,the vegetation carbon sink of them were between-160-0gC·m-2·a-1.By comparison,the regions of carbon sink were the Qianguo,Fuyu,Songyuan,Changling countries and the paddy field irrigation areas of the Baicheng and Zhenlai countries's NEP was 150-300gC·m-2·a-1.The overall NEP showed an increasing trend over the last 10 years,with the carbon sink of the vegetation increasing 47.10gC·m-2·a-1 from 2001 to 2010.