Ecosystem Carbon Flux Simulation And Fire Impact Analysis In Northeast Of China

Global climate change,especially global warming is a hot topic in current ecological research.Carbon flux is an important component of terrestrial ecosystem carbon cycle.Accuracy to estimate global or regional carbon flux will help to quantitative analysis of terrestrial ecosystem carbon flux and its response to global climate change.Forest fire is one of the most extensive and most important disturbances in the world.The amount of CO2 released from forest fires has great significance to the CO2 concentration in the atmosphere.Therefore,in this article,we simulated the terrestrial ecosystem carbon flux in northeast of China during 2001-2010 by the ecological process model BEPS and its response to the climate change.And analyze the forest fire effects on GPP northeast forest ecosystems with MODIS fire product.The main research contents and results are as follows:(1)Gross primary productivity(GPP)simulation and analysis of terrestrial ecosystem in Northeast China from 2001 to 2010.Using BEPS model and combined the meteorological and remote sensing data to simulate GPP in the northeast of China.The result shows that GPP has upward trend during 2001-2010,the annual increase of 6.91 TgC/yr.GPP was single peak in the northeast of China,and there has a significant seasonal trend.The spatial anomaly of GPP is positively correlated with precipitation,and negatively correlated with temperature and radiation,and the correlation is greater than that of temperature and radiation.Within the range of forest coverage,the annual GPP accounts for 55.32%in the whole northeast region.At the inter annual scale,GPP was positively correlated with temperature and precipitation in the northeast of China,and the response of forest GPP to temperature was greater than that of non-forest,and the response of GPP in deciduous forest is greater than evergreen forest.(2)Spatial and temporal distribution of Net ecosystem productivity(NEP)in terrestrial ecosystem in Northeast China during 2001-2010.Use BEPS model to simulate Ra,Rh and NEP spatial and temporal distribution in the northeast of China.The results show that the spatial distribution of Rh in Northeast China is roughly the same as the Ra.In summer and autumn,the Ra values are greater than Rh,and the Ra values are less than Rh in winter and spring.The overall performance of terrestrial ecosystems in Northeast China is the carbon sink,and has the fluctuation downward trend.There was a significant correlation between Ra and Rh and temperature,precipitation and radiation.Compared with Ra,Rh is more sensitive to temperature in Northeast China.The response of Rh to climate change was the most significant in deciduous broad leaved forest.And the response of NEP to climate change was significant in deciduous coniferous forest.(3)The analysis of the northeast forest fire impacts on forest ecosystem productivity.According to the simulation results of GPP and the forest fire products of MODIS,we analysis the forest fire distribution in northeast of China and it influence on GPP.The research results show that the occurrence of forest fires has obvious seasonal variation.When the temperature reaches about 0?,in forest fire burned pixels is mainly affected by precipitation and relative humidity.In the 10 year period,the amount of GPP reduction caused by forest fires was 45.25 TgC,with an average annual reduction of 4.53 TgC.In the northeast area,the annual GPP value is reduced by about 0.8%due to the impact of forest fires.