The Research On Normalized Difference Vegetation Index(NDVI) Response To The Climate Changes In Bcijing-tianjin Sand Source Region

Because of the special geographical location, changes of vegetation coverage in the areaof the Beijing-Tianjin Sand Source Region and will have an crucial impact on the ecologicalenvironment in eastern china and east Asia. Aims to reveal the spatial-temporal charateristics ofvegetation cover variations response of the regional vegetation changes to in Beijing-TianjinSand Source Region from the1982-2009based on GIMMS NDVI, from1982-2006、MODISNDVI, from2006-2009, data sets and monthly average temperature and precipitation datas ofmeteorological stations from1959to2009and by using the linear regression and correlationanalysis. The results were as follows:The temperature, precipitation and potential evapotranspiration have fluctuation changesin nearly50years in Beijing-Tianjin Sand Source Region. The rate of linear change trend forthe average temperature is increasing0.41℃/10a, the rising trend for average temperature inthe different seasons follows: winter>spring>autumn>summer, and precipitation showedobvious downward trend, the change rate is11.34mm/a, spring show a weak rise, the otherthree seasons presents downward trend. High values of temperature and precipitation areas arelocated in Yanshan water source protection areas. Potential evapotranspiration changes showeda weak decreasing trend in the last50years and regional annual evapotranspiration remainlargely around1038.37mm. A decreading trend is shown in spring, summer and autumn,upward trend in winter. Annual potential evapotranspiration is opposited to the rate of annualpotential evapotranspiration tendency.There is a significantly increasing trend for the vegetation in growing seasons inBeijing-Tianjin Sand Source Region from1982-2009. The line rate of average NDVI is0.01/10a. The NDVI value increase in different seasons, especially in spring, slightly increasein summer and autumn from different control engineering areas, the NDVI in Yanshanmountains region is far higher than other three major control engineering areas. The NDVI in desertification of grassland is the minimum value, which showed that vegetation coverage islowest.The NDVI and precipitation in growing seasons were a significantly positively relations,and have no significant correlation between air temperature. The NDVI has significant positivecorrelation in spring and autumn, a negative correlation in summer. NDVI and the temperatureand precipitation in space is given an positive correlation, the multiple correlation coefficientof the NDVI and the temperature、precipitation in the area is between0.023-0.823. The highvalue area is located in the desert grassland subarea, low value area is located in Yanshanmountains region.The relevance of accumulated precipitation and temperature in the engineering region ofBeijing-Tianjin Sand Source Region has a good correlation with lag two months, the relevanceof the correlation coefficient is0.9or above.