Vegetation changes of Loess Plateau and Ansai County and the responding characteristics of climate.

Based on Normalized Difference Vegetation Index(NDVI) data of Loess and Ansai County and the climate data of Ansai County during 1982～2003,the vegetation changes of NDVI and the responding characteristics of climate in Ansai County were analyzed.The results showed that the NDVI of Loess Plateau was significantly increased with 7.0×10-4·a-1 in 22 years,especially in spring and autumn.These indicated that the vegetation coverage of Loess Plateau have been improved obviously.Contrastly,the NDVI of Ansai County have not been increased significantly and it was 22.93% lower than that of Loess Plateau.These resulted in sensitive response of climate in Ansai County to vegetation changes of Loess Plateau.When annually and spring NDVI of Loess Plateau was increased 0.01 that the highest and lowest temperature of Ansai County were increased 0.42℃ and 0.26℃ respectively.The vegetation in growing season decided distribution of the vegetation coverage in Loess Plateau.Therefore,when NDVI in growing season increase 0.01 that relative humidity was increased 1.14%,evaporation and wind speed was decreased 49.70 mm and 0.06 m·s-1.It concluded that the vegetation restoration of Loess Plateau have obvious effects on climate of the county regions that locate in Loess Plateau.