Research of Vegetation Spatial-temporal Variation and Evolution in Yongjiang Basin

The annual mean NDVI time series in Yongjiang Basin in 2000-2010 were obtained by maximum value composite (MVC) method and average value method based on MOD13Q1 data with resolution of 250m, and the spatial-temporal variations of the vegetation status in the river basin analyzed using the methods of simple linear regression & F test, correlation coefficient and variation coefficient. The results showed that: The average values of NDVI in Yongjiang Basin were high in the ambient, but were low in the middle. The values of NDVI in vegetation coverage area in Yongjiang Basin fluctuated in the range of 0.42 ~ 0.54. NDVI in Yongjiang Basin showed high fluctuations from 2000 to 2004, but with relatively slow and stable growth trend since 2004. 92.87% of vegetation covered area presented a medium-low variability, and only 7.13% area showed high fluctuations. During the period of 2000-2010, the area with an increase of NDVI value was much larger than the area with a decrease of NDVI value. The improved area occupied 56.02% of vegetation covered area, the depraved area accounted for 13.36%, and the rest 30.62% remained unchanged.