Abstract:
Based on mathematical statistics and projection pursuit clustering, NDVI of Shaanxi province from 1999 to 2007 was evaluated. The results showed that: (1) NDVI of various vegetation types throughout the year and the four seasons were on the rise in three regions, the largest increase of NDVI throughout the year was distributed in the south of Shaanxi province; and the largest increase of NDVI among four seasons was spring; (2) NDVI of the sparse increased most significantly, followed by the evergreen broad-leaved forest and slope grassland, and the largest increase of NDVI among four seasons was still spring; (3) it was easy for NDVI information to be extracted between class and class in spring, and sub-categories of other types except grass was obtained easily in winter; It was suitable to pick up sub-category of grass and the information between desert and grassland in summer, and it was suitable to extract the information of various types and sub-categories in autumn; (4) The vegetation cover of Shaanxi province improved significantly year by year, and its effect was obvious; the improvement trend of vegetation cover has essentially reached the upper limit and it is important to maintain the vegetation cover state.
