Building and Application of Vegetation Growth State EvaluationModel in the Yellow River Basin Based on MODISData in Time Series

摘要

It is the most important to evaluate changes of environment according to vegetation growth state. In this paper, vegetation growth rules in various underlying surface are analyzed, and the relation between standard deviation and mean value based in feature space is also studied. We select various kinds of vegetation in various positions of the Yellow River Basin. The pixels position of various vegetations in the feature space indicates that the related coefficients between standard and mean value be high, but the differences could be obvious with differences of various kinds. According to above analysis, set up VGSEM model ( VGSEM = 2 x 90 x arctan (S/P) (S —standard deviation , P — mean value ) ) , and then put into application in the Yellow River basin to evaluate vegetation growth state according to real condition of various subzone areas. The research result shows that the vegetation growth condition in the areas above Lanzhou and riverside regions is good, but there exists some deviation due to the difference between vegetation types , so the difference of cropland, leaf — fall and evergreen vegetation should be considered in the actual application.