Seasonal Variation of Vegetation Spectral Characteristics at Yunnan Nujiang River Basin

[Objective]The aim was to analyze the seasonal variation law of vegetations in Yunnan Nujiang River basin.[Method]Based on comprehensive field survey and image analysis,it developed a classification system for Nujiang River basin based on remote sensing,in which the basic units is reference to the subtype in Yunnan Vegetation.In total,there are 19 types of natural vegetation and plantation forest.Make use of TM images in 2009 as data source to interpret the vegetation on the protected areas by human-computer interaction,then used MODIS NDVI data to extract various types of information on seasonal variation of MODIS NDVI.5 indexes of seasonal variation of vegetation spectral characteristics were constructed to analysis vegetation variation.[Result]As for NDVIjmax,evergreen type was more than deciduous type;forest was more than shrubs and shrub-grassland;meadows were the minimum.As for NDVIjmin,forest was more than shrubs and shrub-grassland;meadows were the minimum.As for NDVIjm,evergreen broad-leaved forest was high,the secondly for coniferous forest,deciduous broad leaved forest,plantation and bamboo forest;shrubs and meadows were relatively lower;two kinds of meadows were the minimum.As for NDVIjr,deciduous type was generally more than evergreen type;shrubs and shrub-grassland were more than the other types;the regions with good humidity and temperature were more than the other regions.As for NDVIja,forest was more than shrubs and shrub-grassland basically;meadows were the minimum.[Conclusion]The indexes reflect the seasonal changes of vegetation evidently.