天山北坡天然草场光谱植被指数的基本特征

用1989-1991年在天山中段不同草场类上观测的光谱资料和状草产量资料，分析了天然草场光谱植被指数的日变化、季节变化及年际变化的特征，并比较了不同草场类型的差异。结果表明:天然草场光谱植被指数随太阳高度角的上升而降低;随牧草产量的增加而增加;不同年份的光谱植被指数不同，反映了因气候条件的变化引起的收草产量变化。不同草场类型的光谱植被指数也有显著差异，这种差别可为草场类型的识别和分类提供信息和依据。

The Basic Characteristics of Spectral Vegetation Indices in Tiansan North Slope Natural Grassland

Using grass spectral and yield data observed in different type natural grassland in Tiansan NorthSlope during 1989-1991,the diurnal,seasonal,annual variation characteristics of vegetation in-dices are analysised,the discrepancy of different type natural grassland is compared.The resuItsshow that the spectral vegetation indices decrease as solar altitude increases,and increase as grassyield increases.There is divergence to different years for the same type of grassland,this divergenceis a reflection of grass yield variation caused by the variation of climate conditions.The spectral veg-etation indices have significant diversity for different grassland types,and this diversity provides ba-sis for the grassland distinguishing and classifying.