大针茅（Stipagrandis）草原不同利用强度下植被反射波谱季节变化特征及其与产草量相关性的比较研究

在整个生长阶段三个退化程度群落的近红外反射率之间都存在显差异；在8月底至9月底期间，不退化群落与重度退化群落可见光反射率之间差异显。在6月底－9月底期间建立的估产模型在不退化的中（轻）度退化的群落中都无显差异，但分别与5月底的估产模型差异显；重度退化的冷蒿草原群落在5月底产草量与植被指数之间无显相关性，7月底与8月底建立的产草量估测模型与6月底、9月底的产估模型之间分别差异显。对大针茅草原不同退化程度群落生长高峰时期的产草量平均估测精度在95％左右。

A Comparative Analysis between the Seasonal Multispectral Reflectance and Biomes of Step Grandees in Different Grazing Degradation Degree

The reflectivity on near infrared bands were remarkable difference among the three communities in the whole growth season,the reflectivity on visible light bands were remarkable difference between the non degradation and heavily degradation community from the end of August to the end of September.The were not remarkable difference in the estimating models formed by NDVI among the end of June and the end of September,but they had significant difference with the model in the end of May between non degradation and (light) degradation community;For the heavily degradation community,the relativity among biomass and vegetation indexes were not remakable in the end of May,there were remarkable difference among the models established in the end of June,September and the end of July.August.The average estimating precision of the models at the end of August were about 95%,respectively,for the three different communities of Stipa grandees steppe.