西藏当雄河谷阳坡海拔梯度上植被光谱特征分析

以西藏当雄河谷阳坡海拔梯度上植被冠层光谱为研究对象，分析不同海拔位置上植被光谱特征差异及物理含义，通过植被光谱特征的分层聚类分析，评估当雄阳坡植被垂直分布的遥感识别可行性。结果表明：水分指数(WI)、光谱红边位置(REP)、归一化植被指数(NDVI)分别与叶片水分含量、干重生物量、植被盖度存在较强的相关性，且不同植被类型间的WI，REP和NDVI存在显著差异;基于光谱特征集的分层聚类分析实现了阳坡12个样点逐级分类，其结果与地面调查基本匹配，表明所选择的植被光谱特征能够表征实验区垂直分布的植被类型差异，分析结果可为青藏高原植被垂直分布信息的遥感提取提供光谱特征的先验知识支持。

Analysis on Vegetations Spectral Characteristics along the Altitudinal Gradients in South-Facing Slope of Dangxiong Valley

The present study focused on variation of vegetation types and canopy spectra along the altitudinal gradients in south-facing slope of Dangxiong valley in Tibet. Spectral extraction methods including red edge analysis and vegetation indices were used for vegetation spectral characteristics analysis. Through the hierarchical clustering analysis based on the vegetation spectral features, the feasibility of remote sensing classification of vegetation types along the elevation gradients in the experimental area was evaluated. The experimental results showed that: there were significant differences in spectral features including water index (WI), red edge POSITION (REP), and normalized difference vegetation index (NDVI) in different plots along elevation gradients in the study area, and there were strong correlations between WI and leaf water content, REP and dry biomass, NDVI and vegetation coverage. The hierarchical clustering analysis result of 12 vegetation samples along the altitudinal gradients is consistent with the ground survey, which shows that the selected vegetation spectral features can characterize the vertical distribution of vegetation types in the experimental area. The vegetation spectral analysis in this study can provide the priori knowledge support of spectral characteristics for the vegetation vertical distribution information extraction in the Tibet Plateau.