基于Hyperion和ASTER影像的喀斯特石漠化评价指标提取对比研究

中国西南喀斯特地区以石漠化为特征的生态环境退化现象严重,遥感是获取大尺度石漠化评价指标的主要手段.但目前还没有直接从遥感图像快速、客观有效地提取石漠化评价指标的应用.基于植被指数(NDVI)、石漠化综合光谱指数(KRDSI)和木质素—纤维素吸收指数(LCA),对比分析利用Hyperion 高光谱遥感影像及其模拟的ASTER多光谱遥感影像直接提取石漠化评价指标的可行性和精度.研究表明,利用Hyperion高光谱影像能够比较有效地直接反演绿色植被、干枯植被、裸土等的覆盖信息,但由于不同碳酸盐岩及其不同侵蚀程度的光谱特征差异,直接反演基岩裸露的精度较低；而利用ASTER多光谱影像能够直接有效提取直接反演绿色植被、裸土等的覆盖信息,但由于ASTER影像波段设置的局限性,使其直接提取干枯植被盖度和基岩裸露率的效果较差.

Comparative Study of Indicator Extraction for Assessment of Karst Rocky Desertification Based on Hyperion and ASTER Images

In the karst regions of Southwest China,rocky desertification is one of the most serious problems of land degradation.Because of the inherent merits of macro scale,frequency,efficiency and synthesis,remote sensing is the promising method to monitor and assess karst rocky desertification.However,existing remote sensing methods can not directly be exploited to extract the information on karst rocky desertification owing to the high complexity and heterogeneity of karst environments.Based on NDVI,karst rocky desertification synthesis indices(KRDSI)and lignin-cellulose absorption index(LCA),this study compared the feasibility and accuracy of indicator extraction for the assessment of karst rocky desertification with Hyperion and simulated ASTER images.Results showed that Hyperion imagery can be used to efficiently and directly extract the information on the fractional covers of photosynthetic vegetation,non-photosynthetic vegetation and bare soil,while the proportion of exposed bedrock was not so good due to the different types and weathering processes of carbonate rocks.As for multi-spectral image,ASTER can be used to estimate the fractional cover of photosynthetic vegetation and bare soil,but could not be utilized for accurate estimation of the fractional covers of exposed bedrock and non-photosynthetic vegetation due to the limits of spectral bands and spectral resolution.