基于TM影像的草原沙漠化植被盖度分析研究

Analysis on vegetation coverage of grassland desertification based on TM image

植被盖度是草原沙漠化评价的重要指标,以TM影像为数据源,结合地面调查数据和对应点的NDVI值,建立了植被指数与植被盖度间的回归模型,利用该模型生成植被盖度分布图;同时利用前人的植被盖度计算经验公式,生成同一区域的植被盖度分布图,并分别对其植被盖度数据进行分级。对比分级结果,发现:通过大量的地面调查数据建立的盖度分析模型分类精度较高,总精度达到85.42%,而通过经验公式计算,效果相对较差,其分类精度仅有75.00%。

The vegetation coverage is the key factor for grassland desertification evaluation. Basing on TM images and combining with the ground data and NDVI of storey points, the model of NDVI and the vegetation coverage were established as C = 115. 482 × NDVI ＋ 20. 046. The correlation coefficient was 0. 803, and F test showed a more significant result. According to this model and the acknowledged formula C = （NDVI -NDVIs）/（ NDVIv -NDVIs） , the vegetation coverage map was generated and then was used for grassland desertification evaluation. Comparing the results of classification we found that a higher accuracy of 85.42% can be got with the established model while the relatively poor classification accuracy with the formula as only 75.00%.