基于RS的盐池县近10年植被覆盖度动态变化研究

为研究农牧交错区植被覆盖度的变化,从盐池县1999年、2004年和2010年3期TM/ETM+影像图入手,利用归一化植被指数(NDVI)反演了盐池县的植被盖度,结果表明:1999年、2004年、2010年平均植被盖度分别为24.08%,26.97%和23.92%,总体呈现出现先增加后减少的趋势。对这3a的植被覆盖度进一步进行分级,发现1999年、2004年、2010年3个时期,低植被盖度所占的比例分别为59.61%,50.75%,62.6%,呈现先减少后增加的趋势;中等植被盖度所占比例分别为34.54%,34.58%,29.20%,呈现先增加后减小的趋势,增加的趋势不明显;高植被盖度所占比例分别为5.85%,14.68%,8.2%,先增加后减小。影响植被覆盖度变化的因素主要有人为及政策因素、气候因素(主要是降水)。

RS-based Study on Dynamics of the Vegetation Coverage in Recent 10 Years in Yanchi County

In order to understand the change of vegetation fraction in agro-pastoral transition area,based on TM/ETM+ images in 1999,2004 and 2010,this study deduced vegetation coverage by using the Normalized Difference Vegetation Index(NDVI) in Yanchi County.It was revealed that the average vegetation coverage in 1999,2004,2010 were 24.08%,26.96%,and 23.92%,respectively,the general trend was decreasing following an increase.The coverage vegetation coverage of these years was further classified.The results showed that the low proportion of vegetation coverage were 59.61%,50.75%,62.6% for 1999,2004,2010,respectively,showing decrease and then increase;the moderate proportion of vegetation coverage were 34.54%,34.58%,29.20%,showing decrease after an increase,and increasing trend was not obvious;the high proportion of vegetation coverage accounted for 5.85%,14.68%,8.2%,respectively,showing decrease after an increase.Major factors influencing local vegetation coverage in this area were human activity,policies and climate(precipitation).