基于NDVI的米仓山植被覆盖变化趋势分析

基于1998年4月至2009年12月的SPOT-VEGETATION逐旬NDVI数据,采用MVC(最大值合成法)获得月NDVI值,用均值法计算各季及年均NDVI值;对5种植被类型的年均NDVIy和生长季NDVIg进行一元线性回归,辅助以趋势线分析定量描述研究区植被覆盖动态变化,并采用R/S分析(重标极差法)动态预测米仓山植被覆盖未来变化趋势。结果表明:研究区12年间NDVI整体呈上升趋势,相对于前期(1999~2001年)、中期(2003~2005年)和后期(2007~2009年)的NDVI增加显著;年最大NDVI≥0.70的区域占总面积的98.95%,年均NDVI≥0.70的区域占93.69%,且植被覆盖增加的面积远大于减少的面积;划分的5种植被类型中,阔叶林类NDVI值最高,人工植被类NDVI值最低;R/S法计算结果显示,Hurst指数(H)为0.876 8,表现为很强的持续性,预示未来一定时限内米仓山植被覆盖将有稳定的增加趋势。

Analysis on the Variation Tendency of Vegetation Cover of Micang Mountains

By using SPOT VEGETATION data with a resolution of 1 km,the tempo-spatial dynamic of vegetation was analyzed using cumulative average method,average method,trend line analysis and image differencing with the SPOT VGT-NDVI data and Hurst exponents were utilized to predict the future trends of grassland cover change in Micang Mountains.The results show that:(1)about 98.95% of the total area had a higher annual max NDVI than 0.70,and about 93.69% had a higher annual average NDVI in the region of the Micang Mountains.The area where the vegetation coverage increased was greater than that where the vegetation was degraded.However,12 years NDVI presents the overall uptrend,broad-leaved forest NDVI value is the highest in the five types of planting,and the NDVI value of artificially vegetation is the minimum.Using Hurst index for dynamic vegetation change prediction shows that interannual H value is 0.876 8,means performance for strong sustainability,H value for 5 planting types in spring,summer,autumn are strong.While H value for artificial vegetation in winter have very weak reverse sustainability.