基于MODIS EVI的重庆植被覆盖变化的地形效应

The Response of Dynamic Change in Vegetation Coverage to Topography in Chongqing Based on MODIS EVI

基于2000—2015年的MODIS EVI数据,采用趋势分析结合地形差异修正,分析了重庆市植被覆盖变化在高程、坡度和坡向上的空间分布差异。结果表明:1)近16 a来,重庆植被以低覆盖度和中覆盖度为主,低覆盖度呈下降趋势,劣覆盖度、中覆盖度和高覆盖度呈上升趋势;2)研究区植被显著减少趋势占3.84%,基本不变占81.12%,显著增加占15.04%,植被变化总体上呈恢复趋势;3)在地势低(<400 m)、坡度小(<6°)的区域,植被覆盖度低,但变化趋势显著;在400~1 200 m、6°~15°的区域,植被变化趋势分布出现由优势到非优势或由非优势到优势的转折;4)在地势高(>1 200 m)、坡度大(>15°)的区域,植被覆盖度高,变化趋势较弱,但是在高程大于1 500 m、坡度大于25°的区域也存在植被减少的现象;5)不同坡向上,除了在平地区域植被变化趋势较显著外,其余坡向差异不明显。

The annual change and spatial variation of vegetation coverage in Chongqing during 2000-2015 were studied based on the MODIS EVI datasets.The method of trend analysis was used,and the coefficient was corrected by topography.The response of vegetation coverage to elevation,slope and aspect were analyzed.The results showed that： 1） The coverage of vegetation was dominated by the low and medium coverage.The low coverage was in decline,while the poor,medium and high coverage was increasing.2） A large proportion of vegetation was in increasing trend,however,with fluctuation.The proportions of the decreased,stable and increased trends of vegetation changes were 3.84%,81.12% and 15.04%,respectively.3） The vegetation coverage was low in the areas where the elevation was below 400 m and the slope was below 6°,however,the coverage changed significantly.There were shifts of dominant change types in the areas where the elevation was between 400 m and 1 200 m and the slope was between 6° and 15°.4） The vegetation coverage was high and stable in the areas where the elevation above 1 200 m and the slope was above 15°.However,the vegetation coverage was decreasing in some area where the elevation was above 1 500 m and the slope was above 25°.5） In different aspects of slopes,there was no obvious difference of the vegetation coverage change except in the flat area.