【摘要】 阿拉善盟为中国生态环境重度危急区与北方地区的天然保护屏障,及时、科学、准确地评价其植被指数的地形分异特性,对其植被建植与生态恢复具有重要的参考价值和现实意义。以美国航空航天局的陆地专题产品MOD13Q1-NDVI为时间序列数据集,利用ENVI中波段计算功能提取2000-2016年植被生长季(7-9月)覆盖阿拉善盟的植被指数信息,同时结合栅格化数字高程模型,利用Arc GIS空间统计功能中的表面分析工具提取栅格尺度上的坡度、坡向及地形起伏度等地形因子,并通过区域统计获取各地形因子级别区内植被指数的空间分布特征。结果表明:(1)采用均值变点分析法确定的阿拉善盟地形起伏度的最佳统计单元为0.26km~2;(2)阿拉善盟以中山区为主,所占比例高达79.05%;坡度以第Ⅰ(0-2°)与Ⅱ(2°-5°)级别区为主,所占面积比例高达90.62%,在空间分布上呈分散状态;坡向分布较为均匀;地形起伏度级别区以平原和台地为主,所占比例高达87.83%。该区地形具有西南高、东北低,平坦、起伏小的分布特征;(3)以植被指数低值区(<0.1)和中低值区为主(0.1-0.2),且呈现西北和东南区域两级分化的空间分布特征。总体而言,在地形因子作用下,阿拉善盟植被指数均值分布具有明显的地形分异性,且植被指数高值区主要集中分布在高程为1 000-1 600 m的中山区与坡度>15°的西坡。更多还原

【Abstract】 It is an important prerequisite for further study of spatial patterns and scientific management of vegetation which understand the relationship between vegetation distribution and topographic features because of the Alxa League as a serious ecological area in China and natural protective barrier in the northern region. The relationship between vegetation index and topographic features in Alxa League during the period from 2000 to 2016(7-9 months) based on MODIS-NDVI time series derived from National Aeronautics and Space Administration and DEM datas by using Spatial Analysis Tool with GIS and ENVI was studied. The results showed that,(1) With the support of mean change-point analysis, the curve appeared at the inflection point at the grid of 9×9 mesh size(0.26 km~2) for relief amplitude.(2) Elevation was dominated with the central mountain region(1 000-1 600 m), and accounted for a high proportion with 79.05%; slope was dominated with 0-2° and 2°-5°, and accounted for a high proportion with 90.62%, which was scattered in spatial distribution; the distribution of aspect was relatively uniform; the relief amplitude was dominated with plain and platform, which accounted for a high proportion with 87.83%; the terrain was characterized by high in the southwest and low in the northeast, flat in topography and small in fluctuation. And(3) the vegetation index area was dominated with the low value area(<0.1) and the middle and low value area(0.1-0.2). Further, the spatial distribution characteristics of regional differentiation in the northwest and southeast regions were also presented. Collectively, under the effect of topography factors, the distribution of vegetation index mean had a certain topographic differentiation. Moreover, the high value area of vegetation index was mainly distributed in the middle mountain area with a elevation of 1 000-1 600 m and the west slope greater than 15°.更多还原