半干旱黄土区退耕还林十年植被恢复变化分析——以陕西吴起县为例

摘要

黄土高原退耕还林(草)政策实施已逾10 a,了解植被恢复变化状况及存在的问题,对于制定和完善生态环境治理方略具有重要意义.以吴起县为例,基于实地调查及遥感等数据,对退耕还林(草)以来植被覆盖度、主要植被类型变化及不同立地条件下植被恢复变化的差异进行了定量分析.结果表明:2000年至2009年,植被覆盖度大于30%的面积在全县总面积中的比例由不足1%上升至91.96%;其中缓坡立地类型上的乔灌林地类犁面积增长最为显著,而阳向陡坡等恶劣生境下的植被恢复缓慢;有林地、灌木林地及疏林地均呈现规模增大趋势,属扩张状态;中覆盖度草地、低覆盖度草地、坡耕地及耕地呈现规模减少趋势,属缩减状态.%The project of returning cropland to woodland or grassland has been put in practice for ten years on the Loess Plateau,China.Understanding the situation of vegetation restoration since the project is important for developing further strategy to sustain and enhance the effects.As a case study, change of vegetation coverage, vegetation types in Wuqi county, Shaanxi province, from 2000 to 2009 were analyzed based on the field investigation, DEM and remote sensing data.The results showed that land area with vegetation coverage more than 30％ was not up to 1％ of the total area of Wuqi in 2000, but it made up to 91.96％ of the total area in 2009.From 2000 to 2009, the area of shrub-land and woodland expanded obviously on the gentle slope, but vegetation recovery on steep and sunny slope was very slow.Woodland, shrubland and sparse woodland were in the extended-state.Mid-coverage grassland,low-coverage grassland and cropland decreased in area, being in the shrinking-state.