黄土高原植被覆盖度变化的地形分异及土地利用/覆被变化的影响

Topographical variation of vegetation cover evolution and the impact of land use/cover change in the Loess Plateau

基于16 d合成MODIS NDVI数据提取的时间序列植被覆盖度数据,采用一元线性回归趋势分析,对黄土高原2000-2008年植被覆盖度的时空变化及其地形分异、土地利用/覆被变化的影响进行了定量分析。结果表明:(1)研究时段黄土高原植被覆盖度整体呈快速上升趋势,局部下降;(2)黄土高原植被覆盖度变化存在明显的地形分异,陡坡等植被恢复、重建和保育的主要区域植被覆盖度增速显著;(3)土地利用/覆被变化对植被覆盖度的增加影响突出,土地利用/覆被类型变更区植被覆盖度增速显著高于未变化区域,退耕还林还草区增速尤其突出;(4)土地利用/覆被类型未变化区域植被覆盖度总体上也呈增加趋势,但因植被覆盖度水平相对较高,增速明显低于土地利用/覆被类型变化区。上述结果表明,黄土高原植被保育、植被恢复和重建在植被覆盖度提升方面取得了明显成效。

Based on the fraction of vegetation cover （FC） derived from 16-day composite MODIS NDVI data, us ing linear regression approach, the trend of the vegetation cover evolution in the Loess Plateau during 2000-2008 was quantified. The topographic variation of and the effect of land use/cover change has on the FC change rate were quantitatively analyzed. The results show as follows ： （ 1 ） the FC generally increased in most parts of the Loess Pla teau, accompanied by decrease in some patchy areas; （2） there is apparent topographic variation in change rate of FC, characterized by high increase rate in key areas for vegetation restoration and conservation; （3） the land use/ cover change dramatically impacts vegetation cover evolution, compared with areas with consistent land use/cover types, the FC change rate is particularly higher in areas with shifted land use/cove types, especially in Green for Grain Project areas; （4） for areas with consistent land use/cover types during the assessed period, partly due to the higher FC baseline, the mean vegetation cover also increased, however, at a lower rate. It can be concluded that the vegetation restoration and conservation significantly promoted FC in the Loess Plateau during 2000-2008.