黄土高原典型区植被冗亏

选择了黄土高原中部典型区——泾河流域为研究区域。采用Holdridge潜在蒸发方法计算出了泾河流域的气候干燥度指数,构建了遥感植被指数与气候干燥度指数之间的回归模型。通过该模型反衍出了泾河流域潜在植被指数,提出以该指数为基础的植被冗亏格局的评价新方法。通过该评价方法发现,在泾河流域西北部的大部分子流域的植被冗亏指数小于-0.2,植被亏缺较为严重;在自然环境较差的流域北部,植被冗亏指数介于-0.20到-0.10之间,植被亏缺较轻;而流域东南部山区的大部分子流域的植被冗亏指数介于-0.10到0.10之间,植被亏缺最轻。从植被冗亏的时间尺度上分析,植被亏缺主要发生在植被生长旺盛的6~9月份,其中农田植被亏缺最大,冗亏指数在7月份可达到-0.51;稀疏草原植被亏缺较小,其冗亏指数最小值在-0.18左右;森林植被的冗亏指数接近于0。

Redundancy and deficiency of vegetation in a typical region of the Loess Plateau

Jinghe River Basin was chosen as a typical region of Loess Plateau. Potential evaporation equation of Holdridge was employed to calculate climatic aridity index (AI), and construct the regression model between Normalized Difference Vegetation Index (NDVI) and AI. Based on this model, we reversely deduced the potential vegetation index of Jinhe River Basin and proposed. a novel assessment method to quantify vegetation redundancy and deficiency (VRD). By this method, we found that the VRD indices for most watersheds of the northwestern basin were less than -0.2, displaying a severe vegetation deficiency. In the northern basin with atrocious natural conditions, the VRD indices ranged from -0.20 to -0.10, a relatively slight deficiency. However, in southeastern hilly of the basin, the indices were only between -0.10 and 0.10, the least deficiency. If analyzed in time series, vegetation deficiency generally occurred in high-vigor period from June to September. Farming vegetation had the largest deficiency, with the VRD index of -0.51 in July. Vegetation deficiency of sparse pasture was in the middle, with VRD index of -0.18 and that of forest vegetation was the least.