宁夏植被覆盖动态变化及与气候因子的关系

 利用1999—2009年的SPOT-VGT NDVI数据,计算出宁夏近11 a来的植被覆盖度,对其变化特征进行了研究,结合同期气象观测资料,从空间上分析了植被覆盖度与区域气候因子之间的关系。结果表明,南部六盘山区和北部引黄灌区植被覆盖度高,而中部干旱带等地区的植被覆盖度较低,但中部干旱带却有较高的绝对变化率;从时间变化来看,近11 a来宁夏大部分地区的植被覆盖度在逐年增加。植被覆盖度的变化与气候因子有关,除引黄灌区和六盘山林区外,中部干旱带等地的植被覆盖度与降水呈正相关,区域气候的干湿波动,影响了植被覆盖度的高低;在有灌溉保障条件的农业垦殖区,植被覆盖度还与气温呈正相关,即有效积温的增加,会促进农作物生长,从而导致区域植被的覆盖度提高。

Vegetation Coverage Variations in Ningxia during 1999--2009 and Its Relationships with Climatic Factors

We calculated the vegetation coverage of Ningxia based on the 10-day SPOT VGT NDVI data from 1999 to 2009, and analyzed its variation by use of regression analysis and mean absolute deviation indices. The relationship between vegetation coverage and regional climate factors was also analyzed based on the meteorological observation data of the corresponding period. Results showed that the vegetation coverage was relatively high in the Liupanshan Mountains area of southern Ningxia and Yellow River irrigation area of northern Ningxia, and low in arid zone of middle Ningxia, but there was a large absolute deviation rate in the middle zone during 1999-2009. The vegetation coverage in most areas of Ningxia increased in the recent 11 years. The vegetation coverage variations are related to climatic factors. Firstly, the fluctuations of precipitation influence the vegetation coverage variations. Except in Liupanshan Mountains area and Yellow River irrigation area, there are significantly positive correlations between vegetation coverage and precipitation in the other areas of Ningxia. Secondly, the increase of effective accumulated temperature can promote crops growth and lead to regional vegetation coverage increasing. In the agricultural irrigation areas, there are also positive correlations between vegetation coverage and annual mean temperature.