2000-2012年中国北方草地NDVI和气候因子时空变化

利用2000-2012年的MODIS NDVI数据,结合中国北方187个气象基准站年均温度和年降水量资料,对2000-2012年中国北方草地NDVI的时空变化特征和同期年均温度、降水量动态变化进行了分析。结果表明:(1)草地NDVI无明显变化的区域占北方草地总面积的64.35%,以荒漠草地为主;草地退化区域的面积(占北方草地总面积的23.97%)大于改善区域的面积(占北方草地11.68%)。(2)NDVI变异系数分析结果表明,2000-2012年以来中国北方草地68.37%区域呈稳定状态。其中,荒漠草地植被变异性较小,处于相对稳定状态的草地占其总面积的79.73%;而灌丛草地和典型草地的变异性较大,变化显著的草地分别占其草地面积的41.55%和45.92%。(3)北方草地区中,54.04%的区域年均温度呈升高趋势,大于温度呈降低趋势的区域,温度升高幅度最大为0.159 ℃·a^-1;年降水量呈增加趋势的面积达71.01%,远大于呈减少趋势的面积,降水量增加的最大幅度为23.29 mm·a^-1。

Spatio-temporal Changes of NDVI and Climatic Factors of Grassland in Northern China from 2000 to 2012

Based on MODIS NDVI data, combined with average annual temperature (AAT) and annual precipitation (AP) collected from 187 meteorological reference stations from 2000 to 2012 in northern China, this paper analyzed the spatio-temporal characteristics of NDVI and dynamic change of AAT and AP in past 13 years. The result showed that: (1) The grassland in most study areas doesn't appear significant change trend, and the main type is desert grassland; From view of change region, the degraded region (accounting for 23.97% of the grassland in northern China) is slightly greater than that of improved region (accounting for 11.68% of the grassland in northern China), it's main type is shrubland and typical grassland. (2) The principal part of the grassland in northern China is stable relatively in recent 13 years, which accounts for 68.37%. Among them, the desert grassland has less change, and its area in relatively stable condition accounts for 79.73% of this type of grassland. The shrubland and typical grassland have great change, and account for 41.55% and 45.92%, and their area of the coefficient of variation less than 1.5 accounts for 91.42% in the past 13 years. This shows that most of grassland in northern China is in a relatively stable status. (3)The region with a slight increasing trend of the AAT is larger than that with a decreasing trend of the AAT. The area of increasing temperature accounts for 54.04% of the grassland in northern China, the maximum increasing magnitude of AAT is 0.159 ℃·a^-1; The region with increasing trend of the AP is significantly larger than that with a decreasing trend of the AP. The area of increasing precipitation accounts for 71.01% of the grassland in northern China, the maximum increasing magnitude of AP is 23.29 mm·a^-1.