2000—2012年中国北方草地NDVI和气候因子时空变化

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

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23.29mm·a-1。

Based on MODIS NDVI data,combined with average annual temperature(AAT)and annual precipitation(AP)collected from187 meteorological reference stations from2000 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 than1.5 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.