陕西省植被时空演变特征及其对气候变化的响应

Characteristics of Temporal-Spatial Evolution of Vegetation Cover in Shaanxi Province and Its Response to Climate Change

利用GIMMS/NDVI数据分析了陕西省1982—2006年的植被覆盖时空演变,并探讨了植被时空变化对气候变化的响应。分析发现,陕西省NDVI空间分布具有自南向北递减的特点,陕西北部、中部和南部三区四个季节的NDVI均以夏季最大,春季和秋季相当,冬季最小。25年来,三区NDVI显著增加,其中以春季增幅最大,夏季反而有下降的趋势。三区气温增加趋势明显,导致生长期的延长,这是NDVI增加的主要原因之一;三区年总降水呈减少趋势,降水的减少并未使得NDVI减少,这说明当地降水可以满足植被生长的基本条件;夏季NDVI的减少可能与人类活动增加有关。在年内尺度上,三区温度的增加利于植被覆盖的增长;降水量的增加为植被覆盖的增长提供更充足的水分,NDVI的增加主要出现在月降水量小于100mm时,当该月降水量大于100mm时NDVI并无明显增加趋势。

The paper analyzes the temporal and spatial evolution of vegetation cover and its response to climate change of Shaanxi Province during 1982 to 2006 by using GIMMS/NDVI data.The outcomes show that temporal and spatial distribution of NDVI of Shaanxi Province has the characteristics of reduction from south to north,and the NDVI of the north,south and central areas is the maximum in summer,comparative in spring and autumn and the minimum in winter.In 25 years,the NDVI of the three areas is notably increased,and the growing rate is the maximum in spring and the reduction tendency in summer.The trend of temperature increase is clear,resulting in extension of growing period.This is one of the main reasons of NDVI increase.The total annual precipitation of the three areas shows the trend of reduction,while the reduction of precipitation has not caused the reduction of NDVI which shows that the local precipitation can meet the basic requirements of vegetation growth.The reduction of NDVI in summer may relate to the increase of human activities.In inter-annual scales,the increase of temperature of the three areas is advantageous to the growth of vegetation and more precipitation can supply more water to benefit the growth of vegetation.When the monthly precipitation is less than 100 mm,NDVI increases significantly.however,when the precipitation is greater than 100 mm,the clear growth trend does not exist any more.