秦岭南北地区植被覆盖对区域环境变化的响应

利用GIMMS(Global Inventory Modeling and Mapping Studies)和SPOT VGT(Spot Vegetation)两种数据集的归一化植被指数(Normalized Difference Vegetation Index, NDVI)对1982~2007年26年间秦岭南北地区植被覆盖变化进行了比较，并对其环境驱动力进行了分析.结果表明，研究时段内，秦岭南北地区的植被覆盖均呈降低趋势，且秦岭以北地区的降低速度大于秦岭以南.经计算分析得出，两地区春季和夏季的季平均NDVI与温度的相关系数均通过了p<0.1的显著性检验，其中，秦岭以南地区1982~1997年春季NDVI与温度的相关系数最高为0.61(p<0.05)；秦岭以北地区春季的降水与年NDVI之间也显著相关(p<0.05).值得注意的是，1998~2007年间，秦岭以北地区冬季NDVI与温度相关系数高达0.75(p<0.05)，这是秦岭地区在区域环境影响下植被覆盖变化的一个重要特征，表明秦岭以北地区的植被更多地受气温变化的影响，在全球变暖大趋势下，该地区植被可能更为敏感，是区域生态响应的一个重要信号.人为活动（如土地利用类型的改变）也是影响该区植被覆盖变化的一个重要因子.

Responses of vegetation coverage to regional environmental change in the northern and southern Qinling Mountains

By analyzing the NDVI data from the GIMMS (Global Inventory Modeling and Mapping Studies) and SPOT VGT, we investigated the change of vegetation coverage from 1982 to 2007 and its relationship with climate changes in the northern and the southern regions of the Qinling Mountains. The vegetation coverage in both regions tended to decrease with time over the last 26 years, and a greater rate of decrease was found in the northern regions. Correlation analysis showed that the seasonal mean NDVI in spring and summer were tightly correlated with temperature for both regions (p<0.1), and the highest correlation coefficient of 0.61 was found in the southern regions during 1982 to 1997. The annual mean NDVI in the northern regions was also correlated with the precipitation in spring (p<0.05). In 1998~2007, the correlation coefficient of winter's NDVI to temperature in the northern Qinling Mountains was as high as 0.75 (p<0.05), which represented an important signal of regional ecological response to global warming. The vegetation in the northern regions of the Qingling Mountains was more sensitive to the temperature changes than that in the southern regions. The impact of human activities, such as the land-use types, was also important to the change of vegetation coverage in the Qinling Mountains.