摘要
气候是植被变化的重要驱动因子.利用1981-2006年GIMMS归一化植被指数(NDVI)时间序列数据,结合68个气象站降水、气温数据和DEM地形数据等资料,研究分析了西北干旱区植被活动的年、季变化和空间差异.结果显示:在1981-2006年的26 a,西北干旱区植被的覆盖率增加了4.5%,年平均NDVI增加了3.2%;植被的生长季延长,主要表现在生长季的推迟.从总体来说,植被覆盖率、生长季和NDVI值在2000年以前显著增加,而在2000年以后都呈现减小的趋势;其中,减少明显的区域是在伊犁河谷、中天山及平原区,在河流上游山区或源头以及部分河流两岸呈现增加态势;在年际变化上,大部分区域的气温、降水与NDVI相关性不强.而年平均气温在4.58℃以下低温区和年降水在180 mm以上的相对湿润区,气温和降水都呈现正相关;在季节变化上,NDVI值在春季和秋季与温度相关显著,而夏季与降水相关性强.2000年以后,植被覆盖率和NDVI值开始出现降低趋势与气温持续升高、降水量增幅下降有关.
Meteorological data show that air temperature and precipitation have changed greatly in Northwest China during the past half century. The climate change, combined with human activities with large-scale and high intensity, leads to change in vegetation. Since climate is the major driving factor to vegetation changing, the study of spatial and temporal changes of vegetation due to climatic variation should be carried out in Northwest China, an extremely vulnerable region in ecology and environment. Meteorological and NDVI time series data- sets from 1981 to 2006 and other geographic data were used to reveal the spatial and temporal variations of vege- tation in the arid regions of Northwest China. It is found that （1） NDVI and vegetation area have increased 3.2% and 4.5%, respectively, in the last 26 years. And a lengthening of growing season and a delaying autumn has taken place; （2） Vegetation area had a significant increase before 2000, but followed by a decreasing after that, such as NDVI and vegetation area in the Yili River Valley, the Middle Tianshan Mountains and the plain regions had significantly decreased while in the upper reaches of rivers and mountain areas had increased ; （ 3 ） For the interannual variation, between the NDVI and air temperature and precipitation have no obvious correla- tion in most regions of Northwest China. However, in the areas where the annual temperature is lower than 4.58 ~C, between NDVI and annual temperature shows a positive correlation; moreover, in the areas where the annual precipitation is higher than 180 mm, between NDVI and precipitation also has a positive correlation; （4） Between NDVI and temperature there is a strong correlation in spring and summer, while between NDVI and precipitation there is a strong correlation in fall; （5） Since 2000, the vegetation cover and NDVI values have decreased, associating with air temperature rising and declining of precipitation increasing rate.
出处
《冰川冻土》
CSCD
北大核心
2014年第2期327-334,共8页
Journal of Glaciology and Geocryology
基金
国家重点基础研究发展计划(973计划)项目(2010CB951003)资助
关键词
NDVI
植被覆盖率
相关分析
IDW插值
normalized differential vegetation index （NDVI）
vegetation ratio
correlation analysis
inversedistance weighted （IDW） interpolation
