基于GIS和RS的中国西北NDVI变化特征及其与气候变化的耦合性

NDVI variation and coupling analysis with climate change in northwest of China based on GIS and RS

整合遥感和地理信息技术,对中国西北地区近25a来NDVI时空变化特征及其与气候变化的耦合关系进行了研究,结果表明:高寒草甸和落叶针叶林的NDVI增加趋势较明显,线性倾向率p=0.2%/10a。枯黄期推后导致NDVI明显增加,线性倾向率达0.27%/10a;青藏高原、天山南脉的春季气温和北疆、汉中地区的秋季气温上升较明显,半湿润和半干旱过渡地区降水变幅较大;江河源地区NDVI和气温的相关系数达到0.6,河西-阿拉善、南疆等干旱地区NDVI和降水的相关性较高,相关系数为0.65。夏、秋季汉中、祁连和天山等地区,持续降水会导致NDVI值下降;寒区NDVI对气温变化较敏感,月均温度达到8℃,NDVI值出现快速上升。旱区温度超过22℃,植被NDVI值出现明显的回落。非寒旱区,月气温在19～20℃左右,NDVI达到峰值。寒区当温度条件满足植被生长需要时,NDVI随降水线性增加。旱区月均降水超过60mm后NDVI开始快速上升,直到植被需水的饱和点。生长季内西北地区NDVI随气温、降水的变化存在明显滞后现象。

The paper researched temporal-spatial variation of NDVI and analyzed coupling with climate changes in thenorthwest of China from 1982 to 2006 years based on the GIS and remote sencing. The results show that the NDVI of alpine meadow and deciduous needle-leaf forests increased with a rate of p=0.21%/10 a,the NDVI was ascending（p=0.27%/10 a） which attributed to the growing season delayed. Air temperature increased in Qinghai-Tibet Plateau,the south of Tianshan mountains in spring and northern Xinjiang／Hanzhong in autumn,and the range of variation of precipitation was great in boundary of semi-humid and semi-arid. The correlation coefficient was 0.62 between NDVI and temperature in the Yellow River and Yangtze River source regions. There was a great correlations between NDVI and precipitation in Hexi-Alxa／southern Xinjiang with a coefficient of 0.65. NDVI decline was attributed to precipitation too much in the Hanzhong,Qilian,Tianshan mountains in summer and autumn;NDVI of the cold regions was more sensitive to the changes of temperature and the NDVI was not raised sharply until the average monthly temperature reached to 8℃ . NDVI began to decline when the temperature was more than 22℃ . The NDVI came to the peak with temperature rising（19–20℃） in the non-cold and arid regions. NDVI was linear increment with the rising of precipitation,if the temperature conditions met the needs of vegetation growth in the cold region .The threshold value of monthly precipitation was 60 mm（start） and 220 mm（stop） in the arid region;The changing of NDVI was lag when the air temperature and precipitation changed in North of China .