重庆市NDVI对水热条件变化的响应及其空间特征

Response of NDVI to Variations of Temperature and Precipitation and Its Spatial Characteristics in Chongqing City

降水和气温是影响一个地区植被覆盖度的最主要的气候因子。在利用SPOT VGT-NDVI旬数据、重庆市及周边20个气象站点1999—2010年日气温与降水数据以及研究区相关图件资料的基础上,运用时滞互相关分析法分析了旬平均NDVI(TN)与旬均温(TT)和旬降水(TP)的相关性以及时滞情况。结果表明,NDVI与气温和降水之间存在较强的相关性,且NDVI与气温较与降水之间的相关性更强,表明在研究区气温是NDVI变化的限制因子;NDVI与气温和降水之间的相关性和时滞情况存在明显的东南—西北差异,东南地区时滞较长,相关性低,西北地区时滞较短,相关性高;各植被类型NDVI与气温和降水的相关程度高低以及响应速度的快慢决定于各植被类型的生长发育规律及其对气温或降水要求的高低。

Temperature and precipitation are the main climatic factors affecting regional vegetation coverage. With the time lag correlation method, the correlations between the ten days NDVI（TN） and ten days mean temperature（TT） , ten days mean precipitation（TP） as well as the time lag characteristics were analysised based on ten days SPOT VGT-NDVI data, daily air temperature, and precipitation data from 20 meteorologi- cal stations in Chongqing City and around for the period 1999--2010. The results are summarized as follows： Across the entire study region, both correlations with NDVI existed apparently while air temperature had closer than precipitation, which indicated that the temperature is the limiting factors of NDVI variations across the region; there are significant spatial and temporal variation differences with longger time lag and lower correlations from southeast to northwest; the degree of correlation between NDVI of different vegetation types and air temperature and precipitation is determined by the vegetationrs growth characteristics and its water and heat requirement.