贵州高原NDVI变化及其对气候变化的响应

Vegetation NDVI Change and Its Response to Climate Change in Guizhou Plateau

中国南方喀斯特地区气候变化加剧,植被对气候变化响应反映十分敏感,动态监测植被变化对区域生态环境保护有重要意义。基于1999—2017年贵州高原遥感数据和气象数据,从年、季、月等不同时间尺度研究了NDVI动态变化及其对降水量、平均地表气温、最高地表气温、最低地表气温、平均气温、最高气温、最低气温、大型蒸发量、平均风速、平均相对湿度、日照时数等气候因子的响应特征。研究表明:近19 a,贵州NDVI以0.0073 a^−1的速率呈显著上升趋势,其中,2011—2017年的上升幅度大于1999—2010年的上升幅度,NDVI变化与最低地表气温、最低气温呈显著正相关;春季、夏季、秋季、冬季NDVI均呈显著上升趋势,春季年增长率最大(0.0093 a^−1),其次依次为秋季(0.0070 a^−1)、夏季(0.0069 a^−1)、冬季(0.0046 a^−1);春、秋季NDVI与最低地表气温呈显著正相关,最低气温影响较大,夏季、秋季NDVI受气温和降水共同影响,冬季NDVI受日照时数影响较大,四季NDVI受气温影响程度大于降水;1—12月NDVI均呈上升趋势,其中,4、5、8、10月呈极显著上升趋势,2、3、7、9、11、12月呈显著上升趋势;2、3月份和11、12月份NDVI在增长,表明生长季有所延长。NDVI与当月气象因子相关程度大于其与前一个月、前两个月的相关程度;气温的当月效应和滞后效应大于日照时数和水分条件的效应。温度对贵州NDVI的影响程度大于水分的影响,气温升高促进生长季延长是贵州高原的重要气候效应。

In the karst area of South China,climate change is becoming more and more serious,and the vegetation is very sensitive to climate change.Therefore,it is of great significance to study the dynamic changes of vegetation under climate change for regional ecological environment protection.In this study,vegetation NDVI dynamic and its response to climate change(represented by climatic factors such as precipitation,mean/maximum/minimum surface temperature,mean/maximum/minimum temperature,large evaporation,average wind speed,relative humidity and sunshine hours)were investigated in Guizhou Plateau in 1999-2017 at different time scales(i.e.,annual,seasonal,and monthly).The results showed that annual vegetation NDVI in Guizhou showed a significant upward trend at the rate of 0.0073 a^−1 in past 19 years.Among them,the increase rate in 2011-2017 was greater than that in 1999-2010.NDVI was positively correlated with the minimum surface temperature and minimum temperature.There were significant increasing trends in four seasons.The annual growth rate of NDVI in spring was the highest(0.0093 a^−1),followed by autumn(0.0070 a^−1),summer(0.0069 a^−1)and winter(0.0046 a^−1).Vegetation NDVI values in spring and autumn were significantly positively correlated with the minimum surface temperature and the minimum temperature.Vegetation NDVI values in summer and autumn were affected by both temperature and precipitation,while vegetation NDVI in winter was greatly affected by sunshine hours.Seasonal NDVI was more affected by temperature than precipitation.Monthly NDVI values showed upward trends with very significant upward trends detected in April,May,August and October,followed by February,March,July,September,November and December.Vegetation NDVI increased in February and March,November and December,indicating that the growing season was prolonged.The correlation coefficients between vegetation NDVI and meteorological factors in the current month were greater than those between NDVI and previous one or two month meteorological factors.The influences of current/previous month temperature on NDVI were greater than those of sunshine hours and water conditions.The influence of temperature on vegetation NDVI was greater than the influence of moisture.The extension of the growing season boosted by the increased temperature is the important climatic effect of Guizhou Plateau.