广东省NDVI时空变化特征及其对气候因子的响应

广东省植被类型丰富、气候条件复杂,开展气候因子对植被的影响研究,对于全省保护生态环境、应对气候变化具有重要意义。利用MODIS NDVI数据和地面气象观测数据,基于变化趋势分析、空间自相关分析、相关性分析等方法,研究广东省NDVI时空分布特征及其对气温、降水、日照时数等气候因子的响应。结果表明,2000—2018年广东省NDVI平均值为0.62,总体呈上升趋势,平均年增长值为0.005 3,正增长区面积占比达94.50%。全省73.72%的区域植被呈现显著空间集聚性,其中高值集聚区面积占比48.19%,低值集聚区面积占比25.53%。不同类型植被的NDVI均呈增加趋势,其中常绿阔叶林、常绿针叶林、混交林的NDVI平均值最大,而农田、矮树灌木、混交林平均年增长值最大。NDVI具有明显的季节变化规律,夏季NDVI值最大、年增长值最小,冬季NDVI值最小、年增长值最大。年内NDVI最低值出现在2月,最高值出现在9月。月平均NDVI与气温、降水、日照时数相关性显著,其最大相关系数分别为0.863 7、0.639 4、0.605 7。NDVI对日照时数的响应不存在滞后,对气温存在1个月的滞后,对降水存在1—2个月的滞后。日照时数对NDVI的影响仅持续1个月左右,温度、降水对NDVI的影响可持续4—5个月。

Spatiotemporal Variation of NDVI and Its Response to Climatic Factors in Guangdong Province

It is important to research the impact of climatic factors on vegetation in Guangdong Province,which has rich vegetation types and complex climatic conditions.Using MODIS NDVI data and ground meteorological observation data,the spatiotemporal distribution variation of NDVI and its response to air temperature,precipitation and sunshine duration were studied based on the tendency analysis,spatial autocorrelation analysis and correlation analysis.The results showed that the average NDVI of Guangdong Province from 2000 to 2018 had an overall upward tendency,with an average value of 0.62 and an average annual growth value of 0.0053.The positive growth area accounted for 94.50%in the past 19 years.The vegetated region with high spatial clustering characteristics accounted for 73.73%in Guangdong Province,of which the high value clustering area accounted for 48.19%,and the low value clustering area accounted for 25.53%.All types of vegetation showed an increasing trend,among which the highest average NDVI values were observed in the evergreen broad-leaved forest,the evergreen coniferous forest,and the mixed forest,and the highest annual growth values were observed in the farmland,the Bush,and the mixed forest.About the seasonal variation,NDVI had the largest average value and the smallest annual growth rate in summer,and the smallest average value and the largest annual growth rate in winter.About the monthly variation,the lowest NDVI value appeared in February and the highest in September.The monthly average NDVI was significantly correlated with the air temperature,the precipitation and the sunshine duration,with the maximum correlation coefficients of 0.8637,0.6394 and 0.605,respectively.NDVI had no lag in response to the sunshine duration,one month lag in response to the air temperature and one to two months lag in response to the precipitation.The impact from sunshine duration to NDVI could last for only one month,and the impact from air temperature and precipitation to NDVI could last for about four or five months.