江西省森林活动的时空变化及其对干旱的响应

摘要

基于江西省87个气象站1960～2014年实测资料计算的标准化降水蒸散指数（ SPEI）和2000～2014年MODIS NDVI数据，结合线性趋势分析、最大相关系数等方法，分析了江西省近50年干旱和近10年来森林活动的时空变化特征，以及江西省森林活动对不同时间尺度干旱的响应特征。结果表明：进入21世纪后，江西省受旱程度较以前有所增加，从2009年开始，干旱与湿润年份交替存在；2000～2014年江西省森林NDVI在波动中呈微弱增加的趋势，自2008年以来森林NDVI明显增加，增速为0．03／10 a（ P＜0．01）。森林年均NDVI的年际变化主要取决于春季平均NDVI的变化，两者间的相关系数高达0．92；在春季和秋季，干旱导致对应季节森林NDVI下降，而在夏季，轻度干旱会使森林NDVI呈现增加趋势；在海拔较高地区，干旱对森林NDVI的滞后影响多持续在6个月以上，而在其他地区一般少于3个月。%Using the Standardized Precipitation Evapotranspiration Index ( SPEI) which was calculated based on data from 87 meteorological stations in Jiangxi province during 1960 to 2014 and MODIS NDVI data from 2000 to 2014, analyzed the spatio-temporal characteristics of drought in recent 50 years, and the variations of forest activity and its response to drought in recent 10 years by integrating linear trend analysis and maximum correlation analysis methods.The results indicated that the suffer level from drought in Jiangxi province increased than before after entering the 21st century, the drought and wetness alternation existed since 2009.The annual average vegetation cover had a slowly increasing trend in fluctuation during 2000 to 2014, but it had been in-creased with a rate of 0.03/10 a ( P<0.01) from 2008.The inter-annual variability of forest annual NDVI mainly depended on the variation of the average NDVI in spring with the correlation coefficients as high as 0.92.The change of forest NDVI would be af-fected by the occurrence time and severity of drought.In spring and autumn, seasonal NDVI decreased with drought, on the con-trary, an increasing trend with mild drought was observed in summer.The accumulative lagged effect of drought on forest NDVI had a significant spatial distribution with more than 6 months in high altitude areas and less than 3 months in other regions.