水热昼夜不对称下贵州高原植被动态响应

Dynamic response of vegetation in Guizhou Plateau under the asymmetric rate of water and heat fluctuation

贵州高原为喀斯特高原,其生态环境十分脆弱,研究昼夜水热条件的不对称性及其对植被变化的影响,可为该地区生态保护和防灾减灾提供理论支撑。本研究基于31个气象站昼夜气温和昼夜降水量数据,结合SPOT NDVI数据,利用趋势分析和相关分析等方法,分析了1961-2017年贵州高原昼夜气温和昼夜降水的变化特征及其对植被活动的影响。结果表明,年、月夜降水量大于昼降水量。年昼夜降水量均呈减少趋势,夜降水量的减少率较大。年均昼、夜气温均呈上升趋势,夜气温增幅大于昼气温;各月昼夜气温均呈上升趋势。气温与NDVI的相关程度高于降水,夜气温升高对植被生长有促进作用,而夜降水增多抑制植被生长。当月气温对植被生长影响较大;初春的夜气温和初夏的昼气温对植被生长影响大。初夏和初秋的昼夜降水、初秋的夜气温与植被NDVI变化有2个月时滞。

The Guizhou Plateau is a karst plateau with a fragile ecological environment.Studying the asymmetry of diurnal hydrothermal conditions and its impact on vegetation change can provide theoretical support for ecological protection and disaster reduction.Based on daily temperature and precipitation data obtained from 31 meteorological stations,combined with SPOT satellite image NDVI(normalized difference vegetation index)data,the characteristics and trends of diurnal temperature and precipitation changes were analyzed,and the effects on vegetation activities were discussed using correlation analysis.The results showed that from 1961 to 2017,the annual nighttime precipitation was more than the annual daytime precipitation;however,showed a slight decreasing trend.The annual daytime and nighttime temperature showed increasing trends,with nighttime temperature showing a more significant increasing trend.The average nighttime temperature of each month showed differing increasing trends.NDVI had a closer correlation with temperature than with precipitation.The increase in nighttime temperature promoted the growth of vegetation,while the increase in nighttime precipitation inhibited it.The impact of temperature on vegetation growth in the current month is more significant than that in the previous month or two months.The NDVI in early spring was greatly affected by the nighttime average temperature,while in the early summer,it was greatly affected by the average daytime temperature.There was a two-month lag between NDVI change and diurnal precipitation in the early summer and autumn and between NDVI change and nighttime temperature in early autumn.