青藏高原植被生长季NDVI时空变化及对气候因子的响应分析

Analysis of Spatiotemporal Variation of NDVI in the Vegetation Growing Season and Responses to Climatic Factors in Qinghai-Tibet Plateau

为了探究青藏高原植被覆盖时空演变特征及其驱动因子,对青藏高原的生态环境保护提供科学依据,基于1982—2015年青藏高原内部及其周边139个气象站点的气象数据和同期的GIMMS NDVI数据,研究了青藏高原生长季植被NDVI的时空变化特征及其与气候因子的响应关系。结果表明:(1)在研究期内,青藏高原生长季NDVI总体呈上升趋势,不同干湿地区生长季NDVI变化趋势有所差异,湿润地区植被退化面积占比相对较大,干旱地区植被改善面积占比相对较大。(2)研究区植被未来总体向改善方向发展,植被未来趋向改善面积占62.25%,趋向退化面积占37.58%。(3)研究区植被对各气候因子的响应存在一定的滞后性,草原、草甸、高山植被和灌丛4种主要植被对气温和相对湿度主要当月响应,对降水主要当月或滞后1个月响应,对日照时数主要滞后3个月响应。(4)气温、降水、相对湿度及日照时数4个气候因子对青藏高原植被NDVI变化的相对贡献率分别为37.19%,27.53%,20.30%和14.97%,其中,气温和降水是湿润/半湿润地区、半湿润地区、大部分半干旱地区及干旱地区植被NDVI变化的主要气候驱动因子,日照时数和相对湿度是湿润地区及少部分半干旱地区植被NDVI变化的主要气候驱动因子。整个青藏高原生长季植被NDVI变化的主要气候驱动因子为气温。综上,青藏高原植被整体呈改善趋势,气温为青藏高原植被变化的主要气候驱动因子。

In order to explore the spatiotemporal evolution characteristics and driving factors of vegetation cover on the Qinghai-Qinghai Tibet Plateau Plateau and provide scientific basis for the ecological environment protection of the Qinghai-Tibet Plateau, based on the meteorological data of 139 meteorological stations in and around the Qinghai-Tibet Plateau from 1982 to 2015 and GIMMS NDVI data in the same period, the temporal and spatial variation characteristics of vegetation NDVI and its response to climate factors in the growing season of the Qinghai-Tibet Plateau were studied. The results show that:(1) during the study period, NDVI in the growing season of the Qinghai-Tibet Plateau generally showed an upward trend, and the change trend of NDVI in the growing season in different dry and wet areas was different;the proportion of vegetation degradation area in wet areas was relatively large, and the proportion of vegetation improvement area in arid areas was relatively large;(2) the vegetation in the study area will develop in the direction of improvement in the future;the vegetation area that will tend to improve in the future accounts for 62.25% and the area that will tend to degrade accounts for 37.58%;(3) there was a certain lag in the response of vegetation to various climate factors in the study area;grassland, meadow, alpine vegetation, and shrub mainly responded to temperature and relative humidity in the current month, precipitation in the current month or one month later, and sunshine hours in the current month or three months later;(4) the relative contribution rates of temperature, precipitation, relative humidity, and sunshine hours to vegetation NDVI changes on the Qinghai-Tibet Plateau were 37.19%, 27.53%, 20.30% and 14.97%, respectively;temperature and precipitation were the main climate driving factors for vegetation NDVI changes in humid/semi humid areas, semi humid areas, most semi-arid areas and arid areas, sunshine hours and relative humidity were the main climatic driving factors of vegetation NDVI change in humid areas and a few semi-arid areas;the main climatic driving factor of vegetation NDVI change in the whole growing season of the Qinghai-Tibet Plateau was temperature. To sum up, the vegetation on the Qinghai-Tibet Plateau showed an overall improvement trend, and temperature was the main climatic driving factor of vegetation change on the Qinghai-Tibet Plateau.