青藏高原地区植被指数变化及其与温湿度因子的关系

NDVI variation and its relationship with temperature and precipitation on the Tibetan Plateau

研究青藏高原地区植被的时空分布特征及其与地表温度和降水之间的关系,对区域乃至全球的生态环境均有重要意义。使用MOD13Q1归一化植被指数(NDVI)产品数据,分析了青藏高原地区2000—2019年NDVI的时空变化特征,并通过MOD11A2地表温度数据和TRMM卫星降水数据探究植被变化与地表温度和降水之间的关系。研究表明,青藏高原地区近20 a NDVI空间格局表现为西北低、东南高,北部干旱地区NDVI相对较低,普遍低于0.20,东南地区林地较多,整体NDVI偏高;2000—2019年青藏高原地区植被整体在“变绿”,NDVI处于0.0012 a^(-1)增长的趋势,北部低植被覆盖区显著改善,南部较高、高植被覆盖区变化不显著。研究区植被与地表温度和降水存在一定的相关性,在西藏的中部以及青海的中南部地区,NDVI值与降水呈现正相关性,偏相关系数较高;在西藏的西北部、青海的南部等地,NDVI值与地表温度呈正相关关系;在西藏中部等地,NDVI与地表温度呈负相关关系。

It is of great significance to assess the spatial and temporal distribution characteristics of vegetation on the Tibetan Plateau and its relationship with temperature and humidity factors with respect to regional and global ecological environments.Using MODIS-NDVI data,we analyzed temporal and spatial variation characteristics of vegetation cover on the Tibetan Plateau from 2000 to 2019,and we explored the relationship between vegetation changes and surface temperature and precipitation based on MOD11A2 surface temperature data and TRMM rainfall data.The results showed that the spatial pattern of NDVI in the Tibetan Plateau in the past 20 years was low in the northwest and high in the southeast,the NDVI in the arid area in the north was relatively low(generally<0.20),there was more woodland in the southeast,and the overall NDVI was high.From 2000 to 2019,the vegetation on the Tibetan Plateau was"turning green"as a whole,and the NDVI showed an increasing trend of 0.0012 a^(-1).The low-coverage vegetation area in the north was significantly increased,whereas relatively-high-and high-coverage vegetation areas in the south did not change significantly.There was a certain correlation between vegetation and surface temperature and precipitation in the study area.In central Tibet and central and southern Qinghai,the NDVI was positively correlated with precipitation,and the partial correlation coefficient was high.In the northwest of Tibet and the south of Qinghai,a positive correlation of the NDVI and surface temperature was observed,and a negative correlation of the NDVI and surface temperature occurred in central Tibet.