State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China.
University of the Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2021 Sep 9;11(1):17920. doi: 10.1038/s41598-021-97240-4.
Remote sensing and ground vegetation observation data show that climate warming promotes global vegetation greening, and the increase in air temperature in High Mountain Asia (HMA) is more than twice the global average. Under such a drastic warming in climate, how have the vegetation dynamics in HMA changed? In this study, we use the Normalized Difference Vegetation Index (NDVI) from 1982 to 2015 to evaluate the latest changes in vegetation dynamics in HMA and their climate-driving mechanisms. The results show that over the past 30 years, HMA has generally followed a "warm-wet" trend, with temperatures charting a continuous rise. During 1982-1998 precipitation increased (1.16 mm yr), but depicted to reverse since 1998 (- 2.73 mm yr). Meanwhile, the NDVI in HMA increased (0.012 per decade) prior to 1998, after which the trend reversed and declined (- 0.005 per decade). The main reason for the browning of HMA vegetation is the dual effects of warming and precipitation changes. As mentioned, the increase in air temperature in HMA exceeds the global average. The increase of water vapor pressure deficit caused by global warming accelerates the loss and consumption of surface water, and also aggravates the soil water deficit. That is to say, the abnormal increase of land evapotranspiration far exceeds the precipitation, and the regional water shortage increases. Climate change is the primary factor driving these vegetation and water dynamics, with the largest proportion reaching 41.9%.
遥感和地面植被观测数据表明，气候变暖促进了全球植被变绿，而高山亚洲（HMA）的气温上升幅度超过了全球平均水平的两倍。在如此剧烈的气候变暖下，HMA 的植被动态发生了怎样的变化？在这项研究中，我们使用归一化植被指数（NDVI）从 1982 年到 2015 年评估 HMA 植被动态的最新变化及其气候驱动机制。结果表明，在过去的 30 年中，HMA 总体上遵循“暖湿”趋势，气温持续上升。在 1982-1998 年期间，降水增加（1.16mm yr），但自 1998 年以来呈现下降趋势（-2.73mm yr）。与此同时，HMA 的 NDVI 在 1998 年之前增加（每十年 0.012），此后趋势逆转并下降（每十年-0.005）。HMA 植被变褐的主要原因是变暖与降水变化的双重影响。如前所述，HMA 的空气温度上升幅度超过全球平均水平。全球变暖导致的水汽压亏缺增加加速了地表水的损失和消耗，也加剧了土壤水分亏缺。也就是说，陆地蒸散量的异常增加远远超过了降水，区域水资源短缺增加。气候变化是这些植被和水动力的主要驱动因素，其最大比例达到 41.9%。
