Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Yucheng Comprehensive Experiment Station, Chinese Academy of Sciences, Yucheng 251200, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Yucheng Comprehensive Experiment Station, Chinese Academy of Sciences, Yucheng 251200, China.
Sci Total Environ. 2022 Dec 10;851(Pt 2):158416. doi: 10.1016/j.scitotenv.2022.158416. Epub 2022 Aug 30.
As an important component of terrestrial ecosystem, vegetation acts as a sensitive recorder of changes in hydroclimatic conditions. Long-term time series of remote sensing-based vegetation indices and their influencing environmental driving factors, such as human activities and climate change, have been widely discussed in the literature. Globally, however, little is known about the hydroclimatic processes controlling vegetation changes in mountainous regions, which are conceived as more sensitive to climate change than other landscapes. The present study aims to quantify the respective roles of two dominant hydroclimatic factors, namely, TWS (i.e., terrestrial water storage) and T (i.e., temperature), in the spatio-temporal changes of mountainous vegetation over global six contrasting climate zones (i.e., tropical, arid, subtropical, temperate, sub-frigid, and frigid zones) during the period 2003-2016 based on EVI (i.e., enhanced vegetation index), TWS, T, and elevation data. Results indicate that the mean EVI shows a larger increasing trend (+0.85 %/decade, p-value < 0.01) and a larger decreasing trend in TWS (-85 mm/decade, p-value < 0.01) across the global mountainous regions than other global regions combined together (+0.61 %/decade, p-value < 0.01), particularly over high latitudes. With the increasing latitudes, the positive effect of temperature more dominates mountainous vegetation growth than moisture, as evidenced by the increasing trends of EVI with warming. However, in certain low-latitude mountainous regions (e.g., East Africa, South Asia, the western Tibetan Plateau, Brazil Plateau, and the southern Rocky Mountains), mountainous vegetation may face degradation due to water deficit induced by increased snowmelt, especially among the high-elevation ecosystems. The water availability controls vegetation activities more than T in the mid- and low-latitude regions, including the tropical, arid, and subtropical climate zones. These findings indicate that the potential shifts in mountainous vegetation may occur under the notable interactions with hydroclimatic factors, as the high-latitudes are experiencing ongoing warming and the mid- and low-latitudes are getting dryer.
作为陆地生态系统的重要组成部分，植被是水文气候条件变化的敏感记录者。基于遥感的植被指数及其影响环境驱动因素（如人类活动和气候变化）的长期时间序列已在文献中广泛讨论。然而，在全球范围内，人们对控制山区植被变化的水文气候过程知之甚少，与其他景观相比，山区对气候变化更为敏感。本研究旨在量化两个主要水文气候因素（即 TWS（即陆地水储量）和 T（即温度））在 2003-2016 年期间全球六个对比气候带（即热带、干旱、亚热带、温带、亚寒带和寒带）山区植被时空变化中的相对作用，基于 EVI（即增强植被指数）、TWS、T 和海拔数据。结果表明，与全球其他地区相比，全球山区的平均 EVI 表现出更大的增长趋势（+0.85%/decade，p 值<0.01）和 TWS 更大的下降趋势（-85mm/decade，p 值<0.01），特别是在高纬度地区。随着纬度的增加，温度对山区植被生长的积极影响超过了水分，这表现在随着变暖，EVI 的增长趋势。然而，在某些低纬度山区（如东非、南亚、青藏高原西部、巴西高原和南落基山脉），由于融雪增加导致水分不足，山区植被可能会退化，特别是在高海拔生态系统中。在中低纬度地区，包括热带、干旱和亚热带气候带，水的可用性比 T 对植被活动的控制作用更大。这些发现表明，在高纬度地区持续变暖、中低纬度地区越来越干燥的情况下，山区植被可能会发生潜在的变化，这与水文气候因素的显著相互作用有关。
