Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China; School of Geography, South China Normal University, Guangzhou, China.
Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
Sci Total Environ. 2024 Nov 20;952:175845. doi: 10.1016/j.scitotenv.2024.175845. Epub 2024 Aug 27.
Vegetation change in the Tibetan Plateau (TP) is a crucial indicator of climate change in alpine regions. Previous studies have reported an overall greening trend in the vegetation structure across the TP, especially in its northeastern part, in response to a warming climate. However, variations in the vegetation function and the possible drivers remain poorly understood. Considering the optimal temperature for plants in TP is usually higher than the current temperature, our hypothesis is the function and structure of alpine vegetation have changed synchronously over past few decades. To test this hypothesis, we analyzed satellite-observed solar-induced chlorophyll fluorescence (SIF) and leaf area index (LAI) in the Yellow River source (YRS) region in the northeastern TP to quantify the long-term trends in vegetation functional and structural states, respectively. The results suggest that from 1982 to 2018, SIF increased significantly in 77.71 % of the YRS area, resulting in a significant upward trend of 0.52 × 10 mW m nm sr yr (p < 0.001) for the regional-mean SIF. This represents a 16.1 % increase in SIF, which is close in magnitude to the increase in LAI over the same period. The synchronous changes between vegetation function and structure suggest that improved greenness corresponds to a similar level of change in carbon uptake across YRS. Additionally, we used a multiple regression approach to quantify the contribution of climatic factors to SIF changes in YRS. Our analyses show that the increases in SIF were primarily driven by rising temperatures. Spatially, temperature dominated SIF changes in most parts of YRS, except for certain dry parts in the northern and western YRS, where precipitation had a greater impact. Our results are crucial for a comprehensive understanding of climate regulations on vegetation structure and function in high-elevation regions.
青藏高原（TP）的植被变化是高山地区气候变化的一个关键指标。先前的研究报告称，由于气候变暖，TP 整体的植被结构呈现出绿化趋势，尤其是在东北部。然而，植被功能的变化及其可能的驱动因素仍知之甚少。考虑到 TP 中植物的最佳温度通常高于当前温度，我们的假设是，过去几十年里，高山植被的功能和结构已经同步发生了变化。为了验证这一假设，我们分析了卫星观测到的青藏高原东北部黄河源区（YRS）的太阳诱导叶绿素荧光（SIF）和叶面积指数（LAI），分别量化了植被功能和结构状态的长期趋势。结果表明，从 1982 年到 2018 年，YRS 地区有 77.71%的区域 SIF 显著增加，导致区域平均 SIF 呈显著上升趋势，为 0.52×10mWmnm sr yr（p<0.001）。这代表 SIF 增加了 16.1%，与同期 LAI 的增加幅度相当。植被功能和结构的同步变化表明，绿色度的提高对应于 YRS 地区碳吸收水平的相似变化。此外，我们使用多元回归方法量化了气候因素对 YRS 地区 SIF 变化的贡献。我们的分析表明，SIF 的增加主要是由气温升高驱动的。在空间上，除了 YRS 北部和西部的某些干旱地区外，温度主导了大部分 YRS 地区的 SIF 变化，而降水的影响更大。我们的研究结果对于全面了解气候变化对高海拔地区植被结构和功能的调控作用至关重要。
