Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100190, China; Key Laboratory of Regional Sustainable Development Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2024 Sep 15;943:173727. doi: 10.1016/j.scitotenv.2024.173727. Epub 2024 Jun 3.
Vegetation dynamics is essential for characterizing surface biogeophysical parameters. Speeds of vegetation development and senescence are well documented, however, the effects of vegetation growth rates on surface parameters during different growth stages remains unclear. By using such methods as trend analyses and correlation analyses, this study examines the variations and interactive relationships of leaf area index (LAI) and surface parameters including Albedo, evapotranspiration (ET), and land surface temperature (LST), derived from Moderate Resolution Imaging Spectroradiometer (MODIS), during the intra-growing season (April-October, GS) on the Mongolian Plateau (MP). Generally, LAI exhibited a significant upward trend across GS months. Significant changes in V (the difference in LAI between 2 consecutive months) in April-May and September-October indicated that the vegetation change rates were accelerated in the early GS (April-June) and late GS (September-October). The effect of vegetation activity on surface parameters varies over time and space. The effects of V on the speed of surface parameters were inconsistent during the intra-GS. As a result of the significant changes in LAI, V (the difference in ET between 2 consecutive months) displayed a significant upward trend during the early GS but a significant downward trend during the late GS. With acceleration of vegetation activity, the effects of V and V (the difference in Albedo between 2 consecutive months) on LST could offset each other at different stages of the GS. In addition, the effect of V on the speed of surface parameters varied significantly by vegetation types. Our findings imply that clarifying the impact of vegetation activity on surface parameters at different growth stages can advance our understanding of vegetation responses and feedbacks to climate change.
植被动态对于描述地表生物物理参数至关重要。植被的生长和衰老速度已有详细记录，但植被生长速度对不同生长阶段地表参数的影响仍不清楚。本研究利用趋势分析和相关分析等方法，考察了基于 MODIS 的叶面积指数（LAI）与反照率、蒸散量（ET）和陆面温度（LST）等地表参数在蒙古高原（MP）整个生长季（4-10 月）内的变化及其相互关系。LAI 整体呈显著上升趋势。4-5 月和 9-10 月 V（相邻两个月 LAI 的差值）显著变化，表明植被变化率在生长季早期（4-6 月）和晚期（9-10 月）加快。植被活动对地表参数的影响随时间和空间而异。V 对地表参数变化速度的影响在整个生长季内并不一致。由于 LAI 的显著变化，V（相邻两个月 ET 的差值）在生长季早期呈显著上升趋势，而在生长季晚期则呈显著下降趋势。随着植被活动的加速，V 和 V（相邻两个月反照率的差值）对 LST 的影响在生长季的不同阶段可以相互抵消。此外，V 对地表参数变化速度的影响因植被类型而异。本研究结果表明，阐明植被活动对不同生长阶段地表参数的影响，有助于深入理解植被对气候变化的响应和反馈。
