人类活动对2000—2020年鄱阳湖流域陆地植被覆盖变化的影响

目的] 研究人类活动对近年来鄱阳湖流域陆地植被覆盖变化的作用机制,为推动该流域乃至长江流域生态系统健康发展提供理论依据。方法] 基于鄱阳湖流域最新MODIS增强型植被指数(EVI)数据产品,并结合气象数据以及土地利用和人口数据,采用趋势分析、残差分析、相关分析等方法,分析研究区2000—2020年流域陆地植被覆盖变化特征,深入探讨了人类活动作用的影响机制。结果] 近20 a来鄱阳湖流域地表植被状况明显改善,植被EVI呈显著上升趋势(p<0.05);流域人类活动整体上对植被EVI的增加起着重要的促进作用。在城镇化新扩张区域表现出明显的抑制作用;在流域尺度上,人类活动对EVI增长的贡献率达到32.48%,不同子流域间人类活动的平均贡献率为30%～43%。鄱阳湖流域植被EVI及其残差趋势在人口密度增加0～100人/km²和400～500人/km²时,分别出现了一个峰值。这一结果主要得益于近年来江西省社会经济快速发展和生态文明建设理念的驱动,广大乡村地区人口密度的小幅增加(0～100人/km²)比单纯的人口流失区更能有效改善地表植被状况。与此同时,城市区域人口密度增加幅度在一定区间时(400～500人/km²)也能促进地表植被状况的改善。结论] 人类活动是地表植被覆盖变化的重要促进因素,高质量发展中的“绿色”“协调”理念对生态环境的改善至关重要。

Effects of Human Activities on Terrestrial Vegetation Coverage Change of Poyang Lake Basin During 2000-2020

Objective] The mechanism on how human activities affect vegetation dynamics was studied in order to promote the healthy development of terrestrial ecosystems.Methods] Based on the latest MODIS enhanced vegetation index (EVI) products, meteorological data, land use data, and population data for the Poyang Lake basin, we analyzed how human activities drove changes in vegetation coverage during 2000-2020 by using the methods of trend analysis, residual analysis, and correlation analysis.Results] The surface vegetation of the Poyang Lake basin increased remarkably in the past 20 years, and EVI showed a significant increasing trend (p<0.05). Human activities in the basin generally played an important role in increasing EVI, but also showed an obvious inhibitory effect on EVI in areas where urbanization had expanded. At the basin scale, the contribution rate of human activities to EVI growth was 32.48%, and the average contribution rate of human activities among different sub-basins was 30%~43%. EVI and its residual trend reached peak values when the population density in the Poyang Lake basin increased by 0~100 people/km² and 400~500 people/km², respectively. This was mainly driven by rapid social and economic development and the concept of ecological civilization construction in Jiangxi Province in recent years. A small increase in population density (0~100 people/km²) in the vast rural areas could effectively improve the surface vegetation status more than in the pure population loss areas. At the same time, a population density increase in urban areas within in a certain range (400~500 people/km²) could also increase surface vegetation.Conclusion] Human activities are an important factor for changing surface vegetation coverage. The concepts of "green" and "coordination" in high-quality development are very important for improving the ecological environment.