基于GEE平台的海南岛植被覆盖度时空变化和影响因子探测

Spatiotemporal Variation and Influencing Factors of Fractional Vegetation Cover in Hainan Island Based on Google Earth Engine Platform

摘要:

植被是陆地生态系统重要的一部分，研究植被覆盖度的时空变化特征及其影响因子对于区域生态保护和治理具有重要意义。该文采用GEE (Google Earth Engine)平台，借助像元二分模型计算了2000—2020年海南岛植被覆盖度(FVC)，通过Theil-Sen Median趋势分析、Mann-Kendall检验和Hurst指数等方法分析了FVC的时空变化特征，最后采用结构方程模型和地理探测器分析气候、地形和人类活动等因子对植被空间变化的影响。结果表明，海南岛近21 a的FVC呈显著增加趋势, 增速为0.025/10 a。植被变化以不显著改善和极显著改善为主，占研究区的35.34%和29.38%。未来植被变化以弱反持续性增加和弱持续性增加为主。土地利用类型、海拔、坡度和人口密度是影响FVC空间分布的主要驱动因子。各影响因子对FVC以双因子增强或者非线性增强为主，其中，土地利用类型∩人口密度和土地利用类型∩海拔的交互作用较强，q值为49.56%和48.38%。这可为海南岛植被恢复策略提供理论依据。

Abstract:

Vegetation is an important part of terrestrial ecosystems, and the study of the spatial and temporal variation characteristics of fractional vegetation cover (FVC) and its influencing factors is of great significance for regional ecological conservation and management. By using the Google Earth Engine (GEE) platform and pixel binary model, the FVC of Hainan Island from 2000 to 2020 was calculated. The spatial and temporal variability of the FVC was analyzed using the Theil-Sen Median trend analysis, the Mann-Kendall test and the Hurst index. Finally, structural equation modelling and geographic detector were used to analyze the response mechanisms of the spatial distribution characteristics of FVC in Hainan Island to climate, topography and human activities. The results showed that FVC in Hainan Island had a significant increasing trend in the past 21 years, with a growth rate of 0.025/10 a. The FVC changes were mainly not significantly improved and extremely significantly improved, accounting for 35.34% and 29.38% of the study area. In the future, the vegetation changes was dominated by weak counter-persistent increase and weak persistent increase. Land use type, elevation, slope, and population density were the dominant factors affecting the spatial distribution of FVC. Interaction type was dominated by bivariate enhancement and nonlinear enhancement. The interaction between land use type ∩ population density and land use type ∩ elevation was stronger, with q values of 49.56% and 48.38%. Therefore, it might provide a theoretical basis for the vegetation restoration policy on Hainan Island.