Abstract:

Hainan is a crucial component of ecological functions and ecological civilization experimental zones. As the core region for ecological environmental protection on Hainan Island, studying the ecological environmental quality and influencing factors of Wuzhishan City would have great guiding significance in protecting the integrity of the ecological environment in Hainan. This study focuses on evaluating the ecological environment of Wuzhishan City. In this study, the Remote Sensing Ecological Index (RSEI) was applied as an evaluation indicator of Landsat image data for 2001, 2005, 2010, 2015, and 2021. Then, the Theil-Sen estimator and Mann-Kendall(MK)test were used to determine the variation trend of RSEI, while the Optimal Geographic Detector Model (OPGD) was employed to explain the causes of spatial differentiation of ecological environment quality in Wuzhishan City. The results showed the following. 1) On a given timescale, the RSEI first decreased and then increased from 2001 to 2021, and the mean RSEI increased from 0.579 in 2001 to 0.682 in 2021. During this period, the proportion of general and good RSEI grades was the largest, with the combined total area exceeding 92.27%. Areas with good RSEI grades showed a fluctuating increasing trend, whereas those with general RSEI levels showed a fluctuating decreasing trend. This indicates a trajectory of substantial growth in high-quality RSEI volatility in Wuzhishan City. 2) On a spatial scale, areas with worse and poorer RSEI grades were mainly concentrated in the township areas around the low-altitude water system, whereas the general grades were mainly concentrated around the worse and poorer levels. Good and excellent grades were distributed in the surrounding areas and higher-elevation regions in the central and eastern regions, respectively. The significantly improved RSEI areas corresponded to the delineation of the National Park of the Hainan Tropical Rainforest, whereas the significantly degraded areas were located in densely populated townships. 3) From the perspective of the RSEI change trends, 92.58% of the areas exhibited an increasing trend, of which 5.93% showed a significant increase. Conversely, the area with a decreasing trend was 7.42% and the region of significant reduction was only 0.01%. From 2001 to 2021, the RSEI of Wuzhishan City has exhibited an overall upward trend. However, the area of significant improvement is limited; therefore, it is necessary to continuously strengthen the the ecological environment. 4) From the analysis of the driving factors, the natural factors dominated by temperature and dem, and the social factors dominated by GDP were the main factors influencing the spatial differentiation of the RSEI in Wuzhishan City in 2021. Among these, dem factor had the greatest explanatory power. Precipitation demonstrated no significant explanatory power for spatial differentiation of the RSEI in Wuzhishan City. These results provide a theoretical basis for ecological environment protection and adjustment of key measures in the Wuzhishan area.

Key words: remote sensing ecology index, Wuzhishan, optimal parameters-based geographical detectors, spatial-temporal evolution, driving factors analysis

摘要：

五指山市作为海南生态环境保护的核心区，研究其生态环境质量及成因对保护海南生态环境完整性具有重要指导意义。以五指山市为评估单元，选取2001、2005、2010、2015、2021年Landsat影像，利用遥感生态指数（RSEI）对其生态环境质量进行评价与分析，并用Sen趋势分析和MK检验分析RSEI变化趋势，最后通过最优地理探测器模型（OPGD）分析2021年生态环境质量空间分异成因。结果表明，1）时间尺度上，2001－2021年五指山市RSEI先下降后上升，RSEI均值从2011年的0.579波动上升到2021年的0.682；2001－2021年五指山市RSEI一般和良等级的占比最大，超过92.27%；RSEI等级为良的区域波动增加，RSEI等级为一般的区域波动减少，这表明五指山市RSEI呈高质量波动式增长。2）空间尺度上，RSEI等级为差和较差的区域集中在低海拔水系周边的乡镇；一般等级主要围绕差和较差等级的周围；良和优等级分布在四周、中东部海拔高地区。RSEI显著改善区域与海南热带雨林国家公园五指山片区一致；而显著退化区域则分布在人口密集的乡镇地区。3）变化趋势上，研究区有92.58%的区域呈增加趋势，显著改善区域有5.93%；RSEI呈减少趋势的区域有7.42%，显著变差的有0.01%；趋势变化显示，21年间五指山市RSEI整体呈变好趋势，但是显著改善区域面积有限，仍需持续加强生态环境建设。4）驱动因子分析，气温、高程为主的自然因子和生产总值为主的社会因子是2021年五指山市RSEI空间分异的主要影响因子。高程在单因子中具有最大解释力，气温和高程交互作用对RSEI解释力最高，而降水对五指山市RSEI不具影响力。

关键词: 遥感生态指数, 五指山, 最优地理探测器, 时空演变, 成因分析