基于线性光谱分解的干旱半干旱矿区非光合植被覆盖度变化监测

    Monitoring of non-photosynthetic vegetation coverage changes in arid and semi-arid mining areas based on linear spectral decomposition

    • 摘要: 非光合植被覆盖对于增加矿区土壤肥力、减缓风蚀和水蚀具有重要作用,是矿区土地复垦与生态修复评价的重要指标,但还缺乏有效监测方法。本文以哨兵卫星影像为数据源,采用NDVI-DFI像元三分模型和LIM线性指数模型估算矿区非光合植被覆盖度,并分析不同季节、区域和复垦模式下非光合植被变化规律。结果表明:①准能集团黑岱沟露天煤矿与哈尔乌素露天煤矿NDVI-DFI特征空间表现为三角形,符合像元三分模型的基本假设。②与NDVI-DFI像元三分模型相比,LIM线性指数模型在非光合植被覆盖度反演中明显降低了均方根误差,R2达到0.892 3。③研究区非光合植被覆盖度季节性变化特征明显,并与光合植被覆盖度形成此消彼长的关系,剥离区和开采区四季无植被;排土区有少量非光合和光合植被;复垦区冬春季以非光合植被和裸土覆盖为主,分别占比46%和45%,夏季光合植被覆盖度超过78%。与周边对照区相比,复垦年限较短区域的非光合植被季节波动更强烈。④不同复垦模式的植被覆盖组成与季节变化差异显著,常绿针叶林植被覆盖最稳定,其光合植被覆盖度在四个季节均大于85%,而落叶阔叶林、针阔混交林、灌丛和草丛90%的光合植被在冬季衰退并转化为非光合植被或裸土,冬春季裸土覆盖度相比夏季增加23%~42%。今后应注重冬春季非光合植被的监测和分析,为复垦植被优化和管护提供依据。

       

      Abstract: Non-photosynthetic vegetation cover plays a crucial role in increasing soil fertility and mitigating wind and water erosion in mining areas. It is an important indicator for evaluating land reclamation and ecological restoration in mining areas, but effective monitoring methods remain lacking. This paper uses Sentinel satellite imagery as the data source and employs the NDVI-DFI pixel triad model and the LIM linear index model to estimate non-photosynthetic vegetation coverage in mining areas. The paper also analyzes the variation patterns of non-photosynthetic vegetation under different seasons, regions, and reclamation models. The results show that: ① the NDVI-DFI feature spaces of the Heidaigou Open-pit Coal Mine and the Haerwusu Open-pit Coal Mine of Zhunneng Group are triangular, which conforms to the basic assumption of the pixel triad model. ② Compared with the NDVI-DFI pixel triad model, the LIM linear index model significantly reduces the root mean square error in the inversion of non-photosynthetic vegetation coverage, with R2 reaching 0.892 3. ③ The seasonal variation characteristics of non-photosynthetic vegetation coverage in the study area are obvious and form a reciprocal relationship with photosynthetic vegetation coverage. In stripped and mining areas, there is no vegetation throughout the year; spoil areas have a small amount of both non-photosynthetic and photosynthetic vegetation; in reclaimed areas, non-photosynthetic vegetation and bare soil dominate in winter and spring, accounting for 46% and 45% respectively, while in summer, photosynthetic vegetation coverage exceeds 78%. Compared with the surrounding control areas, the non-photosynthetic vegetation in regions with shorter reclamation periods fluctuates more strongly with the seasons. ④ There are significant differences in the composition and seasonal variation of vegetation coverage under different reclamation modes. Evergreen conifer forests have the most stable vegetation coverage, with photosynthetic vegetation coverage greater than 85% in all four seasons, while 90% of the photosynthetic vegetation in deciduous broadleaf forests, mixed conifer-broadleaf forests, shrubs, and grasslands declines in winter and transforms into non-photosynthetic vegetation or bare soil. In winter and spring, bare soil coverage increases by 23%-42% compared with summer. Future attention should be paid to the monitoring and analysis of non-photosynthetic vegetation in winter and spring to provide a basis for optimizing and managing reclaimed vegetation.

       

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