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    基于GWR模型的艾比湖流域陆地生态系统碳储量估算及时空演变

    Geographically weighted regression-based carbon stock estimation and spatiotemporal evolution in terrestrial ecosystems within the Ebinur Lake Basin

    • 摘要: 陆地生态系统碳储量是反映区域生态产品价值核算和增汇减排的重要指标,利用遥感技术开展陆地生态系统碳储量估算与空间反演,可为生态系统固碳潜力及“双碳”目标达成提供重要参考。该文利用Landsat8 OLI影像提取遥感变量,结合单波段、植被指数、纹理因子和地形因子,通过最小信息准则(Akaike information criterion corrected,AICc)和交叉验证(cross-validation,CV)确定最优带宽,采用Gaussian,Bisquare和Exponential核函数构建地理加权回归(geographically weighted regression,GWR)模型估算艾比湖流域碳储量,并与多元线性回归(multiple linear regression,MLR)模型对比,选择最优模型估算碳储量空间分布。结果表明: ①GWR模型精度优于MLR模型,以CV与Exponential核函数组合的GWR模型最佳,其精度提升16.31%~66.69%,能较好地反映空间异质性; ②2023年流域碳储量约426.28×106 t,地上、地下和土壤碳储量占比分别为31.83%,24.33%和43.28%; ③2014—2023年碳储量呈减少趋势,呈现“环艾比湖区低,四周高”的空间格局,其中,以草地生态系统碳储量下降最为显著。

       

      Abstract: The carbon stock of terrestrial ecosystems serves as an important indicator for regional ecological product valuation, as well as carbon emission reduction and carbon sink enhancement. Remote sensing-based estimation and spatial inversion of the carbon stock in terrestrial ecosystems can provide significant references for evaluating the carbon sequestration potential of ecosystems and achieving the "dual carbon" goals. Based on the remote sensing variables extracted from the Landsat8 OLI images, combined with single-band data, vegetation indices, texture factors, and topographic factors, this study determined the optimal bandwidth using the Akaike information criterion corrected (AICc) and cross-validation (CV). Then, it constructed a geographically weighted regression (GWR) model using the Gaussian, Bi-square, and Exponential kernel functions to estimate the carbon stock of the Ebinur Lake Basin. Through comparison between the GWR and the multiple linear regression (MLR) models, this study selected the optimal one to estimate the spatial distribution of carbon stock. The results indicate that the GWR model exhibited higher accuracy than the MLR model. The optimal GWR model with CV-determined bandwidth and Exponential kernel function achieved an accuracy improvement of 16.31%~66.69%, significantly reflecting spatial heterogeneity. The carbon storage of the basin in 2023 was estimated to be approximately 426.28×106 t, with aboveground, underground, and soil carbon stocks accounting for 31.83%, 24.33%, and 43.28%, respectively. From 2014 to 2023, the carbon stock showed a decreasing trend and a spatial distribution pattern characterized by low stock encircling the Ebinur Lake and high stock in its periphery. Among all terrestrial ecosystems, grassland witnessed the most significant decline in carbon stock.

       

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