基于GF-2影像的武汉市九峰山国家森林公园地上碳储量估算

    Estimation of above-ground carbon storage in the Jiufengshan National Forest Park of Wuhan based on GF-2 images

    • 摘要: 探究国产高分辨率数据在森林碳储量估算研究中的潜力,为构建森林碳储量估算模型提供新思路。选取武汉市九峰山国家森林公园为研究对象,以GF-2遥感影像为数据源,结合地面实测信息,对研究区森林地上碳储量进行估算,共提取6个植被指数、4个波段值、8种纹理特征,筛选出9个与实测碳储量相关的遥感变量,运用线性与非线性方程对单个高相关变量和多个相关变量进行建模,选出最优模型,为进一步提高预测精度,将模型代入4种纹理窗口(3×3、5×5、7×7、9×9)。结果表明:通过遥感图像提取的植被指数之间,具有较强的共线性,单变量建立的模型精度低于多变量模型;利用均方根误差RMSE与决定系数R²对4个窗口下模型的预测精度进行评价,模型在5×5窗口下预测效果最好(R² = 0.73,RMSE = 0.5),3×3窗口下预测效果最差(R² = 0.64,RMSE = 0.8),将所有估测模型进行比较,在纹理窗口下模型精度提高了0.11。利用5×5窗口下构建的多变量模型对研究区碳储量进行估算,九峰山国家森林公园碳储总量为1.06×104 t ,总体平均碳密度为84.59 t/hm2,具有一定的固碳作用。选用国产高分辨率影像GF-2数据对武汉市九峰山森林公园进行反演研究,能很好地运用在森林植被碳储量定量与生长状况领域。研究结果对“双碳”目标下森林生态系统碳汇监测与管理具有重要科学意义。

       

      Abstract: Exploring the potential of domestic high-resolution data in the estimation of forest carbon storage estimation research provides a new approach for the construction of forest carbon storage estimation model. In this study, the Jiufengshan National Forest Park in Wuhan City was selected, GF-2 remote sensing image was used as the data source, and ground measured information was combined to estimate forest AGC storage in the Park. A total of 6 vegetation indices, 4 band values and 8 texture features were extracted, and 9 remote sensing variables that related to measured carbon storage were screened out. Linear and nonlinear equations were used to model a single highly correlated variable and multiple correlated variables, and subsequently the optimal model was therefore selected. In order to further improve the prediction accuracy, the model was carried into four texture Windows (3×3, 5×5, 7×7, 9×9). The results showed that the vegetation index extracted from remote sensing images had strong collinearity, and the accuracy of the single variable model was lower than that of the multiple regression model. The root-mean-square (RMSE) and the coefficient of determination R² were used to evaluate the prediction accuracy of the model under four Windows. We showed that the model had the best prediction power under the 5×5 window (R²=0.73, RMSE=0.5), and the prediction power was the lowest under the 3×3 window (R²=0.64, RMSE=0.8), compared with all the estimated models, the accuracy of the model is improved by 0.11 in the texture window. Therefore, the constructed multivariate model was used to estimate carbon storage with a 5×5 window. The total carbon storage in the Jiufengshan National Forest Park was 1.06×104 t, the overall average carbon density was 84.59 t/hm2, it has a certain carbon fixation effect. Using domestically produced high-resolution image of GF-2 satellite imagery data to invert Jiufengshan Forest Park in Wuhan, it can be well used in the field of quantitative carbon storage and growth status of forest vegetation. The research has important scientific significance for the monitoring and management of forest carbon sink under the “carbon peaking and carbon neutrality” target.

       

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