基于坡度视角的黄土高原退耕还林(草)工程碳汇效应分析

【目的】探究退耕还林(草)背景下黄土高原不同坡度退耕地的固碳效应及存在的差异，根据不同坡度碳储量的变化优化新一轮退耕还林工程。【方法】基于2000—2020年黄土高原固碳数据和2000—2015年土地利用数据，运用GIS空间分析法，分析了近20年黄土高原固碳量的时空变化，以及不同坡度退耕地的碳汇效应。【结果】2000—2020年黄土高原固碳量前期增幅较大，后期增幅较平缓，固碳量变化与森林覆盖面的走向基本一致，呈现南高北低的现象；2000—2015年黄土高原土地利用结构发生明显改变，耕地显著减少，林、草地覆盖率增长至56.42%,且各土地利用类型单位面积固碳量呈增加态势，林地单位面积上固碳量最多；此外，坡度15°～25°林地单位面积上固碳量最大，约716.93 g/m²,8°～15°草地的单位面积固碳量最大，约748.65 g/m²。【结论】黄土高原退耕还林还草工程带来了巨大的碳汇效应，不同坡度林、草地的固碳能力存在明显差异，缓坡度地带草地固碳能力最强，中高坡度地带林地固碳能力最强。

Analysis of carbon sequestration effect of sloping land conversion program in Loess Plateau from the perspective of slope

【Objective】 The aims of this research were to explore the difference of carbon sequestration effect of farmland at different slopes on the Loess Plateau under the background of converting farmland to forest, and optimize a new round of converting farmland to forest project according to the change of carbon storage at different slopes. 【Method】 Based on the data of carbon sequestration in the Loess Plateau from 2000 to 2020 and land use data from 2000 to 2015, the spatial and temporal changes of carbon sequestration and the carbon sequestration benefits of farmland with different slopes were analyzed by using GIS spatial analysis method. 【Result】 From 2000 to 2020, carbon sequestration on the Loess Plateau increased significantly in the early stage, but slightly in the later stage. The change of carbon sequestration was basically consistent with the trend of forest cover, showing a phenomenon of high in the south and low in the north. From 2000 to 2015, land use structure of the Loess Plateau changed significantly, cultivaled land decreased significantly, forest and grassland coverage increased to 56.42%, and the carbon sequestration per unit area of each land use type showed an increasing trend, and the carbon sequestration per unit area of forest land was the largest. In addition, the carbon sequestration capacity of grassland was the strongest in areas with a slope lower than 15°, and that of forest was the strongest in areas with a slope higher than 15°. 【Conclusion】 The project of returning cropland to forest and grassland brought about huge carbon sequestration effect in Loess Plateau. The carbon sequestration ability of forest and grassland at different slopes was obviously different. The carbon sequestration ability of grassland at gentle slope was the strongest, and that of forest at middle and high slope was the strongest.