1987—2020年昕水河流域土地利用变化对碳储量的影响

Impact of land use change on carbon storage in Xinshui River Basin from 1987 to 2020

“三北防护林工程”和“退耕还林还草工程”等重大林业生态工程引起了土地利用变化,进而深刻影响黄土高原等区域的碳储量。然而,目前尚缺乏林业生态工程驱动下土地利用变化对黄土高原碳储量影响的定量研究。基于1987—2020年土地利用数据、2017年林地地上生物量和土壤有机碳实测数据,采用InVEST模型解析黄土高原昕水河流域碳储量时空变化特征,定量分析土地利用变化对流域碳储量的影响。结果表明:(1)1987—2020年昕水河流域林地面积呈上升趋势,增加33.39%;草地和耕地面积呈下降趋势,分别减少31.11%和4.02%。(2)昕水河流域总碳储量增加249.19×10^(4) t,其中,林地碳储量增加1177.85×10^(4) t,草地、耕地碳储量分别减少835.84×10^(4) t和92.79×10^(4) t。(3)林业生态工程实施是昕水河流域碳储量增加的主导因素,林地对流域碳储量增加的贡献率为472.67%。研究可为林业生态建设和保护利用提供科学依据,为增强流域林草固碳功能提供参考。

Significant forestry ecological projects implemented in China,such as the Three-North Protective Forest Project and the Grain for Green Project,have triggered substantial alterations in land use patterns,notably across regions like the Loess Plateau.These initiatives have profoundly impacted carbon storage dynamics within the plateau′s expanse.Nevertheless,a conspicuous gap persists in quantitative research,particularly concerning the precise influence of land use changes resulting from these forestry ecological projects on carbon storage within the Loess Plateau.To address this gap,we conducted a comprehensive analysis leveraging extensive land use datasets spanning from 1987 to 2020,in conjunction with field measurements of aboveground biomass and soil organic carbon conducted in 2017.Our rigorous investigation aimed at unraveling the intricate interplay between land use dynamics and carbon storage within the Xinshui River Basin of the Loess Plateau.Utilizing the InVEST model,we endeavored to dissect the spatiotemporal evolution of carbon storage patterns within the basin,shedding light on the multifaceted factors shaping its ecological landscape.The results showed that:(1)spanning from 1987 to 2020,69.30%of the Xinshui River Basin experienced land use change,and the expanse of forested areas within the basin exhibited a notable upward trajectory,marking a 33.39%increase,while concurrent observations revealed diminishing extents of grassland and cropland,registering declines of 31.11%and 4.02%respectively.Construction land in the basin slightly expanded along stream systems while nonobvious changes were detected for water bodies.(2)Carbon storage in the basin during 1987 to 2020 dispalyed evident spatial distribution patterns with high carbon storage in the east and south while low values in the west and north.The total carbon storage in the basin experienced a considerable augmentation during this period,witnessing a surge of 249.19×10^(4) t.This augmentation was primarily fueled by forested regions,which contributed an impressive increment of 1177.85×10^(4) t.Conversely,grassland and cropland witnessed declines of 835.84×10^(4) t and 92.79×10^(4) t,respectively.(3)The implementation of forestry ecological projects was a dominant factor for the increase of the total carbon storage in the basin,and the contribution of forest land expansion to the increase of carbon storage in the basin was also significant.Particularly noteworthy was the significant role played by forested areas,with their contribution to the basin′s carbon storage enhancement reaching a remarkable 472.67%.However,the declines in grassland conctibuted to-335.42%of the net augmentation of total carbon storage in the basin.The study offers policymakers and stakeholders empirical evidence and quantitative metrics to support the implementation of forestry ecological construction,conservation,and sustainable land management practices.Additionally,it provides guidance for enhancing carbon sequestration efforts in the watershed.