Soil Conservation And Carbon Sequestration Potential Of Ecological Restoration Projects In Red Soil Hilly Region And Its Response To Climate Change

Soil erosion is one of the global ecological environment problems,which affects ecosystem services.Ecological restoration projects are an important measure to control soil erosion and has an important impact on soil conservation and carbon sequestration.In the context of global climate change and "dual carbon",the potential of soil conservation and carbon sequestration and its response to climate change after the implementation of ecological restoration projects remain unclear.In this study,Future Land Use Simulation(FLUS)model,China Soil Loss Equation(CSLE)and soil erosion carbon source/sink empirical model were used in the red soil hilly region of Southern China.The land use change characteristics,soil conservation and carbon sequestration potential in the red soil hilly region driven by ecological restoration projects in the past 30 years(1985-2015)and the next 30 years(2030-2060)were studied.The results have important reference value for understanding the carbon exchange between soil erosion process and atmospheric carbon pool,developing strategies for global climate change,and evaluating the goal of "carbon neutrality".Relevant research conclusions are as follows:(1)The effect of ecological restoration projects on land use change was revealed.Since the implementation of Natural Forest Protection Project in red soil hilly region in 1998,the goal of ecological restoration project has changed from improving agricultural productivity and economic income level to protecting ecological environment.Based on the analysis of land use change in red soil hilly region from 1985 to 2015 driven by ecological restoration project,two land use change models,baseline model(BAU)and ecological restoration model(ERP)were obtained.A model that converts large amounts of natural forest land into cultivated land and protects small amounts of natural forestland and grassland.In BAU mode,under the implementation of ecological restoration project,the area of forestland and grassland increases slightly,while the area of cultivated land decreases.The ERP model is a model that aims at ecological security,forbade the governance of natural forest land,and returned cultivated land with low productivity to forestland.In ERP mode,under the implementation of ecological restoration projects,forestland and grassland increase rapidly,while cultivated land decreases rapidly.(2)The effects of land use change on soil conservation potential under the influence of ecological restoration projects were clarified.Land use change was the main driving factor of soil erosion change in red soil hilly region,and the average soil erosion increased 79% and decreased 16% in BAU and ERP models,respectively.Under BAU model,land use changes decreased soil erosion of cultivated land and grassland,and increased soil erosion of forestland.The land use change of ERP model reduced the soil erosion of forestland and grassland and increased the soil erosion of cultivated land.The changes of soil erosion under moderate carbon emission(SSP2-RCP4.5)and high carbon emission(SSP5-RCP8.5)climate have opposite results.Under SSP2-RCP4.5 scenario,soil erosion of cultivated land,forestland and grassland will increase by 34 t,28t and 51 t from 2030 to 2060,respectively.Under SSP5-RCP8.5 scenario,soil erosion decreased by 51 t,46t and 88 t,respectively.The results of this study have a guiding role in improving soil conservation in red soil hilly region by implementing ecological restoration projects to regulate land use change.(3)The response of soil carbon sequestration potential to global climate change was clarified.Soil carbon sequestration potential under moderate carbon emission(SSP2-RCP4.5)and high carbon emission(SSP5-RCP8.5)climate background showed an increasing trend.Under SSP5-RCP4.5 and SSP5-RCP8.5 scenarios,the carbon sequestration potential of cultivated land,forestland and grassland will increase from 2030 to 2060,but the increase rate under SSP5-RCP8.5 scenario is less than that under SSP2-RCP4.5 scenario.Climate change is the main driving factor of soil carbon sequestration in the red soil hilly region.The combined land use and climate simulation showed that the average soil carbon sequestration increased 98%and 32% under SSP2-RCP4.5 and SSP5-RCP8.5 scenarios,respectively.Soil carbon sequestration potential under SSP2-RCP4.5 and SSP5-RCP8.5 scenarios accounted for 3.84%and 1.41% of the annual average annual carbon sink(201 Tg,1Tg=106t)of the terrestrial ecosystem,respectively.The results provided a new research perspective for increasing the ecosystem carbon sink.In conclusion,the regulation of land use change by implementing ecological restoration projects plays a leading role in soil conservation,and the mitigation of global climate change by limiting carbon emissions plays a role in improving the soil carbon sequestration potential in the red soil hilly region.These results provide a theoretical basis for implementing ecological restoration projects to control soil erosion in the red soil hilly region in the future and have important reference value for improving soil carbon sequestration potential in the red soil hilly region in response to global climate change.