Simulation Of Land Use Change And Carbon Stock Estimation In The Yellow River Basin Based On FLUS-InVEST Model

As a key carbon reservoir for carbon release and carbon sequestration,terrestrial ecosystems play an important role in the process of global carbon cycle.Increasing the carbon stock of terrestrial ecosystems can effectively reduce the concentration of carbon dioxide in the atmosphere and become one of the important ways to mitigate the greenhouse effect.Land-use change affects the structure,function and processes of terrestrial ecosystems,and is an important factor influencing the change of carbon stocks in terrestrial ecosystems.The Yellow River Basin is an important ecological barrier and economic zone in China.Accurately assessing and predicting the impact of land use change on ecosystem carbon stocks in the Yellow River Basin and exploring the optimisation of land use structure to increase ecosystem carbon stocks can help improve ecosystem services in the basin and mitigate climate change,which is important for achieving the national goal of"double carbon".This paper uses remotely sensed data,meteorological data,and other data to examine the impact of land-use change on ecosystem carbon stocks.Using remote sensing data,meteorological data and statistical data,this paper firstly analyses the spatial and temporal characteristics of land use change in the Yellow River Basin from 2000 to 2020 based on the land use change assessment model.Finally,the InVEST model was used to estimate the ecosystem carbon stocks under different development scenarios,providing a scientific basis for the optimal regulation of land use under the"double carbon"objective.The main findings are as follows:(1)Analysis of the current situation of land use.From 2000 to 2020,the spatial distribution and structural composition of land use in the Yellow River Basin were relatively stable.From east to west,the transition was realized from cultivated land to forest land and then to grassland.Grassland>cultivated land>woodland>barren>urban>water area>permanent The size relationship of ice and snow,grassland,cultivated land,and woodland accounted for 50.35±0.45%,35.92%±0.98%,and 9.23%±0.14%,respectively.Specifically,in the past 20 years,the cities in the Yellow River Basin continued to expand,the growth of woodland and grassland was relatively slow,and the reduction of cultivated land and barrenness was relatively large.The upper reaches are dominated by the mutual transfer of cultivated land and grassland,grassland and barren land,and the overall performance is the decrease of cultivated land and barren area,and the increase of grassland and urban area;the middle reaches are dominated by the mutual transfer of cultivated land and grassland,grassland and woodland,and the overall performance is The decrease of cultivated land and the increase of urban and forest and grassland;the transfer of cultivated land to cities in the downstream is mainly manifested in the decrease of cultivated land and the expansion of cities.The repeated transfer of land types indicates intense competition in land type space,reflecting the conflicting land use needs of different stakeholders.(2)Assessment of carbon stock status.The overall carbon stock shows a spatial pattern of"gradually decreasing from south to north,with the southwest being higher than the southeast",and the cumulative values of carbon stock in the Yellow River Basin in 2000,2010 and 2020 are 3.1455×10~9 t,3.1563×10~9 t and3.1527×10~9 t,respectively.The average carbon stock level is the highest in the upper reaches and the lowest in the lower reaches;the total carbon stock in the upper reaches increases first and then decreases during the20 years,while the total carbon stock in the middle reaches shows a continuous increase and the total carbon stock in the lower reaches shows a continuous decrease;the carbon stocks in forest land,cities and waters in the upper,middle and lower reaches all show a continuous increase,while the carbon stocks in arable land show a decreasing trend.In the process of land transfer,the transfer of forest land to other land types will lead to a decrease of carbon stock;the transfer of grassland to other land types will lead to the loss of carbon stock,except for the increase of carbon stock due to the transfer to forest land;the transfer of cropland to forest and grassland types will lead to the increase of carbon stock,and the flow of cropland to cities will lead to the loss of carbon stock.In general,the type of land transfer determines the trend of carbon stock increase or decrease,while the result of carbon stock change is determined by both the type of transfer and the amount of transfer.(3)Characteristics of land use change in different future scenarios.There is a large variation in the variation of categories in the Yellow River basin and in the upper,middle and lower reaches under different scenarios.Under the natural development scenario,arable land in the Yellow River Basin continues to decrease and forest land continues to grow;grassland increases faster and forest land decreases faster in the upper reaches;grassland decreases significantly in the middle reaches;and arable land decreases more in the lower reaches.Under the ecological conservation scenario,both forest and grassland in the Yellow River basin expand significantly;forest land decreases less and grassland increases significantly in the upper reaches;forest land increases more and grassland and arable land decrease in the middle reaches;arable land decreases less and urban expansion is smaller in the lower reaches.Under the arable land conservation scenario,arable land in the Yellow River basin expands significantly;upstream arable land decreases and cities grow;midstream forest and grassland show a decreasing trend and arable land increases significantly;downstream arable land increases significantly and cities show a decreasing trend.The urban expansion scenario is similar to the natural development scenario,but the expansion of cities in the Yellow River basin is more pronounced;upstream cities show a decreasing trend;midstream grasslands show a large decrease and significant urban expansion;downstream arable land shows a large decrease and significant urban expansion.(4)The changes in carbon stocks in the Yellow River basin,the upper,middle and lower reaches of the river vary significantly between 2020 and 2030 under different scenarios.Under the natural development scenario,the carbon stock in the Yellow River basin increases(4.7965×10~6 t);the carbon stock in the upper reaches increases more(1.8764×10~7 t);the carbon stock in the middle reaches and lower reaches both show a decreasing trend(-9.8891×10~6 t,-4.0789×10~6 t).Under the ecological protection scenario,the carbon stock in the Yellow River basin increases more(9.0953×10~6 t);upstream and midstream show carbon sink(1.1330×10~7 t,1.2239×10~6 t);downstream carbon stock shows carbon source(-3.4585×10~6 t).Under the arable land protection scenario,the carbon stock in the Yellow River basin decreases more(-1.7676×10~7 t);both upstream and midstream carbon stocks show a decreasing trend(-6.2152×10~6 t,-1.2332×10~7 t),and the downstream carbon stock increases slightly(8.7174×10~5 t).Under the urban sprawl scenario,the carbon stock in the Yellow River basin decreases(-4.6071×10~6 t),the upstream carbon stock shows an increasing trend(1.5419×10~7 t);the midstream and downstream carbon stocks show a decreasing trend(-1.4552×10~7 t,-5.4743×10~6 t).Overall,the changes of total carbon stock under different scenarios are related to the absolute changes of carbon stock caused by land class transfer,but the trends of total carbon stock depend on the relative changes of carbon stock caused by land class transfer to each other.