Research On Land Use Change And Carbon Storage In Nansi Lake Basin Based On InVEST Model

The global carbon cycle process is closely related to human activities and land-use change.It is of great significance in the long term to reveal the relationship between regional land-use change and ecosystem carbon storage to improve the capacity of regional carbon sequestration and promote sustainable development.We analyzed the trend of land-use change from 1975 to 2050,and simulated and evaluated the change of carbon storage and carbon sequestration capacity in the basin based on the InVEST model carbon sequestration module.The Natural Increase Scenario,Ecological Protection Scenario,and Cultivated Protection Scenario of land-use was simulated by the CLUE-S model combined with the multi-objective function in the Nansihu Lake basin in 2050.With a view to providing a strong scientific basis for further research on the land use layout and improving the carbon sequestration capacity.The main conclusions are as follows:(1)From 1975 to 2015,take 2005 as a node,the large increase of construction land in the previous stage was accompanied by the rapid decrease of cultivated land and ecological land.While in the latter stage,the construction land has been further expanded,and the area of cultivated land and ecological land has also recovered with the guidance of relevant policies.In terms of spatial distribution,urban expansion is the main reason for the decrease of cultivated land;the change of forestland and grassland was small,and the water body is partially transferred,the construction land has been expanded a lot based on the original town in Jining,Zaozhuang and some other areas.From the perspective of the whole basin,the construction land demonstrated a tendency of expanding to the southwestern area.(2)Using the CLUE-S model to simulate the land-use pattern under three scenarios,the results showed that the simulation accuracy of single land-use type is greater than 0.78 and the overall simulation accuracy is greater than 0.88.This can prove that the parameter setting is suitable for the land use simulation in the Nansihu Lake basin.In the Natural Increase Scenario of 2015-2050,large areas of cultivated land were replaced by construction land in the marginal areas of the former cities and towns,and the cultivated land decreased by 1020.16 km~2 at a speed of 29.14%,and the forest land and grassland decreased by 264.28 km~2,532.12 km~2,unused land at a speed of 0.85%,by 28.21 km~2,respectively.In the Ecological Protection Scenario,the cultivated land,the construction land and the unused land were all reduced,the cultivated land decreased the most was 2432.16 km~2,the forest land,the grassland and the water body all extended around on the basis of the present pattern,and the value was 573.14 km~2,2903.37 km~2,35.83km~2 in turn.In the Cultivated Protection Scenario,the small areas of cultivated land and grassland increased on the original basis,the forest land,water body and unused land decreased,and the construction land remained unchanged.(3)During 1975-2050,take 1995,2015 and 2050 as the nodes,the total carbon storage in the basin decreased first,and then keep increased.From the point of temporal pattern,the change rate order of carbon storage in each land-use type were as followed,from 1975 to 1995,forest land>cultivated land>construction land>grassland>water body>unused land,from 1995 to 2015,forest land>construction land>cultivated land>grassland>water body>unused land.In NIS,cultivated land>construction land>water body>forest land>grassland>unused land.In EPS,forest land>grassland>cultivated land>water body>construction land>unused land.In CPS,cultivated land>construction land>forest land>water body>grassland>unused land.From the point of spatial pattern,the middle value of carbon storage was basically consistent with the distribution of cultivated land and grassland,and the high value area mainly corresponds to the forest land,especially in Tongshan,Jiuxing in western basin and Sishui,Zoucheng.And the low-value areas changed with time.The main types of low value land use corresponding to the construction land and unused land during 1975-2015,while in 2015-2050,the main types were water bodies and unused land.(4)In the study period,the carbon sequestration of the basin showed a slightly growth trend,while the carbon sequestration capacity of each region was closely related to the carbon density and area.For the basin,the transfer of cultivated land,ecological land and construction land had a significant influence on the total carbon storage.From the regional point of view,the hot spots of land use change in the basin were also the hot spots of carbon sequestration.In the Natural Increase Scenario,the significant transferred cultivated land and construction in the western and middle of the basin,as well as the ecological land with high carbon storage transferred from southern Xuzhou,were both the keynote.Compared with 2015,the relationship between supply and demand of the total carbon sequestration in the basin tends to moderate,the ratio of supply to demand in the Ecological Protection Scenario is the largest,and the Natural Increase Scenario was tense.