| Land use is a complex process of economic and land reproduction under the cyclical or sustained intervention of human activities.Land use optimization is an important means to alleviate the contradiction between land and people,and realize the sustainable utilization of land resources.From our research,the method of remote sensing(RS)and geographic information system(GIS)integration,spatial mathematical and statistical model analysis were adopted in the field of Mentougou District,Beijing.The spatial and temporal variability of land use/land cover changes in Mentougou area was analyzed on different scales using the TM image remote sensing interpretation in the past 30 years(1985,1990,1995,2000,2005,2010 and 2014),and the relationship between them and the influencing factors were analyzed.This paper also evaluates the temporal and spatial changes in supply services,regulatory services and cultural services in ecosystem services in the study area.Based on the natural environment and ecosystem services in the study area,a set of land suitability evaluation index was constructed.The forecast and optimization(number and spatial)of the land use in the study area in 2030 were carried out.Compared with the present,forecast and optimize the comprehensive utilization of land use and changes in ecosystem services.This research shows that:(1)From land use/land cover changes,23.65%of the land in the Mentougou area had changed over the past 30 years(1985-2014).The built-up land increased by 32.40%,mainly through the occupation of cropland(15.49 km2),orchards(2.58 km2)and wasteland(2.42 km2)to expand the area.The cropland decreased by 20.13 km2,a decrease of 66.97%.The area of orchard before 2000 had been in a downward trend,steadily increased after 2000,an increase of 65.35%.Wasteland also fell rapidly,a decrease of 80.87%.Shrub land increased year by year,especially after 2000.Forested land generally showed a decreasing trend,a decrease of 7.18%.The area of water bodies and grassland did not change much.From the sub-region scales,the built-up land of the plain sub-region(less than 200 meters)had increased by 37.50%,mainly from the cropland and orchard.The wasteland of low mountain sub-region(between 200 and 500 meters)had been reduced by 99.00%.The shrub land of mountain sub-region(more than 500 meters)had increased by 18.40%.Forested land had decreased by 4.21%,and wasteland had reduced by 73.04%.(2)From landscape patterns(1985-2014),the mean patch size of the whole Mentougou area decreased from 21.18×10-2 km2 to 20.09×10-2 km2 on the landscape level.Landscape patterns became fragmented and heterogeneous.The mean patch size in the plain sub-region increased from 21.52×10-2 km2 to 22.85×10-2 km2,and the landscape patterns became more aggregated.The mean patch size in the low mountain sub-region was small and became from 9.06×10-2 km2 to 8.30×10-2 km2,the landscape patterns became fragmented.Landscape patterns of high mountain sub-region did not change much.At the level of class,the built-up land,cropland,wasteland and forested land in the study area were fragmented year by year.The landscape patterns of orchard became heterogeneous first,and then inheterogeneous.The aggregation of shrub land increased.The most obvious landscape patterns changes of plain sub-region was the built-up land.The heterogeneity of built-up land decreased first and then increased.The landscape patterns of wasteland in low mountain sub-region became fragmented year by year.The landscape patterns of shrub land in mountain sub-region became more gathered,and the landscape patterns of built-up land increased.The resident population,annual rainfall and economic factors in the study area were closely related to the landscape patterns of the plain sub-region,but not with the landscape patterns of the whole study area and the mountain sub-region.(3)The results of the ecosystem assessment showed that the spatial distribution of soil carbon storage and soil retention was relatively stable,mainly in the highest mountain area and the lowest in the plain area.The spatial distribution of water production and soil loss varied greatly at different times.In terms of quantity change,the water production in Mentougou area fluctuated relatively large after 2000,reaching a minimum value of 2.20×108 m3 in 2014 and a decrease of 44.20%over 1985.During the study period,the carbon storage increased first and then decreased,and remained stable after 2000.Among the carbon stocks of different land use types,the carbon storage of forested land and shrub land were significantly higher than that of other land use types,basically reached the whole carbon stocks of Mentougou about 90%.Soil loss decreased by 87.73%.Soil retention rate increased year by year and soil conservation function was improved.The cultural services(except aesthetic services)in the study area are mainly concentrated in the plain sub-region.(4)The results of land suitability evaluation and land use optimization based on ecosystem services show that Mentougou area suitable for cropland and orchard land area was small,and suitable for shrub land,forested land and grassland was big.The evaluation of land suitability which based on the results of regional natural conditions and ecosystem services showed that:the area of suitable cropland was 16.45 km2,accounting for 1.13%of the total area,mainly in the plain and hilly area.The area of suitable orchard was 27.79 km2,accounting for 1.91%of the total area,and the distribution range was similar to that of cropland,which is slightly wider than that of cropland.The land use area suitable for froested land,shrub land and grassland at the same time accounts for 89.72%of the total land area.Most of the western and northern mountainous areas were suitable for them,covering the whole study area.Based on the study of land use optimization program of ecosystem services,the built-up land,forested land and water bodies were increased by 13.05 km2,22.91 km2 and 5.88 km2 respectively in 2030.Wasteland was fully planned for other land use types.(5)The comprehensive benefit of land use optimization patterns were obviously improved compared with the present patterns and trend forecasting patterns in 2030.In terms of efficiency,the comprehensive benefit of land use after optimization was 8.31%and 12.94%higher than that of forecast and present situation respectively.From the ecosystem services,the predicted land use ecosystem services had declined significantly,while the optimized land use ecosystem services had been improved.Compared with present land use,water production in optimized’s increased by 31.19%,soil loss decreased by 9.09%,and soil retention rate increased from 98.70%to 98.94%. |
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