| Ecosystem services refer to the benefits that human beings obtain from natural ecosystems.They are the link connecting natural ecosystems and human well-being and are an important way to achieve sustainable development in the region.At present,ecosystem services as a frontier and hotspot in the study of ecology and geography have attracted the attention of many scholars and research organizations.Changes of land use/cover affect the ecosystem landscape and processes,thereby changing the capacity of ecosystem products and services.Understanding the relationship between ecosystem services and changes of land use/cover,and studying the impact of land use/coverage changes on the spatial pattern of ecosystem services can effectively promote ecosystem service management and improve regional human well-being.Strengthening the interaction of ecosystem processes and services driven by land use/coverage changes is one of the frontier scientific issues in ecosystem service research.The solution of such scientific issues will provide important theoretical and methodological support for ecosystem management.The transnational area of Tumen River is an important component of the "The Belt and Road" initiative and the "China-Russian-DPRK-Mongolia" international economic corridor and the key development and opening area at the national level.It is also a key ecological function area and water source conservation and protection area at the national level.It plays an irreplaceable role in maintaining the basin's biodiversity,water conservation,soil and water conservation,carbon storage and ecological security.The region is located at the transnational area of three countries,and there are unstable factors in the ecosystem.The ecosystem is fragile and complex.In this study,the transnational area of Tumen River is taken as the study area,and the changes of land use/cover in 1988,1999,2007 and 2016 were quantified from the whole region and the China,DPRK and Russia scales.Using method of land transfer matrix and landscape indices to analyze the Spatiotemporal pattern and driving forces of land use/cover in the region from 1988 to 2016;Based on that,the method of model simulation was used to assess the four key ecosystem services in the study area,including habitat quality,food supply,carbon storage,and water conservation.Based on the results of model simulation,then the study analyzed the spatiotemporal pattern of four key ecosystem services;finally,Finally,the study evaluated the impact of land use/cover on ecosystem services in the region.The results show that:(1)The total area of the study area in 2016 was dominated by forest land.Among the three types of forest,broad-leaf forest had the largest area,coniferous and broad-leaf mixed forest followed;Followed by dry farmland,grassland,built-up area,paddy field,water,marshland,bare land,bare land area is the smallest.The highest side of built-up area on the Russian side,followed by the Chinese side and the DPRK,s side is the lowest;The highest side of dry farmland on the DPRK,s side,the Chinese side is the second,and the Russian side is the lowest;The highest side of paddy field on the Chinese side,followed by the DPRK's side,the Russian side is the lowest;The highest side of grassland on the Russian side,followed by the Chinese side,and the DPRK's side is the lowest;The highest side of forest on the Chinese side,followed by the Russian side,and the DPRK's side is the lowest;water,marshland and bare land have no significant contrast.The highest side of the degree of landscape fragmentation on the Chinese side,followed by the DPRK's side,the Russian side is the lowest;The highest side of landscape heterogeneity on the DPRK's side,followed by the Chinese side,the Russian side is the lowest;The highest side of the degree of connectivity on the Chinese side,followed by the Russian side and the DPRK's side is the lowest.The total area of built-up area and the dry farmland in the region increased from 1988 to 2016,the paddy field,grassland and forest shows a decreasing trend,coniferous forest has the fastest reduction,followed by broad-leaf forest and mixed forest,water,marshland,bare land increased.The area of built-up area and dry farmland on the three sides of China,DPRK,and Russia shows an increasing trend.The fastest increase in built-up area is on the Chinese side,followed by the Russian side,and the slowest increase on the DPRK's side.The fastest increase in dry farmland on the the Russian side,followed by the DPRK,s side,and the slowest increase on the Chinese side;The area of paddy field on the DPRK's side increased significantly,while that on the Russian side did not increase significantly;The area of paddy field on the Chinese side is decreasing;The area of forest showed a decreasing trend.The fastest decrease of forest on the DPRK's side,followed by the Chinese side,and the Russian side was the slowest.From 1988 to 2016,the largest area of forest in the total area was converted into dry farmland,grassland and built-up area;followed by dry farmland,mainly converted to forest,built-up area and paddy field,the area of dry farmland converted into forest is lower than the area converted into dry farmland during the same time period.Grassland is mainly converted into forest land and dry farmland;paddy field is mainly converted into dry farmland and built-up area;built-up area is mainly converted to forest and dry farmland.The main types of land use/cover on the three sides of change are forest,grassland,paddy field,and dry farmland.The area was converted on the Chinese side,with forest>dry farmland>paddy field>grassland;the area was converted on the DPRK's side,with forest>dry farmland>grassland>paddy field;the area was converted on the Russian side,with forest>grassland>dry farmland>paddy field.(2)The habitat quality of total area in 2016 was 0.638.The habitat quality of the Chinese side,the DPRK's side,and the Russian side were 0.6463,0.6460,and 0.6170,the Chinese side>the Russian side>the DPRK's side.The habitat quality of total area showed a declining trend from 1988 to 2016,DPRK's side>the Russian side>the Chinese side.The food supply of total area in 2016 was 5,475,800 tons.The food supply of the Chinese side,the DPRK's side,and the Russian side were 2,150,200 tons,2,528,200 tons,797,500 tons,the DPRK's side>the Chinese side>the Russian side.The food supply of total area showed an upward trend from 1988 to 2016,the Russian side>the DPRK's side>the Chinese side.The carbon storage of total area in 2016 was 485,000,000 tons.The carbon storage of the Chinese side,the DPRK,s side,and the Russian side were 213,100,000 tons,129,000,000 tons,142,800,000 tons,the Chinese side>the Russian side>the DPRK's side.The carbon storage of total area showed a downward trend,the DPRK's side>the Chinese side>the Russian side.The water conservation of total area in 2016 was 0.92 billion m3.The water conservation of the Chinese side,the DPRK's side,and the Russian side were 0.39 billion m3,0.26 billion m3,0.27 billion m3,the Chinese side>the Russian side>the DPRK's side.The water conservation of total area showed a downward trend,the DPRK's side>the Russian side>the Chinese side.(3)Changes in land use/cover have caused the habitat quality to continue to decline.The main factors causing the declining of habitat quality are:forest converted into built-up area,bare land,dry farmland,paddy field,grassland converted into built-up area,marshland converted into built-up area,dry farmland,paddy field,grassland,paddy field converted into built-up area,water converted into built-up area,bare land,dry farm field,paddy field,dry farmland converted to built-up area,bare land.It can be seen that the expansion of built-up area and the increase of farmland(dry farmland and paddy field)will inevitably result in the felling of forest,the opening of grasslands and marshland,and the existence of farmland(dry farmland and paddy field)occupied by built-up area,land filling of water bodies,and land reclamation around lakes.As a result,soil erosion,aridity,and reduction in nutrients have resulted in a series of human activities that have directly caused the deterioration of habitats and decreased habitat quality.Changes in land use/cover have caused food supply to increase continuously.The main factors causing the increasing of food supply are:forest converted into dry farmland,grassland converted into farmland,and paddy field converted into dry farmland.The main factors causing the reducing of food supply are:dry farmland converted into forest,built-up area and paddy field;paddy field converted into built-up area.The increase is greater than the reduction,resulting in an increasing trend in food supply.It can be seen that the increase in farmland(paddy fields and dry farmland)causes an increase in food supply;at the same time,changes in cropping habits,and the conversion of paddy field into dry farmland,are also one of the reasons for the increase in food supply.Changes in land use/cover have caused total carbon storage continuous decrease.The main factors causing the reducing of total carbon storage are:forest converted into dry farmland,grassland,built-up area;marshland converted into grassland.The main factors causing the increasing of total carbon storage are:grassland converted into forest,marshland and dry farmland converted into forest.The reduction is greater than the increase,resulting in a decreasing trend in total carbon storage.It can be seen that the deforestation of forests and the drying up of a large number of marshland caused a decrease in total carbon storage,which is the main reason for the decline in carbon holding capacity.Changes in land use/cover have caused the average annual water conservation continuous decrease.The main factors causing the reducing of the average annual water conservation are:forest converted into dry farmland,built-up area,grassland;dry farmland converted into built-up area;paddy field converted into built-up area.The main factors causing the increasing of the average annual water conservation are:dry farmland converted into forest;grassland converted into forest,dry farmland;built-up area converted into dry farmland.The reduction is greater than the increase,resulting in a decreasing trend in the average annual water conservation.It can be seen that the increase in built-up area and farmland(paddy field and dry farmland)has resulted in the deforestation;paddy field and dry farmland occupied by the built-up area is the main reason for the decline in water conservation services.The study of changes in the spatiotemporal patterns of ecosystem services under the influence of land use/cover changes has a current application value in the formulation of regional adaptation measures and the realization of regional sustainable development. |
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