Impacts Of Land Degradation On Regional Ecosystem Services In The Transnational Area Of China,North Korea And Russia Area

Land degradation is a hot ecological and environmental issue of global concern and a serious obstacle to sustainable socio-economic development.since the 20 th century,land degradation has become increasingly serious due to rapid population growth,rapid urbanization and industrialization leading to rapid growth in food demand,as well as irrational exploitation of land and damage to the ecological environment.The transnational area of China,North Korea,and Russia is rich in flora and fauna,with great biodiversity and obvious geopolitical advantages.In recent years,with the population movement and trade between the three countries,the land for construction has been expanding and the arable land has also shown an obvious process of growth,especially on the DPRK side,where more arable land has to be expanded to supply the demand for food in order to solve the increasing food problem.The process of land degradation in the form of expansion of construction land and growth of arable land mainly occupies a large amount of habitat and causes more serious ecological and environmental problems.Therefore,timely and effective evaluation of the land degradation process and its ecological and environmental effects in the transboundary region of China,North Korea and Russia.It can provide a reference and reference for the sustainable development of the region.Regional land degradation is a prominent manifestation of land use/cover change.In this study,based on ESA 300 m resolution four-phase land use data from 1992-2020,combined with topographic,meteorological,socio-economic and other relevant auxiliary data,the dynamic attitude model of land use change,transfer matrix,,landscape pattern index,and calculation of key ecosystem services were applied to evaluate the land degradation process and its resulting ecological and environmental effects in the transboundary region of China,North Korea and Russia,and the results are as follows.(1)In 2020,the land use/cover types in the study area are dominated by forest land cover,followed by cropland,both of which account for more than 97% of the total area of the study area,with other land types accounting for a smaller area.Spatially forest land occupies most of the study area and is distributed throughout the region;arable land is distributed in a circular pattern around the study area;construction land is mainly distributed in the center or surrounding areas of arable land with low terrain;grassland area is more on the Russian side;water bodies,wetlands and unused land occupy a small area and are sporadically distributed throughout the region.The changes in the number of land use types show a pattern of "three increases,two decreases and two unchanges".The area of arable land,construction land and grassland increased,the area of forest land and unused land decreased,and the area of water bodies and wetlands remained basically unchanged,with the area of arable land and construction land increasing faster and the area of forest land shrinking faster.Spatially obvious changes are mainly in the southwest,west and northwest regions.(2)Forested land is the main type of land degradation,and the growth of arable land and construction land is mainly carried out by encroaching on forested land.Both the Chinese side and the North Korean side have encroached on large areas of forest land to expand arable land,and a certain area of grassland has been occupied in the expansion of construction land,and the area of wetlands and water bodies is the least significant in the process of land degradation.From 1992 to 2020,the land for construction in the region grew by 866.16 km2,with an average annual growth rate of4.44%.The process of expansion of land for construction occupied the most arable land,followed by forest land,and less grassland,water bodies and wetlands.The arable land in the region grows by 4368.33 km2,with an average annual growth rate of 0.50%.The process of arable land growth occupies the most forest land,followed by water bodies and grassland,and the least wetland.Within the sub-region,on the Chinese side,construction land increased by 669.15 square kilometers,with an average annual growth rate of 5.65%;arable land increased by 2084.49 square kilometers,with an average annual growth rate of 0.41%.On the DPRK side,construction land increased by 118.8 square kilometers,with an average annual growth rate of 2.70%;arable land increased by 2,207.34 square kilometers,with an average annual growth rate of 0.61%.In Russia,construction land increased by 78.21 square kilometers with an average annual growth rate of 5.82%,while arable land increased by 76.50 square kilometers with an average annual growth rate of 0.73%.(3)The distribution of high values of habitat quality and carbon stock are spatially similar and are all distributed in the Changbai Mountain system and its surrounding areas except for construction sites,which are mainly forests,wetlands,and mostly mountains,hills,and gullies.The distribution of high values of habitat quality and carbon stock is spatially similar,and they are all distributed in and around the Changbai Mountain system,except for the construction land,which is mainly forest and wetland,mostly mountains,hills and valleys.between 1992 and 2020,the habitat quality and carbon stock in the study area show a decreasing trend,and these decreasing areas are mainly concentrated in the construction land with more frequent human activities and these decreasing These declining areas were mainly concentrated in the areas around the construction land and cultivated land where human activities were more frequent.The rate of decline in habitat quality and carbon stocks is fastest on the Russian side,followed by the North Korean side,and slowest on the Chinese side,while the soil conservation services in the study area show an overall increasing trend from 1992 to2020.Soil conservation services in the study area show an overall increasing trend from1992 to 2020,with the greatest change in soil conservation on the North Korean side,followed by the Chinese side,and the smallest on the Russian side.(4)Land degradation is an important factor causing habitat quality changes and habitat fragmentation,and changes in the area of built-up land and arable land as a threat factor in the region directly lead to changes in habitat quality.between 1992 and2020,the reduction of forest land area and the increase of arable land area due to land degradation are the main causes of carbon stock reduction,and the carbon loss caused by the reduction of forest land area in 28 years is 131 The loss of carbon caused by the reduction of forest land area in 28 years is 131 million tons.The distribution of soil retention capacity has similarity with the R coefficient of rainfall erosion,which indicates the existence of higher soil retention capacity in areas with high rainfall erosion.The occurrence of land degradation has led to a decrease in habitat quality and carbon stocks.The growth of built-up land area led to an increase in soil retention capacity in addition to a decrease in the first two;the growth of cropland led to a simultaneous loss and decrease in carbon storage and habitat quality,but was not associated with soil retention.