Spatio-temporal Changes And Forecast Of Land Ecosystem Service Value In Gansu Province

The land ecosystem provides various products and services to human beings,which is an important bearing factor for socio-economic development and various human activities.Based on the land use remote sensing monitoring data,this paper constructed a dynamic evaluation model of ecosystem service value in Gansu Province.Then,this revised model was used to estimate the ecosystem services value in Gansu Province from 2005 to 2020,and with the assisstance of GIS and other software analyzed its spatial distribution.Finally,the CA-Markov model was used to predict the ecosystem services value in Gansu Province in 2030.It is intended to provide a certain theoretical reference for promoting the rational land use in the study area,and the scientific delineation and protection of land functional zoning.The main research conclusions are as follows:(1)From 2005 to 2020,the area of different land types in Gansu Province changed to varying degrees.Except for the decrease of cropland and unused land,the area of other land types has increased.Among them,the increase of build-up land area is the most significant(up to 60.58%).The transformation among different land types in the study area was mainly affected by the policies of "returning farmland to forest and grassland" and "Western Development".In space,the transformation of cropland to forests,grasslands are mainly located in the central and eastern regions of Gansu Province;In addition,build-up land is a main transfer-in type,and a large amount of cropland and unused land had been transferred,unused land as the main transfer-out land,is an important source for supplementing various land use types.It plays an important role in maintaining the balance of land use in Gansu Province.The transfer-out of unused land distributed in the Hexi Corridor area in terms of space.(2)During 2005—2020,the ecosystem services value generally showed a trend of first decreasing sharply and then increasing at a constant speed in Gansu Province.The land ecosystem services value is generally at a medium level,and regulation and support services are the main types of services in Gansu Province.Among the 14prefecture-level cities,the ecological system service value per unit area of Linxia Hui Autonomous Prefecture,Gannan Tibetan Autonomous Prefecture,and Longnan City were relatively high.Jiayuguan City,Wuwei City,Jinchang City,and Jiuquan City had relatively low ESV.The remaining 7 cities of land-average ESV cities was at a medium level and the difference is not obvious.Judging from the contribution rate of the ecosystem service value of each land use type,the grassland ecosystem with absolute advantage in area had the largest service value,with a contribution rate of40%.The contribution rate of forest,water,cropland and unused land followed.(3)From the perspective of the spatial distribution of ecosystem service value,the spatial distribution of ecosystem service value in Gansu Province was significantly different during the study period.The low-value areas of ecosystem service value(ESV)are concentrated in the northern part of Gansu Province,where unused land is widely distributed.At the same time,because the Shiyang River、Shule River and Heihe waters with high ESV equivalent factors are distributing in the northern area,the medium-high value areas and high-value areas of ESV are also scattered and staggered in the northern area.Howener,the middle and low value areas are concentrated in the southeastern part of Gansu Province,and the middle value areas are located in the central and southwest part of Gansu Province where forest resources are rich.In the past 15 years,different levels of ESV have experienced different degrees of gain/loss in various periods,but the magnitude of the change is not large.From the perspective of the local spatial auto-correlation relationship of ecosystem service value in Gansu Province,there is a more obvious positive spatial correlation.The spatial auto-correlation index in 2005,2010,2015 and 2020 is generally greater than 0.45.(4)The center of gravity of the land ecosystem service value in Gansu Province are mainly located in Lanzhou City,and the overall location is in the southern part of the geometric center of Gansu Province(103°.08′E,36°.66′N).It reflects that the ESV of the southern ecosystem service value is slightly higher than that of the northern region.During the study period,the center of gravity showed a transfer trajectory from south to north,and the migration distance was continuously shortening,indicating that the ESV between north and south in Gansu Province is balanced and stable.In addition,on the influencing factors of the spatial differentiation of ecosystem service value in Gansu Province,it is found that land use/cover change has the greatest impact on ESV.Therefore,there is a close relationship between the shift of ESV center of gravity and the conversion among land use types.(5)Under the natural development scenario,the expansion speed of build-up land has been controlled,but the reduction of water area is worthy of attention.In2030,the total land ecosystem services value will be declining,and ESV will still focus on regulation and support services.From the perspective of single ESV,the single ESV dominated by water ecosystems has declined due to the decrease in water,and the other 7 single ESV all show an increasing trend.From the perspective of changes in ESV at different levels,the ESV in middle and low value area has increased,while ESV at other levels has decreased to varying degrees.In addition,the positive spatial correlation of ecosystem service value in 2030 has weakened,but the degree of change is small.