| Land use is an important driving factor for changes in ecosystem service,which desert ecosystem is extremely fragile.The study of land use change caused by human activities with a great impact on desert ecosystem is of great importance in assessing the ecosystem service value(ESV).In order to improve the ecological environment in arid regions and prevent desertification,China government has initiated some key ecological projects,such as the construction of“Three North”Shelterbelt,natural forest protection,returning the grain plots to forestry and returning farmland to grassland,which have induced significant changes in land use of arid desert regions,and exerted positive influence on desert ecosystem services.As an arid desert region of Inner Mongolia,Alxa is the study area in this paper.Firstly,the Intersect modules of ArcGIS,PivotTable of Excel and inward/outward transfer rates of land types are adopted to analyze overall characteristics and inherent driving mechanism of changes in land spacial pattern.Secondly,InVEST model is adopted to assess three ecosystem service functions:soil conservation,carbon storage and water conservation.Lastly,zonal statistics,cold and hot spot analysis are used to study the influence of land use changes on ecosystem services.The results are as follows:(1)Based on the land use data in 2000,2010 and 2015,the scope and rate of land use change were quantitatively analyzed through calculating area changes of land-use types and dynamic indexes of unitary land-use type.The results showed that the area of grassland,construction land,cultivated land and water had an increasing trend,while the area of unused land and forest had decreased,which indicated the Alxa had experienced a significant change.Among these land use types,the area of construction land and reservoir pond changed the most.(2)According to the characteristics of ecological services,using shadow project,production cost and alternative market price methods,we evaluated Alax’s ESV by monetizing three kinds of evaluation indcators.From 2000 to 2015,Alxa’s ESV increased from 1025.26×10~8 to 1237.70×10~8 yuan,which indicated that ecosystem service functions in Alxa had constantly strengthened.Alxa Left Banner was an obviously increased region which mainly attributed to the decrease of unused land and increase of grassland.(3)The influence of land use change on ecosystem services were analyzed by Zonal Statistics,cold and hot spot analysis.From 2000 to 2015,Alxa had five hot spot regions,including eastern edge of Alxa Left Banner,northwest of Alxa Left Banner,southern edge of Alxa Right Banner,the downstream of Heihe River and western edges in Ejin Banner.The overall improvements in ESV among these regions are mainly benefited from ecological management projects in recent years.(4)Suggestions on ecological management and protection are proposed.Hot spot regions in Alxa Right Banner and west Juyanhai Lake show the trend of decline.As an important service area of carbon storage,Juyanhai Lake should be given priority in terms of protection.Improving the ecosystem service functions of these regions is of extreme importance to the ecological environment and sustainable development in arid desert regions of Alxa. |
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