Studies On The Grassland Ecosystem Services And Theirs Key Influencing Factors In Inner Mongolia

Inner Mongolia is an important part of the ecological security barrier in north China.Natural grassland is the staple ecological resource in Inner Mongolia.Natural grassland plays an irreplaceable role for enhancing eco-environmental quality,including windbreak and sand fixation,water conservation,soil and water conservation,carbon fixation and oxygen release.However,research about the regulation mechanism of the grassland ecosystem service was not revealed.In this study,we first analyzed the pattern and quality changes of grassland ecosystems in Inner Mongolia from the level of grassland types and the spatial level of regional alliance cities,then evaluated its ecosystem services,finally,identified climatic,environmental and social factors that affect grassland ecosystem services.The study results showed that:1.The temporal and spatial changes of grassland ecosystem pattern in Inner Mongolia were significant.In 2020,the grassland area in Inner Mongolia was 557,700km2,accounting for 48.67%of the total land area of Inner Mongolia.Temperate typical grassland is the largest grassland type,accounting for 45.11%of the total grassland area.Xilin Gol League is the city with the largest grassland area,accounting for 31.78%of the total grassland area.Compared with 2000,the grassland area in Inner Mongolia decreased by 0.2%.In the evolution of the grassland pattern,the transfer-out area is mainly from grassland to cultivated land and construction land,and the transfer-in area is mainly from cultivated land and desert to grassland.Cultivated land is the largest source of grassland area transfer,accounting for 52.66%of the total transfer-in area.2.The productivity and quality of grassland in Inner Mongolia improved overall.In2020,the average NPP of grassland in Inner Mongolia was 203.80 gc·m^-2·a^-1,and the spatial distribution gradually decreased from the northeast to the southwest.Compared with 2000,the average NPP of grassland in Inner Mongolia increased by 29.57%.based on the changes of vegetation coverage and biomass,grassland quality showed increase trend since 2000.More than 34%of the grasslands show an increase in grades,while only 3.7%of the grassland quality decreased.Among the league cities,the areas with obvious improvement in grassland quality include Tongliao City,Chifeng City,Xing’an League,Hohhot City and Xilingol League.Among the grassland types,the grassland types with improved quality mainly include temperate meadow steppe,temperate typical steppe and temperate desert steppe.3.The five serve functions including,pasture production,water conservation,windbreak and sand fixation,soil conservation,and carbon sequestration in Inner Mongolia grasslands have all improved.The 2020 assessment results showed that:（1）Forage yield and forage production capacity of grassland ecosystems in Inner Mongolia were 41.4541 million t and 74.33 g.m^-2.a^-1.The areas providing forage production function were concentrated in the central and eastern part of Inner Mongolia,including Chifeng City,Tongliao City,Xilingol League and Xing’an League,and the cities of Hulunbe and Hulunbe provide more than 80%of the forage output of grassland in Inner Mongolia.（2）The total water conservation and water conservation capacity of grassland ecosystem were 32.611 billion m³ and 58.49 kg.m^-2.a^-1.The water conservation function was mainly concentrated in the central and eastern part of Inner Mongolia,including Hulunbuir city,Xilin Gol League and its surrounding areas as two core areas.（3）The total amount of windbreak and sand fixation and the intensity of windbreak and sand fixation in the grassland ecosystem were 7.049 billion t and 126.40 t.hm^-2a^-1.The windbreak and sand fixation function was mainly concentrated in the Xilingol League area,which provides more than 45%of the windbreak and sand fixation of Inner Mongolia grassland.（4）The total amount and intensity of soil conservation of grassland ecosystem were949 million t and 17.01t hm^-2A^-1.The key regions of soil conservation function were central and eastern Inner Mongolia,and the cities of Hulunbuir,Chifeng,Xilin Gol league and Xingan League provided more than 70%of soil conservation in Inner Mongolia grassland ecosystem.（5）The total carbon sequestration and carbon sequestration capacity of grassland ecosystem were 185 million t and 331.88 gc.m^-2.a^-1.The core area of Khurumbe and Xilingol League provides more than 56%of the carbon sequestration of the whole region.（6）Temperate typical steppe,temperate meadow steppe and lowland meadow were the main grassland types that provided ecological services.The yield of herbage,total water conservation,total windbreak and sand fixation and carbon sequestration were the highest,accounting for more than 53.51%,43.26%,57.87%and 46.16%of Inner Mongolia grassland,respectively.The soil conservation function of temperature meadow grassland was the highest,accounting for 41.52%（7）Compared with 2000,the service functions of grassland ecosystems have generally improved in 2020.Forage production,water conservation,windbreak and sand fixation,soil conservation and carbon fixation increased respectively by 31.17%,51.08%,5.97%,1.92%,and 29.74%.4.The key factors that affecting grassland production function was GDP,vegetation coverage,patch density,average annual precipitation and aggregation degree.The key factors that affecting grassland water conservation function was biomass,vegetation coverage,patch density,GDP and average annual precipitation.The key factors that affecting the windbreak and sand fixation function of grassland was GDP,patch density,altitude,biomass and degree of aggregation.The key factors that affecting the soil conservation function of grassland was biomass,GDP,vegetation coverage,slope and altitude.The key factors that affecting carbon sequestration was biomass,GDP,vegetation coverage,patch density and average annual precipitation.The main factors that affecting the comprehensive service function of grassland ecosystem was biomass,GDP,vegetation coverage,patch density and average annual rainfall.The integrated services of grassland ecosystem were positively correlated with vegetation coverage,biomass,patch density and annual average rainfall,but negatively correlated with GDP.5.The improvement of grassland ecosystem services in Inner Mongolia suggested that it is needed to promote the implementation of ecological protection and construction projects and improve grassland vegetation coverage and biomass.It is critical to implement policies in different areas according to key functions and strengthen the ecological protection of the core area of ecological services.In order to improve the ability of ecosystem service supply,ensure that the demand for regional ecological service is satisfied,and ensure the safety of regional ecological environment,it is necessary to limit the destruction and encroachment of grassland in the key service functional areas for economic development.