Study On Eco-service Function Of Soil Conservation Based On InVest Model

The deterioration of ecological environment in Qilian Mountains has become the focus of the whole society.Soil and water loss is one of the most prominent problems.Soil and water loss mainly manifeste in the intensification of soil and water loss and the decline of forest and grassland quality.In this study,InVEST model was used to study soil erosion and soil conservation in Qilian Mountains of Gansu Province.Soil loss and soil conservation are not only affected by natural environment,but also by human activities.The environmental factors affecting soil loss and soil conservation can be analyzed from altitude,vegetation distribution,slope and soil type at different altitudes.Meanwhile,the different land use types can be analyzed depended on various human activities.Through the calculation results of the model and the analysis of GIS processing,the following main conclusions are drawn:1.In the nature reserve,63.96% of the total area of the nature reserve is mainly slight erosion,which is better overall.However,there are some serious erosion areas whose proportion of erosion area above intensity is 25.22%.The areas with weak soil conservation intensity are mainly distributed in the western and middle parts of the nature reserve.The amount of sediment generated by soil erosion in the western section is relatively large,and its ability to intercept sediment is also weak overall.2.The order of soil erosion modulus from high to low is unused land,Low-covered grassland,mediumcovered grassland,dryland,sparse woodland,high-covered grassland,shrub forest land,woodland.The range of change is 112.25t·hm^-2·a^-1 to292.87t·hm^-2·a^-1.According to the data of soil erosion modulus and soil erosion amount,it is known that unused land is the main land use type that causes the soil erosion.Following,the grassland?area ratio 44.26%?is the largest land use type in the study area,and is also the most widely distributed vegetation type.Its soil erosion amount accounts for 16.90% of total erosion,and the soil erosion modulus is obviously higher than other vegetation types.Grassland soil erosion is the most serious in natural vegetation,and soil conservation capacity is also weaker than other natural vegetation types.However,the grassland is the land use type with the highest total soil conservation.At present,the effect of forest land on soil conservation is the best,but in terms of area and total soil conservation,grassland has the greatest potential for soil conservation.From the overall characteristics of landscape pattern,sparse woodland,woodland and medium-covered grassland are most affected by human activities.The three types of land use mainly distribute in the middle and eastern parts of the protected area,and are the main areas of human activities.Therefore,the protection of forest and grassland should focus on the middle and Eastern parts.3.The soil retention capacity in the protected area increased first and then decreased with the increase of altitude.When the altitude was above 4500 m,there was a slight increase.The soil erosion intensity levelfluctuated with the elevation,and continued to fall back at an altitude of 2500-3500 m.The area above 4,500 m above sea level showed a slight decline;the soil in the range of 2500³500m had the best soil retention;the area of soil erosion above 3500 m accounted for 71.64% of the total erosion,which was the main area of soil erosion.4.In the region with slopes of 25 degrees,the amount of soil conservation accounted for 52.6% of the total amount of soil conservation,but the amount of soil erosion accounted for 66.11% of the total amount of soil erosion.5.The soil erosion modulus of sandy soil in grassland is low,but its soil conservation capacity is only 25.1t·hm^-2·a^-1 by calculation.Felt soil,chestnut calcareous soil and black felted soil are the main soil types that breed grassland.Felt soil and chestnut calcareous soil are the most serious soil erosion in grassland soil types,accounting for 43.3% of the total amount of soil erosion,which indirectly reflects animal husbandry in the protected area.The unbalanced utilization of grassland resources.Although the soil erosion status of black felt soil is generally light,its soil conservation capacity is easily limited by human disturbance,and its soil conservation capacity is only 145.72t·hm^-2·a^-1.6.The value of forest and grassland fertilizer conservation in the nature reserve occupies the largest proportion in the value of soil conservation ecological service function.The total value of forest and grassland fertilizer conservation in Qilian Mountain Nature Reserve in Gansu Province is 90.291 billion yuan.The value of reducing sediment deposition and abandoned land in the ecosystem of the reserve is 576 million yuan and 144 million yuan respectively.