| The soil conservation service of the ecosystem refers to the regulation ability of the ecosystem to control soil erosion and the ability to maintain silt accumulation.The Fen River,the largest river in Shanxi.The abundant water and beautiful scenery used to be the specific geographical symbol of the Fen River.However,with the development of modern chemical industry and the development of man-made coal mining activities,the ecological environment of the Fen River was once deteriorated,which gave life to the river basin.Of people have caused serious distress.Ningwu County and Jingle County are located in the upper reaches of the Fen River.They are independent watershed units in the ecologically fragile area of??the Loess Plateau,and are also important water conservation areas,water and soil conservation ecological function areas and biodiversity protection areas.In order to protect the important water source area in the upper reaches of the Fen River,and to ensure the smooth implementation of the ecological protection and restoration project of mountains,waters,forests,fields,lakes and grasses,this research is supported by Arc GIS,In VEST model,BP neural network,etc.The soil conservation status is studied,and the results are as follows:（1）The overall level of soil erosion in the region is relatively good,roughly in two levels,slight and light,accounting for 73.33%of the total erosion,but there are still severe local erosions that cannot be ignored,accounting for 4.22%of the total erosion.The total amount of soil conservation in the area is 8016419.99t,and the average soil conservation modulus is20.15t·hm-2·a-1.The lower elevation area in the eastern section is the area with strong soil conservation in the study area.Grassland and woodland are the main land use types in this area.（2）According to land types,the order of soil conservation from large to small is:woodland>grassland>arable land>water area>unused land>building land.Among them,woodland was the land type with the highest soil conservation intensity,which was as high as24.1t·hm-2·a-1.The land type with the highest soil conservation amount was woodland and grassland,which was as high as 6171514.97t·a-1.The total soil conservation amount accounted for about 76.99%of the total soil conservation amount in the whole region,exceeding three quarters of the total soil conservation amount.Therefore,forests and grasslands play a pivotal role in soil conservation of the ecosystem.Ecological restoration engineering measures such as tree planting and grass planting can be adopted to control soil erosion and promote ecological protection of the source of Fenhe River.（3）The soil retention intensity shows a trend of first rising and then falling with the increase in altitude.The soil retention intensity is the highest in the range of 1700-2000m above sea level,and the maximum value is 21.61t·hm-2·a-1.The soil retention intensity is the smallest in the area of 2600m,and the minimum is 4.82t·hm-2·a-1.The total amount of soil conservation in the area of 1400-1700m above sea level is the largest,which is 3,162,207.18t·a-1,accounting for 39.50%of the total area.Human disturbance is the main factor leading to the aggravation of soil erosion in the study area.Therefore,it is necessary to implement ecological protection and restoration projects according to local conditions to restore the beautiful scenery of the Fen River.（4）Among the relevant soil erosion factors,their significance is ranked as LS>K>P>R>C,indicating that the LS factor of slope and slope length has the strongest significance on soil erosion.The erosion is the least significant.The prediction error of the BP neural network is controlled within 1%,and the prediction error of the regression model is 2%to 10%,indicating that the BP neural network has higher accuracy and can accurately and effectively predict the significance of each factor to soil erosion.The study area provides a scientific basis for subsequent water and soil erosion control in small watersheds. |
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