Evaluation Of Ecosystem Services In The Chenggou River Basin Based On InVEST Model

The Chenggou River is a secondary tributary of the Zuli River Basin,which is located in the western part of Loess Plateau and belongs to the first branch of the Yellow River.It is a representative basin of the Loess Plateau.In recent years,the government has launched a series of ecological construction projects,including the construction of silting dams,Green for Grain Project,and comprehensive treatment of small basin.In this paper,the sediment delivery ratio,carbon storage and crop production modules from the InVEST model are used to evaluate and classify ecosystem services in the Chenggou River Basin.Our study can provide scientific assessment and protection of ecosystems in this region,as well as in similar areas.The preliminary conclusions are as follows:(1)The high value of rainfall erosion force appears in the western part of the study area.The elevation of the study area generally increases from east to the west,and rainfall increases from east to the west due to the influence of topography.Patch distribution of the soil corrosion K is related to land use types and soil properties.Its high values are widely distributed over barelands,plain fields and slope croplands,and low values are found in shrublands,dam fields and grasslands.(2)The average soil erosion module of the watershed is 716.2t·km-~2·a.The study area is dominated by mild erosion,accounting for 94.69%of the total area.The soil conservation volume is 6.35×10~6t.The unit area amount is 39861t·km-~2·a,and the soil retention rate is 98.34%.The four land use types includes terraces,shrublands,woodlands and natural grasslands,of which the soil conservation volume is 5.37×10~6t and accounts for 84.56%of the whole basin.Our results suggest that the effect of watershed management is remarkable.According to the observation of runoff station,the actual soil erosion of the whole basin in 2014 is 1.01×10~5t,and the simulated soil erosion based on the InVEST model is 1.15×10~5t.The accuracy of the model calculation is87.6%,indicating the module has good applicability in this region.(3)The carbon storage of vegetation and soil is 1.01×10~5t and 2.86×10~5t,respectively.The total amount of carbon storage is 3.95×10~5t.The largest proportion of carbon storage is croplands,accounting for 74.58%of the basin.The croplands in the study area are composed of terraces and artificial grasslands,with a total area of 75.91km~2.The total and unit area yield is 1.25×10~5t and16.40t/hm~2,respectively.Therefore,croplands bring economic and ecological benefits.(4)The spatial distribution of sediment delivery ratio,carbon storage and crop production is examined by using the hotspot analysis.The distribution of hot and cold spots in soil conservation and carbon storage services is spatially overlapped.The distribution of hot spots is discrete,and hot spots are generally located in areas with high vegetation coverage and low human disturbance.The distribution of crop production services is highly discrete due to crop planting.The assembly area of cold spots in the above mentioned three services is basically the same,and is found in roads and residential areas with intensified human activities.(5)The largest area of soil conservation function is the most important area,with an area of122.64 km~2,accounting for 77.1%of the whole basin.The largest area of carbon storage function is the important area,with an area of 70.92 km~2,accounting for 44.58%of the whole basin.The largest area of ecosystem services is the important area(135km~2),accounting for 85.16%of the total study area.