Study On Ecosystem Service Function And Pattern Optimization Of Artificial Forest In Typical Small Watershed Of Soft Sandstone Area

As an important ecological barrier in China,the Yellow River Basin plays an important strategic role in the construction of ecological civilization.As the main source of sediment in the Yellow River,the soft sandstone area is poor in soil and lack of water resources.It has been listed as the key research content in recent years by national strategies such as ecological protection and high-quality development in the Yellow River Basin.With the development of afforestation ecological restoration project,it is urgent to explore the service function and benefit of artificial forest ecosystem,and optimize the pattern to promote the sustainable and high-quality development of ecological environment.In this thesis,the small watershed of contract ditch,the first tributary of Han tai chuan in the upper reaches of the Yellow River Basin,is the research area,and the main artificial forests(Pinus tabuliformis,Caragana Korshinskii and Salix psammophila)are selected as the research objects.From the aspects of water conservation,soil conservation and plant diversity protection,the differences in ecosystem service functions of the main artificial forests are systematically compared.The entropy weight method is used to construct the model for benefit evaluation,and the analytic hierarchy process is used to optimize the pattern of artificial forests in the basin.The study draws the following conclusions :(1)From 2000 to 2020,the main landscape in the small watershed of the contract ditch changed from the grassland(71.35%,18.08%)to the forest land(23.59%,78.25%).The total water yield of ecosystem services decreased first and then increased,while the soil conservation continued to increase.(2)Artificial forest has obvious improvement effect on the ecological environment of soft sandstone area.Caragana Korshinskii has strong tillering ability.The root system can reasonably improve the soil structure,improve the water storage capacity,and perform well in water conservation and soil conservation.The transpiration of Pinus tabuliformis is weak,with good understory water conditions,and it performs well in water conservation and plant diversity protection.The canopy of Salix psammophila has dense branches and leaves,and the roots are staggered and developed,which is better in plant diversity protection and soil conservation.(3)From the three aspects of water conservation,soil conservation and plant diversity protection,the quantitative evaluation of the ecosystem service benefits of the artificial forest in the soft sandstone area was constructed.The order of evaluation results was : Caragana Korshinskii(0.35)> Pinus tabuliformis(0.34)> Salix psammophila(0.33).Based on the evaluation of ecosystem service benefits,the plantation pattern in the small watershed was optimized.After pattern pattern optimization,the area of Pinus tabuliformis and Salix psammophila increased by 20.68% and 4.49%,respectively,and the area of Caragana Korshinskii decreased by 34.40%.The overall forest land area distribution ratio is more uniform.