Evaluation Of Vegetation Communities Restoration In Slope Of Shangdeng Expressway

The construction of Expressway destroys the natural ecological environment along the expressway,and forms a large number of special and harsh slope ecosystems.Discussing the law of vegetation restoration,community dynamic change and interspecific competition has important theoretical and practical value for improving the productivity of road ecosystem,enhancing ecosystem stability and directional management of ecosystem.At present,there are more and more methods to restore the slope ecology of expressway,but the sustainability and stability of the plant community on the slope are poor.It needs a lot of maintenance cost to maintain it reluctantly,or it needs to sow fast-growing herbs frequently to achieve short-term landscape effect.The reason is the lack of scientific and rational plant allocation for the ecological restoration of slope plant communities in the early stage,the lack of continuous attention to the dynamic changes of plant communities and soil components in the process of restoration,and the lack of targeted and effective artificial intervention.In this study,four experimental sections of Shangdeng Expressway in Henan Province with different plant allocation patterns were selected as the research objects,and three samples were selected for monitoring the 12 sample plant communities for two years.Through sorting out the changes of species composition,species importance value and species diversity in the community in two years,the dynamic change characteristics of the community at the initial stage of restoration were analyzed;the physical and chemical properties of soil were calculated and evaluated by principal component analysis method when 12 plots were restored for 1.5 years,and the main factors affecting the improvement of soil physical and chemical properties were explored;the ecological factors and planting were selected by AHP-fuzzy comprehensive evaluation method.The restoration effects of 12 plots were ranked from four aspects: community factors,soil nutrients and soil physical properties,and the main limiting factors affecting the restoration of plant communities on the slope of Shangdeng Expressway were obtained.The restoration effects of four artificial near-natural plant community allocation modes in the experimental section were ranked based on the evaluation results of plant communities and soil physicaland chemical properties.Based on the above evaluation of plant community,soil quality and community restoration quality in the early stage of restoration,the suitable methods of community allocation and artificial intervention are summarized,which can provide scientific basis and practical experience for plant selection,soil improvement and community restoration of vegetation ecological restoration on Expressway Slope in the future.The main conclusions are as follows:(1)After 1.5 years of restoration,the four test sections all evolved into tree-shrub-grass community structure.The order of family richness in four test sections was test section 1(S1)> test section 4(S4)> test section 3(S3)> test section2(S2);the diversity index increased significantly compared with the previous year,with S1 being the most significant;herbaceous canine root,alfalfa,tangerine,astragalus,Bush and thorn bark.Ulmus pumila occupies a relatively dominant position in the community.The initial plant allocation of "Ulmus pumila + Ailanthus altissima-Jingzhi + Caragana Caragana-Bermudagrass + Persian chrysanthemum" in the S1 experimental section is more conducive to the rapid enrichment of vegetation types and community structure in the early stage of restoration.(2)The evaluation results of soil physical and chemical properties in Shangdeng high-speed test section are mainly affected by soil bulk density,total porosity and saturated water holding capacity;the contents of total nitrogen and available potassium in soil chemical composition are the main factors affecting the evaluation results of soil physical and chemical properties in the study section;the order of 12 soil physical and chemical properties is S1 > S3 > S4 > S2.(3)Weighted by analytic hierarchy process(AHP),it can be seen that the main criterion layer affecting the quality of community restoration is the growth status of community plants;the most important factors affecting the quality of community restoration are species diversity index,species evenness index and saturated water holding capacity of soil.The final evaluation results showed that the recovery quality of 12 samples concentrated on "good","medium" and "poor".Among them,the evaluation results of S1 were the best,and that of S2 was the worst.