Study On Vegetation And Soil Characteristics At Early Succession Stage Of Abandoned Cropland In The Northern Yinshan Mountains

With the rapid growth of population and the progress of science and technology,the blind and predatory exploitation of natural resources by human beings to meet their own needs,coupled with the long-term utilization beyond the carrying capacity of natural ecology,has caused serious damage to the natural ecosystem.At present,restoration ecology to restore and rebuild the damaged ecosystem has become one of the key topics in the field of ecological research.In this study,the abandoned field in the northern foot of Yinshan Mountain was taken as the research object,and the field investigation and laboratory test were used to analyze the changes of vegetation and soil characteristics in the early succession of abandoned corpland,so as to find out the change law of vegetation and soil in the early succession of abandoned corpland in the northern foot of Yinshan Mountain and provide theoretical and practical basis for the restoration of abandoned corpland in this area.The main results are as follows:(1)At the early stage of succession in the abandoned land at the northern foot of the Yinshan Mountains,the total above-ground biomass of the community and the aboveground biomass of first and second-year plants in the community showed a significant decrease year by year,while the above-ground biomass of perennial grasses and perennial miscellaneous grasses in the community increased significantly,and the composition of the community changed significantly,with perennial grasses and perennial miscellaneous grasses such as Leymus chinensis and Artemisia scoparia gradually replacing first and second-year plants such as Chenopodium glaucum and becoming the dominant species in the community.The number of species in the community increased from 16 in the first year of abandonment to 21 and 20 in the second and third years of abandonment respectively.As the succession progressed,species with lower niche breadth were gradually replaced by species with higher niche breadth,and the niche differentiation was more obvious.In addition,there was no significant difference in species diversity in the community at the beginning of the succession,except for a significant decrease in species richness,and as the number of years of succession increased,the similarity of species composition in the community compared to natural grassland showed an increasing trend year by year,but there was still a large difference compared to the similarity of natural grassland communities.(2)The changes in soil physicochemical properties at the early stage of the succession in the abandoned land were more obvious in the top soil layer,while the changes in the rest of the soil layer were not significant(P>0.05),with the p H,conductivity,total phosphorus and total potassium contents not significantly different from those of the farmland.The organic carbon,total carbon and total nitrogen in the soils of the natural grassland were significantly higher(P<0.05)than at the beginning of the abandoned succession,and the p H,conductivity and total phosphorus content were significantly lower(P<0.05)than at the beginning of the abandoned succession.In addition,C/N was significantly higher in farmland than in natural grassland and in the early stages of the abandonment succession(P<0.05),and C/P and N/P were significantly higher in natural grassland than in farmland and in the early stages of the abandonment succession(P<0.05);however,the stoichiometric ratios in soil were not significantly different between the early stages of the abandonment succession(P>0.05).(3)Soil properties did not have the same impact on community biomass and diversity.The soil factors that had the greatest effect on above-ground biomass of the community at the early stage of the abandonment succession were conductivity and total phosphorus(P<0.05),which were positively correlated with total above-ground biomass and biomass of first-and second-year plants in the community;they were negatively correlated with biomass of perennial grasses and not significantly correlated with biomass of miscellaneous perennial grasses.Soil properties had the greatest influence on community species diversity as N/P(P<0.05),which was positively correlated with the ShannonWiener index,Simpson index,Pielou evenness index and species diversity index in the community.