| In order to explore the soil quality status of different vegetation types in the natural restoration process of the project accumulation and the influence of vegetation restoration on the organic carbon components,the soil under 0?80cm of the different vegetation types(arbor,shrub,grass)of the engineering accumulation with the same restoration period was selected.The content of organic carbon and its components,the change characteristics of reserves and their correlation with influencing factors,and the comparison study with bare land,analyze the distribution of soil organic carbon and its components according to the two types of soil and rock engineering accumulations with or without vegetation cover and the degree of influence of the affected factors.From the perspective of carbon sequestration capacity,we hope to screen out the types of vegetation suitable for the slope treatment of soil and rock accumulations,in order to provide a data basis for the treatment of engineering accumulations and ecological reconstruction,and to improve the soil carbon sink function of the engineering accumulations,and provide a theory for the sustainable development of the accumulations support.The main findings are as follows:(1)Soil organic carbon content of soil and rock engineering accumulations,soil particulate organic carbon,easily oxidizable organic carbon,microbial biomass carbon,light group organic carbon and dissolved organic carbon content are the lowest in bare land and highest in arbor,but each organic carbon group The difference in sub-content between shrubs and arbor forests is not obvious.At the same time,it is also found that the influence of vegetation types in the study area on the content of soil organic carbon and its components is greater than that of the thickness of the overlying soil.(2)The soil organic carbon content in the study area is between 7.83?59.24g·kg-1,which has large variability and obvious"surface accumulation".The content of soil particulate carbon of different vegetation types is between 0.27?11.04 g·kg-1,the content of soil oxidizable carbon is between 0.16?4.49g·kg-1,and the content of soil soluble organic carbon is between 26.75?173.66mg·kg-1,The soil microbial biomass carbon content is between 154.66?576.98 mg·kg-1,and the soil light group organic carbon content is between 0.048?1.302 g·kg-1,and its content decreases with the increase of soil depth and increases with the restoration of vegetation.The organic carbon content of soil particles accounts for a large proportion of the soil organic carbon content.The EOC reserves,DOC reserves,and MBC reserves under each vegetation type are specifically expressed as arbor woodland>shrubs>herb>bare land.The ROC reserves are highest in shrubs.The vegetation type has no obvious influence on LFOC reserves.(3)Vegetation restoration has a significant impact on the environmental factors of earth-rock engineering deposits.The soil structure is improved and the nutrient content increases.Among them,the capillary porosity and gravel content decrease significantly with the vegetation restoration;the total nutrient content is highest in trees,and the available nutrients are grassland and shrubs.Higher;C/N and C/P are also highest in shrubs.The total biomass,fine root biomass and plant biomass of vegetation litter are the highest in the arbor layer,and there are significant differences in litter biomass between different vegetation types(p<0.05).The biomass of fine roots decreases with increasing soil depth,showing obvious surface aggregation.The diversity index of each species showed a gradual decline trend with the restoration of vegetation.The Margalef index and Shannon-Wiener index are significantly different in different vegetation types(p<0.05).(4)Redundancy analysis and forward-looking selection analysis show that in bare land,soil available nutrients play an important role in soil organic carbon;after vegetation appears,vegetation litter and nitrogen are the sources of organic carbon and its components Important supplementary channels.To enhance the accumulation of organic carbon in soil and rock engineering deposits,the supplement of nitrogen and potassium should be considered under bare land conditions.Under other vegetation types,attention should be paid to changes in plant litter biomass and nitrogen on the soil and rock engineering deposits.The impact of carbon pools.Therefore,considering all aspects,it is reasonable to give priority to shrubs from the perspective of soil carbon sequestration for earth-rock engineering accumulations,but the specific shrub vegetation types depend on the dominant species of shrubs on the engineering accumulations. |
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