Preliminary Study On Vegetation Restoration And Succession Of Tailings Accumulation In The North Foot Of Qinling Mountains

The northern foot of Qinling Mountains is rich in mineral resources and has a long history of mining.Due to the backward mining technology and unreasonable mining methods in the early stage,the micro-geomorphology in the mining area has changed greatly,which is easy to form disasters such as collapse and debris flow.The tailings pond formed by a large amount of slag piled up nearby seriously occupied a large number of land and destroyed the local ecological environment;the physical composition and structure of the tailing pond make it impossible to grow plants on it for a long time,and the natural recovery speed is quite slow.In order to promote the vegetation restoration of tailings accumulation body in the northern foot of Qinling Mountains,it is necessary to understand the law of community succession,the adaptive changes of plants and the characteristics of environmental changes in each stage of restoration,so as to use natural laws for artificial restoration.Therefore,this paper adopts the method of spatial sequence instead of time series,selects 28 sample plots of tailings accumulation body with different recovery years in the northern foot of Qinling Mountains and 4 undisturbed native communities in the control group as the research objects,carries out community investigation and determines the soil characteristics of tailings accumulation body.By analyzing the community characteristics of sample plots,the community succession law of sample plots in different stages was summarized.Through literature research,the CSR classification basis was summarized,and the CSR classification of plants in the sample plots at different succession stages was judged,and the root characteristics of some plants were measured,so as to obtain the adaptive changes of different countermeasures plants with succession.Canonical correspondence analysis(CCA)was performed by CANOCO 5 software to explore the influence of environmental factors on vegetation restoration and the internal mechanism of adaptive changes of plants,so as to lay the foundation for the study of vegetation restoration in mining areas.The main results are as follows:(1)A total of 209 species,157 genera,67 families were found in the study plot.Among them,Compositae,Leguminosae,Gramineae and Rosaceae occupy an important position in the succession process of tailings accumulation community in the region.The community species composition is generally characterized by a majority of species belonging to a few large families and genera,and a few species belonging to single families and single genera.The number of total families and genera in plant communities at different restoration stages showed a trend of first increase and then decrease.The natural vegetation restoration in the study area experienced the succession sequence of 1-year-old herbaceous community,perennial herbaceous community,shrub-grass community and small shrub community.The Margalef index,Simpson index and Shannon-Weiner index increased gradually,while the evenness index decreased first and then increased.Compared with the original shrub community in the control group,the natural recovery rate of the abandoned tailings land was quite slow.(2)The analysis of soil nutrient grade showed that the overall soil nutrient content of tailings was low.With the succession,the organic matter content increased significantly.The adaptation strategies of plants in different succession stages began to gradually occupy the dominant position from weedy plants as pioneer plants to competitive plants.The root traits of different countermeasures plants had different degrees of adaptation and change in different succession stages.(3)By CCA sorting,the main environmental factors affecting the vegetation succession of non-metallic tailings deposits with different restoration years in the northern foot of Qinling Mountains are bare surface age.The distribution difference of sample plots was greatly affected by slope direction;with the succession,weedy plants were replaced by competitive and stress-tolerant shrub plants.It is suggested that the introduction of stress tolerant and competitive plants in advance by using plant life history strategy,soil seed banks and Miyawaki method in the mine wasteland at the initial stage of restoration is conducive to accelerating the plant succession process,thus accelerating the community succession speed in the mining area and creating a good and sustainable ecological landscape in the mining area.