Study On Seasonal Variation Of Plant Community And Soil On The Slope Of The Sub-alpine Highway In Erlang Mountain

Highway construction has brought great benefits to the subalpine area of Erlang mountain,but it has also caused damage to original vegetation in the area where the highway passes.The exposed slope is prone to natural disasters such as landslide and debris flow,and the ecological environment is seriously damaged and difficult to recover naturally.Studies by many scholars have shown that artificial vegetation restoration can effectively improve the destroyed ecosystem.However,due to the large differences in natural conditions between regions,it is necessary to classify and study their inherent characteristics before formulating restoration plans according to local conditions.Therefore,it is of great theoretical and practical significance to study the characteristics of vegetation and soil changes on subalpine highway slopes for their ecological restoration.In the present study,with 8 sampling points set up on the highway slope between 1960 meters and 2430 meters above sea level in Erlang mountain,the dynamic changes of slope vegetation floristic characteristics,plant community composition,soil physical and chemical properties and soil bacterial community composition in different growing seasons were carried out.The main results and conclusions are as follows:(1)The plant community in the study area was dominated by world distribution families and temperate distribution families at the family level,while temperate distribution genera occupied an absolute advantage at the genus level.The floristic composition in the study area was simple and the species richness was low.The root scanning results of herbaceous dominant species showed that all dominant species had absolute dominant fine roots with 0-0.1 mm,and the total root length and total surface area in June were significantly higher than those in March(p < 0.05,similarly hereinafter),but decreased in October compared with June.(2)The physical and chemical research results of slope soil showed that there were significant differences in soil total nitrogen,ammonium nitrogen,nitrate nitrogen,organic nitrogen,total phosphorus and organic matter among growing seasons.Compared with March,nitrate nitrogen accumulation was obvious in June and ammonium nitrogen accumulation was obvious in October.The total phosphorus content in the soil at all sites was less than 0.8 g/kg,indicating that there was insufficient phosphorus supply capacity in the soil at all sites.Principal component analysis results showed that nitrate nitrogen,organic matter and total phosphorus in the soil in the study area played a major role in the physical and chemical properties of slope soil.Results from study on the diversity of soil bacterial community in slope showed that the composition and species diversity of soil bacterial communities were significantly affected by seasons.The abundance of soil bacterial communities and the number of OTU in June and October were significantly higher than those in March.Proteobacteria,Bacteroides,Firmicutes,Acidobacteria and Actinobacteria were the dominant microbiota at the phylum level,while Massilia,Acinetobacter,Psedomonas and Flavobacterium were the dominant microbiota at the genus level.(3)Correlation analysis showed that the increase of soil total nitrogen and total phosphorus content in the study area could promote the diversity of herbaceous plants and the stability of community structure,the increase of soil total nitrogen and nitrate nitrogen content could increase the number of lateral roots of herbaceous plants,and the increase of soil total potassium content could promote the increase of root surface area of plants;Bacteria of Massilia and Stenotrophomonas could promote the accumulation of soil ammonium nitrogen through denitrification and ammoniation,while the increase of Sphingomonas bacteria abundance could promote the accumulation of soil nitrate nitrogen and organic nitrogen.Combined with these results mentioned above,it is necessary to give priority to the reasonable proportion of nitrogen nutrition and phosphorus nutrition in the fertilizer allocation during the slope vegetation restoration process,which can not only promote the growth of lateral roots of herbaceous plants,but also improve the soil quality in the area.