Study On Plant Community Allocation And Functional Improvement In The Riparian Zone Of The Qingyi River Basin

As an important part of the riparian ecosystem,the riparian vegetation buffer zone is a key measure to control soil erosion and non-point source pollution and improve the water environment.And it has an important influence on the ecological and hydrological processes of riparian ecosystem.However,there are many problems in the current tidal vegetation in the Qingyi River Basin,which seriously affects the normal function of the riparian ecosystem.Through the investigation of the status quo of the riparian plants in the Qingyi River Basin,it is found that the biodiversity of the Qingyi River Basin is generally low.From the composition of plant communities and the impact on the function of the riparian zone,there are mainly these problems:1)single species,poor diversity;2)poor winter landscape effect;3)poor water purification effect.Based on these problems in the riparian zone,it is urgent to use phytore mediation technology to screen and configure the plant communities in the riparian zone of the Qingyi River Basin,and to strengthen the research on the functional improvement of the riparian zone.This study has certain guiding significance for the application of riparian plant measures in similar watersheds in the north.The main results were as follows:?1?Based on the problem of single plant species and poor diversity in the riparian zone of the Qingyi River Basin,screening and configuration studies were carried out.A total of 25 plants suitable for the Qingyi River Basin were screened out.It included 16 kinds of trees and shrubs with good landscape effect and certain ecological functions,2 kinds of native herbs with strong soil-slope protection ability?Cynodon dactylon,Setaria viridis?,3 kinds of strong cold-tolerant herbs?Liriope minor,Carex lasiocarpa,Saxifrage?,and 4 kinds of aquatic plants with good water purification effect?Iris sibirica,Iris pseudacorus,canna,Phragmites australis?.At the same time,on the basis of the screening results of plant species,the plant communities with different slope positions?below the normal water level,normal water level-design flood level,design flood level-embankment top,embankment top?on the riparian zone were configurated.The species richness and shannon wiener index of the riparian plant communities after the configuration are higher than the original plant communities,the plant species are richer,the species diversity is higher,and the community stability is better.?2?In view of the poor cold tolerance of herbaceous plants,the near-winter season began to wither and wither,leading to the poor winter landscape effect of the riparian zone and the decline of landscape function,it is necessary to carry out optimization experiments on the cold tolerance of herbaceous plants.Under low temperature stress,H₂O₂ and melatonin had little effect on the cold tolerance of Liriope minor.The best effect of salicylic acid on the cold tolerance of Liriope minor under the condition of 0.8mmol/L concentration.The three exogenous substances of salicylic acid,H₂O₂ and melatonin had different degrees of cold tolerance to Saxifrage and Carex lasiocarpa.The best effect of H₂O₂ on improving the cold tolerance of Saxifrage under the condition of 5mmol/L concentration,and salicylic acid had the best effect on improving the cold tolerance of Carex lasiocarpa under the condition of 0.5mmol/L concentration.?3?Based on the excessive planting density of aquatic plants in the Qingyi River Basin,the water purification effect was poor,and the water purification function of the riparian zone was affected.Therefore,the water purification effects of four aquatic plants under different planting densities were studied.Among the four aquatic plants,Iris sibirica had the best removal effect on COD.When the optimal planting density was 20cm,the COD removal rate reached 50.29%;the best removal effect of NH₄⁺-N content in water was canna.The rate of NH₄⁺-N removal was 89.96%when the optimal planting density was 50cm;the removal rate of TN by the four aquatic plants was higher than 90%.Among them,the canna had the best removal effect on TN when the planting density was 20cm,which could reached 98.45%;the best removal of TP was Phragmites australis.When the optimal planting density was 20cm,the TP removal rate reached 91.37%.