Study On The Characteristics Of Vegetation Composition In Different Habitats In The Riparian Zone Of Yulin River

The Yulin River is a first-class tributary of the Yangtze River,flowing through the eastern part of Chongqing's Yubei District.This paper takes riparian zone of Yulin River as the research object.First,it uses Arc GIS 10.2 and Patch Analysis to analyze the land use status and vegetation landscape pattern distribution and divide different habitat conditions.Second,a detailed investigation of the riparian plant communities in the lower reaches of the Yulin River.Conduct research from the aspects of species composition characteristics,the relationship between communities and the environment,and species diversity to summarize dominant species and types of communities,analyze the relationship between plant community composition and environmental factors,and compare the differences in species diversity under different habitat conditions.Finally,based on the study of the relationship between the species composition of the plant community and the environment,a plant configuration model suitable for the habitat conditions of the riparian zone is summarized.The study of the composition of riparian vegetation can provide a theoretical basis for riparian plant community optimization,regional biodiversity protection,ecological governance restoration and landscape construction.The main conclusions are as follows:(1)According to the comparison of the types of land used in the study area,the woodland area is the largest(accounting for 49.8% of the total area).The second largest area of cultivated land and the third is construction land,which shows that it is generally affected by agricultural activities and urban construction.The vegetation landscape pattern distribution in the southwestern riparian zone is more integrated,with higher diversity and uniformity,and higher landscape heterogeneity.The vegetation types of different river sections are obviously different.Among them,the lower reaches of the Yulin River are rich in vegetation types,including deciduous broad-leaved forest,coniferous forest,coniferous and broad-leaved mixed forest,and shrub grass.The distribution of land types in riparian zones is different in different habitats.(2)After surveying 37 plots in the riparian zones of Yulin River,a total of 463 species of 319 genera in 114 families were recorded.There are 18 species of 10 families and 10 genera of fern,11 species of 6 genera and 10 genera of gymnosperm,and 434 species of 299 genera and 99 families of angiosperm.The dominant species mainly include Musa basjoo ? Broussonetia papyrifera ? Melia azedarach ? Rhus chinensis?Jacaranda mimosifolia?Citrus maxima?Viburnum chinshanense?Morus alba?Pyracantha fortuneana?Humulus scandens?Artemisia argyi?Zoysia japonica?Sinosenecio oldhamianus.There sum up the 56 formations and 169 associations.The main formations were the Broussonetia papyrifera,the Rhus chinensis,the Pterocarya stenoptera,the Morus alba,the Metasequoia glyptostroboides,and the Jacaranda mimosifolia.In general,deciduous broad-leaved forests are the majority,and coniferous forests are few.(3)The overall number of species is more herb species and fewer shrubs and trees.The riparian plant communities in different habitats showed "moderate dissimilarity".TWINSPAN was used to classify the number of communities,and7 groups were divided at once,29 groups were divided twice.Sorting analysis of the plot community found that the influence type,elevation and slope had a significant correlation with the plant community species composition.The type of influence has the greatest influence on the community distribution and the highest interpretation of environmental factors.Naturally grown trees are greatly affected by slope,ornamental trees have a higher correlation with the type of impact,and the distribution of plant species in agricultural plants has a higher correlation with altitude.(4)Under different habitat conditions,the diversity index values of community species are significantly different.Among them,the diversity index of undeveloped riparian zone and urban developed riparian zone is significantly different,and the uniformity of vegetation in each layer of urban developed riparian zone is higher than that of agriculturally developed and undeveloped riparian zone.From the analysis of the elevation zone,the diversity index,Pielou index of the tree layer and shrub layer vary significantly with the elevation zone,showing that the farther away from the river,the higher the index;In the stable plant communities in the riparian zone at an altitude of 140m-183 m,the herb layer diversity index value changes with the elevation zone:the closer to the river,the higher the index value.The above results illustrate the differences in land type,landscape pattern,species composition,community similarity,species diversity,and species diversity of riparian plant communities in different habitats and the relationship between plant community distribution and habitat conditions.Finally,based on the results of the investigation and analysis,12 planting patterns of riparian plants in different habitats were summarized.Among them,there are 4 types of undeveloped river zones,3 types of agricultural developed river zones,and 5 types of urban developed river zones.