Study And Evaluation Of The Characteristics Of Semi-natural Forest Land In The Hills Of Chongqing City

The semi-natural forest in the urban hills located inside the urban built-up area,because of its unique ecological adaptability and stability,can bring ecological benefits to the city.It is the current research hotspot-the most needed and most suitable in the construction of naturalized urban gardens Plants and communities.The scattered and unique layout structure and fragmented forest land distribution characteristics of Chongqing’s main urban area have created unique advantages for the remnants of seminatural forest land in the city,but Chongqing currently lacks the hilly vegetation in the transition zone between the urban built-up area and the mountain the study.This paper takes the hilly plant community in the main urban area of Chongqing as the research object,investigates the species composition and community characteristics of the plant community in different habitats of the hilly woodland in the main urban area of Chongqing through typical sampling methods,and analyzes the composition of family and genera Indicators such as abundance and diversity index are used to classify community types by dominant species and cluster analysis to understand the composition characteristics of hilly woodland plant communities in the main urban area of Chongqing and their relationship with habitats.It will provide reference for follow-up scholars to study other types of vegetation in Chongqing,as well as provide theoretical reference for the development and utilization of hills,and provide a basis for the conservation and landscape utilization of wild plants in hilly semi-natural forests.The main findings are as follows:1.177 species,belonging to 73 families and 155 genera,were recorded in the survey area.Among them,there are 6 families,8 genera and 9 species of ferns,67 families,147 genera,and 168 species of seed plants,among which 3 families,3 genera and 3 species of gymnosperms are Pinus massoniana,cypress,and Chinese fir respectively.There are32 species of monocotyledons,29 genera,7 families,136 species of dicotyledons,118 genera,60 families.There are 44 kinds of trees,42 kinds of shrubs,6 kinds of vines,and85 kinds of herbs(including 5 kinds of bamboos).The proportion of native plants is as high as 87.01%.There are 122 species belonging to 105 genera in 45 families,accounting for 68.93% of the total.There are 65 species with high ornamental value.2.According to the Chinese vegetation classification system,the plant communities in the main urban area of Chongqing belong to 3 vegetation type groups,9 vegetation types,and 54 formations.Among them,deciduous broad-leaved forest occupies the dominant position,including 14 formation types,accounting for 25.93% of the total formation,followed by evergreen,deciduous broad-leaved mixed forest,which has 12 formation types,and the evergreen broad-leaved forest is the least.In the case of clustering analysis,Euclidean distance 9 and Euclidean distance 6 are used to cluster,which can be divided into 21 formations and 61 clusters.3.This paper analyzes the degree of human disturbance to hilly forest land,including two major directions of accessibility and human flow,specifically the type of land use outside the hills,building density,road grade and quantity,distance from the surrounding residential areas,and analyzes the internal footpath conditions of the hilly forest land,and divides the degree of human disturbance to the hilly habitat into three levels.4.Analyze the community species composition of trees,shrubs,and herbs in different habitats.Generally speaking,under six different types of habitats,tree species in tree layer are ranked as Broussonetia papyrifera,Ficus virens,Robinia pseudoacacia,Melia azedarach and Quercus fabri according to their important values;the most significant dominant species in shrub layer are occupied by Broussonetia seedlings,and the rest are Morus alba,Ligustrum sinense,Viburnum odoratissimum,and Jasminum mesnyi according to their important values.The vine layer is mainly dominated by Anredera cordifolia and Parthenocissus tricuspidata.The herbaceous layer is dominated by Humulus scandens and Chrysanthemum indicum,followed by wild plants such as Bidens pilosa,Sinosenecio oldhamianus and Erigeron acris.In addition to the above-mentioned dominant plants,the composition of dominant species in different habitat type gradients also shows as follows:(1)Interference degree: when the interference degree is low,the dominant species are Bambusa emeiensis,Rhus chinensis,Jasminum mesnyi and other plants.When the interference degree is high,the dominant species are mainly artificial cultivated plants such as Ligustrum sinense,Ligustrum × vicaryi,Bougainvillea spectabilis and so on.(2)Slope: when the slope is more than 15 °,the planting of garden plants such as Ligustrum sinense,Prunus cerasifera and Viburnum odoratissimum is also more advantageous.Paulownia fortunei,Ficus microcarpa,Senna bicapsularis and Eremochloa ciliaris are also emerging as the dominant species in the habitat with a slope of more than25 °.(3)On different slopes,the arbor layer showed a higher dominance of Bambusa emeiensis in the semi-shady slopes.In the sunny environment,light-loving plants such as Viburnum odoratissimum,Jasminum mesnyi and Senna bicapsularis prevail,and the dominant plants in the vines were Cayratia japonica,Argyreia pierreana,etc.(4)Slope position: Pinus massoniana is the dominant species in the hillside type,Paulownia fortunei is the dominant species in the Piedmont type,and artificial shrubs such as Distylium chinense and Pittosporum tobira are also the dominant species.(5)Area: this factor has little effect on the dominant species of plants.(6)Soil: in purple soil and limestone soil,the arbor layer is dominated by Broussonetia papyrifera and Ficus virens.In contrast,in yellow soil,the dominant arbors are Pinus massoniana,Cinnamomum camphora,and Cunninghamia lanceolata.5.Overall,the abundance of trees and shrubs in the hilly woodlands in the main urban area of Chongqing is very close,both around 40,while the abundance of herbs is85,which is twice that of trees and shrubs;the species uniformity index is low,both are less than 0.8;the diversity index is relatively close,with the highest herb.6.In the built-up area of the city,there are abundant plant resources in the hilly forest land,and there are many local plants that can be used and popularized.The unique seminatural community structure formed by it can also be used for reference.Using AHP analytic hierarchy process to establish the evaluation model of landscape utilization value for the wild plants on the hilly forest land in the urban built-up area,four evaluation indexes of ornamental value,ecological adaptability,resource potential and application cost are selected,which are divided into four utilization grades according to the comprehensive score.The selected plants are used for the ecological protection forest,ecological,landscape forest,ecological economic forest and mountain park,etc.Suggestions on plant utilization are put forward for the natural urban landscape.