| Under its special highland environment,Tibet Autonomous Region has formed a distinctive type of celebrity gardens under the influence of religious culture.In recent years,with the rapid development of urbanization,the construction of Tibetan administrative agencies,social service agencies,and road construction systems,the construction of Tibetan gardens has also entered a period of rapid development.With the rapid development of Tibetan garden construction,the development and utilization of garden plants has become an important softness to improve the local environment.Due to the environmental characteristics of Tibet,which is different from the plain area of the same latitude,how to make the garden plants meet the appropriate tree conditions in the application process In principle,giving full play to its ecological,landscape and social benefits has become an important basis for garden planning and design.This paper investigates the common garden tree species in Nyingchi,Tibet,and selects 58 families of 19 common garden trees and shrubs to study their photosynthetic physiological characteristics.Based on the study of their physiological characteristics,an analytic hierarchy process model is established for 58 gardens.Plants were evaluated for ornamentality.This paper investigates common garden tree species in Bayi Town,Nyingchi City,Tibet,and screens 58 common garden plants for Light response characteristics and ornamental characteristics to evaluate photosynthetic light response curves.The maximum net photosynthetic rate（Pmax）,apparent quantum Comparison of photosynthetic physiological parameters such as efficiency（AQY）,light compensation point（LCP）,light saturation point（LSP）,transpiration rate（Tr）,and water use efficiency（WUE）.The viewing characteristics were evaluated.It is hoped to provide a certain theoretical basis for the selection of tree species and the selection of cultivated land in the future urban landscape planning and construction in Nyingchi,Tibet.The findings are as follows:（1）According to the research on the net photosynthetic rate of 41tree species,the photosynthetic capacity of different tree species is quite different.The tree species with higher Pn are Populus×beijingensis,Robinia pseudoacacia,P.szechuanica var.tibetica,Sophora japonica var.japonica f.pendula,Salix alba,Pinus densata,Fargesia setosa;shrub plants include Chaenomeles speciosa,Rosa multiflora Thunb.var.carnea,and R.chinensis.When selecting fast-growing tree species for afforestation activities,tree species with a high Pn can be preferentially selected.（2）Among the tree species,Tamarix ramosissima,Cupressus gigantea,Phyllostachys nigra,Ligustrum lucidum,And Pyrus bretschneideri,Amygdalus triloba,Abies georgei var.smithii,Pinus griffithii etc.Both LCP and LCP are not suitable for planting in strong light environment;Salix alba,P.×beijingensis,P.szechuanica var.tibetica.Platycladus orientalis,C.torulosa,Robinia pseudoacacia,Larix kaempferi,Sabina chinensis var.Chinensis‘Pyramidalis’,R.pseudoacacia‘tetraploid’,R.pseudoacacia‘idaho’,Fargesia setosa,Juglans regia,Fraxinus bungeana,Acer palmatum,A.truncatum,Malus halliana,A.mira,M.pumila,M.baccata,P.banksiana,Cedrus deodara,P.tabulaeformis,Platanus×acerifolia,Ginkgo biloba,Ulmus pumila,P.alba 26 tree species show high LSP and high LCP characteristics.In the selection of cultivated land,an environment with sufficient light can be selected to ensure the accumulation of photosynthetic organic matter and the role of ecological benefits.Salix matsudana Koidz.var.matsudana f.‘Tortuosa’,P.alba,Sophora japonica var.japonica f.pendula,Crataegus pinnatifida,A.persica,Crataegus pinnatifida,A.persica,P.cerasifera,Morus mongolica var.Diabolica,P.densata and the LSPs of 8 tree species are between 0-13μmol·m–2·s–1,and the LCP is above 1000μmol·m–2·s–1,showing the characteristics of high LSP and high LCP.The choice of ground can meet the conditions of insufficient light and the environment of strong light.（3）Among the shrub plants,the native plant Clematis tenuifolia has shown strong adaptability,with an LCP of 4.43μmol·m–2·s–1and an LSP of 2126μmol·m–2·s–1.It indicates that C.tenuifolia has a wide range of suitable light,which is both shade-tolerant and adaptable to strong light.It has a wide selection of cultivated land in garden planning and is very suitable for Tibet.The special environment of the area.Other plants with strong shade tolerance and high light saturation point are:Hypericum choisianum,Celastrus stylosus,Paeonia delavayi var.lutea,etc.It has some shade-tolerant species for most of the happy light,and can be planted under sparse forests or dense forest edges.（4）The comparison of arbor transpiration rate and water use efficiency can be concluded:Populus×beijingensis is a tree species combining high transpiration rate and high photosynthetic rate,and the characteristics of large evaporation need to be considered when selecting the cultivation site;Sophora japonica var.japonica f.pendula,Robinia pseudoacacia‘idaho’,Fargesia setosa,Amygdalus mira,Larix kaempferi,Salix alba,Platycladus orientalis,Cupressus gigantea,Juglans regia,Acer palmatum Thunb,A.palmatum,A.persica,Ligustrum lucidum,Abies georgei var.smithii,Phyllostachys nigra,Pinus banksiana,Fraxinus bungeana,Cedrus deodara,and other 18 tree species are trees with high water use efficiency and low transpiration rate.Compared with other tree species,these tree species accumulate photosynthetic organic matter.The process consumes less water and lower transpiration,which is very suitable for planting in semi-arid areas with insufficient water conditions.（5）The comparison of transpiration rate and water use efficiency of shrub plants shows that Euongmus japonicus has the largest water use efficiency,which is more than 16μmol·m–2·s–1,but the water use efficiency of boxwood is greatly affected by light intensity.Shrub plants with high water use efficiency and low transpiration rate include:Hypericum choisianum,Ligustrum ovalifolium‘Aureum’,Clematis tenuifolia,E.japonicus Etc.These shrubs are more drought-tolerant.The evaporation of Rosa chinensis,Chaenomeles speciosa,Sorbaria arborea,and R.multiflora‘Platyphylla’are large.When dealing with arid climates,the amount of irrigation needs to be fully considered.（6）This paper establishes an analytic hierarchy process model with58 kinds of common ornamental plants as the target layer and 9ornamental factors as the criterion layer.The difference evaluation method is used to analyze the results of landscape evaluation,and the comprehensive score of ornamental evaluation is graded.GradeⅠevaluation value is>2.225,gradeⅡevaluation value is 1.68～2.225,gradeⅢevaluation value is 1.465～1.68,gradeⅣevaluation value is1.07～1.465,gradeⅤevaluation value is 1.465 or less.Plants with score above 2.225 are:Amygdalus mira,A.persica,Prunus cerasifera,A.triloba,Platanus,Malus halliana,A.palmatum,Weigela florida And Rubus biflorus.Plants with scores between 1.68 and 2.225 are:Robinia pseudoacacia‘idaho’,Sophora japonica var.japonica f.pendula,R.pseudoacacia,Crataegus pinnatifida,M.baccata,M.pumila,Ginkgo biloba,Lonicera japonica,Chaenomeles speciosa,Pyracantha fortuneana,Rosa multiflora‘Platyphylla’,Hypericum choisianum,Paeonia delavayi var.lutea,Paeonis ludlowii,Clematis tenuifolia etc;Plants with scores between 1.465～1.68 are:Pinus griffithii,Tamarix ramosissima,Ulmus pumila,Fargesia setosa,Phyllostachys nigra,Fraxinus bungeana,Robinia pseudoacacia‘tetraploid’,Acer truncatum,Pyrus bretschneideri,Juglans regia,Ligustrum×vicaryi and L.ovalifolium‘Aureum’;Plants with scores between 1.07 to 1.465 include Salix matsudana‘Tortuosa’,Populus szechuanica,P.×beijingensis,P.alba,Platycladus orientalis,Morus mongolica var.diabolica,Cupressus torulosa,Cupressus gigantea,Sabina chinensis var.chinensis‘Pyramidalis’,P.tabulaeformis,P.banksiana,P.densata,Cedrus deodara,Larix kaempferi,Abies georgei var.smithii,Vitis vinifera,Celastrus stylosus,Euongmus japonicus,Rubus biflorus,Sorbaria arborea Etc;Plants with a score of≤1.465 include Salix alba. |
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