Study On Physiological And Ecological Plasticity Of Common Street Tree Species In Hefei Under Road Paving Environment

With the intensification of urbanization,the urban ecological environment is gettin g worse.Due to the shortage of groundwater resources and insufficient irrigation cause d by the large-scale application of surface hardening,the mortality rate of urban road trees is increasing year by year,and this phenomenon is likely to be further aggravate d by the emergence of extreme climate.Surface hardening has changed the physical an d chemical properties of the soil beneath it,and also greatly changed the habitat cond itions of urban road trees.With the influence of urban street exhaust and human activ ities,urban road trees are under the multi-aspect stress brought by urbanization due to the lower soil permeability and drier environment.The study of the interaction mechan ism between plants and environment and the physiological response of plants has beco me an important part of modern plant physiological ecology.In this study,seven kinds of common street trees in hefei urban area were taken as research objects,which are Cinnamomum camphora,Platanus acerifolia,Sapium sebif erum,Sapindus mukoross,Albizia julibrissin,Acer buergerianum and Koelreuteria bipinna ta.var.integrifoliola.Select distribution in impermeable pavement trees as the object,an d distributed in large area of grass compared to the same trees,by comparing two dif ferent habitats of plants under physiological and biochemical performance,using moder n physiological ecology analysis methods and measurement means,to study the anato my of the seven species in different habitat conditions(xylem,veins,palisade tissue a nd porosity)and chemical characteristics,analyzed the non-structural carbohydrates con tent,pigment content,such as characters,expounds seven trees cope with impermeable road pavement phenotypic plasticity.The results show that:(1):From the perspective of the anatomical characteristics of wood,Sapium sebiferu m made more adjustments in the environment of road paving,with significant changes in the wall thickness,catheter cross section area,catheter length,catheter width and catheter circumference,which were far lower than those of Sapium sebiferum growing in the park.The catheter density of Acer buergerianum and Koelreuteria bipinnata.var.i ntegrifoliola also decreased in the pavement environment;However,the catheter density of Sapindus mukoross increased in the pavement environment;The duct width of Plata nus acerifolia significantly increased in the pavement environment compared with the p ark environment.(2):According to the anatomical characteristics of leaves,under the environment of road paving,the vein density of Albizia julibrissin changed significantly was higher tha n that of the park,and its density decreased significantly Cinnamomum camphora.The specific leaf area,vein density and the thickness of the upper epidermis all reduced significantly under the conditions of road paving,especially the vein density Koelreute ria bipinnata.var.integrifoliola.Under the environment of road paving,the density of leaf veins and the thickness of the lower epidermis decreased significantly,but compar ed with the leaf area in the park,it increased significantly Platanus acerifolia.The spe cific leaf area decreased significantly in the pavement environment Sapindus mukoross ratio leaf area increased in the pavement environment.Sapium sebiferum in the environ ment of road paving,the density of leaf veins,the thickness of the upper epidermis a nd the thickness of palisade tissue all decreased compared with the environment of th e park,but the specific leaf area increased significantly.(3):In terms of stomatal anatomical characteristics,stomatal length of Cinnamomum c amphora decreased and SPI decreased significantly in the pavement environment Albizi a julibrissin.The stomatal length and stomatal width were significantly increased in th e pavement environment,and the stomatal index was far higher than that of the park albizzia.(4):According to the chemical characteristics of the leaves,the content of Platanus a cerifolia starch decreased in the urban pavement environment Cinnamomum camphora.The contents of soluble sugar and starch increased significantly in urban pavement env ironment,while the contents of chlorophyll and carotenoids decreased.The content of A lbizia julibrissin starch increased significantly in the pavement environment,while the c ontent of chlorophyll b and total pigment decreased.Koelreuteria bipinnata.var.integrifo liola the soluble sugar content in the pavement environment was significantly higher t han that in the park environment.(5):In the study of anatomical and chemical characteristics of phenotypic plasticity,t he phenotypic plasticity index of street tree anatomical traits on hard pavement in ord er from high to low is Sapium sebiferum>Albizia julibrissin>Koelreuteria bipinnata.va r.integrifoliola>Sapindus mukoross>Acer buergerianum>Cinnamomum camphora>Platanu s acerifolia.The phenotype plasticity index of chemical properties on hard pavement fr om high to low is: Cinnamomum camphora>Albizia julibrissin>Koelreuteria bipinnata.v ar.integrifoliola>Platanus acerifolia>Acer buergerianum>Sapium sebiferum>Sapindus muko ross.In the context of global environmental changes,the research results will be of gr eat significance to the research on the physiological ecology of plants and the physiological mechanism of resistance to stress,and can provide important insights on how t o choose an excellent walking tree species in eastern China and other cities.