Study Of Garden Tree Species Selection Regarding Air And Heavy Metal Pollution Resistance In Baotou, Inner Mongolia

With the development of modern industry, the waste, emissions and sewage made by factories, residence and transport become more and more, the influence is extensive. And the heavy use of fertilizer and other chemical substances in modern agriculture induces the increase of residual poisonous substances. Environmental pollution is increasing seriously.Environmental pollution not only harms human health and safety directly, but also brings great harm to plant growth and development, such as all the important economic crops will reduce output observably because of pollution. A large number of collective pollutants can cause the plant death, even damage the entire ecosystem.Environmental pollution can be divided into the air pollution, water pollution, soil pollution and biology pollution. In which, air pollution and water pollution affect the plant most. Besides their wide range, they are easily transformed into soil pollution and biology pollution. Based on a comprehensive investigation on the growth of the garden tree in Baotou City, this paper focus on the research of dominant factors of the habitat, the resistance of trees to heavy metal elements, the resistance to pollution and the ability to purify the atmosphere. The purpose is to choose the plants that have strong resistance, health protection capability, high economic profits, as well as with rich historical and cultural foundation and the local characteristics, to use into urban forestry development. This can significantly improve the scientific and technological content and integrated benefits of urban landscape. Following conclusions reached from the study:1 All of 6873 trees which belong to 9 conifers,29 shrubs and 42 deciduous species were classified into 3 groups according to their growth status and adaptabilities to environment. 15 species were growing well and performed as most extensively adaptable,such as Pinus syivestris var.mongolica,P.tabulaefomis var.mukdensis,Juniperus regida, Ulmus pumila, Fraxinus pennsylvanaca, Morus alba,Euonymus bungeanus, Crataegus pinnatifida,Malus baccata,Prunus siberica,Prunus davidiana,Syringa amurensis, Xanthoceras sorbifolia and Betula platyphylla respectively. And Pinus bungiana, P.tabulaeformis, Pica meyei,Platycladus orientalis, Populus Canadensis,P.simonii, P.alba, P.nigra var.italica, P.cathayana, P.cana, Ulmus laevis, U.pumila var.pendula, Acer negundo, Salix babylonica, Sophora japonica, Sophora japonica cv.pendula, Robina pseudoacacia,Gleditsia japonica,Eaegnus angmistifolia,Phyllodendron amurense, Juglans mandshurica,Pyrus ussuriensis,Malus prunifolia, Prunus salicina, M.pumila cv.and Ailanthus altissima performed moderately. But 6 tree species including larix principis-repprechtii, Sabina chinensis, Populus pekinensis, P.tomentosa,Salix babylonica and S.matsudana cv.tortulsa belonged to the category of bad growth and weak adaptability.All 26 shrubs performed well except Weigela florida,Fontanesis forthunei and Celestrus robiculatus.2 The capacity of pollutant-resistance was variable with tree species.Tamarix chinensis,Ulmus pumila,Euonymus bungeanus,Populus canadensis and Lespedeza bicolor were higher in pollutant-tolerance,and Gledtsia sinensis,Fraxinus chinensis,Betula platyphylla, Ulmus macrocarpa,Populus cathayana,Sorbatia kirilowii,Sambucus williamsii, Acer negundo,Syringa reticulata var.mandshurica,Populus alba,P.bollaena and P.hopeinsis were at the middle,whereas the capacity of pollutant-tolerance of Prunus triloba, P.tomentosa,Ampelopsis brevipedunculata,Ulmus spp.And Humulus lupulus were the weakest serial.3 SO2 accumulation in leaves of tree was different with coniferous and deciduous species.The content of S in leaves of Populus bollaena and Syringa vulgris remained at lower level and unstable before May.It was relatively stable from June to July,Increased gradually after August,and reached the highest level before defoliation.But the content of S in leaves of Juniperus regida kept a relatively high level before June,dropped down from July to August,and increased again after September.A little of SO2(only 6.48%)which was absorbed and accumulated by leaves of Fraxinus pennsylvanica was transmitted into branches and bulk.The transmission was higher for Platycladus orientalis,it reached 24.9% of the accumulation in leaves.4 The dynamic of fluoride absorption for trees showed as a quadratic parabola.The quantity of fluoride absorbed by leaves increased with the increase of ambient concentration,if the level of fluoride advancedly accumulated in leaves was low.And it decreased with the increase of ambient concentration,if the advanced accumulation in leaves was at high level.The content of fluoride in leaves of Picea meyeri was the highest among conifers,followed by Juniperus regida,Pinus tabulaeformis and Platycladus orientalis,that of Sabina chinensis was the lowest one.And that of Salix babylonica and S.matsudana were the highest among the deciduous, followed by Populus hopeiensis,P.bolllaena,Pruns davidiana, Ulmus pumila var. pendula and Sophora japonica cv.pendula,that of Ulmus pumila and Populus canadensis were the lowest,Leaves of Sabina vulgris absorbed fluoride at the maximum level among shrubs,leaves of Prunus triloba,Rosa xanthina and Forsythia suspensa at the moderate level,and leaves of Syringa vulgris at the minimum level.Based on the maximum absorption level,Picea meyeri ranked the first one among conifers,and Platycaldus orientalis the last one,Populus hopeiensis,P.bollaena and Salix matsudana were the highest among the deciduous,Ulmus pumila var.pendula and Sophora japonica cv.pendula the lowest,Syringa vulgris reached the top among shrubs,and Rosa xanthina the bottom.5 The quantity of S accumulation in leaves increased linearly with the ambient concentration of SO2.The linear inclination was biggest for Platycladus orientalis among conifers,followed by Sabina chinensis,Picea meyeri and Juniperus regida,and least for Pinus tabulaeformis.Salix matsudana and S.babylonica were belonging to the steepest group among the deciduous.Populus hopeiensis,Euonymus bungeanus,Populus Canadensis, Fraxinus chinensis, Sophora japonica,Robina pseudoacacia,Prunus davidiana,Ulmus pumila, Sophora japonica cv.pendula and Populus bollaena were included onto the middle group,and Salix babylonica the gentlest one.It was the first one for Sabina vulgris among shrubs,followed by Sorbaria kirilowii and Syringa vulgris,Forsythia suspensa appeared the last one.Based on the total accumulation in leaf biomass,the inclination was highest for Platycladus orientalis among conifers,Populus hopeiensis and Salix matsudana among the deciduous and Syringa vulgris among shrubs respectively,the lowest were Pinus tabulaeformis,Salix babylonica and Sophora japonica cv.pendula,Rosa xanthia in the same order respectively.6 The order of heavy metal elements average levels in the soil of Baotou is Mn>Cr>Cu>Co>Ni>Zn>Pb.7 The distribution of heavy metal Mn in plants is leaf> branch; The distribution of heavy metal Zn and Cu is branch>leaf; Heavy metal Cr elements only distributes in the branch plant and the roots;Populus bollaena, P.simonii, Rosa rugosa can be used to indicate Mn element; Salix matsudana can be used to indicate Zn element; Ulmus pumila, Sorbatia kirilowii can be used to indicate Cr elements.8 Heavy metals in soil of Baotou have a significant correlation between each other, in which, relevance between Ni and Cu, Ni and Zn are the largest, about 0.9997.9 The heavy metals quantity contained in soil of Baotou has a significant correlation with soil PH value, the largest one is Cr element.