Study On Composition And Dust Accumulation Capability、Sulphur Absorption Ability Of Main Plant Communities In Central Districts Yongchuan

With the process of accelerated urbanization, the quality of urban environment is declining increasingly, The construction of urban green space affects the urban environment’s quality. Therefore, in recent years, The construction of urban green space system developed to a greater emphasis on the stage of the ecological functions of green space system, improving the ecological benefits of green space system has become an important direction for urban greening.Study of foreign on ecological benefits started earlier and obtained more achievements. Research trend has been changed from qualitative description to quantitative research. However, domestic study in this area started lately, most studies are qualitative description、one-sided scope of the study and lacking of system. But in recent years, many studies in the quantitative study of eco-efficiency have made a meaningful attempt and obtainned some achievements.In this study, Yongchuan is the survey region, select green space which is representative in Yongchuan urban green space system as the research object. Widely used、grow well and representative plant species surveyed and experimented. From September2010to September2011, survey community composition、dust accumulation capability、sulphur content and sulphur absorption ability、LAI of Yongchuan urban green space system, Analysising community composition and the ecological benefits of green space system from the three points. The results of this study include the following:1. The species composition of plant communities:①The evennes index and the species diversity index are all large in the three plots, the evennes index of and the species diversity index of street greenbelt are the least one;②The ranking of species richness of there plots is the public park area> control area> street greenbelt.③Magnoliaceae、Lauraceae、Moraceae are main arborous layer flara plant, Oleaceae、 Hamamelidaceae and Pittosporaceae are main flara Shrub-layer flara plant.2. There were great differences in the dust accumulation capability of he different test greenery species, chindensevar> OphiopogonJaponicus> F.microcarpa> Photinia.s> Osmanthus fragrans> Camellia japonica> Ligustrum lucidum> Fatsiajaponica> m.grandiflora> Pittosporum tobira> Michelia alba> Ilex purpurea Hassk> ginkgo> J. nudiflorum Lindl, from2.0903g/m2(J. nudiflorum Lindl) to12.361g/m2(L. chindensevar),with the maximum being6times more of them minimum; there are great differences in the dust accumulation capability of the same test greenery species in different urban areas, following the trend according to landuse the commercial and transport area microscopic scanning showed that:first, different tree species which had different leaf epidermal micro-configuration had different dust-retainning capability, street greenbelt> the residential area> control area; The results of leaf surface electron ridge like rumple, their dust-retaining capability was stonger, the leaves had smooth or ceraceous surfaces, their dust-retaining capability was poor; The dust-retaining capability is bound up with the eare of unit leave.3. leaf blades of different species has different sulphur content and sulphur absorption ability in same area, and the leaves of Osmanthus fragrans、Gardenia jasminoides Ellis、 Ilex purpurea Hassk、Erythrina indica Lam bear high leaf sulfur content and have strong ulfur-accumulating ability markedly higher than other species; The leaf blades in heavily polluted area has higher sulphur content and stonger sulfur absorption ability than leaf blades in lightly polluted area; The one which has higher sulphur content has stonger sulfur-accumulating ability.4. Three plots were selected to study leaf area index (LAI) by plant canopy analyzer, combined LAI, we analysed total dust-retainning quantity of representative plant in whole community.The leaf area index of Ficus microcarpa var、Osmanthus fragrans、Fatsia japonica、Pittosporum tobira are bigger than other plant, the leaf area index of ginkgo、Ligustrum lucidum、Jasminum nudiflorum are less than other plant.