Study On The Configuration Mode Of Green Roof Eco-efficiency In Downtown Chengdu

The system of city's greening is one of the major parts of the city's ecosystem, and it's eco-efficiency directly influences the ecological quality of the whole city. The use and development of city's green roof will expand it's area, better the heat island effect, lower energy consumption, buffer the conflicts between constructive field and greening area. It has become the focus of many urban greening. There are lots of studies on urban green roof Eco-efficiency at home and abroad. Among them, the overseas studies have been carried out for years and are more systematic. However, the studies in China are unbalanced and not systematic. To put the green roof plants in scientific use, I did a through investigation about the whole green roof pattern and plants in downtown, CD, which including photosynthesis, temperature humidity, antibacterial, absorption of sulfur dioxide, dust-effective. Results:1. Presently, there are four green roof patterns in downtown, CD:roof, wall, porch and overpass. Among the four patterns, the roof is the best place for plants' growth. There are 32 typical plants applied to the green roof. Three of them used on the wall occupy 9.4%. Four of them used on the overpass occupy 12.5%. Two of them used on the porch occupy 6.3%. Twenty-five of them used on the roof occupy 78.1%. After five-season observation I can draw the conclusion:plants growing on the wall, such as Parghenocissus quinquefolia, Parthenocissus tricuspidata and Mucuna sempervirens, are growing well. Parthenocissus quinquefolia has highly ornamental value. Mucuna sempervirens has blight. Plants growing on the overpass include Jasminum nudiflorum, Viburnum macrocephalum, Ligustrum quihoui, Parthenocissus tricuspidata, and euonymus fortunei. Jasminum nudiflorum not only grows well but has a highly ornamental value, but Viburnum macrocephalum and euonymus fortuner grow slow. Plants growing on the porch such as wisteria Sinensis and Rosa banksiae, are growing well and have highly appreciative value. But Wisteria sinensis is foliage, it'll ruin the greening effect in winter. Twenty-five types of Plants growing on roof are growing well, have highly ornamental value, which are best ones for the green roof except that few of them have blight.2. Of the 32 types of plants, Viburnum macrocephalum and Gardenia jasminoides ellis have the strongest ability of carbon fixation and oxygen release. Prunus cerasifera ehrhart and Dichondra repense forst have weak ability of it. Gardenia jasminoides ellis and Ligustrum quihoui have great power of temperature drop and humidity increase, whereas Jasminum nudiflorum and Acerpalmatum cv. atropurpureum have less power than them. Rosa chinensis and Mucuna sempervirens have shown strong antimicrobial activity but Loropetalum chinense var. rubrum and Nandina momistica thunb have less activity than them. Nephrolepis auriculata and serissa japonica have great power to absorb co2 but Ficus virens aiton var and Parghenocissus tricuspidata can not. Ligustrum x vicaryi hort and Viburnum macrocephalurn's dust-retention ability is strong but Rosa hybrida and Acer palmatum cv. Atropurpureum's is not.3. Parthenocissus tricuspidata or Parthenocissus quinquefolia are the best choices for the improvement of heat island effect in a vertical space. Mucuna sempervirens, Hedera nepalensis var. sinensis and Parthenocissus quinquefolia can be used to ameliorate urban pollution. Viburnum macrocephalum as a overpass green plant has the strongest ability of carbon fixation and oxygen release and the cooling effect of Parthenocissus tricuspidata is very well. The porch green plant, Rosa banksiae has a better comprehensive benefit than wisteria sinensis. Furthermore, wisteria sinensis is a deciduous plant, which has no green landscape in winter. Therefore, Rosa banksiae is more suitable for corridor plantation. In level space, the green plants used to improve the heat island effect are Cinnamomum japonicum, Osmanthus fragrans, Pittosporum tobira, Prunus cerasifera ehrhart, Rhododendron moupinense, Buxus bodinieri, Ligustrum quihoui, Parthenocissus quinquefolia, and Nephrolepis auriculata. The green plants used to alleviate urban pollution and purify air are Cinnamomum japonicum, Osmanthus fragrans van, Pittosporum tobira, Rhododendron moupinense, Ligustrum x vicaryi hort, Rosa hybrida, Gardenia jasminoides ellis, Rosa sikangensis.4. At last, I've come up with 8 allocation models. Model 1:arbor, bush, herbal, climbing plant. Model 2:bush, herbal, climbing plant. Model 3:bush add bush. Model 4:bush, herbal. Model 5: arbor, bush, herbal. Model 6:arbor, bush. Model 7:bush, climbing plant. Model 8:herbal, climbing plant.