| The urbanization pace is developing rapidly, causing some environmental problems like smog, green effect, heat island effect and etc. Since these problems lead to the acute contradiction with living environment, solving the urban environmental problem has become people's urgent need. Roof afforestation is a new type of urban afforestation, it can release the problem of shortage of urban green land, improve urban ecological environment, extend the life span of architectures and improve energy conservation. Thanks to the advantages of roof afforestation, the roof afforestation in big and medium-sized cities develops quickly. Up to now, the researches of roof afforestation done by domestic scholars focus on engineering technology, cultivation substrate, plant selection and ecological effect. Among these studies, engineering technology and cultivation substrate have been relatively mature, while the selection and comment of roof afforestation plant is quite immature. Now take the city of Haikou, where the writer studies and lives, as an example. Haikou, one of the biggest cities for relaxation and holiday, as well as the window city for Hainan to build an international tourism island, its urban afforestation index ranks the top of the country, but its roof afforestation develops slowly with little research work. Therefore, by surveying the roof afforestation places of Haikou, this paper studies the situation, species and landscape design of roof afforestation in Haikou. Meanwhile, based on the reality of Haikou, this paper makes the selection system and index assessment system of roof afforestation, selects a batch of roof afforestation plants with high appraise, with the purpose of providing a general direction for designers when they choose afforestation plants. In the process of plant landscape designing, in order to provide reference frame for designers, we take the planting form of plants and spatial position of roof as the research target and analyze the cases of landscape design.The findings show that green roof has122kinds of plant species in Haikou, Including51families and103genera.30kinds of trees, accounting for24.6%of all species.48kinds of shrubs, accounting for39.3%.8kinds of vines, accounting for6.6%.36kinds of herbs, accounting for29.5%. At the same time, there are five problems of green roofs in Haikou:1Small number of green roofs, and the type of single.2Plants improper selection.3Plant improper maintenance and poor management in part of green roofs.4The relevant laws and regulations, technical standards need to improve in Haikou.By Delphi expert consultation, the convergence of expert advice, so delete water logging capability (P3), widely degree (P5), humanities historic(P19). Priority sort results of10Ornamental indicators:ornamental characteristics (r10)> best viewing period (r9)> plant type (r8)> flower and fruit color (r4)> the degree of exotic flower and fruit shape (r5)> leaf color (r1)> leaf area (r3)> flower and fruit quantity (r6)> leaf shape (r2)> flower and fruit size (r7),and r2, r6, r7priority is less than0.6. After sorting screening ornamental indicators identified three types of ecological adaptability, ornamental, and potential applications, a total of13evaluation. On the basis of the5-point method, through theoretical analysis, consulting experts and industry practitioners, for each indicator to develop the appropriate level. The indicators screening system and the classification of indicators to provide a reference for the evaluation of green roof plants in Haikou.In the roof greening plants evaluation system, rules layer weights results show that the ecological adaptability weight peaked at0.4871, ornamental weight is0.3931and the application potential weight low as0.1198, the above description should first consider its ecological adaptability and it has high ornamental value and some potential applications in green roof plants selection.The results of ecological adaptability single sort weights showed that high temperature capacity is the highest, drought resistance, wind resistance weights are0.3295,0.2477. It shows the green roof plant first need to have high temperature capability, followed by drought and wind resistance capacity are also important.The size of ornamental indicators single sort weight is ornamental characteristics> plant type> flower and fruit color> best viewing period> leaf color> the degree of exotic flower and fruit shape> leaf area. Ornamental Characteristics highest weight0.2622, followed by plant type weight, indicating that when people appreciate the plant, the first focusing on whether the plant can watching flower, leaf, fruit. Compact plant type, shape regular trees, shrubs, and better visual effects into a piece of dense growth of vines, herbaceous. Flower and fruit color and best viewing period to some degree related and share a similar value of flower and fruit color and best viewing period, flowering plants, when is the best time of their viewing. Leaf color and the degree of exotic flower and fruit shape share a similar value, show brightly colored or seasonal changes in leaf color, flowers and fruit peculiar shape of the plant more attractive people's attention, which have prominent landscape function in the plants landscape. Leaf area lowest weight, can be appropriate to use some of the larger leaves of the plant, so rich and varied in plants landscape.The results of potential applications single sort weights showed that maintenance costs are the highest weight, the instructions roof plant selection, we should first consider whether it facilitates maintenance and management. Price cost weight is the second, and indicating the cost of seedlings is also one of the important factors affecting the roof plants selection. Regional characteristics low weight, the appropriate use of indigenous plants and landscape features tropical plants can enrich plant landscape effects.122kinds of green roof plants were gray correlation sorted. The results showed that the relational degree of trees greater than0.65have Plumeria rubr, Cycas revolute, Pandanus utilis, Areca catechu, a total of four kinds of plants can be used as the basic-tone tree species or the main tree species. The relational degree of shrubs greater than0.65have Murray a exotica, Duranta repens'variegata', Duranta repens'goldenleaves', Loropetalum chinense var.rubrum, Duranta repens, Ixora williamsii 'DwarfPink', Ficus microcarpa 'goldenleaves', Fagraea ceilanica, Pedilanthus tithymaloides, Schefflera odorata 'variegate', a total of ten kinds of plants can be used as the basic-tone tree species or the main tree species. Lianas, the higher overall evaluation has Ipomoea cairica and Bougainvillea spectabilis. The relational degree of herbs greater than0.65have Ophiopogon intermedius'argenteo', Catharanthus roseus, Sansevieria trifasciata, Sansevieria trifasciata'laurentii', Agave americana var. marginata, Agave americana var.marginata-alba, Crinum asiaticum var. sinicum, Hymenocallis littoralis, Altemanthera Ficoidea 'ruliginosa', Ipinia katsumadai, Rhoeo discolor, a total of11kinds of plants can be widely used. Plant selection result is intended to provide general direction for the green roof designers in the selection of plants.In this paper, for common forms of cultivation and different spatial in Haikou roof greening, analysis of relevant plant configuration examples and recommended use part of comprehensive evaluation of higher plants, to provide a reference for Haikou green roof plants landscape design. |
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