Plant Community Characteristic And Landscape Evaluation Of Urban Parks In Shanghai

Plant community in urban parks is a significant factor of urban park landscape, its structure and functions are important characters of the plant communities. Via understanding plant community characteristics and landscape aesthetic functions and establishing landscape evaluation model and construct community configuration optimization model, the results can supplement landscape aesthetic theories and it also provides scientific basis for urban park plan community constructions and researches.This research took typical plant communities of urban parks in Shanghai as research objects, with method of French-Swiss schools to study characters of plant communities, and with SBE to evaluate characters of landscape aesthetic. On this basis, by studying characters of plant communities and landscape aesthetics benefits, researching the influence community characteristics factors have on its landscape aesthetics benefits, and finding out the major community characteristics factors that influences landscape aesthetics benefits performance, so that we can build up the design patterns of plant communities' configuration. In total, 58 plant communities in 17 urban parks are investigated. The results show that: (1) 224 kinds of plants are involved.(2) The indigenous plant proportion is 13.2%. (3) There are various plant communities in Shanghai urban parks: evergreen broad-leaved forest, evergreen and deciduous broad-leaved forest, open forest-grassland, deciduous broad-leaved forest, grassland, deciduous coniferous forest, broad-leaved and coniferous mixed forest, evergreen coniferous forest, bamboo forest, palm forest, most of which are deciduous broad-leaved forests and evergreen broad-leaved forests. (4) Most of plant communities are"tree-shrub-herb"multilayer-community pattern.(5)Height level distribution of trees is mainly 6.1~10.0m, and DBH distribution of trees is mainly 10.1~25.0cm. (6) According to the space, these plant communities are divided into 4 types: open space type, semi-open space type, covering space type and completely closed space type, with 6 communities belonging to the first type, 16 to the second, 12 to the third and 24 to the last.On the basis of community investigation, 38 typical communities are selected for landscape aesthetic assessment, to makes efforts to build up a landscape aesthetic evaluation system with SBE method. The results show that: (1) SBE average value descending order by vegetation type is: deciduous broad-leaved forest, broad-leaved and coniferous mixed forest, evergreen broad-leaved forest, open forest-grassland, grassland, evergreen and deciduous broad-leaved forest, evergreen coniferous forest, deciduous coniferous forest, bamboo forest, palm forest. SBE average descending order by space type is: sightseeing type, grassland with space in one side, covering space type, grassland with forest in above, open space type, environment protection type. (2) There are some aspects of tree structure characteristics that impact the community SBE values: the highest SBE values are calculated when the tree DBH is in the range of 10~20cm, and the lowest SBE values are found when the tree DBH is less than 10cm. The community SBE values of straight trunks are higher than curving trunks. Soft crown shape is the best, followed by mixing mass crown shape, the worst is rigid crown shape. (3) There are some aspects about the shrub and herb structure characteristics that impact the community SBE values: SBE values of shrub-herb coverage 60~90% are the highest, >30% and 30~60% in the middle, and <30% are the lowest. SBE values of communities, whose shrub-herb height is 0.5~1.0m are the highest, more than 0.5m in the middle and when their shrub-herb height is less than 0.5m, it is the lowest. (4) Physical characteristics of the community have impacts on the community landscape. Forest canopy line provides the biggest contribution to the SBE values, followed by the seasonal dynamics. (5) Species diversity has impacts on the community landscape through stand diversity and the composition of species. Stand diversity shows a significant correlation with the in-forest SBE values in urban parks, and others are not. When the stand diversity is in the range of 1000~1500 piece/hm~2, SBE gets the highest value, the second is that the stand diversity is less than 1000 piece/ hm~2, the worst situation is that the stand diversity is more than 1500 piece/ hm~2. In another word, the SBE value is high when the stand diversity is proper.The remaining work is on the base of investigation and landscape aesthetic assessment. Directing against different spatial pattern communities, some optimizing plan about the plant species and configuration are submitted, wishing to be a practical and highly-efficient reference in the planting design of urban parks.