Plant Diversity Of Urban Greenspace In Wuhan

Cities, as the centers of gathering and housing for human beings, provide the crucial material base for the sustainable and stable development of the industry and agriculture and the main support for the physical life as well as the most important environmental evaluation, such as modulating regional climate, lowing noise, discomposing pollutants, beautifing environment etc., depending on its biodiversity. At the same time, they play an important role in recreation, aesthetics, social culture, S&T education, spirit and history. The urban biodiversity is a ecological testing index for the establishment and maintainess of the high effective and positive banlance of the ecological system, which has turned to effect the city's sustainable development.The plant species diversity of artifitial vegetation in Wuhan was reaserched on the basis of different structure communities in this paper. 185 samples (600m2/sample)were selected to investigate the plants of different communities separately in central city region, suburban and remote rural area ,which can provide effective guidance for the conservation of urban sepecies diversity and the development of urban vegetation, in order to grasp its current situation and characateristics. The species diversity of different structure communities in different cycles around city was analized and compared based on richness indexs, diversity indexs and eveness indexs, also the species diversity of the same community of different cycles around city. Then, the evaluating system of urban species diversity was established by selecting several suitale indexes through comparison. Some useful results are given as follows:1. The life-form spectum of artificial vegetation of Wuhan shows the characters of the subtropical climate. The percentage of phanerophytes and that of therophytes are high, which shows the specialty of the urban vegetation, from the view of life-forms' change tendency of the three cycles around city. The tree-shrub-herb communities are regarded to be more than the other three types and the tree-herb communities and the shrub-herb communities are more than the tree-shrub communities. There are more tree-shrub-herb communities and shrub-herb communities in the central city and the suburban. In the remote rural area, the tree-shrub-herb communities and the tree-herb communities are more than the other ones.2. The sequences of different structure communities are same, according to richnessindex, diversity indexs and evenness index, among three cycles around city. According to richness index, the sequence is as follows: tree-shrub-herb community > shrub-herb community > tree-shrub community >tree-herb community; according to diversity index, the sequence is as follows: tree-shrub-herb community > tree-shrub community > shrub-herb community > tree-herb communiyt; according to evenness index, the sequence is as follows: tree-shrub community>tree-shrub-herb community > shrub-herb community > tree-herb community. The result indicates the species diversity of different structure communities is different. The richness index and diversity indexs of the three-layer structure communities are higher than that of the two-layer structure communities, while the sequence of evenness index is uncertain. The diversity index of the same structure community of different cycles around city is different that the richness index, diversity indexs and evenness indexs of central city are higher than that of suburban and remote rural area.3.The percentage of trees of Wuchang (36.70%), shrubs of Hanyang(46.39%) and herb of Hankou(22.33%) are the higest ones in central city. The sequences of richness index, diversity indexs and evenness index of different structure communities are not same in three cycyles around city. Generally, the indexes of Wuchang are higher than that of Hankou and Hanyang.4. Mclntosh diversity index and Mclntosh evenness index are not suitable to calculate the species diversity when the species diversity is calculated with the the important value.While Shannon diversity index is more suitable than Simpson diversity index, Pielous 1 evenness index than Pielous 2 evenness index. Gleason richness index is more suitable than Patrick richness index when the area of community type is not equal.5. According to the evaluating value of different communities, the result is that the longer the distance from central city is, the less the species diversity of tree-shrub-herb community is. The species diversity indexs of tree-shrub community, tree-herb community, shrub-herb community of central city are higher than that of suburban and remote rural area. According to the evaluating value of different communities, the sequence in central city is as follow: tree-shrub-herb community(l 1.3 8) > tree-herb community( 10.50) > shrub-herb community(8.36) > tree-shrub community(8.12). In suburban, the sequence is as follows: tree-shrub-herb community(7.01)> shrub-herb community (5.68) > tree-shrub community (5.05) > tree-herb community(3.83). In remote rural area, the sequence is as follows: tree-shrub-herb community (6.83) > shrub-herb community (5.94) > tree-shrub community (5.58) > tree-herb community (4.08). The result shows that the value of three-layer community is higher than that of two-layer community.6.Based on the species diversity evaluating index Y of urban greenspaces, the sequence of three cycles around city is as follows: central city region(9.75)>remote rural area(5.67)>suburban(5.59).The species diversity indexs of greenspaces do not drop along with the distance from central city region to remote rural area increasing. In fact, the species diversity of remote rural area is higher than that of suburban. So, according the difference of each layer of different communities, the adjustment and increasement of species and cultivated area will help increase the species diversity of artificial vegetation in Wuhan, especial for suburban and remote rural area.