| The sample survey method was used in this study. Ten plant communities in Xuezi Park of Zhengzhou were selected as the sample plots, all sample plots were representative linear green space in Zhengzhou. According to the plant community structure and diversity level, spatial structure of community, coenotype, health conditions in sample plots were surveyed and analyzed. In June 2014 to February 2015, the negative air ions concentration in four different vertical structures of the ten plant communities was measured, the air anion level and its influencing factors were analyzed. Then, ten evaluation factors were selected and appraised using scenic beauty estimation method (SBE). On this basis, the further optimization measures were put forward to the existing urban zonal greenbelt plant community landscape. The results were as follows:1. In the ten samples of the research, plant species in total are 31 species belonging to 30 genera in 22 families. There are 8 species,7 genera,6 families in arbor,17 species,17 genera,11 families in shrub,6 species,6 genera,5 families in grass and ground cover plant,28 species,28 genera,20 families in angiosperm. Among them, there are 15 species in deciduous plants,16 species in evergreen. The proportion of native tree species accounted for 45 percent, exotic tree species accounted for 55 percent.2. The artificial community in Xuezi Park has a certain zonal characteristics, evergreen and deciduous broad-leaved mixed forest of artificial cultivation accounted for a large advantage (55%). And next is evergreen broad-leaf forest (22%), the last is deciduous broad-leaved forest and mixed needle leaf and lowest, each occupied 11 percent. It can be seen that the evergreen and deciduous broad-leaved mixed forest accounted for a large advantage in the artificial plant community vegetation types.3. According to the whole situation of the green community, the average of species abundance degree of arbor, shrub, grasses in sample communities is 2.375. The average of Gleason index is 0.5157, the average of Margalef index is 0.5224, the average of Simpson index is 0.3528, the average of Shannon—Wienner index is 0.5937. And the average of Berger-Parker index which reflect ecological predominance degree of preponderant species is 0.7083, the average of Pielou index E is 0.5721. The integral level of species richness, coverage and uniformity in sample area plant community is not high. In each layer of plant community, the richness index of shrub layer is the highest, while the arborous layer and herbaceous layer is single.4. The change features of negative air ions concentration. (1) According to the comparison of negative air ions concentration between plant community sample area and control area in June 2014 to February 2015, the negative air ions concentration in plant community sample area was the highest in summer (time of duration was almost two months), the second is autumn, winter was the lowest. The control area had the same change trend, anion concentrations were all below the threshold. (2) Air quality was the best in summer, the second was autumn, winter was the worst. (3) One-Way ANOVA was used to analyze difference significantly, the results showed that the air negative ions concentration of linear green space in different seasons was significant difference (P<0.05).5. The impact factor of negative air ions concentration in different seasons was analyzed, and the mutual relation between urban zonal greenbelt air negative ions concentration, temperature, relative humidity, illumination intensity and PM10 was compared. The results showed that in summer, the air negative ions concentration was significantly positively related to temperature (P<0.05), it was significantly negative related to relative humidity (P<0.05), and it has no significant related to illumination intensity and PM10. In autumn, the air negative ions concentration was significantly positively related to temperature (P<0.05), it has no significant related to relative humidity, illumination intensity and PM10. In winter, the air negative ions concentration was significantly positively related to illumination intensity (P<0.05), it has no significant related to temperature, relative humidity and PM10. The research showed that the correlation between negative air ions concentration and other factors in air were impacted by seasons, and the discrepancy was different in different seasons.6. The negative air ions concentration in different plant community structure of urban green space was significantly difference. In same plant community, the negative air ions concentration in summer was apparently higher than autumn, winter was the lowest. The negative air ions concentration in different community structure type was as follows:arbor-shrub-grass community> arbor-grass community> shrub-grass community> grass> pavement.7. The evaluation result using SBE methods was as follows:different community score has a certain difference. According to the evaluation result, typical plant community landscape S1, S6, S7, S10 was selected and analyzed in detail in order to show certain reference significance to other construction of urban zonal greenbelt. |
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