| Global warming and extreme climate pose serious threats to human survival and the sustainable development of society and economy,becoming one of the greatest challenges for human development in the 21 st century.China has proposed the concept of green development based on the constraints of ecological environmental capacity and resource carrying capacity,and regards environmental protection as an important development mode for sustainable development.As one of the practical carriers of green development,Chongqing green and eco-residential district often rely on existing mature plant configuration methods in the process of green space construction,with less consideration for the expression of biodiversity and the degree of ecological function after plant configuration.The current evaluation of green space in residential communities still uses a two-dimensional indicator system,which has limited evaluation of the ecological value of green space,and the overall quality of green space construction is low.Therefore,it is of great significance to carry out research on plant configuration modes based on the three-dimensional indicator Green Plot Ratio(GPR)in Chongqing green and ecoresidential district.This study takes low,multi,and high-rise green and eco-residential districts in Chongqing’s central urban area as research areas,conducts field surveys on various types of green spaces within the community,measures plant physiological data and plant configuration data on site,and analyzes the existing plant configuration modes of various types of community green spaces;measures GPR and Leaf Area Index(LAI)of commonly used native plants in Chongqing on site,analyzes the key plant configuration characteristics for optimizing plant configuration modes based on GPR,selects the optimal combination of plant configuration characteristics through establishing an ENVImet scenario simulation model for microenvironments;optimizes existing plant configuration modes for various types of green spaces with this optimal combination,proposes a plant configuration mode optimization plan,and verifies its effectiveness through instance optimization and scenario simulation.The research results can be applied to upgrading existing green spaces in Chongqing green and eco-residential districts and future green space construction,with the expectation of improving the ecological benefits of green spaces in residential communities and practicing green ecological concepts.The main research results are as follows:1.Basic survey of green spaces in Chongqing green and eco-residential districts.The richness of commonly used plant species and ornamental plant species in green spaces is arranged as high-rise residential communities > multi-story residential communities >low-rise residential communities,among which the use of mid-level trees is relatively small,and plant configuration is concentrated in low-level trees,with less application of herbaceous ground cover plant species.The plant configuration modes of various types of green spaces in the three types of green and eco-residential districts are different in terms of plant hierarchy,plant species,and plant specifications.2.Field measurement and analysis of LAI of commonly used native plants in Chongqing.(1)LAI measurement of native plants in Chongqing.Among the 113 surveyed plants in summer,the maximum LAI was 5.80 for Sloanea sinensis,and the minimum LAI was1.60 for Triadica sebifera;the highest frequency of use was Osmanthus fragrans,with an LAI of 4.17,and the lowest frequency of use was native plants such as Celtis julianae Schneid,Alnus cremastogyne,and Elaeocarpus sylvestris.(2)Clustering and grading of native plants in Chongqing.The final cluster center divided LAI into three cluster groups: high-LAI trees(LAI>=3.73),mid-LAI trees(2.73<=LAI<=3.73),and low-LAI trees(LAI<2.73).There are 41 high-LAI trees,including native plants such as Sloanea sinensis,Celtis julianae,and Alnus cremastogyne with high LAI but low frequency of use;native plants such as Chimonanthus praecox,Livistona chinensis,and Acer truncatum with high LAI values and high frequency of use;21 low-LAI plants,including Prunus cerasifera f.atropurpurea,Broussonetia papyrifera,Lagerstroemia indica,and Caryota maxima with high frequency of use and low LAI values.(3)Analysis of LAI of native plants in Chongqing.The LAI value of native plants in summer is significantly higher than that in spring,autumn,and winter,and the LAI value of evergreen trees in summer is higher than that of deciduous trees at the levels of life form,crown width,and tree height.The main factor affecting the LAI of evergreen trees is tree height,while the main factor affecting the LAI of deciduous trees is crown width.When selecting tree species for planting,try to choose evergreen trees with h<5m and deciduous trees with crown width ≥8m.3.The simplified calculation formula for GPR has errors.The plant configuration characteristics that affect GPR are tree LAI,tree-shrub-grass ratio,and tree planting spacing;by comparing the measured and calculated values of GPR in residential community sample plots,it is verified that the error of the simplified calculation formula for Chongqing GPR is relatively large,and a conversion equation of y=1.373x-0.694 is given,where x is the estimated value of GPR and y is the measured value of GPR.4.Optimal plant configuration feature combination based on GPR.The experimental results ruled out the possibility of the influence of building height.Under the scenario where temperature and humidity are ecological factors,the best combination of plant configuration characteristics for micro-environment performance is high tree LAI(4.2),tree-shrub-grass ratio of 2:1:1,and tree planting spacing of 6m(tree crown width is 5m).5.Verification of plant configuration optimization based on GPR.The optimal plant configuration feature combination was used to optimize the plant configuration patterns of various types of green spaces in existing green and eco-residential districts,and a plant configuration pattern optimization scheme was proposed.The optimization was verified in two aspects: instance optimization and scenario simulation.Finally,the optimization range of GPR was 4.55-7.32,and the degree of optimization varied according to the current situation of the green space,ranging from 3.2% to 141%. |
PDF Full Text Request