Holistic Research Of Green Building And Afforestation System In Haikou City

Afforestation system has ecological functions such as improving air quality,regulating microclimate,and maintaining urban plant diversity in green building systems.At present,there is a lack of systematic research on the status quo of green building greening system in tropical coastal cities,how greening affects the site thermal environment,green building and afforestation system integration design strategies.In view of the above problems,the following research is carried out:Firstly,the paper investigates the application status and existing problems of five representative 2-star green building plant systems in Haikou through field investigation.Secondly,the characteristics of urban island heat island effect,the inversion of green building land area and surface temperature,and the characteristics of green building thermal environment are analyzed its influencing factors from the perspective of time and space through multivariate remote sensing data,Thirdly,the method of "investigation-evaluation-verification" is adopted.Naturally,the plant species suitable for building walls near Haikou are selected:the species of near-natural wall(rock)plants in Haikou City are investigated,and the comprehensive evaluation system,evaluation index,screening and application varieties are constructed by Delphi method and AHP method.Then,through experiments,the accuracy of the evaluation system and the feasibility of plant introduction and cultivation were studied.The research results are as follows:1.Green building plant greening application survey:field survey of the current status of green building afforestation systems in Haikou,the results show that:(1)Green infrastructures are well used in green buildings of Haikou City,but the greening system is monotonously structured,with a low space utilization rate;(2)Among the 32 plots of the five buildings,there are 170 species of plants belonging to 120 genera and 54 families.Native species account for 22.9%,and the local characteristics are not highlighted;(3)Plant diversity is abundant,but the community structure is simple,the community stability is poor,and the maintenance cost is high.Therefore,it is necessary to holistic architecture and afforestation design,build a horizontal and near-natural greening system,improve the utilization of building space,make use of native plant resources,and introduce plants into the building,thus develop vertical greening and Green Roof.Meanwhile we can learn from the natural landscape model of tropical rain forest,which can be achieved by import the energy-saving,ecologically stable and water-saving plant community model in Hainan forest,to construct an ecological,economical and sustainable plant system with native tree species.2.Analysis of thermal environment characteristics and influencing factors of green building sites:the distribution and evolution of the heat island area are basically consistent with the urban development and expansion trend.The downtown area of Haikou shows typical heat island characteristics.In December 2016 and May 2018,29%and 34%is covered by“heat islands" respectively;the thermal environment of green buildings is better than the average condition of its surrounding area.Principal component analysis find that the land cover type index is the main influencing factor of the green building thermal environment,followed by the distance from the coastline,the proportion of grassland area,and the proportion of forest land area.By linear regression fitting the relationship between land cover change and surface inversion temperature,it is found that for every 10%increase in forest area,the surface temperature can be reduced by 0.84℃;for every 10%increase in road area,the surface temperature is increased by 0.45℃..3.Holistic design of green building’s vertical greening and near natural wall(rock)plant:(1)Investigation of plant resources in near-natural wall(rock).According to the survey and statistics,a total of 101 species of 81 genera and 47 families were recorded,including 17 species of 13 genera and 7 families of ferns,and 84 species of 48 genera and 40 genera of angiosperms.There are 73 species of herbs,11 species of vines,5 species of shrubs,and 12 species of trees.Native species 39 families,64 genera and 76 native plants,accounting for 75.24%of all species.The density of the rock plant family collected in this survey is not high but the dominant species are obvious.Mainly distributed in Compositae,Moraceae,Gramineae,fern plant Pteridaceae,water dragon orthopedics.(2)Comprehensive evaluation of plant resources in near-natural wall(rock).Through the Delphi index screening and analytic hierarchy process,a near-natural wall(rock)plant evaluation system was established,and 101 species of the survey were evaluated from four aspects:growth adaptability,ecological benefit,economic benefit and landscape benefit.There are 19 at the Ⅰ level,accounting for 18.81%of the total;37 at the second level,accounting for 36.63%of the total;37 at the third level,accounting for 36.63%of the total,and 8 at the Ⅳ level,accounting for 7.92%of the total.There are 56 kinds of near-natural wall(rock)plants in Grade Ⅰ and Ⅱ,accounting for 55.45%of the total.It is used as a plant resource information base and introduction recommendation for green building vertical greening.(3)Research on plant growth adaptability of near-natural wall(rocks)plant.Seven plants with higher comprehensive and ornamental values were screened for growth adaptation test from the two perspectives of plant shape and growth index.All the 7 plants had strong drought-tolerant and thin-tolerant characteristics,and the comprehensive growth index and external morphological changes of the plants were analyzed.It was found that Kalanchoe daigremontiana,Hoya liangii and Portulaca pilosa had strong drought tolerance and lightfastness under natural stress;Talinum paniculatum,Zebrina pendula and Pyrrosia lingua rank behind and has a wide range of application.The Nephrolepis auriculata have a lower comprehensive evaluation and is a shade-tolerant plant.This is consistent with the evaluation of the Delphi method and the AHP method.The results also show that in high temperature,strong sunshine and no rain days,Talinum paniculatum and Nephrolepis auriculata are irrigated at least every 20-30 days,and the ideal time for Portulaca Pilosa,Hoya liangii,Zebrina pendula to hydrating water is 30 days.Bryophyllum pinnatum has no need for artificial water supply.Overall,this study carried out a survey on the status quo of green building plant systems in Haikou City,analyzed the thermal environment characteristics and influencing factors of the urban area and green building sites in Haikou,collected the near-natural wall(rock)plant,proposed a vertical green plant evaluation system and provided the holistic strategies for green building and afforestation system.It can provide theoretical and data support for the holistic research of ecological,economical and sustainable green building afforestation systems in Haikou City.