北京城市绿地群落结构对降温增湿功能的影响

ttttt目的ttttt城市绿地具有改善环境、保护环境和美化环境的重要作用；它在提升人居生活环境、打造宜居城市方面具有不可替代的地位。为更好地了解中国新兴卫星城市的绿地状况，以南京仙林大学城为例，对绿地群落的物种组成和多样性进行了调查分析，以期为此类绿地建设提供科学参考。ttttttttttttt方法ttttt在南京仙林大学城的绿地随机设置30个20 m×20 m的样方进行分层调查；利用重要值、多度、多样性指数等对所调查的结果进行分析。ttttttttttttt结果ttttt(1)仙林大学城公共绿地共有木本植物27科36属41种，以蔷薇科、木犀科和木兰科植物居多；整体上，外来物种的运用比例偏高，乔木层尤为明显。(2)重要值结果表明香樟、东京樱花、银杏及金边冬青卫矛、石楠、海桐分别为乔木层和灌木层的优势物种；同时这些物种的多度明显高于其他物种。(3)乔木径阶结构表明：该区域以中小径级树木为主，仍有较大的发展空间。(4)群落垂直结构不高，乔木层多数个体集中在3～6 m；灌木层高度集中在0.4～1 m。(5)与其他城市绿地多样性指数比较，该区绿地多样性明显偏低。ttttttttttttt结论ttttt改善群落结构特征、提升物种多样性、加强景观特色营造是今后仙林大学城公共绿地建设应着重考虑的方面。tttt

Multiple health benefits of urban tree canopy: the mounting evidence for a green prescription

tttttPurposetttttPublic green space of urban plays a significant role in improving environment, protecting environment and decorating environment; it has an irreplaceable status on improvement of living environment and creation of livable city. To understand the species composition and diversity of public green space of new satellite city, a case study of Xianlin college town in Nanjing metropolitan, the objective of this paper was to provide scientific reference of construction of green space for the management.tttttttttttttMethodttttt30 plots (each 20 m×20 m) were surveyed randomly by the method of stratified sampling. The data was analyzed by importance value, species abundance, diversity indices etc.tttttttttttttResultsttttt(1) There were 41 species belonging to 27 families and 36 genera; Rosaceae, Oleaceae and Magnoliaceae contained more species than other families. Generally, alien species were more than native one, particularly arbor layer. (2) Based on the importance value, Cinnamomum camphora, Cerasus yedoensis and Ginkgo biloba were the dominant species in arbor; in shrub layer, Euonymus japonicus var. aureomarginata, Photinia serratifolia and Pittosporum tobira were top three species. Their species abundance were far more than the others. (3) Structure of diameter at breast height (DBH) displayed that more individuals assemble in the height class of 3-6 m and 0.4-1 m in arbor layer and shrub layer respectively. (5) Compared to the other cities, species diversity was lower in studied area.ttttttttttttttttttConclusiontttttWe can draw conclusions that improvement of community structure, increasement of species diversity and creation of special landscape should be paid more attention on the public green space of Xianlin college town.tttt