北京城区医院绿地林木树冠覆盖与城市森林结构分析

Analysis of the urban tree canopy and community structure of hospitals in urban areas of Beijing

城市森林对人体健康的促进作用已经得到广泛的证实,医院是城市人流最聚集,生态健康需求最迫切的地区之一,急需加强对医院城市森林现状以及建设潜力的研究工作。利用2013年7—9月份0.5m分辨率的World View 2遥感影像以及基于面向对象解译平台eCognition软件解译得到的2013年北京市城区树冠覆盖栅格与矢量图,并结合实地调查,对北京城区医院绿地林木树冠覆盖与城市森林结构进行分析。结果显示:医院总体林木树冠覆盖率为18.59%,潜在树冠覆盖率为1.55%;无论是现实还是潜在林木树冠覆盖率,三级医院均高于二级医院;各环路现实树冠覆盖率表现为:五环—六环外1km(19.15%)>三环—四环(13.03%)>二环—三环(11.64%)>四环—五环(11.18%)>二环内(8.16%),潜在树冠覆盖率表现为五环—六环外1km(0.03%)>四环—五环(0.01%),其他各环路均为0;六个行政区间现实树冠覆盖率表现为:石景山区(24.49%)>海淀区(21.67%)>朝阳区(20.11%)>丰台区(19.43%)>西城区(13.52%)>东城区(10.55%),各行政区潜在林木树冠覆盖率值几乎均为0;本次调研共记录到植物62种,分属于33科54属,其中乔木层树种中雪松(Cedrus deodara)、紫玉兰(Magnolia liliflora)、银杏(Ginkgo biloba)的重要值以及应用频度较高;灌木层树种中榆叶梅(Amygdalus triloba)、石榴(Punica granatum)、金银木(Lonicera maackii)等观花观果树种重要值以及应用频度较高;医院城市森林群落的平均密度为55株/hm2,平均胸高断面积为2.23m2/hm2;平均胸径、冠幅、树高分别为17.69cm、4.65m、6.60m,树种规格整体较小。

The promotion effect of urban forests on human health has been widely confirmed.The hospital is one of the areas with a congregation large number of people who have the most urgent need for ecological health.It is important to strengthen the research on the current situation and construction potential of urban forest in hospitals.This paper analysed the Urban Tree Canopy and urban forest structure of hospitals in urban areas of Beijing.Analysis was based on World View 2 remote sensing images with a resolution of 0.5m from July to September 2013,and the tree canopy cover grid and vector map of Beijing urban areas in 2013 obtained from the object oriented interpretation platform eCognition software and combined with field investigations.The results showed that the Existing Urban Tree Canopy(EUTC)of the hospital was 18.59%,and Possible Urban Tree Canopy(PUTC)was 1.55%.Both EUTC and PUTC values were higher in tertiary hospitals than second class hospitals.The EUTC of each ring road was 1km out from the 5th—6th Ring Roads(19.15%)>3rd—4th Ring Roads(13.03%)>2nd—3rd Ring Roads(11.64%)>4th—5th Ring Roads(11.18%)>Within the 2nd Ring Road(8.16%).The PUTC was 1 km out from the 5th—6th Ring Roads(0.03%)>4th—5th Ring Roads(0.01%)and all the other rings were 0.The EUTC of six administrative regions was Shijingshan District(24.49%)>Haidian District(21.67%)>Chaoyang District(20.11%)>Fengtai District(19.43%)>Xicheng District(13.52%)>Dongcheng District(10.55%).The PUTC of all administrative districts were almost 0.There were 62 species of plants recorded in this study,which belong to 33 families and 54 genera.Among them,the most important species based on Important value and Frequencies for trees were Cedrus deodara,Magnolia liliiflora,Ginkgo biloba and for shrubs were Amygdalus triloba,Punica granatum,Lonicera maackii.The average density of urban forests in the hospital was 55 plants per hectare,and 2.23 m2/hm2.The average diameter at breast height(DBH),crown width and tree height were 17.69cm,4.65m,and 6.60m,respectively.The overall size of the tree species is small.