上海市区主要行道树粗根的空间分布特征及其与立地环境的关系

Spatial Distribution Characteristics of Thick Roots and Their Relationship with Site Environment of Main Street Trees in Shanghai

【目的】研究城市行道树根系分布和立地环境的关系,为城市道路绿地植物群落配置提供依据。【方法】选取上海中心城区21条道路绿地,采用树木根系雷达仪对香樟(Cinnamomum camphora)、悬铃木(Platanus acerifolia)、榉树(Zelkova serrata)、银杏(Ginkgo biloba)、广玉兰(Magnolia grandiflora)、女贞(Ligustrum lucidum)和栾树(Koelreuteria bipinnata)等7种主要树种直径2 cm及以上的粗根系分布及根型进行研究。【结果】7种行道树根型可分为4种类型:栾树为垂直与水平型,香樟和悬铃木为横走型,广玉兰、女贞和榉树为直角型,银杏为垂直型。在垂直方向上,香樟、悬铃木、银杏、女贞和栾树的根系密度占比随土壤深度的增加而减少,榉树和广玉兰的根系密度占比随土壤深度的增加而先增加后减少;水平方向上,所有树种的根系密度占比均随着与根基距离的增加而减少,根系集中分布在距离根基1 m处。针对乔—乔配置,硬质覆盖立地条件下的根系密度在水平方向上随着与根基距离的增加而减少,在垂直方向上随着土壤深度的增加而减少;针对乔—灌—草配置,地被覆盖下的根系密度在水平方向上随着与根基距离的增加而减少,在垂直方向上随着扫描深度的增加而先增加后减少。【结论】城市道路的立地条件对行道树的根系分布及根型影响较大。

[Purpose]To study the relationship between the distribution of urban street tree roots and site environment,providing a basis for the allocation of plant community in urban road green space.[Methods]A total of 21 road green spaces in central areas of Shanghai were selected,tree radar(Tree Radar Unit)was used to detect the distribution and type of thick root(diameter≥2 cm)of seven main street trees:Cinnamomum camphora,Platanus acerifolia,Zelkova serrata,Ginkgo biloba,Magnolia grandiflora,Ligustrum lucidum and Koelreuteria bipinnata.[Results]The root types of the seven street trees were divided into four types:root of K.bipinnata was vertical and horizontal type,root of C.camphora and P.acerifolia were parallel and horizontal type,root of M.grandiflora,L.lucidum and Z.serrata were right angle type,and root of G.biloba was vertical type.In the vertical direction,the proportion of root density of C.camphora,P.acerifolia,G.biloba,L.lucidum and K.bipinnata decreased with the increase of soil depth,while the proportion of root density of Z.serrata and M.grandiflora increased first and then decreased with the increase of soil depth;in the horizontal direction,the proportion of root density of all street trees decreased with the increase of the distance from the trunk,and the street tree’s roots were concentrated at one meter away from the trunk.For arbor-arbor community composition,trees under the tree configuration and hard floor cover,root density in horizontal direction decreased with the increase of the distance away from the trunk,in vertical direction,the root density decreased with the increase of soil depth.For arbor-shrubs-herbs community composition,the root density in horizontal direction decreased with the increase of distance away from the trunk,but in the vertical direction,the root density first increased and then decreased with the increase of scanning soil depth.[Conclusion]The root distribution and root type of street trees are greatly influenced by the site environment of urban roads.