基于街景测量的南昌市行道树结构特征与健康状况研究

Abstract

行道树作为城市绿地系统的网络和骨架, 在城市居民生活中发挥着无可替代的作用。快速准确的掌握城市行道树的结构特征和健康状况, 有利于城市森林建设与管理, 进而提升其生态服务功能。基于百度街景平台, 通过街景测树法对南昌市的963个样方, 共计26727株行道树展开调查。测量内容包括行道树大小指标(树高、胸径、冠下高和冠幅)、健康状况(支架比例、枯稍比例、叶色不健康比例和死亡比例)和植被垂直结构配置情况; 并且探究了不同行政区和不同城市化强度(环城道路发展下的城乡梯度)下行道树的空间分布特征。结果表明: (1)南昌市行道树小树比例较高: 胸径在10-20 cm的占65%, 冠下高在1.5-2.5 m间的占76%, 树高在4-8 m间的占71%, 冠幅在2-6 m间的占76%;行道树生长整体表现为健康, 各指标所占比例较小, 但是叶片健康较差; 35%的样地无叶色不健康, 77%的样地无支架, 76%的样地无枯梢, 93%的样地无死亡; 植被垂直结构配置状况良好, 以乔-灌-草复合结构为主(比重为75%); (2)在空间分布上, 不同行政区行道树大小指标和垂直结构配置上差异显著、健康状况(支架比例和叶色不健康比例)均表现显著性差异(P < 0.05);不同环路行道树大小指标存在显著差异, 表现为1环>2环>3环, 垂直结构从内环到外环更为复杂, 配置等级为1环 < 2环 < 3环, 不同环路行道树健康状况(支架比例和叶色不健康比例)表现显著性差异(P < 0.05)。综上所述, 南昌市行道树整体健康状况良好, 行道树个体较小, 而且以复层结构为主, 本研究基于百度街景对南昌市行道树结构特征和健康状况进行比较全面的评价, 为南昌市今后城市行道树的规划和管理提供了基础数据支持。;As the network and skeleton of urban green space system, roadside trees play an irreplaceable role in urban residents' life. Rapid and accurate grasp of the structural characteristics and health status of urban roadside trees is conducive to the construction and management of urban forest, thus improving its ecological service function. Based on the Baidu Street View platform, this study investigated 963 quadrats, a total of 26, 727 roadside trees, in Nanchang by street view tree measurement method. Measures included indicators of street tree sizes (diameter at breast height (DBH), underbranch height (UBH), tree height (TH) and canopy size (CS)), health status (the proportion of Tripod-supporting, the proportion of Dieback, the proportion of Non-greenness leaf color and the proportion of Death trees), and vertical structure configuration of vegetation. Moreover, the spatial distribution characteristics of road trees under different administrative regions and different urbanization intensities (urban and rural gradient under the development of ring roads) were explored. The results showed that: (1) there was a high proportion of small trees in Nanchang: DBH of 10─20 cm accounted for 65%, UBH of 1.5─2.5 m accounted for 76%, TH of 4─8 m accounted for 71%, CS of 2─6 m accounted for 76%. The overall performance of the growth of street trees was healthy, the proportion of each index was small, but the leaf health was poor. In 35% of the plots, no leaf color was unhealthy, 77% of the plots had no Tripod-supporting, 76% of the plots had no Dieback and 93% of the plots had no death. The vertical structure of vegetation was in good condition, mainly composed of arbor-shrub-herb (75% of the sample land). (2) In terms of spatial distribution, there are significant differences in the sizes index and vertical structure configuration of road trees in different administrative areas, and significant differences in health status (proportion of Tripod-supporting and proportion of Non-greenness leaf color) (P < 0.05). There were urban-rural differences in the size index of road trees in different ring-road areas, which are manifested as 1^st ring > 2^nd ring > 3^rd ring, the vertical structure of the outer ring is more complex, configuration grade is 1^st ring < 2^nd ring < 3^rd ring. There were significant differences in the health status of different ring-road (proportion of Tripod-supporting and proportion of Non-greenness leaf color) (P < 0.05). To sum up, the overall health status of the roadside trees in Nanchang is good, the individual of the roadside trees is small, and they are mainly composed of multiple layers. Based on the Baidu Street View, this study makes a relatively comprehensive evaluation of the structural characteristics and health status of the roadside trees in Nanchang, which provides basic data support for the planning and management of the urban roadside trees in Nanchang in the future.