关键词: 百度街景, 城市森林, 行道树, 10/20/30经验法则

Abstract: Clarifying the composition of the urban forest tree is the base of urban forest construction and management.Previous studies were mostly located in a singlecity or region, and it was difficult to reveal its general rule.We selected China's 35 majorcities, with a total of 88 632 plots by using Baidu Street View(BSV).These cities were divided into Northern, Southern, Qinghai-Tibet and Northwestern cities, according to their geographical region location. We compared the differences in street tree composition between cities and between regions. Results showed that:①There were 99street trees commonly used in the 35 cities based on the street BSV survey.The most common tree species were Populus spp., Salix spp., Cinnamomum camphora, Cedrus deodara and Sophora japonica. ②Most of the street trees in Southern cities are broad-leaved trees e.g.,Cinnamomum camphora, while in Northern and Northwestern cities, Populus spp., Salix spp. and S.japonicawere dominant, and in the Qinghai-Tibet area, Populus spp. and conifer were dominant. ③Only Kunming and Guilin street species configuration were reasonable at species levelaccording tothe 10/20/30 "rule of thumb". In particular, the relative abundance of Populus spp. was as high as 61.2%, in Karamay. The proportion of Cinnamomum camphora trees exceeds 50% of the total number of tree species in Changsha and Hangzhou.The primary reason was that single-species occupy absolute predominance which made the relative abundance ratio of other tree species less or even no. In the four areas,street tree configuration was unreasonable at the species level. To solve this problem, we should reduce the use of Populus spp., Salix spp., Cedrus deodara, S.japonica in the North, and other trees suitable for native growth should be added in Northwest, Qinghai-Tibet, and Southern. Our study provides important parameters for the nationalplanning of urban forest, scientific evaluation and construction, systematic comparison of multiple cities, support of urban forest management and comprehensive improvement of ecological service functions.

Key words: Baidu Street View, urban forest, street tree, 10/20/30 “rule of thumb”