Abstract
Urban forest ecosystems are being developed to provide various environmental services (e.g., the preservation of urban trees) to urban inhabitants. However, some trees are deteriorated asymptomatically without exhibiting an early sign of tree displacement, which results in a higher vulnerability under dynamic wind loads, especially during typhoon seasons, in the subtropical and tropical regions. As such, it is important to understand the tilt and sway behaviors of trees to cope up with the probability of tree failure and to improve the efficacy of tree management. Tree behaviors under wind loads have been broadly reviewed in the past literature, yet thorough discussions on the measurement methods for tree displacement and its analysis of broadleaf specimens are lacking. To understand the behavioral pattern of both broadleaf and conifer species, this paper presents a detailed review of sway behavior analysis from the perspectives of the aerial parts of the individual tree, including tree stem, canopy, and trunk, alongside a highlighted focus on the root–plate movement amid the soil-root system. The analytical approaches associated with the time-space domain and the time-frequency domain are being introduced. In addition to the review of dynamic tree behaviors, an integrated tree monitoring framework based on geographic information systems (GIS) to detect and visualize the extent of tree displacement using smart sensing technology (SST) is introduced. The monitoring system aims to establish an early warning indicator system for monitoring the displacement angles of trees over the territory of Hong Kong’s urban landscape. This pilot study highlights the importance of the monitoring system at an operational scale to be applicable in the urban areas showcasing the practical use of the Internet of Things (IoT) with an in-depth understanding of the wind-load effect toward the urban trees in the tropical and subtropical cities.
Highlights
Urban forests are essential components to the makeup of urban ecosystems to maintain environmental quality and sustainability
The objective of this paper is to provide a comprehensive review of the technologies for the measurement of tree sway, tree tilt, and root–plate movement under wind load, with a special focus on broadleaf trees
This paper reviews a wide range of sources, including journal papers, conference proceedings, books, and online resources between the year 1962 and 2019 through the keywords search in different combinations, i.e., tree sway, tree uprooting, root anchorage, natural frequency, static and dynamic pulling, wind tunnel test, tree architecture and tree– wind interaction relating to tree sway, tree tilt, and root–plate movement
Summary
Urban forests are essential components to the makeup of urban ecosystems to maintain environmental quality and sustainability. Trees reduce atmospheric carbon dioxide concentrations [1], minimize the occurrence of urban hazards (e.g., flooding, drought, and landslides) [2], ensure water security [3], and sustain and enhance biodiversity [4], in which the ecosystem can be balanced and regulated [5]. In urban and peri-urban areas, trees provide the aesthetic value [6] of the inhabited streetscape. Often planted under stressful conditions, urban trees are threatened by multiple factors, e.g., natural disturbances (earthquake, strong wind, typhoon), invasive species, construction damages [7], and negligent management practices [8]. E.g., windstorms, hurricanes, and tropical cyclones may lead to the snap of branches or the crown parts of urban trees, and even resulting in uprooting events. A thorough understanding of wind-tree interactions is of paramount importance to minimize economic losses and damages to human life caused by tree failure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
