#Trees
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[LCSDPlusss] The "Magic-hand" in the urban greening
This story is only available in Chinese. For more information on the subject, please visit the Leisure and Cultural Services Department Facebook Page.
There is a large number of trees in the territory. Different tree species can be seen along roadsides and in parks. For trees to grow healthily, apart from the comprehensive risk assessment and regular maintenance of trees carried out by tree management departments, the co-operation of the public is also very important. The Development Bureau (DEVB) is now launching a scheme of tree labels with QR codes, hoping to raise public awareness of trees and their maintenance so that Hong Kong people can work together to reduce the risk of tree failure. Currently, about 1.7 million trees in Hong Kong are under the regular maintenance of the Government and amongst them, about one million are in areas of high pedestrian and vehicular traffic flow. In view of the wide distribution of trees in the territory, the Government adopts an “integrated approach” for tree management, under which departments are responsible for managing the trees in the facilities and land within their purview, so that appropriate routine tree maintenance can be carried out having regard to the characteristics and locations of different trees. On the other hand, trees located on private land are under the care of respective private lot and property owners.Facilitating the public to report problematic treesThe DEVB has been actively exploring ways to apply smart technologies in tree management to enhance its efficiency and effectiveness. Displaying tree labels with QR codes is one of the new initiatives. Tree Management Officer, Ms Chan Yuen-man, Paula, of the DEVB says that through the use of QR codes, the scheme brings convenience both to the public in reporting problematic trees and to the DEVB in providing more tree knowledge, such as tree species, whether the species are indigenous or foreign, tree characteristics and other fun facts. The work to display QR-coded labels has commenced and will be completed in phases. The DEVB expects to first display QR-coded labels on about 200 000 trees along roadsides in early 2022. Tree labels placed at pedestrians’ eye levelsMr Chan Yuen-king, Paul, Landscape Architect of the consulting company implementing the scheme, tells us that tree labels with QR codes will be hung on trees at the eye level of pedestrians. Tree labels carry basic tree information including Chinese, English and botanical names. The labels mainly have two functions. Firstly, in case a problematic tree is found, the public can report to the authorities by, for example, calling 1823. As each tree has a unique number printed on its label, the public can tell the accurate location of a tree. Secondly, the public may scan the QR code on the tree label with a mobile phone to enter the website of the tree management authority for more tree information. Covering locations with higher pedestrian flowMr Paul Chan says that the scheme of tree labels with QR codes covers the whole territory, involving trees at locations with higher pedestrian flow, such as major transport nodes which include areas outside MTR stations and ferry terminals. About 10 000 tree labels for around 100 tree species will be produced for distribution to various districts across Hong Kong in the first phase of the scheme. He says that as Hong Kong is a dense and compact city where people and trees are closely related, he hopes that the scheme will raise public concern about trees. Tree information being scientific and interestingCurator of Shiu-Ying Hu Herbarium of the Chinese University of Hong Kong, Dr Lau Tai-wai, David, who is responsible for collecting and compiling tree information, says that he is excited that the herbarium can take part in the scheme. With the dedication of his colleagues to collecting information, the tree information thus compiled is both scientific and interesting. Quoting an example, he says that there is a tree species called Autumn Maple in Hong Kong. It is an indigenous species of ecological significance under the family of Euphorbiaceae. One Autumn Maple growing in Lai Chi Wo of Sha Tau Kok has a history of more than 100 years and is registered as an Old and Valuable Tree. The most interesting information is that the fruits of Autumn Maple can be used for brewing wine while leaves can be used as a spice for preparing a dish called “Jia Dong Ji (Autumn Maple Chicken)”. Harmonious co-existence of the community and treesDr David Lau says that the public can simply scan the QR codes on the tree labels for more detailed information to understand tree species from various perspectives. He hopes that the scheme will inspire the public to respect and cherish trees more to achieve harmonious co-existence of the community and trees, which is also the aim of his team in compiling tree information. Trees are integral parts of our outdoor environment. They provide amenity areas, moderate temperature, improve air quality and enhance biodiversity. It is hoped that, through the scheme of tree labels with QR codes, the message of tree care can be integrated into the daily life of the public and a positive attitude towards tree care will be fostered, so that our trees can grow more vigorously and healthily and Hong Kong will continue to be a safe, livable and sustainable city. (The video is in Cantonese) (The video is provided by Development Bureau)
Smart sensing technology to monitor tree stability
Every year before the onset of wet season, tree management departments will complete Tree Risk Assessments (TRAs) and implement appropriate risk mitigation measures to protect tree health and public safety. In recent years, the Government has launched several pilot schemes to explore the use of technology in tree management to enhance its quality and efficiency. Here we invited a colleague of the Greening, Landscape and Tree Management Section (GLTMS) of the Development Bureau (DEVB) to talk about tree inspections before wet season. We also invited Dr WONG Man-sing, Charles, Associate Professor of the Department of Land Surveying and Geo-Informatics of the Hong Kong Polytechnic University (PolyU), to introduce how to apply smart sensing technology to monitor tree stability.Risk assessments before wet seasonAccording to the “Guidelines on Tree Risk Assessment and Management Arrangement”, every year before the onset of wet season, tree management departments are required to complete TRAs in areas with high pedestrian and traffic flow professionally and systematically and implement appropriate risk mitigation measures based on the assessment results, such as crown pruning and installation of support systems. Dangerous trees with untreatable problems need to be removed as soon as possible to safeguard public safety. Mr TSANG Kwok-on, the GLTMS’s Tree Management Officer, said that tree inspection personnel mainly perform ground inspection to examine and assess various parts of a tree, including the crown, leaves, branches, trunk, roots and the surrounding environment of the tree, etc. Inspection personnel would also employ tools to aid their work, for example, using a plastic mallet to tap the trunk to assess its structural condition and using binoculars to observe the growing conditions of the higher branches and leaves. If necessary, inspection personnel would climb up the tree to inspect the hidden parts from different angles. If decay or other structural problems are found or suspected, they would use a resistograph or sonic tomograph (pictured) to examine the internal structural condition of the tree. Applying smart sensing technology in tree managementUnder adverse weather such as rainstorm or typhoon, it is inevitable that trees would suffer different degrees of damage. A research team formed by DEVB, the PolyU and other tertiary institutions is conducting a 3-year Jockey Club Smart City Tree Management Project to monitor tree stability on a large scale through smart sensing technology and Geographic Information System. The research team will assess the risk of tree failure by monitoring trees’ swaying or tilting condition, thereby strengthening tree risk management.Dr WONG Man-sing, Charles, Associate Professor of the Department of Land Surveying and Geo-Informatics of the PolyU, said that the sensors are installed at the lower trunks of the trees to assess the trees’ tilting angles and directions, and the data would then be sent to the university’s data centre via network transmission for big data analytics. If it is shown that the tilting angle of the lower trunk of the tree exceeds the threshold, the system would immediately send an alert to the designated parties to undertake timely and appropriate risk mitigation measures. Large-scale monitoring of tree stabilityDr WONG said that the Smart Sensing Technology pilot scheme started in February in 2019. An initial trial was conducted in Tai Tong, Yuen Long, to set reference for the design of sensors and monitoring system. Upon fine tuning the system, the research team has installed the second batch of sensors in Wan Chai and Kowloon East districts to test the network transmission performance in urban areas. The whole pilot scheme involves the installation of a total of 8 000 sensors on selected urban trees and all stonewall trees across Hong Kong Island and Kowloon, which will be completed in phases between the end of 2019 and early 2020. The trees are mainly located in areas with high pedestrian and traffic flow such as pavements, slopes and parks.Trees are very much intertwined with our daily lives. In an urbanised city like Hong Kong, trees let us have a green living environment. While we make our best endeavours to manage tree risks, we also need private property owners and property management companies to conduct proper tree care within their properties. (The video is broadcasted in Cantonese) (The video is provided by Development Bureau)