LCQ4: Tree management work

     Following is a question by the Hon Chau Siu-chung and a written reply by the Secretary for Development, Ms Bernadette Linn, in the Legislative Council today (November 16):


     Regarding tree management work, will the Government inform this Council:

(1) of the number of tree failure incidents involving trees maintained by the Government since 2019, and set out in respect of each incident the following information:

(i) the cause of the tree failure;
(ii) whether casualties, traffic disruption and damages to vehicles or facilities were caused;
(iii) whether tree tilt sensors had been installed on the tree concerned; and
(iv) the government department responsible for maintaining the tree concerned;

(2) of the following information in respect of each tree management department of the Government in each District Council district at present:

(i) the number of trees managed;
(ii) the staffing establishment for tree maintenance work (including the number of government employees and such employees' respective category of profession (e.g. landscape architect and certified arborist), and among the personnel concerned, the number of those with professional qualifications in arboriculture); and
(iii) the number of tree maintenance personnel employed by outsourced service contractors and such personnel's respective category of profession (e.g. tree risk assessor, tree work supervisor, tree climber and chainsaw operator);

(3) of the number of relevant training courses provided by tree management departments of the Government for tree management personnel since 2019, and set out in respect of each course the nature of training, course date and number of participants; and

(4) of the latest progress made by the Government in enacting legislation on tree management, and whether there is a legislative timetable; if so, of the details; if not, the reasons for that?



     The Government is committed to the proper management of tree to ensure healthy tree growth and at the same time emphasises the importance of public safety. In respect of the questions raised by the Hon Chau Siu-chung, the reply is as follows:

(1)  Before the onset of the wet season every year, the tree management departments (the departments) conduct tree risk assessment in areas with high pedestrian and vehicular flow according to the "Guidelines for Tree Risk Assessment and Management Arrangement" (the Guidelines) issued by the Tree Management Office (TMO) of the Development Bureau (DEVB). The Departments will take appropriate mitigation measures according to the results of the tree assessment, including crown pruning and removal of dead branches. If the tree with risks of failure is identified, the departments will remove it as soon as possible to ensure public safety.

     Proper tree maintenance and systematic tree risk assessment are effective to reduce the risk of tree failure and safeguard public safety. Like other living organisms, trees will go through stages of a life cycle, including growth, aging, sickness and death. Numerous internal physiological and external environmental factors may interact and affect tree health and stability. Unforeseeable variables inevitably exist. Common causes of tree failure include inclement weather, poor tree health and structural conditions, aging, and pests and diseases.

     According to the record, the reports of damage and casualty caused by tree failure from 2019 to 2022 (as at October 31) are set out below:
  2019 2020 2021 2022
(as at October 31)
Number of individual tree failures (Note 1) 244 358 295 204
Number of incidents caused by tree failures (Note 2)
Casualties 23 16 13 18
Traffic obstruction 35 109 92 26
Damage to vehicles, properties or other facilities 81 137 127 87
Note 1: Excluding the number of tree failures after the issue of Tropical Cyclone Warning Signal No.8 or above. Tree failures include broken branches or tree collapse. Departments involved include the Architectural Services Department, the Highways Department, the Housing Department, the Lands Department and the Leisure and Cultural Services Department, etc.
Note 2: An individual tree failure may result in more than one incident.

     The TMO has launched a three-year pilot study since August 2021 in which smart sensors had been installed in about 8 000 trees. The study targets to assess the stability and reliability of the smart sensors in monitoring tree movement. According to the record, none of the trees mentioned in the above tree failure reports has been installed with a smart sensor.

(2) Trees on government land and within government facilities are managed by the respective tree management departments through in-house teams, outsourced contracts or both. As at end of 2021, the number of trees maintained by the nine core tree management departments and their number of tree management personnel (including Certified Arborist, Certified Arborist Municipal Specialist and Tree Risk Assessment Qualification of the International Society of Arboriculture; Professional Tree Inspection by Lantra Awards; Technician of the Arboriculture Association or equivalent) are as follows:
Core tree management department Number of trees
(Note 1)
Number of tree management personnel (Note 2)
Agriculture, Fisheries and Conservation Department 31 500 (Note 3) 87 (87)
Architectural Services Department 145 600 5 (3)
Civil Engineering and Development Department 8 900 10 (10)
Drainage Services Department 14 600 9 (3)
Highways Department 585 000 58 (49)
Housing Department 88 000 63 (58)
Lands Department N/A (Note 4) 41 (7)
Leisure and Cultural Services Department 558 600 263 (263)
Water Supplies Department 145 700 17 (3)
Note 1: Rounded to the nearest 100.
Note 2: The figures in brackets represent the number of tree management personnel of the Government with professional qualifications or equivalent in arboriculture, but excluding contractors' staff.
Note 3: The Agriculture, Fisheries and Conservation Department manages all the trees in country parks. The figures include only the number of trees in frequently used areas and facilities.
Note 4: The Lands Department is responsible for the non-routine maintenance of trees on unallocated and unleased government land that are not maintained by any designated government departments. Due to their large number, trees on such land cannot be counted. The Lands Department will follow up on referrals and complaints when they arise.

     Each department manages trees in a different division of regions according to its operational needs. Therefore, the number of trees, the staffing establishment and the number of tree maintenance teams of each department cannot be listed according to the 18 District Council districts.

     The DEVB launched the Registration Scheme for Tree Management Personnel (the Scheme) on December 1, 2020 and encourages five types of in-service arboriculture practitioners, namely arborists, tree risk assessors, tree work supervisors, tree climbers and chainsaw operators, to register. The DEVB also encouraged the government departments to specify in their contracts for new projects and maintenance work the requirements to employ tree management personnel registered under the Scheme to undertake tree-related works with tender invitations to be issued on or after December 1, 2021. The outsourced contractors shall follow the contract specifications to arrange eligible personnel to assist relevant departments in implementing tree care or risk mitigation works. As the number of staff and their professional category will be adjusted according to the work nature, no fixed number of staff in general is required. 

(3) The DEVB has been actively arranging on-the-job training in arboriculture for the management and frontline staff of the government tree management departments. The training includes sponsoring the study of academic programmes and attainment of professional qualifications, and arranging training courses, seminars or technical conferences to ensure that the relevant staff possesses adequate professional and vocational skills for discharging various duties in tree management and care in a proper manner and enhancing their academic levels and professional qualifications, with a view to building up the tree management competency of tree management departments. The TMO sponsors tree management and maintenance staff to attend tree management courses organised by local or overseas education and training institutions, including the preparatory courses for certified arborist organised by the International Society of Arboriculture in the United States, the professional tree inspection certificate course accredited by Lantra Awards in the United Kingdom, etc. As for vocational skills training, the TMO arranges a number of training courses, seminars or technical conferences for the frontline and the management staff of departments. The key areas include:

(1) arboriculture and horticulture project administration and management;
(2) occupational safety and health for the arboriculture and horticulture industry ;
(3) plant selection, cultivation and propagation;
(4) planting, caring and management of plants;
(5) diagnosis and treatment of pests and diseases; and
(6) survey, inspection and risk assessment.

     The numbers of programmes and participants attending the training programmes organised by the DEVB from 2019 to 2022 (as at October 31) are set out below:
Year Number of Programme Number of Participants
2019 73 5 579
2020 51 2 989 (Note 1)
2021 74 5 174
2022 (as at October 31) 60 4 542
Note 1: Due to the COVID-19 pandemic, a number of training courses originally planned for 2020 were cancelled.

(4) To whether there should be a tree ordinance, the DEVB has conducted an in-depth study and learned that many other cities (such as Melbourne, London and New York) are adopting a similar approach as Hong Kong, i.e. tree management is carried out through a combination of some ordinances that support tree protection (in the case of Hong Kong, the related ordinances included Forests and Countryside Ordinance (Cap. 96), Country Parks Ordinance (Cap. 208), Public Health and Municipal Services Ordinance (Cap. 132), etc.), strategies and administrative measures and without specific tree legislation pinpointing on tree management. The Government has no plan to enact tree legislation at this stage but will focus on the actual operation of tree management and enhance its effectiveness.

     As a result, the DEVB has set up a Task Force chaired by the Permanent Secretary for Development (Works) in September this year to review the existing tree management arrangement, including the review of the Guidelines, methods of tree inspection (including the application of technology and instruments), tree species planted by the roadside, aboveground and underground growth spaces for trees, soil quality management requirements, etc. The Task Force will also monitor the work and implementation by the departments after tree inspections, and consider whether the relatively large trees along the existing roads are compatible with the current environment and explore the direction of treatment, and will aim at putting forward appropriate enhancement and improvement suggestions on the abovementioned issues by the end of this year.
Ends/Wednesday, November 16, 2022
Issued at HKT 15:20