Hong Kong has an enormous number of trees, with over 16 million trees planted by various government departments in the past decade alone. In this crowded city, trees enhance our quality of life by improving air quality, lowering the temperature and beautifying our landscape. These precious natural assets are treasured and valued by all of us. However, just like all other living organisms, trees are subject to the laws of nature and go through the natural life cycle of birth, ageing, illness and death.
Tree management is professional work and a specialised field of knowledge that requires continuous learning. Therefore, in addition to setting well-defined policy objectives for tree management, we also strive to enhance professional knowledge and standards of arboriculture of all those involved, so that trees can grow healthily and robustly and we can live happily in a green environment.
Over the years, we have been promoting greening in a holistic approach, from developing excellent landscape designs and choosing suitable species for planting in early stages, to caring for plants in a professional manner and monitoring the growth of trees regularly in later stages. Public safety, of course, is always our prime consideration.
To achieve the above policy objectives, we have to improve the professional knowledge and standards of tree management in the relevant departments, solicit tree experts’ views and engage the community in our work.
Scientific research is vital to enhancing professional tree management. Let’s take the identification of Phellinus noxius as an example. When suspected cases of the disease in local trees were reported in 2007, the department concerned had to send samples overseas for identification as there were no scientific research institutions to carry out diagnosis in Hong Kong. Now, thanks to years of efforts and the wealth of experience accumulated, the identification and diagnosis of Phellinus noxius have become quite mature in Hong Kong, a development which is crucial to the prevention of brown root rot disease.
To enhance the professional knowledge and standards of tree work, the Tree Management Office (TMO) of the Development Bureau has been conducting scientific researches on trees and exchanging views with overseas experts. In addition, we have commissioned universities and consultants to research tree management topics that lack relevant information or need further studies. Here are a few examples of the topics under research:
(1) Wood strength assessment for common tree species in Hong Kong: Each tree has its unique biomechanical structure, and wood strength varies among different tree species. To better understand the wood strength parameters of the common tree species in Hong Kong, we have commissioned a local university to conduct wood strength assessment for some common trees, so as to establish a database for the reference of the authorities in selecting tree species for planting and in conducting tree risk assessments.
(2) Occurrence and distribution of common wood decay fungi on trees of Hong Kong: At present, there is not much information on wood decay fungi which might affect the structure of local trees. In view of this, we have commissioned a local university to carry out a survey of the types of wood decay fungi found in the territory and to collect baseline data on their distribution, so as to gain a better understanding of the local wood decay fungi and their effects on tree maintenance. We will, based on the research results, develop guidelines on the diagnosis and control of wood decay fungi for the reference of the tree management departments and the industry.
(3) Evaluation of the Trichoderma species as a biological control agent against Phellinus noxius-infected trees in Hong Kong: The fungus which causes brown root rot disease is a kind of highly contagious pathogen, and so far there is no effective cure for the disease. Nevertheless, according to overseas experience and the literature on tree care, the Trichoderma species may be used to control or prevent the infection of Phellinus noxius in trees. We have therefore commissioned a local university to conduct a study on the feasibility of using the Trichoderma species as a control agent against Phellinus noxius.
The TMO will share the results of the above research projects with the tree management departments and the industry to facilitate tree management work and enhance its effectiveness.
Regarding the collection of views from tree experts, I have in an earlier blog post introduced the Expert Panel on Tree Management established in 2011. The Panel is currently composed of a chairman, a secretary, 11 non-official members and three official members. The non-official members come from a number of places such as Australia, the United States, Malaysia, Guangzhou and Macau, and they include a plant pathologist, a microbiologist, experienced tree experts, a professor of forestry, a municipal arborist and utility arborists. They give professional advice to us on a voluntary basis, and the Panel has held 11 meetings and 18 on-site inspections since its establishment.
Each non-official member of the Expert Panel specialises in a particular field and provides valuable advice in many aspects of tree management, such as the management and preservation of old and valuable trees, tree risk assessment and management, occupational safety and health of tree work, monitoring and managing strategies for brown root rot disease, protection of stone wall trees, protection of trees on worksites and management of tree pests and diseases, as well as a number of studies on tree management. In addition, members always share their tree management knowledge and skills in tree thematic talks, so that the industry can better grasp the development of tree management. I would like to take this opportunity to express my gratitude to all Panel members for their great efforts and outstanding contributions to tree management work in Hong Kong over the past two years.
20 October, 2013
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