Due to the increasing number of new development and building renovation projects in Hong Kong, trees are inevitably being affected. Trees play an important role in our living environment. Preserving the right trees and protecting them from damages is important. Not only it can maintain our greenery, but it can also minimize subsequent repairing costs or removal costs for damaged trees. Therefore, careful consideration of tree preservation starting from the planning stage to the end of development projects is essential. The development projects could then achieve their goals together with minimum impact on the retained trees.

Not all trees are deserved to be retained. In order to balance between effective land use, resource utilization and conservation, normally only valuable trees are preserved. Unless the tree is high in ecological value or it is a species of special conservation status, several factors are assessed at the same time to determine a tree is retain or fell, e.g. health condition, structural conditions, tree form, survivorship during the construction, the extent of conflicts to the construction activities. Most of the trees recover slowly from construction injuries. There are very few remedial treatments for tree damage too. During tree preservation and protection, the major principle, therefore, is to avoid tree injury and damage.

When the tree preservation and protection were conducted, the following should be considered.

• Setting up the Tree Protection Zone
  • Tree protection zone is the minimum area around a tree deemed to contain sufficient roots and rooting volume to maintain the tree’s viability. Within this zone, there shall not be direct interference of construction activities and free from all machinery. In addition, protection of the roots and soil structure is treated to be a top priority. The size of the tree protection zone normally determined by the “Dripline method”, “Tree height method” or “Trunk diameter method”.
  • The “Dripline method” is commonly adopted in Hong Kong. However, for narrow canopied trees, the “Tree height method” would be appropriate. The Trunk diameter” method would be suitable for trees that are leaning or of irregular conformation.
  • On Tree protective measures and design, factors such as site conditions, technical issues and cost-effectiveness, etc. should be considered. The advice from the tree professionals has to be sought.

• Building tree protection fences
  • Tree protection zone must be surrounded by appropriate fences based on the conditions of the construction site. The propose is to withstand impacts from construction activities including the entrance of vehicles, machinery, trampling by workers and soil contamination by chemicals.

• Establishing tree preservation and protection plan
  • Tree preservation and protection plan should be prepared to provide clear information, including the marked area of tree protection zone, tree location, tree size and conditions of tree, and the type of protective fence.
  • Tree preservation zone should be shown on a layout plan showing the spatial relationships between trees and the construction. Besides, the type of tree protection or other measures to protect tree roots from compaction should also be indicated.

Successful tree preservation requires the commitment and involvement of all parties throughout the project. Members of the project team should be familiar with the rudimentary aspects of tree growth and development. They should try to arrange better construction procedures to help the trees from surviving in the project site. Tree specialists/arborists should be involved earlier to give professional opinions on tree surveys, tree assessment, preservation measures and on-site monitoring, etc. 

Tree preservation service from Tak Tai,

• Making assessment and monitoring by experienced landscaping specialist, qualified arborist and registered safety officer.
• Giving professional advices and formulating tree preservation solutions based on customer requests and the actual situation.
• Coping with the construction programme, monitoring tree health and proactively advising improvement works.
• Providing a one-stop service including tree risk assessment, planning and executing tree preservation works.