What is a significant tree?
A significant tree is a woody plant, that is at least four (4) metres tall and meets one of the following criteria:
- For a single-trunk species, a trunk circumference of at least 500mm at a height of one (1) metre above ground level
- For a multi-trunk species, a trunk circumference of at least 250mm on two or more stems, at a height of one (1) metre above ground level.
Generally, The City will not accept palm or cactus species as significant trees for retention (or new advanced trees for installation).
How do I protect retained significant trees during construction of my development?
Trees which you have chosen to retain on your land, and trees on the adjacent verge, must be protected from accidental or wilful damage during demolition and construction.
A tree protection zone (TPZ) must be established around each tree. As a minimum, this should be 2.4m by 2.4m around the tree trunk.
Storage, excavation, vehicle and machinery parking, waste dumping, and any other activities harmful to the tree are prohibited within the tree protection zone.
The TPZ should be fenced, typically with four panels of temporary construction fencing (each 2.4m wide by 1.8m high). Footings and bracing to the fencing should be located above ground.
In some cases, the developer may have to submit a management plan that outlines how the tree will be retained and protected.
I have a significant tree on my property that I would like to retain, although I am worried it may pose a risk to my development. What are my options?
Retaining a significant tree and integrating it into your development can provide an excellent outcome for both the future occupants and the neighbourhood. With some early planning, a new property can be designed and constructed around a significant tree in such a way that it will not pose any substantial risk to the development, or damage to the tree.
If you are concerned about the risk that a significant tree may pose, we recommend that you engage a professional arborist (not a tree lopper) to make a quantified tree risk assessment (QTRA).
Before engaging an arborist, make sure that they are suitably qualified and hold a degree or diploma in arboriculture and certification with the International Society of Arboriculture. Tree loppers are not arborists and will not provide you with the expertise you need for your development.
The arborist will assess the structure and health of the tree and calculate the risk of damage from falling limbs. They should provide a report which includes a risk assessment and actions you can take to minimise risk of damage to both the tree and property. This will help developers and homeowners to balance safety with the benefit of tree retention.
In most cases, the cost of a QTRA will be less than the cost of tree removal.