Tree Risk and Why it's Important to Manage

For all the benefits trees provide, they can also inherently present a level of risk to people and surrounding structures. However, the level of risk and what is considered acceptable are perhaps the most important factors. 

Everything in life that we do comes with an inherent level of risk, from brushing your teeth to base jumping and driving your car. Rarely do we consider the risks of driving but according to the National Safety Council, the chances of dying from a motor vehicle crash is 1 in 103. The risk of dying from a tree is somewhere in the realm of 1 in 10 000 000. The benefits of driving a car are varied and many but the risk is significant. Equally, the benefits of trees are varied and many but the risk they pose is much less. Unfortunately, there is an irrational fear of trees because they are poorly understood which has in the past resulted in a lot being cut down or pruned for no reason.

Why it’s necessary

In New South Wales and most of Australia, landowners and managers have a duty of care to ensure the risk to site patrons and visitors is acceptable. Section 5B(1) of the Civil Liability Act 2002 (NSW) indicates that landowners and managers have a duty of care to take precautions against a risk of harm that is foreseeable and not insignificant. This provision, as well as the common law duty to protect one’s neighbour, results in urban trees being inspected and reported on by arborists. These arborists are completing risk assessment methods to prevent foreseeable personal injury and property damage. 

Identifying Tree Risks

It is the duty of the tree owner to guarantee the safety of those who enter their site or property. By being able to understand and address the possible risks associated with trees, as a tree owner, you can, at a minimum, understand the risk is low and nothing needs to be done. But if necessary; make your property safer and ensure the longevity of the treescape.

Here is a list of things Canopy Consulting’s arborists look for when completing a tree inspection and risk assessment. These are also things the general public can look out for and call an arborist if they have concerns.

  • Large and dead branches
  • Detached or hanging branches
  • Fallen tree branches
  • Loose bark on the trunk
  • Cracks or splits in the trunk or tranches
  • Cavities or rotten wood (decay) within the trunk or branches
  • Presence of mushrooms under the tree
  • Changes in soil level
  • Area altered by construction or installation of pavements
  • Leaves developing in smaller size 
  • Leaves growing unusual yellow color
  • Tree being topped or heavily pruned

Arborist Recommendations

Once the potential tree risks are identified and assessed by the arborist. They then provide a report on the tree’s current condition, factors that may increase or decrease the likelihood of failure (and therefore risk) and give recommendations.

A skilled and experienced arborist will likely suggest the following:

  • Tree Pruning

If the tree’s branches pose a risk to properties, structures, and people that surround it, it is best to have it pruned. Take note that pruning work is best done by a minimum AQF Level 3 arborist as unskilled pruning may weaken the tree.

  • Cable and Brace the Tree

Weak branches and stems that may fall and cause damage may need physical support by cabling and bracing it. But it does not guarantee a failure-free tree if not regularly checked by an arborist or experienced bracing professional.

  • Proper Routine Care

Adult trees, as dictated by its structure and the season, need to have regular care in the form of water and nutrients. 

  • Relocating/Removing the Target at Risk

As much as possible, arborists make it a priority to protect and preserve the trees. In situations wherein the target at risk are moveable objects, such as tables, vehicles, and garden landscapes, removing or transferring the target would be the best option. 

  • Tree Removal

In cases when none of the previous options are possible or feasible, removing the tree may be the best option. 

Managing Tree Hazards

Despite their ability to live for a long time and generally being very strong and, in ideal situations, suited to their environment, trees can be easily damaged and their resistance to natural and man-made hazards is very low. 

Severe weather and construction are two major factors that can cause a lasting and significant impact. As with most things, prevention is better than cure which is why it’s important to consider trees and their growing environment when selecting for planting and also in the case of construction projects.

Tree Damage during Extreme Weather

Excessive rain can cause the soil to soften and loose its cohesive properties. Together with the strong winds that usually accompany heavy rain during storms, trees can be completely uprooted. Lightning strikes can also dry up the water inside the trees, resulting in the tree’s wood to split and bark exploding.

In order to reduce the damage caused by weather, here are steps listed by the International Society of Arboriculture that tree owners can follow.

Before the storm, tree owners should:

  1. Train the trees to improve their form - this is why formative pruning is important when trees are young
  2. Identify the parts of the tree that may have defects
  3. Seek an arborist’s help to recommend ways to manage the tree
  4. Remove dead or defective branches
  5. Correct inappropriate practices done in the past such as topping
  6. Install lightning protection systems especially if trees are tall and on hill tops

After the storm, tree owners should:

  1. Take Safety Precautions. Call the emergency services to clear the area for any hazard
  2. Assess the damage by having an arborist inspect the tree
  3. Not consider doing it yourself

Tree Damage During Construction

Homes, roads, pavements, and commercial buildings are often built near existing trees.

Sadly, the process that it takes to complete the construction can cause serious damage to the tree if not considered during the development process. Proper planning and the presence of a project arborist onsite is needed to ensure the safety of the tree.

Here are the steps that the arborist and the construction and planning team needs to follow:

  1. Planning
  2. Inspection and Assessment
  3. Installing physical barriers to restrict access
  4. Strict Supervision if work is required in exclusion zones
  5. Immediate treatment to damaged trees
  6. Monitoring for Decline and Risk
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Canopy Consulting
Macquarie Park NSW 2113
1300 122 667
(1300 1CANOPY)
info@canopyconsulting.com.au

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