THE MECHANICS OF TREE HAZARDS ACCOMPLISHED TREE MANAGEMENT When we do not take care of our cars and send them for regular maintenance checks, the car can easily become a hazard and a danger to us. The same goes for trees in our urban environment. They cohabit with other greenery, with people, with buildings, with other urban infrastructure around them. These trees need care and maintenance for their own health, for aesthetic reasons and most importantly, for safety issues. We have shared about what happens when trees become hazardous and how home or property owners can look out for warning signs. Today we take you with us so you can see what happens on the arborists’ side of tree hazard assessments.
AFTER THE FLOODS Recently, Australia has, unfortunately, had to endure another battering of the elements and the floods have caused great damage in the Mid North Coast, New South Wales. It is not just the properties and infrastructures that have been destroyed. The trees around have also fallen victim to their own destructive forces of nature. Fallen trees, which are still standing but have heavy branches that are left hanging, can become hazardous and they need to undergo hazard assessments and management so they do not cause further damage to the property or infrastructure around them, or cause injury to people near them.
BREAKING DOWN HAZARD ASSESSMENTS Accomplished Tree Management is experienced with the hazards that trees pose and while they may be our passion and we are dedicated to their care, we also recognise they are large, heavy structures that need to be respectfully managed. Usually what happens is that the owner of the property where there is a problem contacts us and explains the nature of the hazard, how the tree looks and how it is “behaving”. As in the case of the recent floods, it is generally a weather-related event that has prompted the property owner to call us. So even before we actually get down to seeing the tree and assessing it, we already have some important information from that call. Accomplished Tree Management breaks down hazard assessments into two categories: •
Non Invasive (Stage 1) and
•
Invasive (Stage 2)
STAGE 1 - INTERPRETING BODY LANGUAGE What happens in Stage 1 assessment is reading the trees. This means observing and picking up any information the tree may give us, understanding the signs the tree is sending out. Trees have their own unique body language (and the beauty of it is each species of tree has its own way of expressing itself) and as arborists we understand what they are trying to say. Are some branches or even the entire tree predisposed to failure and cannot be saved? Any change in their environment can affect trees and they respond with their own signs to show if they are adapting well to the changes or not. So at this first stage of assessment,
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arborists need acute and detailed observations. You can see Stage 1 as a merely visual assessment where we walk around the tree in question looking for any obvious problems e.g. broken parts, dead bits, any large cavity openings etc. We also use this initial screening to identify which trees need more urgent attention in terms of hazard level.
STAGE 2 - BRING OUT THE TOOLS Stage 2 of hazard assessments is an “invasive” one, and it involves having to physically manipulate the tree itself. We always work with care to ensure that it does not cause the tree any long-term harm. As long as we have not passed a final decision that a tree needs to be removed due to its hazard threat, we treat each tree with care and respect and our aim is always to ensure life carries on as best as it can. Depending on what each tree needs, we recommend two different techniques in Stage 2. One technique uses a Resistograph®. This may sound like a rather negative name for a tool, but it really is simply a specialised drill that creates a very discreet hole (approximately 1.5 - 3mm in diameter) in the tree. Think of it like giving the tree a tiny injection. It is essentially a decay detection equipment typically used at the more advanced stage of tree hazard assessments. This tool helps detect any internal decay in trees that cannot be observed from the outside. When the drilling needle passes through the tree, it records the resistance it encounters. So if there is sign of low resistance, this tells us that there is a possibility that a crack or an area of decay is present. This is minimally invasive to the tree and gives arborists useful information which we would otherwise not have access to. The Picus® Sonic Tomograph is another tool for this stage of the assessment. It uses the velocity of sound waves in the wood to detect and calculate the area of decay within a tree. Sensors mounted into the cambium (external) layers are placed radially around the tree and these activate the sound waves. If a tree has any damage or disease (causing fractures, cavities or rot), the sound waves get blocked and
