Don’t fear big trees after fall – arborist
Assessing whether a tree is healthy or about to topple in spectacular fashion is ‘‘more an art than a science’’, an expert says.
The consequences of such a fall were shown on Monday when a massive oak tree came down on commuter traffic in Hamilton.
Within a car length of their lives, some motorists who were in the queue of traffic when the tree fell had wondered in the past about the integrity of the trees lining River Rd.
Tom Chang, whose Tesla Model 3’s dash-cam captured footage of the tree coming down, said: ‘‘I always think about those huge trees. Nothing has been done about them.’’
Hamilton City Council checked the downed tree on August 18. It was one of the, on average, 13 trees the council checks daily. Since May 2, city arborists have checked some 2687 street trees.
The trees – ranging in species, size and location – undergo a thorough ‘‘visual check’’ by the council’s team of qualified arborists.
‘‘Our routine tree inspections are done visually by qualified arborists. They are generally looking at multiple aspects of a tree to assess its health and identify any potential risks and issues,’’ the council’s parks and recreation manager, Maria Barrie, said.
Fungal brackets, root decay and obvious rot were clear signs a tree required maintenance or felling, Chris Corfe, the managing director of Hamilton arborist company Marc Doyle Treework, said.
‘‘The council are looking for those things all the time,’’ he said.
Corfe said that while there were some tell-tale signs a tree was unwell, assessing a tree was ‘‘more an art than a science.’’
The council’s well-regarded tree maintenance staff had a ‘‘mammoth task’’ assessing trees and were not helped by soil types in some parts of the city, Corfe said.
‘‘If the subsoil, what’s underneath the topsoil, is clay that’s quite strong. If it’s rock the roots might be well in the rock. Lots of places in Hamilton down by the river have sandy soil. Trees fall over in it because they’re just sitting on sand, it’s just so loose.’’
The tree that came down on Monday was located by the river.
A tree’s root structure, Corfe said, extended only about half a metre below the ground.
He said trees posed the most risk after wet and windy weather and he had some tips for those who owned, or lived near, large, established trees.
‘‘My advice has always been, if you have got big trees just have someone look over them as often as you can . . . do it every few years. After a storm always go and have another look: look up, has anything changed? Has anything broken? Has anything come down?’’
After sustained, heavy rainfall the leaves of a deciduous tree could triple in weight, he said.
But Corfe had some reassurance for those with lofty canopies looming above them.
‘‘Don’t be scared of big trees. There’s no need to be scared of big trees. If you look at the injuries caused by big trees – it’s minuscule.’’