A spate of storms and high winds over winter has seen Mahurangi arborists out clearing fallen trees that have posed a threat to life and property.
Tree King managing director Luke Cabrol says nearly all of his company’s fallen tree callouts this year relate to dead trees, and he says prompt action by landowners can prevent serious accidents.
He says a dead tree might appear to be more stable since it has fewer leaves and branches, which are inclined to cause a healthy tree to sway more in high winds.
A dead tree may not sway as much, nevertheless a dead tree generally has rotting or weakened root systems making it even more prone to falling.
Luke says the worst case Tree King dealt with this year concerned a dead tree in Auckland that fell on to a neighbouring property. It narrowly missed the neighbour’s house, but fell on to his garage and crushed three cars.
To make matters worse, the neighbour had issued several warnings to the landowner that the tree needed to be removed safely.
“The longer you leave your dead trees, the more dangerous they become and the more costly they are to deal with,” Luke says.
He says as soon as a landowner sees a tree in decline, they should contact a qualified arborist. Very often through techniques such as pruning and mulching, a tree might be able to be saved. If saving the tree is not possible, he recommends that all dead or dying trees be removed within a year of the first signs of decline.
Luke says high rainfall and high winds are the most common causes of a tree unexpectedly falling. High winds cause constant moving back and forth, which weakens the roots until one day they break.
“It may take years of this movement before the tree fails, but there is no way to judge this until it is too late,” he says.
Meanwhile, excessive rain weakens the base that the roots are attached to, making a tree less stable.
Luke says trees often die due to the fact that their root systems are unable to extract sufficient nutrients from the soil. This can be due to prolonged drought or excessive drainage, meaning roots cannot extract sufficient water from the soil. Conversely, too much rain can saturate roots, making them unable to secure necessary oxygen.
Another problem is compacted soil, which does not allow roots to extract vital minerals.
He says if it is done early enough, loosening up the soil around the base of a tree and putting in a layer of mulch can rescue a dying tree. The mulch will help release nutrients into the soil and help keep the soil moist.