Trees fail due to a number of reasons
In an urban environment new kerbing or driveways chop into the root systems. This practice can cause root decay problems through wounding of the tissues and the strong structural roots that support the trees weaken and start to rot due to infection. This leads to failure over time and then you see large tree failures all over the place under strong climatic events. Many of these root incursions are incremental and don’t seem like much but they add up over time.
Compaction of the soil which prevents the fair exchange of soil air and causes suffocation. The larger the tree the longer it takes to fail. Some trees I have observed receiving this treatment can take up to 2 years to die back and then die and often people don’t understand why they died as they didn’t observe what happened a few years ago. Parking your cars or stockpiling goods and products under trees also affects the root plate (the root zone) of any size tree and over time causes tree failure. Obviously rain cannot penetrate soil root zones that are covered up and allow the tree to grow a well developed root system that provides great anchorage and even growth.
The effects of poor quality pruning events cannot be ignored when discussing tree failure as this is the cause of vast numbers of tree deaths. Cavity formations create water pooling in the heartwood and rot sets in. This is particularly common with Poinciana trees.
Dieback of tree branch stubs are also ideal for the entry point of fungal diseases with the build up of decaying/dead matter or excess moisture the main offenders.
The other big issue is periodic flooding which can cause long term fungus zoospores to grow flare up within the root system. When the flooding recedes the dormant fungal zoospores flare up again when the ideal host conditions are met; usually moist and warm conditions as we see in South east Qld summers. Very large old trees can die for this reason if they are along water courses and there is no obvious reason to the layman or resident of the property.
This leads to another slow death as the trees slowly die back bit by bit. shedding more leaves and branches as time goes by. Dieback is a serious issue and should be assessed by a qualified arborist. There is a cause and effect element to this outcome. Tree failure can affect your property or your neighbours property.Look after your trees and pick trees that will fit the vertical and horizontal spaces available to them when they are fully grown. Plan your panting ; don’t plan to prune.
Species selection is important and there is a range of trees for your area that can survive and enhance. Choose wisely and then sit back and enjoy the pleasures they bring.