Things have changed with regard to pruning in the last 22 years.
In 1984, when I began this Arboreal journey, aggressive pruning was standard practive. Trees were often topped, overthinned, or sidewalled to achieve pruning objectives. AS the science of Arboriculture has matured, so has the philosophy of pruning. This is where I believe Tree Awareness creates the most separation from other tree companies.
As we know "topping" is a horrible practive which results in profound truck and root decay. It also produces rapidly growing, poorly attached limbs, prone to future failure.
Overthinning is bad for a couple of reasons. One, a certain percentage of foliage is supposed to remain in the interior portion of the tree. Secondly, it affects branch taper. Branches get smaller in diameter after each branch union. By stripping the branches and having too much distance between limbs the branches do not taper, become weak and can break under their weight. This condition is called liontailing.
This leaves us with sidewalling. This is when clients want to cut all of the limbs on one side of the tree to clear the overhang of a property line, house, fence, or parking area. This practice is bad because it normally removes too much foliage at once. Also it leaves the bark open to sunsald and makes too many large wounds.
All three of these practices really define bad tree work.
The Board of Tree Experts and the ISA have set the pruning standards to say that no more that 25% of the entire leaf surface of a tree should be removed in one growing season. This rule or standard can be bent according to the age and species of the tree. It is up to the knowledge and experience of an Arborist to apply these standards. It is essentially art rooted in science. AS to how much and in what direction to bend them.
A well pruned tree should really look natural with just the offending branches removed. Only take off what is needed, dead wood, crossing and rubbing limbs, or clearing for houses, walkways, utility, etc. The tree should be balances and almost like nothing was done, "but the trees looks great."
Pruning Standard Definitions
Crown Cleaning - Removal of dead, dying, diseased, decayed, interfering, objectionable or weak branches.
Crown Thinning - Includes Crown Cleaning as well as pruning for air movement, light penetration, reduced wind sail effect and heavy limbs.
Crown Raising - Removal of branches from the bottom of the crown to provide clearance for pedestrians, vehicles, building and lines of sight.
Vista Pruning - Selective thinning to create a specific view.
Crown Restoration - To improve structure of previously topped, vandalized or storm damaged trees.
Crown Reduction - Reduces the height and/or spread of a tree. Used as a last resort to clear utility lines or when there is significant crown die back.
Pruning Classes
- Fine Pruning - 1/2 inch and larger
- Standard Pruning - 1 inch or larger
- Hazard Pruning - 2 inches or larger
