Canopy Thinning, End-Limb Weight Reduction, and Winter Storm Preparedness
November 24, 2015
Micah Pace, M.S.
Urban Forestry Specialist
ISA Certified Arborist
Tree Risk Assessment Qualified
In native stands, trees grow much more densely than they do in our planted urban and suburban properties. As a result of mutual shading, most trees in native stands grow taller and thinner with few (if any) over-extended limbs. In contrast, most of our urban shade trees are allowed to grow in the open where they tend to develop much fuller canopies with large diameter horizontal branches.
Large open-grown trees can be beautiful and scenic, but grown close to streets, driveways, and homes, they may represent increased risk for property damage and/or injury. Through time, this horizontal growth can increase the risk of failure. This is especially true for relatively weak-wooded species such as ash and pear. However, this is also true for trees like live oaks because they retain their foliage all winter long. When freezing rain or snow occurs the leaves provide ample surface area for ice and snow to build up causing long extended limbs to become more susceptible to breakage.
The excess rainfall this past spring was both a blessing and a curse. While replenishing our reservoirs is very important, the large amount of rain also lead to excessive canopy growth. This dense growth increases the overall weight of the canopy and for long, over-extended limbs in particular. This extra weight can increase the risk of failure and breaks in the canopy. Secondly, excessive soil moisture also resulted in an increase in fungal diseases which if left uncontrolled could decrease the structural integrity of trees as well.
Preparing your large shade trees for upcoming winter storms is very important to protect the long-term health of your trees. Canopy thinning is a pruning technique to reduce the overall volume (i.e. weight) of a tree’s canopy. This can be targeted to specific limbs or portions of the tree or for the entire tree. Reducing end limb weight will reduce the risk of loss during storms. The images below depict the same open-grown live oak both before and after thinning. The significant weight reduction of this tree’s canopy has lowered the potential for damage during an upcoming storm this winter and next spring, while not dramatically altering the tree’s appearance.
Preservation Tree cares about your trees. Call us for an evaluation today and allow us to increase both the value and safety of your property.