Forestry & Wildlife
AUBURN UNIVERSITY, Ala. – The warming season has arrived in Alabama. This period can bring sporadic weather activity. Preparing trees for seasonal storms can help homeowners improve the longevity of trees and prevent a potential disaster.
Preparing Trees for Storms
Spring is a good time of year to survey trees around a home. Preparation for inevitable high winds from thunderstorms, tornadoes and even hurricanes is crucial for human and tree safety.
“Alabamians need to evaluate their trees every year, and especially after each storm occurrence,” said Alabama Extension Community Forestry and Arboriculture Specialist Beau Brodbeck. “We often forget how large trees can be. One tree could be thousands of pounds hanging over your home or landscape.”
Brodbeck recommends homeowners inspect their trees with a critical eye. A thorough examination of a tree will prevent any present defects from becoming detrimental to its health and surrounding property.
What to Look For
“The first and best thing to understand about trees is that there is no such thing as a perfect tree,” Brodbeck said. “All trees have defects or decay that can lead to failure. Just living long enough to become a big tree means that trees accumulate problems, similar to how we can accumulate problems as we age.”
According to Brodbeck, there is a systematic process that every property owner can use to help them inspect their trees. This process contains five steps including:
- Identifying tree targets (i.e., people and property under trees)
- Determining the species of tree
- Noting the tree’s defects
- Documenting any findings (i.e., pictures, notes, etc.)
- Obtaining a professional second opinion
Becoming a Tree Detective
There are some key factors that can influence the life of a tree. Most of these can be cumulative, and without proper management, can lead to tree failure in time. At this point it is necessary to become a ‘tree detective.’ Look out for clues to avoid a tree disaster.
Pay Attention to Wind Exposure
The larger trees get, the greater the risk they pose to property. In the same aspect, the taller trees grow and the wider branches extend, gravity and wind forces increase. It is important to note that trees will develop different types of wood to mitigate these forces. However, the urban environment is forever changing, and the sudden changes around large existing trees can be particularly concerning.
The removal of trees, forests or buildings that buffered the tree from winds can cause failures, as these trees have not developed the appropriate defense. Brodbeck encourages people to consider the changes around existing trees as these newly-independent trees will not be accustomed to catching more wind from future storms.
Don’t Abuse Tree Canopies
Evaluating the canopy can be challenging because portions of it are high in the air and often blocked by lower branches and leaves. Consider using binoculars to look for common defects like hanging or dead branches. Remember, the higher the branches, the bigger the fall and ultimately the greater damage to roofs, cars or people. Look for more subtle defects like cracked branches and decay or cavities in larger branches. Also, decay and cavities at the union of large branches or areas large enough to house wildlife should be especially concerning.
When pruning the canopies of large trees be aware of techniques that can increase risk of failure. Brodbeck explains that some companies sell their services as ‘wind-reduction pruning.’ Typically referred to as ‘lion’s tailing,’ this technique removes many of the smaller interior branches leaving only large branches. This has the unfortunate effect of causing the branches to have greater sway. New research has shown that smaller branches distributed along the large stems help trees shed the wind energy and can serve as a solution.
Be Careful with Aesthetics
Some property owners might raise canopies to enjoy a clean view through their landscape. Although aesthetically pleasing, removing too many branches can raise the tree’s center of gravity. When the wind blows, tree trunks bend halfway between their roots and lower canopy. Raising canopies moves the bending point higher on the trunk where trunks are thinner and could have past pruning wounds, making them more likely to break. This occurs often in recently-opened pine plantation after a powerful storm.
Topping trees is another aesthetic practice. It is defined as pruning trees back to a predetermined spot or giving them a flat top. While this might reduce wind load in the short term, it creates large pruning wounds at the top of each branch. When new buds emerge around these wounds, they will be weaker, especially as limbs grow larger. In time they can peel away from rotting limbs and fall on people and property below. Total removal is often the only solution.
When considering pruning trees for wind or otherwise, hire International Society of Arboriculture certified arborists. These experts have knowledge—rooted in science—on the most appropriate techniques.
Inspect the Trunks
Tree trunks are responsible for supporting thousands of pounds of canopy and should be evaluated carefully. Serious problems could include cracks caused by either twisted trunks or the union of forked trees.
Also, look for evidence of decay in the trunks. Common signs of decay include sprouting mushrooms, oozing wounds, loose bark, carpenter ants or cavities. Most trees have some decay, but the extent and location of the decay is key. Cavities or decay at the union of large branches are especially troubling. Forked trunks with tight ‘v-shaped’ unions can increase risk of failure in high winds.
So Go the Roots, So Goes the Tree
While all roots are important to the health of the tree, roots located within eight feet of the trunk are critical to tree stability. Most root problems are not visible. Instead, consider any past work (e.g., trenching for underground utilities, new construction, etc.) that possibly cut or damaged roots. Even shallow trenches can be a problem as 90 percent of tree roots are located within the first two feet of the surface. Be aware of leaning trees with heaving roots on the opposite side of the lean, and check for root rot by looking for mushrooms or cavities around the base of the tree.
“When planting trees, I recommend the idea of mimicking nature,” Brodbeck said. “One of the best ways to do this is to plant trees in groupings.”
Rather than inserting a lone tree, it could be beneficial to add a couple more along with it. This creates a group barrier to wind, giving each individual tree a better chance at resisting seasonal storms. When using this method, it is important to think about the tree’s size at maturity based on species. This information will be helpful for spacing purposes.
For new trees, staking them down to the soil provides an extra level of rigidity. However, this is not a solution for larger trees. Staking should only be performed for new trees in the first six months to one year in age. Root and wood strength must be formed independently after this period. Removal of these assemblies is imperative after the tree has become established in the landscape.
“The best step of great tree care is to take responsibility for trees on the property,” Brodbeck said. “Be proactive and always get a professional second opinion.”
It is also recommended to document any inspected trees every year by photography. This method will give property owners a visual representation to compare with in time.
Storms will continue ramping up as temperatures get warmer throughout Alabama. Prepare trees for seasonal storms by researching how severe weather can affect trees on residential or commercial property.
Visit the first of two editions of trees and storms research for outlined information on tree preparation. To learn more about trees and how they are affected by storms, please visit the Alabama Extension website at www.aces.edu.