This is the inaugural column that will appear monthly to discuss tree issues in the Puget Sound region.
My credentials include being a Certified Arborist, having conducted hundreds of hazard tree assessments and discussing tree problems and questions in “The Arborist” column for more than five years in The News Tribune.
Fortunately, the recent storms have not resulted in massive tree failures as in the past few years. Extreme ice and snow events such as the 1995 winter adventure are rare. However, conditions created by heavy rainfall accompanied by high winds are much more common.
Unfortunately, severe storms often result in concerned homeowners removing more trees than necessary. While it is reasonable to be cautious, the standing trees have withstood foul weather conditions for decades. This is why it is important to attempt to determine why a tree may have fallen – particularly if a root disease is suspected.
Generally, I have recommended leaving most worrisome trees alone. This is based upon closely observing the structure of trees, their health and growing conditions and their proximity to targets. However, there are certain situations of which a homeowner should be aware.
Reasons for Tree Failures
Saturated ground conditions and severe winds. These conditions can result in tree failures if they have one or more of the following problems. The comments generally refer to our taller trees such as fir and hemlock species found in our landscapes, greenbelts and urban forests.
• Diseased trees. Root problems account for the majority of whole tree failures. When enough roots have decayed, they no longer will anchor a tree during severe winds. Some of the more common root diseases can be spread through the roots to nearby healthy appearing trees.
• Trees exposed by clearing. This is common in housing developments or when a homeowner clears trees and exposes a neighbor’s trees to the elements. Loss of decades-old protection can stress trees over time and result in failures.
• Shallow roots. Trees in good soils can develop roots 4 to 5 feet or more under a tree. The outer roots are generally within 18 to 24 inches of the surface. Clay layers typical in some areas can inhibit root penetration. High water tables also limit the growth of roots. These conditions, often in combination with root diseases, can cause tree failures during storms.
• Roots damaged by construction. Trenching can sever roots. Heavy equipment can compact the soil and damage roots. Removing or adding soil around a tree’s root system can cause long term stress. Any of these factors may shorten a tree’s life.
• Leaning trees. If a tall tree is leaning and a portion of the root is exposed, the tree may need to be removed. If a tree is about 20 feet tall or less and the root is not totally exposed, it could be pulled upright, the soil tamped around its base and the trunk staked up.
If the soil is cracked or slightly uplifted around a large leaning tree and it would strike a man-made target were it to fail, remove the tree. If the lean is slight and no target is present, the tree could be left standing.
January and February are two of the stormiest months of the year. So if a tree is of concern, a professional evaluation may be prudent.
Certified arborists are the best bet for objective assessments and recommendations. They have been accredited by the International Society of Arboriculture (ISA) by completing a strict certification process. They must also maintain ISA membership and participate in continuing education programs to keep their certification.
Topics to be covered in future columns include how to deal with a neighbor’s “problem” tree, pruning tips, diagnosing tree pests and numerous other subjects. Questions from readers are welcome.