Let Dead Logs Lie (or Stand)
Balancing the Benefits of Dead Trees with the Risk they Pose
by Keith Salowich, City of Novi forester/contracts supervisor
For many, spring inspires spring cleaning, but you may just want to hold off. Decaying wood greatly benefits local wildlife. Once a tree dies and begins to break down, nutrient-rich organic matter is gradually released to support soil health and nourish other plants. Deadwood also serves as a microhabitat for countless wildlife species, ranging from microscopic organisms and insects to birds, mammals, reptiles, and amphibians.
Dead Logs are Habitat
A huge variety of species require access to decaying wood. However, dead trees in landscaped spaces tailored to human needs are often not welcome. Wildlife does not have access to vital habitat when there is zero tolerance for dead or decaying trees around human activity. Trees showing any signs of decay are oftentimes removed out of an abundance of caution. The risk trees pose is very frequently overstated, however
A formal data collection and analysis process exists to assess tree risk. Arborists can become credentialed in the process through the International Society of Arboriculture’s Tree Risk Assessment Qualification (TRAQ) program.
Tree risk is determined by assessing three things:
How likely is the tree part to fail, based on its condition, growth form, site factors, etc.?
If part of the tree fails, what targets are within its range and how likely are they to be impacted?
What is the severity of the damage to targets if they are struck by a failing tree part?
A 60-foot tall oak tree can be dead and likely to fall at any moment, but if there are no significant targets within its reach, then it poses no risk.
Mitigating Risks
There are also risk mitigation options beyond removal of the tree. Targets like picnic tables or fire pits can be relocated. Pruning cuts can be made to reduce the length and weight of branches, thus reducing their likelihood of failure.
High risk trees can also be cut to a “high stump,” which removes the upper portion of tree while allowing the lower 8-16 feet of the trunk to remain standing. These high stumps can still be used by cavity-nesting birds, and generally pose very little risk.
Tree risk does need to be mitigated at times to keep people and property safe. However, there is more than one way to mitigate risk and maintaining dead and decayed wood as wildlife habitat is a worthwhile effort.
