Got Trees, Got Spare Parts? Part II: Above Ground


In Part I of this blog, I talked about roots – the portion of the tree that’s often taken for granted: out of sight, out of mind. Perhaps, these are spare parts. In this post, I draw focus to the crown of the tree (from the bottom of the lowest branch to the top of the tree). People have different ideas about the importance of the tree crown. As arborists, we assess priorities: potential risks from falling trees or limbs, then plant health, and finally, aesthetics. Yet, the aesthetic opinion may be the tree owner’s priority when it comes to pruning…or maybe not!

Ulnus parvifolia/Chinese elm, poorly pruned
Tipuana tipu, poorly pruned

If a person learns the science of trees and how they grow, they may embrace a “treemendous” new view on tree care.  Leaves make food (carbohydrates) for the tree through photosynthesis.  Food is used for metabolism, growth, reproduction, defense, and storage.  As trees get bigger, they require more food.  When leaves are cut, there is less photosynthesis.  Mature trees rely on stored carbohydrates to sustain life when there is limited foliage.  If stored carbs are depleted, the tree stresses and becomes more susceptible to pests and disease.  Many stressed trees decline and die.  Leaves are not spare parts!

It’s true that many trees vigorously re-sprout after severe pruning.  This phenomena suggests that trees may be healthy after harsh trimming.  However, new growth is often fast growing, weakly attached, uncharacteristic of the natural form, and high in maintenance.  Vigorous sprout growth invites pest and disease, and can lead to long term structural problems.  Sometimes harshly trimmed trees may die.

So why do people still cut trees in this fashion?  It could be lack of knowledge, poor advice, imitating the actions of their neighbors, opportunist tree services, apathy, and other reasons not based on the science of tree. Therefore, I encourage you to say “No! to spare tree parts!

Front yard trees contribute to the health and beauty of our community forests.  What you do for your trees may affect your neighbors’ tree benefits.  Before you trim your trees, know that poor work based on a non-scientific perspective, can create problems.  This may include creating structural defects, increasing risks, and decreasing property values.  Select qualified professionals that have knowledge, experience, and integrity to work on your trees.  Certified arborists and tree workers should be able to help you; but first, check references.  Tree workers should be knowledgeable about the industry’s A300 Pruning Standards.  Be sure tree services are fully insured with personal liability, property damage, and worker’s compensation.  Certificates of insurance are easily available upon request.

How can I help you with your trees?

Treemendously yours,

Bill Spiewak

Chinese elm, poorly pruned
Chinese elm’s response to pruning is the production of vigorous & weakly attached limbs
Chinese elm, well pruned
Tipuana tipu, poorly pruned
Tipuana tipu’s response to pruning is the production of vigorous and weakly attached limbs
Well pruned tipu trees

One Euc topped for power lines, dies
Surviving Eucalyptus’ response to pruning


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