Take care of your trees—don’t “top” them!

This Modesto Ash has been well cared for.

An extreme example of topping.

 
​By now, just about everybody has heard about the many benefits of trees in the urban landscape. They fight climate change by storing carbon in the soil; cool and clean the air; provide critical wildlife habitat—and these are just a few of the ways trees help cities like Concord. 

Valuing our trees is not a new thing in this town. For the last 42 years, Concord has been named a Tree City USA by the National Arbor Day Foundation. 

Unfortunately, over the past several years, many mature trees have been lost due to extreme weather. Weakened by years of drought, many have fallen during severe winter storms or simply died of thirst. Of course, it’s important to replace them with young trees without delay. It’s also critically important to care for the mature trees that remain. 

If you own property with trees, you can contribute a lot to our community by caring for them properly and making sure they are pruned correctly.

In pruning mature shade trees, the number one mistake to avoid is the practice called “topping”—that is, indiscriminately cutting branches to reduce the overall size of the tree. (Pruning fruit trees is a different matter entirely; learn how to do that here.)

What’s so bad about topping? According to Craig N. Huegel in his wonderful book The Nature of Plants, trees and other plants have something called an apical meristem--apical meaning “of the apex” and meristem meaning the cells that are capable of producing new cells. Young plants’ growth centers on this area.

As plants grow, they develop meristematic tissue at the tips of branches as well as the main stem. When a branch is lopped off (pruned or chomped), the area just below the damage starts acting like an apical meristem. That’s why pruning a shrub makes it bushier. 

But trees shouldn’t be pruned like shrubs. They need to have one main trunk. When multiple branches are hacked off, the tree no longer knows where its apical meristem is. It is confused. To quote Huegel, ”'Topping' produces long-term damage to a tree as it forces the tree to continuously reconfigure its growth. Instead of a strong main trunk, multiple weaker trunks are formed and the tree will be forever perplexed as to where it should allocate its resources. The trunk below will grow normally, but the area above will never do so.”

Topping stresses a tree in other ways as well. Removing too many leaves reduces its food supply; exposing its bark to too much sun and heat damages the tissues underneath; and leaving open wounds at branch ends makes the tree vulnerable to insect and disease infestations.

Topping can even kill a tree. To find out more, click here. 

The Sacramento Tree Foundation’s website has detailed information on pruning techniques. They include step-by-step instructions for pruning a young tree—but recommend that mature trees be pruned only by a certified arborist. Although an arborist will charge more than a landscaper with a chain saw, their expertise will preserve the tree’s health and beauty—and enhance your property’s value.

In some cases, when big trees are too close to power lines or buildings, there’s no way to prune them properly. The best course of action may be to remove the tree and replace it with a different species that’s more appropriate for the location. 

If you own property, consider planting trees where possible, and be sure to choose the right kind of tree for the space. Native species are often ideal because they support the local ecosystem and generally need less maintenance. 

If you have mature trees, please care for them and help them thrive. In this time of climate crisis, every living tree is precious.

-​​Friends of Concord Creeks