Keeping trees healthy will keep them standing

The character of Idaho is often defined by its native trees. Pine, fir, spruce, hemlock and cedar cover the mountains around us. Although most of the timber in the lower areas was logged in earlier times, many communities retain remnants of the forests that once covered the valleys.

Native ponderosa pine and Douglas fir are the trees most often encountered in the river/lake communities of Post Falls, Coeur d’Alene and Hayden. The tall, stately trees provide many benefits, including shade, storm-water mitigation, clean air, wildlife habitat and increased property value.

Following windstorms, homeowners are often concerned about the risk of living with tall trees. While this risk is real, it is important to remember that, as trees grow to their mature height, they develop form and strength. That is why our neighborhood “residual forest” of trees exceeds 70 feet in height. The majority of trees withstand winds like those we have experienced in recent storms and become stronger as a result. A small number do, however, succumb to uncommon wind bursts or downdrafts by breaking or uprooting.

We live with risk every day, while driving, flying and even walking. Living with tall trees also poses some risk, but there are actions we can take to lessen the risk.

Hiring a certified arborist to assess the condition of your trees is probably the best insurance you can buy. Arborists will have the experience and tools necessary to look for and assess defects that may contribute to tree failure. If a risky condition is discovered, they will be able to discuss a course of action – pruning or cabling, for example, or as a last resort, removal.

Topping a tree to reduce its height is an expensive decision and is not an acceptable course of action. Rather than reducing risks, it actually may increase the risk of tree failure. Topping stresses a tree, introduces decay into the top and creates hazardous conditions.

Topping also is expensive. The practice destroys the natural branching structure of a tree, making a tree ugly and reducing its value. If a tree survives the ordeal, side shoots begin to grow rapidly. These branches are not well attached to the stem, are prone to breaking and need to be pruned every few years to ensure safety. An ethical arborist will not recommend topping as an alternative.

Homeowners can perform an initial visual assessment of a tree. Most trees are not “perfect” and they are healthy even while hosting some insects or disease. However large wounds at the base of a tree, unusual swellings, or other defects may indicate problems that call for further investigation. Other things to look for include:

“Broken limbs that may have caught in the upper canopy of the tree;

“Cracks along the trunk, at the base of a tree, or along large branches;

“Large cracks or raised soil on the windward side of a tree;

“New or increased leaning following a windstorm (which may indicate root problems);

“Mushrooms on the trunk or at the base;

“Many large branches rising from one point on the trunk, which may be weakly attached to the trunk.

The environment around a tree has much to do with its health as well. The root system of a tree is its anchor. In the past, it was thought that all trees had taproots growing in a fashion similar to carrots. Research has shown that trees actually have root plates that spread two- to three times the width of a tree’s canopy. (Picture a wine glass sitting on a dinner plate.)

Roots stay in the top 18- to 24 inches of soil in order to take advantage of nutrients and oxygen found in topsoil. Trenching too close to the base of a tree severs structural roots, compromising tree stability. Grade changes are damaging to trees as well. Digging down through the root plate destroys many of the roots nourishing the tree, leading to starvation and sometimes death. Mounding soil on top of a root plate may suffocate roots and contribute to stem rot.

Surrounding environments also contribute to tree strength. Trees grown in groves support each other by filtering wind, reducing its force. If trees are harvested, leaving only one or two standing, their “support system” is lost and stability may be compromised.

Remember, trees are dynamic, living organisms that respond to conditions around them. They enhance our environment and add value to our homes. By being aware of factors that may impact the health of your tree, you can live with and reap their benefits.