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Five Myths about Trees

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Article and photo (Sara Holtz) by Plant NOVA Natives

It’s no myth that trees hold a special place in our collective psyche. Trees play a prominent role in myths, often symbolizing life and rebirth. Unfortunately, some of the stories about them are just plain wrong.

1. Trees need big piles of mulch. Or perhaps we should call this The Myth of the Angry Volcano Gods, who are appeased by stuffing trees down their maws. It’s hard to know how this harmful practice got started, but we are seeing it everywhere. Trees should be planted with the top of their roots level to the ground, just as in nature. Mulch should never be allowed to touch the trunk, as it causes bark rot. Shredded mulch can form a barrier to water when it mats down, so arborist wood chips are preferred – assuming mulch is needed at all – and no more than 2-4 inches deep. The Fairfax County Tree Basics booklet, which you can download for free, shows proper tree planting and care practices and is available in multiple languages.

2. Tree wounds need dressing. Trees cannot heal the way we do after they are cut, which is one reason why topping a tree is such a bad idea. A broken limb should be trimmed back to just beyond the branch cuff then left alone to try to close over, which with luck it may accomplish before fungi set in. Painting tar on the surface just encourages rot.

3. All leaning trees are dangerous. It is normal for trees to grow toward the light. They reinforce their wood to make themselves stable. If you are worried that a tree may become hazardous, you can get an opinion from a consulting arborist who is certified by the International Society of Arborists (ISA) and who has no financial interest in cutting it down.

4. Trees litter. Well, trees do create leaf “litter”, but that’s an unfriendly word to use to describe feeding the soil and providing habitat for fireflies and wintering grounds for butterflies. The best thing you can do for a tree and the ecosystem is leave the leaves underneath where they fall. If you are afraid they will smother the grass, you can chop them up with a lawn mower so they at least add organic matter to the soil, a practice that is good for the trees and the grass (but hard on the critters).

5. One tree is as good as another. Not so! All trees can provide shade and capture stormwater, but only native trees support biodiversity. In fact, native trees are the very backbone of our local ecosystem, providing the majority of the leaves upon which our native caterpillars feed, which in turn provide the diet required by baby songbirds. In fact, not only do some non-native trees do nothing to feed the birds, they are actually invasive, taking over and destroying what is left of our remnant woods and starting to threaten our bigger forests as well. With few exceptions, there are native trees to serve any landscaping need. Find out all about them on the Plant NOVA Trees website.

Be Nice to Your Trees

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Article and photo by Plant NOVA Trees
On a recent day, driving out of the sun into a wooded community resulted in a temperature drop from 91 to 86 degrees. We all try to stay in the shade in hot weather, competing for the parking spaces under trees. What we may not realize is that tree-lined neighborhoods are cooler not just because of the shade but because the trees themselves act as air conditioners. The basic concept is that it takes energy to turn a liquid into a gas – we see that when boiling water. When a tree sucks up water through its roots and releases it as a gas through its leaves, a process known as transpiration, the energy that causes the water to evaporate is absorbed from the surroundings in the form of heat, and the result is a lower air temperature. This principle of physics also explains why sweating cools our bodies.
Newly planted trees are particularly vulnerable to high heat, so the most basic care needed from us is to provide enough water until they are well established. Seedlings establish quickly, but a landscaper-sized tree needs several years for its root to grow out of the planting hole into the surrounding soil. Our torrential summer storms can fool us into thinking we are getting enough rain, but many of them are brief and don’t even budge the rain gauge. A young tree with brown leaves is a very sad sight. At the same time, overwatering any plant can be worse than underwatering, by depriving the roots of oxygen, so we need to be careful to follow instructions in that regard and allow the soil to dry out between waterings.
Once a native tree gets established, though, little if any care may be required for the next twenty years or so. Our oaks and other native trees evolved here and are accustomed to the local soils and our variable temperatures and rainfall, although those 91 degree days are adding to the stress of living in an urban or suburban environment. Because older trees may start to develop issues, it is wise to have those that are near houses inspected every two years by an independent consulting arborist, meaning one who has no financial incentive to sell tree care services. They can recommend procedures that may prevent a tree from becoming hazardous. Even better, they may be able to provide reassurance, for instance, that a tree that is leaning a little may be quite stable, despite the dire warnings of a marketing rep from a tree company that is eager to keep its crew busy. Always use the services of arborists certified by the ISA (International Society of Arboriculture.)
When future residents are facing temperatures even higher than today’s, a five degree lower temperature may make a life or death difference. Consider what hundred degree weather does to the human body when a prolonged blackout shuts down everyone’s air conditioning. It pays to take good care of our trees. Find out how on the Plant NOVA Trees website.