Caring for Elderly Trees

Mature trees have much in common with mature human beings. Those that have successfully overcome developmental challenges and reached maturity enjoy some distinct advantages that come with being all grown up. Both also require some extra care and attention in order to remain healthy and enjoy a dignified old age.

Trees have the edge over humans when it comes to longevity. Some, typically hardwood species such as oak, maple and beech live 200 to 300 years. They are a legacy from our ancestors to our children and future generations. A healthy tree increases in value as it ages and our community enjoys the dividends–enhanced property values, improved air quality, stormwater control, moderate temperatures, energy savings, reduced crime rate, and wildlife habitat. We are still learning about all the ways our mature trees protect us.

As the foundation of our community forest, our mature trees deserve our respect and care as they pass their prime. Having grown as tall and as wide as their species DNA dictates, these aging trees inevitably begin to deteriorate. While their branch canopy gradually loses its lovely, species distinctive pattern, their shape begins to reflect the burden of senescence in strikingly beautiful ways. They begin to dismantle gracefully and their profile becomes interestingly irregular as they shed the occasional branch. Over time their posture stoops a bit because their structural stability declines, giving them a careworn look. Even as they decline, geriatric trees still give to us. Their trunks still hold the soil and store carbon, their foliage shades us and shelters wildlife and their decaying bark tissue hosts lots of bugs and worms that provide food for birds. Plus, they hold the history of our community and ourselves.

Is my tree a “mature” tree?

For every tree species there is a different middle age. Some, such as birches and willows, reach maturity in a couple of decades; others reach maturity after 50 plus years. It is helpful to know which tree species you have on your property and their current ages, so that you can anticipate when each one will reach advanced maturity. A certified arborist can identify your trees and estimate their current age for you. Keep records for those that you have planted yourself.

It has been said that trees, like humans, experience middle age spread. As they age, tree growth slows because they are less able to store energy. They produce fewer leaves relative to their biomass so they are not as efficient at photosynthesis. Thus they are less tolerant of stress, either environmental stress such as drought, weather, soil problems, disease or insect attack, or man-made stress, such as mower damage, compacted soil, pesticide use. However, regular preventative maintenance will ensure that they enjoy a long, happy life and decline with dignity.

Ways to promote tree longevity

The better a tree is cared for over its lifetime, the longer it will live in a healthy condition and be able to protect us.

Regular Inspection: An ounce of prevention; we do not think twice about the value of annual checkups for ourselves and our families. Similarly, regular checkups for your trees by certified arborists every year or two are important. They promote tree health by catching minor problems before they become serious. Arborists are trained to look for symptoms, including branch die-back, discolored leaves, reduced growth and loose or rotting bark. If you notice any of these things on your trees, don’t wait for a scheduled checkup, contact an arborist promptly. He may recommend lightening protection, cabling of branches, pest management treatments or other preventative measures.

Proper Mulching: A thin layer of mulch provides a number of important advantages—especially to very young and very mature trees. It retains moisture, and retards soil erosion, discourages weeds and prevents soil compaction that deprives tree roots of oxygen. When it decomposes, organic mulch feeds the microorganisms in the soil around the tree’s roots. They, in turn, produce nutrients that the tree roots can take up. Mulch also helps prevent bark damage by keeping lawn mowers and string trimmers from getting too close to the base of the tree.

Your mature tree’s root system extends way beyond the dripline of the foliage canopy, so it is unlikely that you will want to spread a 2-3 inch layer of organic mulch (composted wood chips, shredded leaves, pine needles, etc.) that extensively. Do what seems reasonable. Resist the temptation to pile on the mulch too thickly. Never pile mulch against the trunk because it promotes bark decay and invites winter damage from burrowing critters like mice and voles.

Soil care: In their prime, your aging trees were able to manage fine without fertilizer. However, as their systems become less efficient, it is worthwhile to check out the soil situation where they are growing. Over the many, many years the trees have lived there, soil conditions have likely changed. Important nutrients may be depleted; the soil chemistry (pH) may have shifted. The appropriate fertilizer, spread at the right time and in the correct amount may boost geriatric tree vigor. A certified arborist can recommend and even apply it for you (if you want). Do not forget that tree roots and grass roots often share the same soil, so be cautious about using weed killer chemicals on nearby lawn areas.

Pruning: All trees need pruning for a variety of reasons, and aging trees, especially, benefit from it. Periodic, judicious removal of weak branches and careful clean cutting of wounds where branches have broken off will prevent future problems. Incorrectly done, pruning can alter a tree’s growth pattern and create stress, especially for an older tree. Since pruning can require special equipment and potentially dangerous climbing, it is best handled by a professional.

Is it time to remove my aging tree?

So, eventually, decision time comes. Is it necessary, finally, to remove an aged tree? Ideally, it would be left to die with dignity in place. This is the natural way in the forest, but it is not usually possible in communities where trees share their space with humans who would be endangered by falling branches. Certainly, time for removal has arrived when the tree has become either irreparably hazardous or has died. It is also time when one or more of the following conditions develops:

  • Most or all of the tree branches have failed to produce new leaves in the spring
  • The tree is causing harm to other, vital trees nearby.
  • Branches throughout the canopy are decaying and breaking.
  • The trunk begins to split along its length.
  • Bark begins to fall from the trunk revealing rot or insect tracks or tunnels beneath.
  • Woodpeckers and other animals can make large holes in the trunk tissue
  • The tree begins to conspicuously lean toward the ground.
  • Fungus develops on the roots near the base of the tree.
  • “Shelves” of fungus (mushrooms) grow on the trunk.

The Marple Tree Commission offers assistance in the assessment of hazardous trees and recommends that residents get an appraisal of the tree and a removal estimate from an insured and reputable arborist. Since taking down large, old trees is difficult and dangerous, it should be done by experienced arborists.

By Ed Sevensky, Marple Tree Commission