Broken down simply, there are three main tree life stages: youth, maturity, and old age. These can be further categorized into sprout or seedling, sapling, prime of life, middle age, senior, twilight or ancient, and death. All trees go through all life stages, but not within the same time frame.
Tree Life Stages
What does that mean, exactly, and why should you care?
Depending on species, soil conditions, and climate, trees native to the Portland area, like oak or ash, can easily live well past 100 years old. The average lifespan for dogwood or willow in this region is much shorter: 70 to 75 years. Some fruit-bearing trees have even shorter lifespans. Being able to identify which stage of life your trees are in will help you determine how much care they need to remain healthy for as long as possible.
Even if you knew the chronological age of every tree in your landscape, determining the various life stages would mean researching each species and variety to find the expected life span under the regional growing conditions. But you don’t have to go to all that trouble. It’s easy to identify the tree life stages by observing size, appearance, and productivity.
This tree life stage includes the infant tree, also referred to as sprout or seedling, and the sapling.
The sprout or seedling is easy to identify, with its spindly twig reaching up from the soil and sporting a set of leaves at the top. This is the most vulnerable stage for the tree. It requires attentive care and protection from elements and predators to grow strong.
Most of us bypass this stage by purchasing landscape trees from nursery stock. If you do plant seedlings or barefoot specimens, space them with enough room to grow to their mature size. Keep the soil moist but not wet, and consider some type of fencing or cage to prevent hungry critters, like rabbits and deer, from nipping the seedlings off at the soil line.
When the seedling has produced a few sets of branches and grows two to three feet tall, it’s considered a sapling. The trunk is slender and still somewhat flexible, with thinner bark than a mature tree. Trees remain in the sapling stage, regardless of their size, until they begin to produce flowers or fruit and, subsequently, seeds.
Younger saplings remain susceptible to many of the same dangers as seedlings. The use of tree wraps, shelters, and staking can help protect saplings but must be used carefully and maintained to prevent potential injury to the growing tree.
The mature tree life stages include the prime of life and middle age. This is the most productive and beneficial stage of the tree’s life span. With proper care and attention, you will enjoy a healthy, mature tree for many years.
Once a tree begins producing flowers or fruits and seeds, it’s in the prime of life. Trees in this stage have long, sturdy branches and rounded, full crowns. Trees in the prime of life practically take care of themselves, as long as they receive adequate moisture and favorable light conditions.
The onset and duration of this productive tree life stage depend on the species and variety of each tree. Certain oak trees don’t produce acorns for three or more decades from a seedling. A rowan tree will produce berries somewhere near 15 years of age and a bitter cherry in 10 years or less.
During this stage, trees require the least maintenance, though flowering and fruit trees can benefit from regular pruning to shape the tree and remove crossed or dead branches. Read our tips for pruning or contact our professionals for more information.
In middle age, tree crowns begin to flatten and limbs grow thicker and heavier. Though technically past prime, this is often the most beautiful stage for shade trees. Growth slows, but trees will remain healthy for some years, while developing the striking characteristics of age. The only thing to watch for is infestation and disease; mature trees will become more susceptible to both as years progress.
Old age includes two tree life stages before death. Once again, depending on the species and variety, it will likely be several years, even decades, before an older tree finally succumbs to death.
Flat-top canopies become more pronounced in senior trees, with a visual imbalance of heavy limbs covered in short sprouts. There are also noticeable gaps in the canopy where large limb systems have died. Timely removal of these dead limbs can help prolong the overall life of the tree.
As a tree nears the end of its life, or the twilight stage, dead limbs break off easily, leaving an irregularly shaped crown of large limbs and tiny twigs. The trunk of the tree is likely decaying inside and will eventually become hollow. This can cause instability and the danger of falling and possible damage to nearby structures or other trees and plants.
Without external intervention, the twilight stage can last for several years. Near the end of this stage, the decaying trees are sometimes referred to as snags. But even then, their useful life is not over.
Decaying trees provide homes to insects, which in turn are a food source for birds and small animals. Many small animals make homes in hollowed-out trees, in turn providing a thriving food source for larger mammals.
All trees eventually die. If you choose to leave a dying or dead tree in place, it will eventually fall and decay, providing nutrients that enrich the soil and support a healthy, biodiverse environment.
Dying or dead trees that pose a potential safety hazard should be removed. Additionally, decaying trees attract insects that may be problematic in your yard and home. Allowing a tree to decay in place is perhaps best left for woodland settings.