The Lifecycle of a Tree

The circle of life; it’s something every living, breathing thing on earth goes through.

The lifecycle of a tree is no different. It has various stages of life: conception (seed), birth (sprout), infancy (seedling), juvenile (sapling), adult (mature), elderly (decline), and finally death (snag or rotting log).

For the lifecycle to run full circle, both internal and external conditions must be favorable for a tree to thrive. That means it must have adequate space, water, nutrients, and sunshine at peak levels based on the needs of the species.

If a tree does best in sunny conditions, having adequate sunshine all year through will be important. For a tree to thrive in the heart of the city, considering what conditions it will face all year through should be top of your mind.

Just like any city, Portland has its own climate with varying degrees of temperature and environmental changes. To give Portland trees a chance to thrive and increase the potential for growth and survival through a complete cycle, it’s important to understand how the cycle works.

At any time, stresses from things like insects, diseases, injuries, competition from other trees, weather, and even time itself can weaken a tree and cause it to die. Learning about the important factors at each level can greatly increase the chances of your Portland tree thriving.

Seed

Seeds come in all shapes and sizes, depending on the variety of the tree. All seeds develop from male and female parts of the trees by producing fruits. However, not all of them are easily recognizable or edible for other life.

Some seeds come with a protective nut or shell around the seed. You’ll find this on acorn and hazelnuts. Some seeds are found inside the flesh of the fruit. Pear, apple, or cherry trees are good examples. Some seeds are found in protective pods or cones. These seeds drop to the ground as is the case of a pinecone, or helicopter away when falling in the wind.

While humans have changed nature by having the ability to control the planting process, nature disperses seeds in different ways. The wind can carry seeds for miles. Drop a seed in the water, and it can land in different zones. Animals can carry them in a variety of ways, moving them throughout their territory. Anywhere conditions are favorable, a seed will stick, germinate, sprout, and grow.

Sprout

While every seed is a tiny embryo, not all seeds will germinate. The seed needs favorable conditions to sprout to life. It needs the right environmental conditions and the perfect nutrients (including water, a food source, and sunshine) to break through the seed coating, grow, expand, and come to life.

If conditions are right, the sprout starts forming roots from the very beginning. It grows downward into the soil to anchor the sprout and begins looking for water and nutrients it will need to thrive. It also grows upward seeking sunlight. And if it finds the right combination, it will produce leaves, needles, or scales to further allow the tree to begin making its own food through photosynthesis.

Seedling

If all conditions are met, the sprout will very quickly take on a woody appearance. The soft stem will begin to harden and develop a thin protective bark. Leaves or needles continue to unfold in their search for sunlight. The root system continues to filter underground depending on the layout of the land. The majority of a tree’s root system will lie along the upper portions of the soil, where absorption of water and nutrients is prime.

At this point, the seedling has competition. Other trees fight for the same nutrients, water, sunlight, and space. Other threats include fire, flood, drought, ice, snow, disease, pests, and the threat of being consumed by animals. At this stage, the tree is most susceptible to being killed. Providing ample opportunity for the tree to thrive is imperative.

To give a tree the opportunity to thrive, it’s important that you plant the proper tree for the conditions that exist all year long. To have a tree thrive in Portland, choosing one appropriate for Portland weather is imperative.

The Plant Hardiness Zones divide the U.S. and Canada into 11 areas based on a 10 degree Fahrenheit difference. The United States falls within Zones 2 through 10. You’ll often find trees listed to be hardy for multiple zones. This means the tree can be expected to grow in that area’s temperature extremes. Portland falls into hardiness zone 8b or 9a for the major parts of the city.

Sapling

A sapling is a tree in its juvenile state. It is usually one to four inches in diameter. This is the size you’ll typically find at your local nursery waiting to be planted.

A juvenile tree is perfect for transplanting into your yard. However, it is not mature enough to reproduce. It’s growing rapidly and has lots of energy to give it the best chance at life. It needs care to keep it on the right track and ensure it stays a part of your landscape for years to come.

Mature

If all conditions are met, the sapling will continue to grow and mature. During this stage, each tree will grow as much as the species allows and the site conditions permit. It will flower during the appropriate season, reproduce, form fruit, and disperse seeds back into the environment.

Maturity is the optimum time for harvesting. It’s when a tree provides the most benefits for its intended use. Careful tree trimming or tree pruning can assist in a longer, healthier life for your tree. It’s when forests can be brought in for wood consumption. 

If a tree is never harvested, over time it continues to provide benefits until it slowly begins its decline.

Decline

At this point, a tree’s very survival is threatened. External stresses continue to impact the tree, sometimes in a big way. These stresses take a toll on the tree, making it more susceptible to everything. Pests and disease can get in and have an impact until eventually, it succumbs to the pressures. It then gives way to other growing plants on the property that have greater potential. 

Snag

Trees’ lives vary greatly. But no matter the lifecycle of a particular species, whether it’s 30 years or 300 years, all living things eventually die. Usually, it’s a combination of factors that lead to its demise. Injury, drought, or even disease may start the process. Eventually, rot, root injury, coupled with more damage from lightning strikes or a pest infestation will take it down. Trees that pose a threat or danger to power lines, homes or structure should be addressed or have the tree removal process started.

Yet, the cycle doesn’t end here. A dead tree, or a snag, still plays a vital role. Decomposition takes time. A snag breaks down and returns nutrients to the soil. Also, snags provide habitat, cover, and even nutrients to different wildlife.

Finally, the snag breaks down and returns as nutrients to the soil, where the lifecycle of a tree begins again.