Tree Facts: The life cycle of trees

Farm Forum

The life cycle of trees includes the following stages – pollination, seed, sprout, seedling, sapling, mature, decline and death. The cycle begins again either with the help of people planting trees or new trees growing in the wild from seed. Conditions must favorable for a tree to complete its life cycle. This includes adequate space, water, nutrients, and sunlight. However, even with ideal conditions, various problems such as insects, diseases, injuries, competition from other trees, weather, and time itself weaken the tree and can cause it to die. Trees may die from a variety of causes. Then a new tree grows either from a seed or as a sprout from roots or stumps.

Seeds come in a wide variety of shapes, weights, colors, and sizes, depending on the species. They develop from conception of male and female parts of the trees. Some seeds are contained in a protective nut like an acorn, buckeye or walnut. Other seeds are found in fleshy fruits, like chokecherry, buffalo berry, plums and currant. The fruit of a pine is a cone and winged seeds resembling miniature helicopter falls from open pine cones. Seeds are spread by wind, water, animals, and people to open fields, yards, rocky slopes, and roadsides. Anywhere the conditions are favorable for germination, seeds will sprout and grow.

A tree is born when sprouts occur from seeds growing, expanding, and breaking through the seed coat using the stored food supply in the seed to grow. The root grows downward into the soil to anchor the sprout and for water and nutrients. The sprout emerges from the ground seeking sunlight and the leaves and needles make food for the tree through photosynthesis.

The sprout grows into infancy as a seedling and begins to develop woody structure of a trunk and branches. The soft green stem begins to harden, change color, and bark develops. The roots grow into a mirror image of the tree resembling an upside down underground tree with a flattened top. The majority of the roots are in the upper portions of soil in order to breathe and to absorb water and nutrients. The seedling must compete with other trees and plants for its share of nutrients, water, sunlight, and space. At this stage, the tree is most susceptible to being killed by fire, flood, drought, ice and snow, disease, insect attacks, and the threat of being consumed by animals.

The seedling grows into a sapling or juvenile tree. A sapling is usually between 1-4 inches in diameter and 3-15 feet in height, such as the trees handled by commercial nurseries. A tree in this stage grows very rapidly but is not developed enough to produce seed. Saplings encounter the same types of competition and threats as seedlings.

If everything goes right a sapling grows into a mature or adult tree. During this stage it will grow to its mature size, flowers develop and reproduction occurs. Mature trees are harvested for forest products. In South Dakota products made for example from Ponderosa pine include dimensional lumber, cabinets, molding, doors, pallets, boxes, crates, trusses, furniture and etc.

If a tree is not harvested, over the course of time it becomes elderly, declines and dies from insects, diseases, and competition from vigorously growing young trees. If it remains standing it has become a snag. The cycle does not end here as decomposition occurs over time. A snag slowly breaks down and returns nutrients to the soil as small limbs, bark, and branches fall to the ground. The snag also provides habitat, cover, and food for wildlife. Eventually, the snag will fall to the ground returning nutrients to the soil and they are absorbed by other trees providing for their life cycle.

My source for this news release was the Texas A&M Forest Service. If you would like more information about the “Life Cycle of Trees,” contact Bob Drown @605-244-5222 Extension 109 or by e-mail at