Pine trees belong to the genus Pinus. Approximately 115 species of pine exist around the world, the majority of which are native to the Northern Hemisphere. As evergreens, pine trees retain green foliage during cold seasons. Most trees in a new stand of pines are the same age, or within a few years of each other. Old-growth stands of pines feature trees that are in all stages of growth. With appropriate growth, pine trees provide essential timber for the United States.
Pine trees grow well in open sunny locations on acidic, sandy soils. Coniferous forests consisting of pine trees cover approximately 15 percent of the earth's surface. Seed distribution generally occurs directly beneath the parent trees, creating stands of pine. Animals, such as birds, squirrel and deer, use the pine seeds as a food source, spreading the seeds to new locations.
The majority of pines grow in stands that create protection from wind and snow. Closely packed growing locations encourage tall, straight growth with little understory.
Certain varieties of pine trees require fire to maintain healthy growth and trigger reproduction. Featuring thick barks and branch-free trunks, the older trees resist damage to summer fires, while benefiting from the elimination of competition from undergrowth. Fire acts as a catalyst for the release of seeds from the cones in species such as the lodgepole pine.
Rate of Growth
In general, well-managed stands of pine trees grow 10 percent annual until the age of 50. According to the Arkansas Cooperative Extension Service, the healthy pine tree almost doubles in volume every seven years.
Age and Height
While generally known to be fast growing trees, pines are also long-lived and exhibit tall growth. Longleaf pines live approximately 250 years, with few documented to be older than 450 years, according to The Longleaf Alliance. The Eastern White Pine features the tallest growth among North American pine trees, reaching heights of 110 feet when mature.
Thinning Encourages Growth
According to the Arkansas Cooperative Extension Service, a new stand of pine timber requires 30 to 50 years to reach economic maturity. However, not all pines are fully matured before harvesting. Thinning of trees from a stand helps to encourage faster growth in the remaining trees through reduced competition for light, soil and nutrients.
Growth Determines Use
While often featured as ornamental plantings, the majority of pines are grown for use as timber, producing wood for furniture, construction and turpentine production. The size of a pine at harvest determines how the wood will be utilized. Young pines in the 6- to 9-inch range become pulpwood. Pine trees over 10 inches in diameter are sold are sold as sawlogs. Larger diameters, greater heights and straight growth increase the value and uses of pine wood.