Forests are managed to meet a variety of conservation and societal needs. In western Oregon, we utilize our region’s most abundant tree species, the Douglas-fir, to provide renewable wood products.
Harvesting the raw material to create essential products is misunderstood and controversial, but science and years of experience tells us every method employed to manage forests is important. Regenerative harvests such as clearcuts are not only ecologically appropriate, but the most effective and efficient way to sustainably manage the timber resource in Oregon.
I’ve been asked plenty: Why can’t we just thin? The answer is complex and requires an understanding of forest dynamics, the basic needs of Douglas-fir and a grasp of forest economics.
Douglas-fir trees are shade-intolerant, meaning they need full and direct sunlight to establish and grow vigorously. Their seeds respond well to the warmed ground. If a seedling is planted under a darkened canopy, it is unlikely to survive. This notion of sunlight needs applies to all plant life and is evident on plant tags from your local nursery.
Managing forests for sustainable timber production requires a long-term approach. Douglas-fir trees take several decades to reach a harvestable size. This long-term vision is cyclical in nature: plant, nurture, harvest and so on.
The goal is a robust and healthy forest that is capable of thriving throughout its life cycle. Foresters determine the timing and intensity of the treatments in the cycle to meet this goal.
The “nurturing” component consists of thinning. Thinning is an intermediate treatment designed to reduce competition and create a more healthy and vigorous forest.
Thinning consists of removing some trees while retaining others – achieved through a desired spacing or by utilizing a basal area reduction. Basal area refers to the space a tree takes up and therefore considers the size of the tree rather than the number of trees in a given forest.
A forester can “thin from below,” where the smallest trees are removed or “thin throughout the diameter class,” where the health of the tree dictates removal and the size of the tree is less important.
Thinning is a necessary piece of the larger forest management cycle. However, it is just that – a piece. After a forest is thinned, the remaining trees will continue to grow and thrive. So, then what?
If a forester’s goal is sustainability, then the larger trees will eventually be harvested and replaced by the next generation. This is achieved through a final (aka regeneration) harvest.
Normally, nature would reestablish whole forests through natural disasters such as fires or insect outbreaks. When foresters prescribe one of these final harvests, we are mimicking natural disasters. Amazingly, modern science and technology allows us to reestablish the forest with all the carbon benefits and without harmful smoke.
Regeneration harvests may be unsightly in the short term, but they are living demonstrations of a dynamic and resilient forest, providing many different benefits that meet our everyday needs. Better understanding of forestry, and the science behind decision making, can help bring our community closer and tear down divisive and alarmist narratives.
Amanda Astor is a forester with the American Forest Resource Council. She writes a monthly column for The Register-Guard.
