Silviculture is a specialized field of forestry that is concerned with the long term health and productivity of a stand of trees, or many stands of trees. While a forester’s job often ends with the completion of a timber sale, the silviculturist is a practicing forest/plant and fire ecologist who uses state-of-the-art science to manage stands of trees into the future. A “certified” silviculturist has been exposed to the latest scientific research and uses it in his or her daily toils, and has achieved the equivalent of a master’s degree from one or more major American universities. A certified silviculturist is the “tip-of-the-spear” in the field of forest management.
Thinning an overstocked stand of trees is one of the most important and cost-effective practices a silviculturist can prescribe, especially in cold and dry environments, with short growing seasons, such as we have here in the Northern Rockies. The primary purpose is to give the remaining trees adequate room and resources to grow, in a healthy manner, until the next scheduled treatment, which may be another thinning, twenty years hence. Just like humans, healthy trees are more likely to defend themselves from illness. In the case of trees, that means attacks by insects, disease and wildfire.
If we want to see stands of large, “old-growth-like” trees, like existed when the first settlers arrived, thinning is absolutely required and will, over the long-term, reduce the use of clearcutting, and reduce the possibility of stand replacement fires. Acclaimed fire ecologist, Steve Arno of the Bitterroot Valley, has been making this case for decades.
In the Northern Rockies, we have millions of acres of overstocked stands of Douglas fir, white fir and ponderosa pine that are now susceptible to a variety of insects and diseases. Once to overstocked status, trees begin to send off chemical messengers, called pheromones, which attract insects such as the western spruce budworm and western pine beetle that will attack “en masse”, causing widespread injury, including extensive mortality. Douglas fir can survive repeated defoliation by the budworm if given adequate resources to grow in a healthy fashion throughout its life. Without thinning, the Douglas fir bark beetle will finish off the tree after defoliation by the budworm.
Thinning these many acres of mixed conifer species is absolutely necessary to achieve the forests that we all desire many years from now. Our warming climate is making that job even more imperative.
Chris A. Linkenhoker
Corvallis