Forest Management
Gifford Pinchot National Forest lands are supported by productive soils, plentiful rainfall, and mild temperatures which provide an ideal land base to manage forest vegetation for forest and watershed health. The Forest Service works closely with two long standing collaborative groups that support active vegetation management and work to meet restoration initiatives.
Vegetation treatments (such as commercial thinning) on the Gifford Pinchot National Forest are planned to help make stands more resilient to fire and disease as well as restore some of the natural complexity that is missing due to past forest management practices. All projects are planned based on long-term forest health goals outlined in a 10-year vegetation management plan, which tiers to the overarching forest management plan.
A large portion of the Gifford Pinchot National Forest is classified as matrix lands which support sustainable timber production, and this is where a majority of the vegetation management program work is focused. Abundant tree growth and engaged collaborative groups, plus local milling infrastructure help vegetation management on the Forest, provide benefits to local communities.
Forest Types
Stands of conifers occupy about 84 percent of the Forest. Below 3,500 feet, Douglas-fir is the predominant species. Other species commonly found in association with Douglas-fir are western hemlock and western redcedar. Between 3,550 and 5,000 feet several true fir species are found, including Pacific silver fir, grand fir, and noble fir; smaller amounts of subalpine fir also occur. Mountain hemlock, Engelmann spruce, and lesser amounts of lodgepole pine grow here, as well as at higher elevations. A relatively small amount of ponderosa pine is found just south of Mt. Adams. Western white pine and western larch are sparsely scattered throughout the Forest. Both overstory and understory vegetation are affected by the transition from wet conditions in the west to a drier climate in the east.
Developing Future Forests through Silviculture
The practice of Silviculture consists of a body of knowledge and techniques that can be applied to shape development of forests to meet whatever objectives are selected, whether the emphasis be on watershed protection, scenic values, ecological restoration, development of wildlife habitat, or wood production.
Silvicultural knowledge and practice have been evolving in the Pacific Northwest for nearly a century. Most research and management activities to date have focused on two major topics: (1) methods to regenerate older, naturally established forests after fire or timber harvest; and (2) growth and management of young stands.
Today, Forest Service Silviculturists use available knowledge, science as well as climate modeling and other tools to create plans and prescriptions to help forests grow to be as resilient and healthy as possible in the future, while managing for habitat, clean water, recreation, forest product harvest and other priority forest management needs.
Commercial thinning treatments as a method to create structural complexity.
Scientific research has shown that the old-growth forest’s structural complexity is the key to its biological diversity. As managers work to help forests develop into more complex and resilient ecosystems, commercial thinning is often “prescribed” as a treatment by silviculturists. These thinning projects are designed to help forested landscapes grow into more complex and resilient ecosystems with more old-growth characteristics.
Variable-density thinning is the primary commercial thinning method used to accomplish these restoration goals within forested stands. It entails increasing the variation of tree spacing to promote structural complexity, increase plant community diversity, and create a mosaic of habitat conditions. An area treated with variable-density thinning will have both “skips,” untreated areas, and “gaps,” where most trees are removed to create small canopy openings, usually less than a quarter acre.
Studies show that when variable-density thinning is used, thinned stands usually have better developed understories, higher shrub densities, a greater richness of understory plant species, and more plant cover than un-thinned stands. Just as natural processes are variable, a thinning design is site-specific and depends on the characteristics and landscape context of the individual stands.
Commercial thinning projects also provide the national forest with funding that can be used for aquatic restoration, recreational improvements, and other key forest management tasks, while providing jobs and resources to communities.
More information:
- Restoring complexity: second-growth forests and habitat diversity
- Promoting Habitat Complexity in Second – Growth Forests
- Silviculture for Multiple Objectives (1998)