| The landowner’s choice of a harvest and regeneration method is based on ecological, economic and operational factors. Harvest and regeneration methods fall into two general categories: even-aged management and uneven-aged management. Within each is a range of methods to suit different forest types and conditions as well as different objectives. In all cases and regardless of the site, regenerating the forest is a key factor in choosing the best harvest method. The choice of method is determined by a complex evaluation of landowner objectives, economic considerations, regulatory constraints, site characteristics (terrain, tree species and soil type) and effects on fish, wildlife and other natural resources. Harvests themselves are just a single occurrence in the decades-long life cycle of a managed forest. |
Even-Aged Management
Even-aged management is a well-tested way to grow wood, particularly in the Douglas-fir forests of western Oregon. Commonly called clearcutting, it sets the stage for reforestation and a new cycle to begin. It is the most common method for regenerating Douglas-fir because the species grows best in openings that allow full sunlight. After harvest, foresters plant Douglas fir, often mixed with other species to emulate historical conditions. Thinning may occur several times before the final regeneration harvest at 40 to 80 years, which starts the cycle anew. Variations of even-aged management include shelterwood harvesting, where some trees are left to shelter the natural regeneration; seed-tree harvesting, which leaves mature trees to provide for some natural regeneration; and patchcut harvesting, a series of smaller, scattered clearcut harvests. |
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Uneven-Aged Management
As its name implies, uneven-aged silviculture involves the cultivation and periodic harvest of selected trees of various ages in a stand. Uneven-aged stands often contain mixed species as well. Trees are harvested either singly (single tree selection) or in groups (group selection) as they reach maturity. The small gaps created by harvesting leave room for natural seeding or planting of nursery-grown seedlings. A common management method east of the Cascades, it is often called selection harvest. Some view it as more visually pleasing than clearcutting, and it usually is the harvest and regeneration method of choice in the drier, colder climate of eastern Oregon. |
