Pre-commercial thinning (PCT), also called juvenile spacing or juvenile thinning, is a silvicultural treatment used to provide young crop trees with enough diameter space to grow optimally by reducing density through the selective removal of less desirable competing trees.
This process is referred to as pre-commercial thinning because trees are selected and removed before they reach a size of commercial value, usually on stands between 10 to 15 years of age. In softwood tree stands, pre-commercial thinning may occur when the stand reaches a height of 6.6 to 23 feet (2 to 7 m). In a hardwood stand, trees must reach an average height of six to nine feet (1.8 to 2.7 m).
Trees selected in the stand must be healthy and free of deformity, insects, and disease. When adjacent trees are removed, it reduces competition and the residual trees are able to receive more water, sunlight, and nutrients. The end result over the long-term is a better quality end product when final harvesting takes place.
Pre-commercial thinning also produces slash. Slash is defined as any tree debris or residue left on the ground as a result of the forest and surrounding vegetation being altered by forest practices or other land activities. Various techniques are used to get rid of slash. Sometimes the trees cut and removed are left on the stand to decompose naturally and enrich the soil. Another technique, called pile-and-burn, involves piling the slash by hand or using a bulldozer and burning it. Underburning, a prescribed burning of fuel under a residual stand, is another method that is common but risky. Lop-and-scatter involves cutting the harvested trees into several sections. The limbs of the trees are then trimmed and scattered throughout the stand assist in decomposition.
- ↑ Juvenile Thinning. BC Ministry of Forests and Range. 2008-10-28.
- ↑ Pre-Commercial Thinning. Kruger Publication Papers. 2008-10-28.
- ↑ PreCommercial Thinning. Scott and Stewart. 2008-10-28.
- ↑ Using Precommercial Thinning to Enhance Woodland Productivity. Oregon State University. 2008-10-28.
- ↑ Ministry of Forests and Range. Glossary of Forestry Terms in British Columbia. 2008-10-28.
- ↑ Understanding Thinning. MRNF. 2008-10-28.
- ↑ Slash Disposal. Oregon State University. 2008-10-28.