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Commercial Thinning Research

Last updated on January 26, 2024

Commercial thinning is an intermediate harvest in immature stands, where trees have reached merchantable size, and all or part of the felled trees are extracted for useful products.

As practiced in British Columbia, commercial thinning is generally part of a clearcut silvicultural system. As such, the intent of commercial thinning is a partial harvest and not to regenerate the stand. The traditional objectives of commercial thinning are to: 

  • obtain wood volume or revenue earlier than the final harvest 
  • improve the growth of residual trees 
  • improve the quality of the stand by removing dead, diseased and deformed trees 
  • capture some of the production that would otherwise be lost to mortality 
  • obtain certain species and size classes for specialty products 

In British Columbia, increased flexibility of wood flow at the forest level is a primary goal. Commercial thinning likely only provides marginal increases in the cumulative merchantable volume available from a stand over a rotation. However, commercial thinning can provide flexibility by redistributing harvest over time, thereby cushioning the effects of timber supply shortfalls caused by age-class imbalances in the timber supply. Commercial thinning can also provide harvest volume while meeting visual quality objectives and adjacency constraints. 

Several commercial thinning experimental projects (EP´s) have been established in coastal and interior forests. Growth and yield data from commercial thinning experiments is a vital source of data for the calibration and validation of stand growth prediction models.

On this page

Experimental projects - coast

 
Experimental project # Title # Inst. Year established
364 Commercial Thinning Experiment : North Arm Forest (Cowichan Lake) 1 1950
365 Thinning study in Douglas fir at Cowichan Lake Research Station 1 1950
388 Commercial Thinning in Western Hemlock 1 1952
418 Correlated Curve Trend Studies in Coastal Douglas-fir 1 1952
469 Thinning Experiment in Douglas-fir 1 1955
499 Practical Demonstration of Thinning and Pruning on a Farm Woodlot 1 1954
554 Correlated Curve Trends Thinning Experiments in Douglas fir 2 1959-1966
703 Extensive Studies of Fertilizing and Thinning Coastal Douglas-fir and Western Hemlock 78 1971-1975
1213 Silviculture Treatments for Ecosystem Management in the Sayward 3 2001-2008
1256 Levels-of-Growing-Stock (LOGS) 2 1969-1970

Experimental projects - interior

 
Experimental project # Title # Inst. Year established
384 and 385 Thinning lodgepole pine in southeastern British Columbia 1 1952
511 Crop-tree thinning of western larch in southeastern British Columbia 1 1958
1184 The effect of commercial thinning on the growth and yield of interior Douglas-fir 1 1994

Commercial thinning publications

B.C. Ministry of Forests publications can be downloaded from the following website: https://www.for.gov.bc.ca/scripts/hfd/pubs/hfdcatalog/index.asp 

  • Darling, L.M. and S.A.Y. Omule. 1989. Extensive studies of fertilizing and thinning coastal Douglas-fir and western hemlock: an establishment report. Can. For. Serv. and B.C. Min. For., Victoria, B.C. FRDA Rep. 054.
  • de Montigny, L., R. Eriksen, V. Strimbu, D. Goldie, and T. Hooper. 2018. Silviculture treatments for ecosystem management in the Sayward (STEMS): establishment and progress report for STEMS 3, Gray Lake. B.C. Min. For., Lands, Nat. Resource Ops., Victoria, B.C. Tech. Rep. 114.
  • de Montigny, L. and G. Nigh. 2009. Silviculture treatments for ecosystem management in the Sayward (STEMS): establishment report for STEMS 2, Elk Bay. B.C. Min. For. Range, Res. Br., Victoria, B.C. Tech. Rep. 049.
  • de Montigny, L. 2004. Silviculture treatments for ecosystem management in the Sayward: establishment report. B.C. Min. For., Res. Br., Victoria, B.C. Tech. Rep. 17. 
  • de Montigny, L. and G. Nigh. 2007. Density frontiers for even-aged Douglas-fir and western hemlock stands in coastal British Columbia. For. Sci. 53 (6):675–682.
  • Joergensen, C. 1952. A commercial thinning experiment in Douglas-fir. B.C. Min. For., Victoria, B.C. Res. Note 22. 
  • Johnstone, W.D. 1997. The effect of commercial thinning on the growth and yield of lodgepole pine. In: Proc. Commercial Thinning Workshop, October 17–18, 1996, Whitecourt, Alta. FERIC Spec. Rep. SR-122, pp. 13–23. 
  • Johnstone, W.D. 2002. Thinning lodgepole pine in southeastern British Columbia: 46-year results. B.C. Min. For., Victoria, B.C. Work. Pap. 63.
  • Omule, S.A.Y. 1988. Growth and yield 35 years after commercially thinning 50-year-old Douglas-fir. Can. For. Serv. and B.C. Min. For. Lands, Res. Br., Victoria, B.C. FRDA Rep. 021.
  • Omule, S.A.Y. 1989. Growth and yield 32 years after commercially thinning 56-year-old western hemlock. Can. For. Serv. and B.C. Min. For., Res. Br., Victoria, B.C. FRDA Rep. 029.
  • Omule, S.A.Y. 1984. Results from a correlated curve trend experiment on spacing and thinning of coastal Douglas-fir. B.C. Min. For., Res. Br., Victoria, B.C. Res. Note. 93.
  • Omule, S.A.Y. 1990. Net basal area response nine years after fertilizing thinned and unthinned Douglas-fir. Can. For. Serv. and B.C. Min. For., Victoria, B.C. FRDA Rep. 097.
  • Omule, S.A.Y. and G.M. Britton. 1991. Basal area response nine years after fertilizing and thinning western hemlock. Can. For. Serv. and B.C. Min. For., Victoria, B.C. FRDA Rep. 137.
  • Stone, J.N. 1994. Extensive studies of fertilizing and thinning coastal Douglas-fir and western hemlock: an installation report. Can. For. Serv. and B.C. Min. For., Victoria, B.C. FRDA Rep. 227.
  • Thompson, C.F. 1992. Crop-tree thinning of western larch in southeastern British Columbia: 30-year results. B.C. Min. For., Victoria, B.C. Res. Note 110.