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Twenty-year results of precommercial thinning in a balsam fir stand

Summary

Published in Forest Ecology and Management 168: 177-186

A precommercial thinning trial, conducted in 1978 in a 20-year-old balsam fir (Abies balsamea [L.] Mill.) stand in the province of Québec, Canada, produced a broad range of stand densities over 60 permanent plots. Plots were measured at 5-year intervals until 1998 and the data were analyzed to verify the principal effects that are expected from this treatment in terms of individual tree growth and production per hectare. The diameter growth during the 20-year period following thinning was inversely related to the residual density. The increase in diameter of trees in thinned plots accumulated mainly during the first 10-year period. One explanation why thinning did not increase the diameter throughout the entire 20-year inventory period involves a spruce budworm (Choristoneura fumiferana [Clem.]) outbreak that occurred during this period. Total volume per hectare after 20 years was proportional to residual stand density, while merchantable volume per hectare was similar through the range of densities. If trees larger than 15 cm in diameter at breast height are considered exclusively, then thinning significantly increased 20-year stand yield. Therefore, the most important effect of precommercial thinning is to increase the volume per hectare of large diameter trees. Any conclusions on the impact of this treatment on stand yield must take into account the minimum usable diameter that is considered.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Silviculture

Author(s)

POTHIER, David

Year of publication :

2002

Keywords :

silvicultural regimen, precommercial thinning, stand density, growth and yield, spruce budworm, balsam fir, Choristoneura fumiferana, Abies balsamea, stem, height-age relationship, height-diameter ratio, silviculture and yield of natural forests - softwood stands, sylviculture et rendement des forêts naturelles - peuplements résineux, sylviculture des forêts naturelles résineuses

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