Effect of selective precommercial thinning on balsam fir stand yield and structure


Silvicultural tools such as green retention harvesting and multiple variations of partial cut systems are being developed to implement ecosystem-based forest management. However, very little effort has been expended in developing silvicultural treatments for young stands. Results for a selective precommercial thinning (three thinning intensities and control) covering a 28-year period in a balsam fir-dominated stand are presented. Thinning did not significantly increase stand yield, nor change stand diameter diversity or distribution. Furthermore, diameter distributions and diversity of dead stems also did not differ significantly (P > 0.05) among thinning intensity. More important than intensity effects, statistical differences were found between initial stand densities. Low initial densities had greater yields and more diverse diameter distributions. Nevertheless, for low initial stand densities, light to moderate thinning seemed to increase yield, whereas moderate to heavy thinnings would be appropriate for high initial stand densities. Although selective precommercial thinning does not result in significant changes in stand structure, it could be used as a first step in increasing stand complexity within the context of ecosystem-based management.

In The Forestry Chronicle.