Root rot damage in naturally regenerated stands of spruce and balsam fir in Ontario

Abstract

In an 11-year study in northern Ontario, root rot damage was heaviest in balsam fir, intermediate in black spruce, and least in white spruce. As a result of root rot, 16, 11, and 6%, respectively, of dominant or codominant trees of the three species were killed or experienced premature windfall. Butt rot, which resulted from the upward extension of root rot into the boles of living trees, led to a scaled cull of 17, 12, and 10%, respectively, of gross merchantable volume of the remaining living trees in the three species. The total volume of wood lost to rot was, therefore, 33, 23, and 16%, respectively. Of 1108 living dominant and codominant balsam fir, 1243 black spruce, and 501 white spruce in 165 stands, 87, 68, and 63%, respectively, exhibited some degree of advanced root decay. Losses resulting from root rot increased with tree age. Significant amounts of root decay and stain (>30% of root volume) first occurred at 60 years of age in balsam fir and 80 years in black spruce and white spruce. For the three species together, the proportion of trees that were dead and windfallen as a result of root rot increased from an average of 3% at 41–50 years to 13% at 71–80 years and 26% at 101–110 years. The root rot index, based on the number of dead and windfallen trees and estimated loss of merchantable volume, also increased, from an average of 17 at 41–50 years to 40 at 71–80 years and 53 at 101–110 years. Death and windfall of balsam fir and black spruce were more common in northwestern Ontario than in northeastern Ontario. Damage to balsam fir was greater in the Great Lakes–St. Lawrence Forest region than in the Boreal Forest region. In all three tree species, the degree of root rot (decay and stain) was highly correlated with the number of dead and windfallen trees, stand age, and root decay at ground level (as a percentage of basal area) for a 10-tree sample.

Estimating windthrow risk in balsam fir stands with the ForestGales model

“…Displacement of the stem is calculated from the bending moment applied by the wind, Young's Modulus and the second moment of area of the cross-section following the method described by Wood (1995). From this displacement and the crown and stem mass calculated by the model, the additional turning moment is computed.…”

Evaluating a single tree-based growth model for even-aged stands against the maximum size–density relationship: Some insights from balsam fir stands in Quebec, Canada

“…Patry et al (2004) reported a 50% probability of observing butt rot for 65-year-old balsam fir trees. This corresponds to the age at which root decay becomes a risk (Whitney 1989) and is a little less than the age identified by Basham (1991) at which balsam fir should be harvested in order to avoid serious decay losses. These damaging agents are known to affect the mechanical stability of balsam trees, making them more vulnerable to windthrow as they become older (Frank 1990).…”

Quality of eastern white pine 10 years after damage by logging

“…Actual cull as a result of this decay can only be determined when the logs are sawn into lumber. This cull, or lumber volume reduction, can be five to ten times greater than the actual decay volumes (Whitney 1989).…”