Edmonton (March 12) - Sustainable Forest Management Network Principal Investigator, Dr. Jens Roland has discovered a correlation between forest tent caterpillar infestations and the amount of forest left standing after an area has been harvested. Says Roland, "In larger forest stands, the mortality factors which cause collapse of the tent caterpillars infestation (parasites and disease) are more effective than they are in small stands." Dr. Roland's work suggests that a forest tent caterpillar outbreak and the rate of collapse is a critical indicator of the overall health of Canada's aspen boreal forest, and provides various new options for forest managers who would like to minimize the effects of forest tent caterpillar outbreaks.
The impact of forest tent caterpillars should not be underestimated. For comparison purposes, at the peak of a caterpillar outbreak, the biomass of caterpillars per km2 would be equivalent to 657 caribou per km2. Similarly, the biomass of the tiny parasitic flies that attack and feed on these caterpillars would be equivalent to 82 wolves in the same one km2 area.
Given the immense scale of the predator-prey battle going in our backyards, parks, and forests, it is not surprising that the forest tent caterpillar is the principal defoliating insect of trembling aspen in the boreal forest across the country. "During a major outbreak," says Roland, "forest tent caterpillars can completely defoliate an aspen forest; virtually stop their growth - reducing growth increment by as much as four cubic metres of wood per hectare each year. "While we can't stop a tent caterpillar infestation," said Roland, "we don't want to do anything to prolong it either, such as rendering its natural enemies ineffective through effects of altered forest structure." If the number of y
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