Estimating white trunk rot in aspen stands

Abstract

Advanced decay caused by Phellinus tremulae was estimated in 295 trembling aspen on 30 plots in 2 Minnesota counties using existing inventory guides, and then measured by felling and sectioning the trees. In standing trees, decay volume was underestimated by 38% compared to measured decay volume in felled trees. The most reliable external indicator of decay was the presence of conks of the fungus. Results indicate that decay associated with conks in the first 16ft of the trees accounted for nearly 70% of the total volume loss. Decay volume in trees with no conks averaged less than 2% compared to 14% in trees with conks. There was little merchantable volume lost from decay associated with poplar borer (Saperda calcarata) damage, closed wounds, andhypoxylon cankers. We recommend that inventory guides for estimating aspen decay in Minnesota be revised, and a suggested guide is provided.