PILOT STUDY ON THE PREDICTION OF HEART ROT IN APPARENTLY SOUND WESTERN LARCH
Since many cavity-excavating birds require trees with heart rot, managers routinely emphasize decayed trees in their snag retention prescriptions. Where too few trees are present with obvious indicators of decay, apparently sound trees are left to meet retention objectives. These trees may also contain decay, and may offer advantages in longevity and protection over more extensively decayed trees. Better information regarding conditions and heartwood decay-causing fungi important to heart rot in apparently sound trees would aid in retention decisions. We combined data from the 2003 Westside Reservoir and Roberts Fire burns with data from the USFS Forest Health Protections 10-year western larch (Larix occidentalis) merchantability study on the 2001 Moose Fire burn, all collected on the Flathead National Forest. We used dissection data from 284 apparently defect-free fire-killed western larch to predict the probability of heart rot related to tree age, diameter at breast height (dbh), elevation, aspect, habitat type, and sapwood-to-heartwood ratio. Fungi were isolated from trees with heart rot and identified through DNA analysis. We isolated Stereum sanguinolentum, Echinodontium tinctorium, Sistotrema brinkmannii, Antrodia serialis, Phellinus chrysoloma, and Fomitopsis cajanderi from trees in the three burn areas. All variables tested except elevation and slope were significantly associated with probability of heart rot (á=0.05), with sapwood-to-heartwood ratio and dbh showing the highest predictive power through CART analysis. These findings support large tree diameter as a critical characteristic in retaining trees most useable to wildlife, as well as retaining heart rot-causing fungi, which have undergone marked declines in other parts of the world.
Advisor:Dr. Jack Ward Thomas; Dr. Richard L. Hutto; Dr, Cindy S. Swanson; Dr. Carl Fiedler
School:The University of Montana
School Location:USA - Montana
Source Type:Master's Thesis
Date of Publication:01/18/2008