Professor and Director University of Notre Dame, Indiana, United States
Abstract: Internal stem decay affects both common and rare species in the forest to varying degrees. These consequences have serious implications for species survival and ecological succession. However, the underlying defects are hidden and difficult to detect through visual inspection of signs and symptoms or without a destructive sampling of tree hardwood disks. Non-destructive sonic tomography provides an accurate estimate of this disease from incipient decay to the advanced stage of decay. The study hypothesized that common species have a high incidence of decay and decay faster than rare species, giving rare species an advantage in the ecosystem. Furthermore, functional traits are the best predictors of tree decay, such as tree decay increases with tree density and tree size and decreases with wood-specific gravity. The study used ArboSonic 3D Tomography to investigate the internal stem decay of hardwood species in midwestern forests and quantified the decay based on species abundance, taxonomy, and frequency distribution. The relationships between internal stem decay and tree functional properties such as wood density and tree size class were investigated. Topography and soil moisture content were also examined in relation to tree stem decay. The frequency distribution of decay by species revealed that trees decay at a rate ranging from 0% to 68% in hardwood forests. Fraxinus americana and Ostraya virginiana were discovered to be 87% and 70% decayed inside out, respectively, followed by other species in the forests. Rare species have a higher percentage of decay at lower dbh classes and decay linearly decreases with higher size classes, whereas common species showed no distinct patterns. The study discovered a significant positive relationship between internal stem decay and tree dbh. However, there were no discernible differences in decay rates between common and rare species. Also, no significant relationship between soil moisture and elevation with tree stem decay. Internal stem decay is a complex and slow-moving disease in the forest. This study is currently underway, and it is assessing decay progress as well as calculating decay rates based on tree and stand age, history, location, height class, and growth rate.
