Using Acoustic Tomography to Infer Stem Wood Quality of Pine Forests Affected by a Fungal Pathogen in Different Latitudinal Regions and Plantation Densities

Diplodia pinea is a fungal pathogen that causes Diplodia shoot blight in pines and is widely spread in red pine (Pinus resinosa) and jack pine (Pinus banksiana) forests in Michigan. The objective of this study was to examine whether infection with D. pinea compromises wood quality in pine stands. Acoustic data was collected using an acoustic tomographer from the stem region at breast height (1.3 m) of red pine and jack pine trees across two categories of forest health condition (control vs. Diplodia-affected), in two latitudinal regions (Lower Peninsula vs. Upper Peninsula), and two levels of initial stand density (low vs. high). The acoustic data was used to infer the wood quality (i.e., density) in these two tree species since material of higher density generally has higher sound velocity rates. Red pine had significantly higher wood quality (i.e., higher sound velocities) in the Upper Peninsula region compared to the Lower Peninsula region. Within each latitudinal region, red pine sound velocities did not show significant differences between forest health condition or initial stand density levels. Jack pine showed no significant differences in sound velocities across the treatment categories. The results indicate that latitudinal region appears to have more impact on red pine wood quality than the influence of forest health condition (presence of Diplodia shoot blight) or initial stand density. All analyzed factors (latitudinal region, forest health condition, and stand density) did not have a significant impact on the wood quality of jack pine.