Spatial distribution of dark heartwood and wood rot in sugar maple at the northern edge of its range

The wood of sugar maple trees (Acer saccharum Marsh.) is generally perceived as containing more defects, such as dark heart-wood and wood rot, at the northern limit of its range compared to southern locations; however, assessments of these internal defects have primarily relied on direct observation, limiting the scope of analysis. To enable large-scale assessments, models are needed to estimate the internal quality of individual trees based on external defects. Accordingly, this study aimed to investigate the relationships between external and internal defects within sugar maple stems. Then, large-scale estimates of the importance of such defects were produced to understand the effects of site conditions and climate. Increment cores were sampled from 1108 trees across 108 plots. Results revealed that the probability of wood rot and the proportion of internal defects were associated with the presence of cracks and fungal fruiting bodies. Also, colder sites increased the probability of wood rot as well as the proportion of the stem affected by internal defects. Moreover, the western Balsam fir–Yellow birch subdomain had both the highest probability of wood rot and the greatest proportion of internal defects. Future studies should examine how this spatial distribution could evolve with climate change.