Eastern hemlock (Tsuga canadensis) is projected to experience shifts in suitable habitat distribution in response to climate change. Models predict the southern boundary of eastern hemlock will remain geographically stable, but that eastern hemlock will decline in dominance and abundance along the boundary. In 2003 and 2013, 10 disjunct eastern hemlock stands on the southernmost portion of the Cumberland Plateau in Alabama were surveyed to characterize the vertical structure and diameter distributions of eastern hemlock. This work represents the third survey over 20 years and provides more complete insight into the stand dynamics of these disjunct stands. No trends were common among all stands, but there was a general decrease in the number of canopy eastern hemlock from 2013 to 2023. Despite the loss of canopy dominance, the majority of stands experienced an increase in the number of stems in the larger diameter classes. We expect these stands to remain viable and predict no shift in the southern range limit of the species. If, however, climate change effects begin to manifest in the stand structure or a severe disturbance occurs, eastern hemlock may lose dominance and be unable to regenerate. In 2021, an EF1 tornado obliterated one stand, and removed all canopy stems from another. Although the hemlock woolly adelgid (Adelges tsugae) is perhaps the most well-known threat to eastern hemlock, non-species specific disturbances have the potential to be equally as devastating to these disjunct populations.
