Establishment and Growth Patterns of Southern Appalachian Carolina Hemlock Ecosystems.

Carolina hemlock (Tsuga caroliniana), an endemic species to the southern Appalachian Mountains, has vast ecological value because of their associated ecosystem services such as avian nesting sites, wildlife food, and winter shelter. The non-native, invasive hemlock woolly adelgid (Adelges tsugae) has threatened the health and longevity of both Carolina and eastern hemlocks (Tsuga canadensis) in the Appalachians since their establishment in the early 1950's. Climate change may worsen this threat as warming temperatures may promote adelgid infestations as well as alter hemlock habitat. Compared to eastern hemlock, less is known about the establishment and growth dynamics of Carolina hemlock. We used dendroecological methods to describe these patterns for five Carolina hemlock populations in North Carolina and Tennessee using 1,250 tree cores. The majority of the Carolina hemlock establishment dates within the five sites were concentrated between 1920 and 1990 and tapered off such that by 2000 no recent establishment had occurred. Maj or and minor growth release events are present in the hemlock populations across the sites. Our next step is to correlate these releases with climatic and disturbance records, to gain a better understanding of how this unique ecosystem persists. Understanding the structure, composition, and establishment patterns within and across these sites is important for figuring out if Carolina hemlock growth will be sustainable with a changing climate and an increase of the deadly hemlock woolly adelgid. [ABSTRACT FROM AUTHOR]