DENDROCHRONOLOGICAL STUDY OF HEMLOCK (TSUGA CANADENSIS) FROM WINDOW CLIFFS STATE PARK, TENNESSEE

Current climate models predict that as anthropogenic climate change continues, there will be continued effects on weather and a shift in biological species with consequences for local ecosystems. The shifts in temperature and precipitation expected for current climate change is thought to result in shifts in insect populations and growth of insects that cause destruction of host tree species. The hemlock woolly adelgid (Adelges tsugae), an invasive insect species that was introduced presumably from Japan to Virginia during the early 1950s, has caused a massive, rapid die-off of the Eastern hemlock (Tsuga canadensis) and Carolina hemlock (T. caroliniana) across the eastern USA. In the Middle and East Tennessee regions there are very scarce amounts of paleoclimate data available that extend into the Holocene past modern records. However, dendrochronological records of yearly ring thickness can also serve as important paleoclimate records, with tree rings being sensitive to changes in temperature and precipitation. Herein we have studied Eastern hemlock that were collected from Window Cliffs State Park in order to determine a paleoclimate record for eastern and central Tennessee. Counting of tree rings has led to a maximum age of 128 years, and an average age of 64 years for the Eastern hemlock in Window Cliffs State Park. Using the National Oceanic and Atmospheric Administration data we have acquired precipitation data from 1970-2018. Comparison of modern tree rings to collected precipitation values allows for a relationship between tree ring thickness and precipitation to be determined and a regression to be modeled. We then ran our tree ring thickness measurements through R-Studio to determine precipitation estimates for times where no known values existed. The reconstruction of past precipitation has allowed me to provide key information for an area of Tennessee that is currently lacking long-term climate data.