USING STABLE ISOTOPES (δ13C AND δ18O) IN TREE RINGS OF THE LOBLOLLY PINE (PINUS TAEDA) TO DETECT PALEO-HURRICANE STORM SURGES

Forecasted increases in hurricane frequency and strength threaten to drastically affect coastal populations and environments. To accurately model climate change driven effects on hurricane frequency, a comprehensive record of paleo-hurricane frequency is vital. One possible tool to create such a record lies in the stable isotope ratios of alpha-cellulose in tree rings. Our study organism, the Loblolly Pine (<i>Pinus taeda</i>), ranges from northern Florida to southern Maryland. As such, modeling techniques developed in this species have the potential to generate a record of paleo-hurricane frequency for much of the US eastern coast. We are assessing if an increase in soil salinity via storm surges manifests itself as a change in integrated water-use efficiency, as measured by &delta;¹³C. We are also assessing if hurricane associated precipitation signatures appear as changes in &delta;¹⁸O. Preliminary results suggest that carbon isotopes do clearly respond to changes in soil water salinity, as trees sampled from sites with different soil water salinity exhibited a clear response in both their needles (high salinity = -30.1 ± 0.6 ‰ and low salinity = -32.2 ± 0.8 ‰) and stem alpha cellulose (high salinity = -26.0 ± 0.9 ‰ and low salinity = -27.4 ± 0.6 ‰). The high-resolution tree ring data (earlywood/latewood) are not straightforward to interpret and more data are needed to adequately assess the Loblolly Pine as a high-resolution paleo-hurricane proxy.