CHLORIDE CONCENTRATIONS IN GROWTH RINGS OF TAXODIUM-DISTICHUM IN A SALTWATER-INTRUDED ESTUARY

Element analysis by proton induced X-ray emission spectroscopy was per formed on growth rings of baldcypress (Taxodium distichum) growing wit hin the Cape Fear River estuary, North Carolina, USA. Trees from estua rine reaches heavily intruded by saltwater flooding contained larger c oncentrations of chloride, bromide, and sodium than did trees from les s intruded reaches. At three intruded sites, trees nearest open water contained larger concentrations of these elements within outermost sap wood rings than did trees farther from open water and presumably flood ed less often. Chloride was translocated from outer to inner sapwood r ings of saltwater-intruded trees, resulting in larger concentrations w ithin heartwood than within the inner sapwood. Chloride concentrations along the heartwood radius were used to estimate the position of the heartwood-sapwood interface during the beginning stages of intrusion, thus permitting historical estimates of the local onset of intrusion. Element analysis of the wood of baldcypress may aid assessments of tre e growth and mortality in regions already subjected to saline flooding , and in coastal forests at risk from predicted sea level rises.