FRESH-WATER AND SALTWATER FLOODING RESPONSE FOR WOODY SPECIES COMMON TO BARRIER-ISLAND SWALES

Flood sensitivity of five woody species common to barrier island swale habitats was quantified in a glasshouse study to examine potential me chanisms affecting observed small-scale distribution patterns. Differe ntial response to short-term (30 d duration) freshwater and saltwater flooding occurred among the five species. Only Baccharis halimifolia w as sensitive to freshwater flooding. At both low (2 and 5 g L(-1)) and mid-range (10 g L(-1)) salinity, Myrica cerifera, Pinus taeda, and B. halimifolia were more sensitive than Juniperus virginiana or Iva frut escens. At low salinity, stomatal conductance was significantly reduce d for M. cerifera, P. taeda, and B. halimifolia, although recovery occ urred and there was no mortality. At midrange salinity, all five speci es showed reduced stomatal conductance, but recovery differed. Mortali ty was highest for M. cerifera and B. halimifolia (60%), followed by P . taeda (40%), I. frutescens (25%), and J. virginiana (20%). In contra st, 100% mortality occurred for all species in high salinity treatment s of 20 and 30 g L(-1). Interspecific differences in response to flood ing may be a mechanism affecting small-scale distribution patterns of woody species in barrier island swales.