RESPONSE OF BALDCYPRESS AND LOBLOLLY-PINE SEEDLINGS TO SHORT-TERM SALTWATER FLOODING

Six-month-old and eighteen-month-old baldcypress and loblolly pine seedlings were subjected to a simulated saltwater surge (salinity = 30 parts per thousand) for 0 to 5 days followed by flushing and daily watering with fresh water. Growth, biomass, and survival were monitored for 9 weeks following inundation. Six-month-old seedlings of both species were extremely susceptible to saltwater flooding, and survival percentages declined rapidly beyond 1 day of saltwater flooding. Eighteen-month-old seedlings were better able to survive saltwater flooding, with some pine seedlings surviving up to 3 days of flooding and some baldcypress up to 4 days of flooding. The general response of surviving baldcypress seedlings to saltwater flooding was to die back and then resprout. For loblolly pine, growth was slowed until a threshold level was reached, at which point the seedlings died. There was a direct correlation between duration of saltwater flooding and diameter growth with six-month-old seedlings but not with the eighteen-month-old seedlings. There was a steady decline in diameter with increasing days of saltwater flooding in surviving eighteen-month-old baldcypress, whereas eighteen-month-old loblolly seedlings showed some diameter growth even after 3 days of saltwater flooding. Root:shoot biomass partitioning in surviving seedlings was not appreciably affected by treatments.