On 21 September 1989 Hurricane Hugo struck the South Carolina Coast, causing a storm surge of 5 to 8 m. At the North Inler Long-Term Ecological Research site, this salt water surge inundated the forest > 150 m from the marsh edge with over 3 m of salt water. Two days after the storm, water standing on the forest floor had an average salinity of 21 parts per thousand. Significant changes in forest soils occurred. Two weeks prior to the storm, soil total ionic conrent (TIC) ranged from 1.6 to 3.4 meq/liter. Two days after the storm, TlC was 227 to 778 meq/liter or 2.3 to 12 parts per thousand salinity. Four months after IIugo, TIC remained elevated by 58 to 142 times. Dominant ions (Na.1 and Cl-) in soil solution increased in importance in the overall ionic budget. After Hugo, Na1 and Cl- accounted for > 76 to 81 percent (Bh and A horizons, respectively) of the ion balance: in 1986 Na+ and Cl- accounted for 52 to 72 percent (mineral soil and Bh horizons, respectively). Ammonium and hydrogen ion mobilization accompanied increased ionic strength of soil solutions. Following the storm, ammonium in soil solution from the A horizon increased from < 0.1-mu-eq/l (annual average for 1986) to a maximum of 178-mu-eq/l 5 d after the storm. Increased ammonium concentrations were detected for mineral soil solution (5.6-fold increase) and B horizon soil solution (115-fold increase) over the 1986 concentrations. Ammonium concentrations in water standing on the forest floor reached 1764-mu-eq/l with soil solutions in the A horizon (1000-mu-eq/l) and Bh horizon (557-mu-eq/l) increasing concurrently. Maximum mineral soil solution concentrations were detected 2 mo after the storm at 386-mu-eq/l. Hurricanes with salt inundation decrease nutrient use efficiency through the rapid loss of leaves without reabsorption of the nitrogen, decrease nitrogen retention through decreased uptake potential by vegetation and microbial immobilization, and decrease physiochemical retention mechanisms (absorption of ammonium ion on exchange sites) by swamping exchange sites with salt catious.
