SHORT-TERM EFFECTS OF SALINITY REDUCTION AND DRAINAGE ON SALT-MARSH BIOGEOCHEMICAL CYCLING AND SPARTINA (CORDGRASS) PRODUCTION

To assess the biogeochemical effects of tidal restrictions on salt-mar sh sulfur cycling and plant growth, cores of short-form Spartina alter niflora peat were desalinated and kept either waterlogged or drained i n greenhouse microcosms, Changes in net Spartina production, and porew ater and solid phase chemistry of treated cores were compared to natur al conditions in the field collection site over a 21-mo period. Net pr oduction among treatments increased significantly in drained and water logged peat compared to field conditions during the first growing seas on. Constantly high sulfide in waterlogged cores accompanied reduced p lant growth. Aeration invigorated growth in drained cores but led to o xidization of sulfide minerals and to lowered pH. During the second gr owing season, growth declined in the drained treatment, probably becau se of acidification and decreased dissolved inorganic nitrogen. Result s are pertinent to the success of current wetland protection and resto ration activities in the coastal zone.