The role of salt spray in maintaining coastal sandplain heathland plant communities.
GRIFFITHS, M.E.* and C.M.ORIANS
Tufts University, Medford, MA 02155, USA 1
Coastal sandplain heathlands are disturbance-dependent communities that occur in the northeastern United States. It is hypothesized that salt spray plays a role in maintaining heathland communities as dwarf shrublands. We investigated the effects of salt spray in heathlands on Martha's Vineyard, Massachusetts, with the following goals: (1) to determine spatial patterns of salt spray accumulation in heathlands and (2) to identify a mechanism by which salt spray might maintain these plant communities. We found that salt spray accumulation rate decreased in heathlands as distance from the ocean increased, while the height of heathland plant species increased as distance from the ocean increased. Based on results from manipulative experiments, we propose that this change in plant height could be attributed to the effects of salt spray. We subjected plants to three levels of salt spray treatment: none, moderate (equivalent to salt spray accumulation during normal conditions at 25 meters from the ocean), and high (equivalent to salt spray accumulation during hurricane conditions at 25 meters from the ocean). Using these treatments, we found that xylem pressure potential (-MPa) became more negative in heathland plant species as salt spray levels were increased. We also found decreased shoot growth, decreased leaf production, and increased leaf necrosis with increased salt spray levels. The effects of salt spray on heathland plant physiology may provide a mechanism by which this abiotic factor maintains heathland plant communities.
Keywords: salt spray, heathlands, disturbance
This abstract is being presented at: 11:15 AM in session:
Oral Session #45: Water Relations in Shrubs and Annuals.