PARENT SESSION
Oral Session #16: Disturbance in diverse systems: Flooding and other. Presiding: T. Stohlgren.
Monday, August 6, 2001. 1:00 PM to 5:00 PM. Hall of Ideas G.

Salt spray, fire, and water availability: complex interactions in managed coastal heathland plant communities.

Griffiths, Megan¹, Orians, Colin¹, ¹

ABSTRACT- Coastal sandplain heathlands are disturbance-dependent communities that occur in the northeastern United States. Without disturbance these dwarf shrublands become overgrown by trees, so many heathlands are actively managed with prescribed fire. Previous research has demonstrated that salt spray plays a role in maintaining the composition and stature of these communities in areas close to the ocean. We hypothesized that fire, by stimulating new growth in heathland plants, would increase the effects of salt spray because young leaves are more susceptible to damage. We carried out a manipulative experiment on Martha's Vineyard, Massachusetts to test the interactive effects of fire and salt spray. Quadrats were established in burned and unburned areas following a prescribed fire and randomly assigned a control or salt spray treatment. As expected, following ten weeks of manipulation we found that salt spray increased plant water stress, increased leaf necrosis, and inhibited shoot elongation. Contrary to our hypothesis, fire did not increase the negative effects of salt spray. In both salt spray and control treatments, plants growing in burned areas showed less water stress and leaf necrosis than those in unburned areas. This may be due to increased water availability in the burned area because of less evapotranspiration. These results suggest that water availability mediates the effects of salt spray and that prescribed fire, while effective as a management tool, actually decreases the effects of salt spray.

KEY WORDS: salt spray, fire, water availability, coastal heathlands