Selective herbivory and plant community structure in a mid-Atlantic salt marsh
-
-
Authors: C. E. Furbish, and M. Albano
Date: 1994
Journal: Ecology
Volume: 75
Number: 4
Pages: 1015-1022
Summary of Methods: The effects of feral horse herbivory on two salt marsh plants were investigated in a series of trials on Assateague Island, Maryland from May 1998 to May 1999. Tidal flooding and height and surface and subsurface water salinity were measured during high and low tide during the spring at four Spartina alterniflora and four Distichlis spicata patches. Redox potentials were monitored at three sites during the year. Every other month during the year-long study, percent cover and percent utilized stems were measured. A three day diet selection trial was conducted with five corralled horses. In addition, each month during the study, twenty wild horse fecal samples from each patch were examined for the presence of D. spicata. The three small plots within an exclosure received no treatment, clipping S. alterniflora with trampling, or clipping S. alterniflora and D. spicata with trampling. Percent cover and stem density measurements were conducted pre-treatment, three times within the year, and post-treatment.
Article Summary / Main Points: Tidal flooding and height, water salinity, and redox potentials were similar between the S. alterniflora and D. spicata patches. S. alterniflora was preferred over the D. spicata during the diet trial and no D. spicata was found in the field study fecal samples. Clipping of both species reduced the cover of both grasses, but did not reduce D. spicata density. D. spicata cover increased when S. alterniflora was preferentially clipped. The results suggest that abiotic factors are not influencing the increase of D. spicata in the salt marshes, but grazing pressure on S. alterniflora allowed D. spicata to increase cover.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 153B Tidewater Area
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Documented Case History
Keywords: assateague island, distichlis spicata, spartina alterniflora, halophytes, herbivory, plant competition, salt marsh ecology, zonation
Annotation: Releasing certain plants from competition through selective grazing by herbivores occurs in many vegetation types. However, the results of this study are applicable to other salt marshes with these grass species and feral horses. The diet of these horses has evolved over time for vegetation on this particular island. Additional years of study would also help to explain long term responses from herbivory.
-
Get article
Cite article with DOI
-