The potential impact of herbivores on the susceptibility of the marsh plant Sagittaria lancifolia to saltwater intrusion in coastal wetlands
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Authors: J. B. Grace, and M. A. Ford
Date: 1996
Journal: Estuaries and Coasts
Volume: 19
Number: 1
Pages: 13-20
Summary of Methods: Simulated flooding and herbivory were used at the Southeastern Louisiana University Turtle Cove Environmental Research Station to determine the effects of hurricanes and grazing herbivores (nutria) on Sagittaria lancifolia populations. Plots received one of three treatments or combinations of those treatments (un-clipped, clipped, flooded with 15% salt water for one week at one of two depths - 5 or 20 cm, flooded with marsh water for one week at one of two depths - 5 or 20 cm and prolonged flooding by marsh water for the balance of study). Treatments were applied in November, and plants were harvested and dried the following June. Soil conductivity was measured continuously, and soil pH and Eh was measured at the end of the study.
Article Summary / Main Points: Two treatments, clipping plus salt water flooding followed by marsh water flooding, and clipping plus salt water flooding followed by prolonged marsh water flooding decreased biomass. Ambient marsh water had a salinity of 3%, while sites flooded with15% salt water at 5 cm reached 8.5%-9.2%, and sites flooded with15% salt water at 20 cm reached a salinity of 11.0%-11.7% salinity. Soils that had prolonged flooding were less acidic (higher soil pH) than non-flooded soils. Soil conductivity declined after the removal of salt pulse and returned to normal for all treatments by the end of the experiment the following June.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 131A Southern Mississippi River Alluvium
Agrovoc Control Words: Riparian zones Grazing Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: sagittaria lancifolia, herbivory, coastal marshes, grazing, saltwater intrusion, nutria, myocastor coypus, tolerance
Annotation: Study shows that the greatest threat faced by S. lancifolia would be a culmination of extreme herbivory in conjunction with a tropical storm surge. The threat posed by growing numbers of introduced nutria in the swamp warrants further monitoring. The applicability of these results if limited outside gulf coast swamps.
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