Effects of migratory geese on plant communities of an Alaskan salt marsh
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Authors: A. Zacheis, J. W. Hupp, and R. W. Ruess
Date: 2001
Journal: Journal of Ecology
Volume: 89
Number: 1
Pages: 57-71
Summary of Methods: The effects of annual browsing by migrating snow (Anser caerulescens caerulescens) and Canadia geese (Branta canadensis) on two salt marsh vegetation communities (herb and sedge meadow ) in Upper Cook Inlet, Alaska (61° 15' N, 150° 30' W) were investigated. Paired plots (grazed and ungrazed) were installed to examine the effects of herbivory on plant species composition and litter accumulation on two salt marsh communities. Standing crop was clipped in August; species composition and fecal counts were also recorded. Additional paired plots were established to estimate takeoff or forage removed by geese. These plots were clipped after geese foraging ended (May).
Article Summary / Main Points: Although the two geese species consumed the same plants, snow geese preferred below-ground plant parts, while Canada geese consumed mostly aboveground plant parts. Fecal counts indicated that geese used the sedge meadow community slightly more than the herb meadow community. Vegetation measurements showed that grazing in the herb meadow community altered the species composition, whereas, no differences were detected in the sedge meadow community, after three years of grazing. A possible reason for the difference in the response of the two plant communities to grazing may be the greater below-ground grazing that occurred in the herb meadow. Increased below-ground grazing may be more detrimental to certain plant species; thereby altering of competitive relationships between plant species on areas preferred by snow geese.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Marshes Herbivory Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: canada goose, carex ramenskii, herbivory, plantago maritima, potentilla egedii, snow goose, triglochin maritimum
Annotation: This four year replicated study and its results are applicable to salt marsh communities and wetlands of subarctic and arctic regions. As is true for all grazing research, the results are most directly applicable to areas with similar landscapes, similar goose species, and weather conditions. Grazing was not controlled by researchers; sites were only classified as grazed or ungrazed. The lack of a control or ungrazed pasture limits the strength of generalized statements made. Examination of various levels of goose grazing intensities on plant communities is needed. Additionally, Zacheis et al. (2002, EcoScience, 9:320-331) studied the impacts of goose herbivory on plant biomass, tiller density, and tissue nitrogen concentration of salt marsh communities and Zacheis et al. (2002, Oecol, 130: 600-608) studied the impacts of lesser snow goose and Canada goose grazing and trampling on nitrogen cycling and availability in the salt marsh communities, also available in the RSIS database.
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