Effect of grazing by greater snow geese on the production of graminoids at an arctic site (Bylot Island, NWT, Canada)
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Authors: G. Gauthier, R. J. Hughes, A. Reed, J. Beaulieu, and L. Rochefort
Date: 1995
Journal: Journal of Ecology
Volume: 83
Number: 4
Pages: 653-664
Summary of Methods: A three year study at Bylot Island (73° N, 80° W), examined the response of sedges and grasses to summer grazing by greater snow geese (Chen caerulescens atlantica). Above-ground biomass and net above-ground primary production in grazed (no exclosure), ungrazed (long-term exclosure) and regrowth (short-term exclosure) areas was measured over a three year period. To simulate the ungrazed treatment, exclosures were constructed annually in mid-June on breeding grounds. Additional exclosures were constructed in mid-July through mid-August to analyze the regrowth treatment. Vegetation measurements were taken bi-weekly from mid-June to mid-August. Intensity of use was calculated by conducting fecal counts near each exclosure.
Article Summary / Main Points: Utilization rates by brood rearing geese increased every year. Grazed and ungrazed areas experienced no difference in biomass production prior to beginning of grazing each year, but biomass was less on grazed sites from mid-July through mid-August. Over all 3 years, net aboveground primary production (NAPP) in grazed areas was lower than NAPP of the ungrazed areas at the end of the summer. It was estimated that geese consumed 65-113% of the cumulative NAPP of Eriophorum scheuchzeri, and 30-78% of the cumulative NAPP of Dupontia fisheri. Dupontia was less palatable than eriophorum thus, as grazing intensity increased, consumption of Dupontia increased. Nitrogen content of grazed shoots was higher than ungrazed shoots. Indicating that forage quality is higher on grazed sites than ungrazed sites.
Vegetation Types: Tundra
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: dupontia fisheri, eriophorum scheuchzeri, grass, nitrogen, polygon fens, sedge, arctic
Annotation: Study was designed to assess the effects of grazing on plant production so care should be taken when making generalizations regarding the impacts of goose grazing at the landscape level. NAPP at Bylot Island is lower in areas that experience grazing than in areas that had no grazing, this is opposite of what has been observed at La Perouse Bay. Possible reasons for Bylot Island having lower NAPP could be that grazing occurs later in the growing season at Bylot, or could be due to rapid uptake of fecal nutrients by mosses found on the island. In addition, no evidence of over compensation in Dupontia or Eriophorum was observed.
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