The effects of grazing by greater snow geese on the vegetation of tidal marshes in the St Lawrence estuary
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Authors: J. F. Giroux, and J. Bedard
Date: 1987
Journal: Journal of Applied Ecology
Volume: 24
Number: 3
Pages: 773-788
Summary of Methods: Distribution and grazing effects of greater snow geese (Chen caerulescens atlantica) on productivity of salt marsh species was studied at Montmagny (47° 00' N, 70° 35' W) and Cap St. Ignace (47° 02' N, 70° 28' W), Quebec. Three experiments were conducted to compare net above ground primary production (NAPP) and net below ground primary production (NBPP) between grazed and ungrazed sites, changes in NAPP of all plant species and geese use of sanctuaries and adjacent areas during spring and fall staging. Plants were clipped and soil core samples were taken during the first year to determine NAPP and NBPP at Cap St. Ignace, but non-destructive methods were utilized in the second year. In addition to biomass measurements, seed production was estimated at Montmagny. Goose use was determined through daily observations made from elevated stands at observation zones located within and outside of both sanctuaries.
Article Summary / Main Points: In autumn, geese foraged primarily within sanctuaries, whereas in spring, they were more dispersed and made greater use of adjacent marshes. The sanctuary at Montmagny was utilized more than twice the level of Cap St. Ignace. There was no difference in total NAPP between grazed and ungrazed plots at Cap St. Ignace. After one year of exclusion at Cap St. Ignace, NAPP of S. americanus increased. NAPP of S. americanus, S. torreyi and Elocharis increased with removal of grazing throughout the duration of the study in the Montmagny sanctuary S. americanus produced more shoots in the ungrazed treatments at both Cap St. Ignace and Montmagny, than in the grazed treatments. The number of seeds per inflorescence did not vary between grazing treatments though the number of inflorescences produced was greater outside the sanctuary at Montmagny.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: greater snow geese, chen caerulescens atlantica, tidal marshes, scirpus americanus, forage, net above-ground primary production (napp), below-ground biomass
Annotation: While grazing and grubbing by snow geese can be detrimental and damaging to the Scirpus marshes, the marshes appear to be resilient to grazing and no irreversible trends in composition or production were detected. Author suggests rotating sanctuaries as a potential management consideration to allow marshes to recover. The results from this study have limited applicability to rangelands in the Intermountain West region.
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