Effects of simulated feeding by snow geese on Scirpus americanus rhizomes
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Authors: J. F. Giroux, and J. Bedard
Date: 1987
Journal: Oecologia
Volume: 74
Number: 1
Pages: 137-143
Summary of Methods: Over two years a series of experiments were conducted at Cap St. Ignace, Quebec (47° 02' N, 70° 29' W) to examine the effects of underground biomass herbivory on mortality, net above ground biomass and below ground biomass of Scirpus americanus. Rhizomes were dug, washed, sorted, assigned to treatments, and planted in metal basins located in the salt marsh that were free of non-test rhizomes. Number of shoots, buds, inflorescences, rhizome length and production were recorded. Intensity of rhizome removal was simulated by clipping rhizomes to various lengths (year one 25, 50 or 75%; year two 5, 10, 15, 20, and 25%). Grazing intensity was tested by correlating the number of bites (1, 2, 3) to percentage of rhizome removal (25, 50 or 75%). Rhizomes were collected, clipped and planted in prepared basins. The effect of bud removal on S. americanus was investigated by removing 1, 2, or 3 buds while keeping the length of rhizome removed constant for all three treatments. Rhizomes were treated and planted in plots.
Article Summary / Main Points: Simulated Greater Snow Geese feeding on rhizomes of Scirpus americanus negatively affected plant production. Less than 15% of underground biomass removal had no effect on S. americanus, though removal of 15-35% of underground biomass resulted in a decreased number of shoots being observed one month after treatment, and removal of >35% resulted in decreased number of shoots two weeks after treatment. Removal of underground biomass negatively affected final rhizome length, total above- and below- ground biomass production, and final number of buds and plant growth rates. Results indicate one "bite" had little effect on rhizome growth, while two bites decreased rhizome growth and three bites resulted in no subsequent decrease from the two bite treatment. Removal of one bud did not affect production, while the removal of two and three buds reduced above ground (41%, 63%) and below ground- production (60%, 67%), respectively.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Riparian zones Grazing Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: primary production, simulated feeding, rhizomes, biomass, scirpus americanus, coastal marsh, chen caerulescens atlantica
Annotation: Study has limited applicability to West rangelands, but is applicable to arctic marshes with caution. Test basins had less rhizome density than observed in natural populations, potentially decreasing the effect of competition on survival of damaged rhizomes.
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