Lesser snow geese and the nitrogen economy of a grazed salt marsh
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Authors: D. R. Bazely, and R. L. Jefferies
Date: 1989
Journal: Journal of Ecology
Volume: 77
Number: 1
Pages: 24-34
Summary of Methods: To determine if nitrogen fixation replaces at least some of the incorporated nitrogen from forage plants into the tissue of lesser snow geese that graze on the tidal flats at La Perouse Bay, Manitoba (58� 04� N, 94� 03� W), acetylene-reduction technique was used to measure nitrogenase activity of surface sediments of a subarctic salt marsh. Nitrogenase activity was measured on two grazed and ungrazed sites. The first ungrazed site was excluded from grazing for four years and the second site has not been grazed for three years.
Article Summary / Main Points: Nitrogenase activity was consistently higher in grazed plots compared with rates in ungrazed plots. Estimates of total amounts of nitrogen fixed in grazed plots between June and September were approximately 1 g N m��. Levels of exchangeable and soluble ammonium ions were low throughout most of the growing season, but higher levels were detected in early spring and fall, particularly in grazed plots. Grazed sites unlike ungrazed swards, where plant litter accumulated, mats of cyanobacteria were present on the surface of sediments between individual plants. The amount of nitrogen fixed was greater on grazed sites than ungrazed sites.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Riparian zones Rangelands Geese
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: lesser snow geese, chen caerulescens caerulescens, acetylene-reduction, nitrogenase activity, salt marsh, nitrogen cycle, cyanobacteria
Annotation: This study has limited applicability to the range managers in the western United States. This study only had one exclosure established each year, limiting the area of influence of these findings.
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