Foraging by geese, isostatic uplift and asymmetry in the development of salt-marsh plant communities
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Authors: D. S. Hik, R. L. Jefferies, and A. R. E. Sinclair
Date: 1992
Journal: Journal of Ecology
Volume: 80
Number: 3
Pages: 395-406
Summary of Methods: The response of the salt-marsh plant communities to grazing by lesser snow geese (Chen caerulescens caerulescens) and isostatic uplift at La Perouse Bay, Manitoba, (58˚ 04’ N, 94˚ 30’ W) was examined on short- and long-term scales using a multiple state model. Data presented here include the results from a current study and also previously published floristic and biomass data. These two annotations can be found in RSIS and are both by Jefferies (1988). Changes in vegetative composition relative to isostatic uplift was measured in three stable vegetative states: ungrazed swards dominated by Calamagrostis–Festuca (state K), grazed Calamagrostis–Festuca (state C), and grazed Puccinella-Carex (state A). Floristic composition and biomass inside and outside exclosures were measured (1986-1987) by removing sections of turf and clipping biomass at ground level.
Article Summary / Main Points: Under protection from grazing, the vegetation in the lower marsh exclosure remained a pure sward of Puccinellia because it was not influenced by water uplift, while the second exclosure in the upper marsh’s Puccinella and Carex plant community was replaced by Calamagrostis and dicotyledonous species. The balance of these results was determined from previous studies whose details were not included in the above summary of methods. Production was similar in grazed sites and adjacent control swards (state A). Growth rate rapidly increased when swards were protected from grazing in state A. Biomass production decreased during the second year of sampling resulting in a transition from state A to state K; although state K contributed only 2% to total biomass. Reintroduction of goose grazing to state K (July 1990) resulted in a shift to state C. Changes in species composition from state A to the state C occurred in presence of grazing as a result of isostatic uplift, however, grazing delays this shift.
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: arctic salt-marshes, edaphic processes, grazing lawns, lesser snow goose, multiple-state communities
Annotation: The results from this study have limited applicability for most rangeland grazing situations, but can be applied to salt-marshlands and wetlands that are grazed by geese with and without isotonic uplift. This research illustrates the change from one vegetation state to other vegetation state.
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