The Effects of Grazing by Lesser Snow Geese on the Vegetation of a Sub-Arctic Salt Marsh

Cargill, S; Jefferies, R

(1) Net above-ground primary production of ungrazed marsh vegetation dominated by Puccinellia phryganodes and Carex subspathacea was approximately 100 g m -2 year -1 in 1979 and 50-60 g m -2 year -1 in 1980. (2) Grazing by lesser snow geese significantly increased net above-ground primary production (NAPP). In 1979 NAPP of a grazed sward containing both Puccinellia and Carex was approximately 135 g m -2 year -1 . Corresponding figures in 1980 were 99 g m -2 year -1 for grazed Puccinellia and 92 g m -2 year -1 for grazed Carex. (3) Productivity of grazed and ungrazed sites was similar early in the growing season. After mid-July productivity continued at a similar rate on grazed sites, but declined on ungrazed sites. (4) Geese consumed approximately 80primary production of the grazed marsh. (5) Grazed plants of both species had significantly higher total nitrogen concentrations than did ungrazed plants, and maintained high nitrogen levels until late in the growing season. (6) Grazed and ungrazed plots did not differ significantly with respect to standing crops of dead above-ground biomass or below-ground biomass. (7) It is suggested that grazing may stimulate primary production by accelerating nitrogen cycling in the marsh ecosystem. Other possible effects of grazing on plant growth are discussed.

The Effects of Grazing by Lesser Snow Geese on the Vegetation of a Sub-Arctic Salt Marsh

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