Nutrient limitation of plant growth and forage quality in Arctic coastal marshes.

摘要

As their preferred salt-marsh habitats have become degraded in recent years, lesser snow geese at La Perouse Bay, Manitoba, have increasingly utilized alternative forage species and freshwater habitats. Above-ground net primary productivity in the salt marsh and the freshwater marsh is nitrogen- and phosphorus-limited respectively, based on soil analyses and fertilization experiments. This indicates that goose fecal deposits, which are rich in nitrogen, will not increase forage availability in the freshwater marsh. Declines in nitrogen and phosphorus use efficiencies of forage plants occur in fertilized plots. Preferred forage species have higher nutrient concentrations than either alternative or non-forage species, and lower carbon: nitrogen and carbon: phosphorus ratios. Overall, these results suggest that the geese are increasing obtaining forage of lower nutritional quality, which may contribute to the recorded decline in gosling size and survivorship.