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On the Yukon-Kuskokwim delta, Alaska, Person et al. investigated the effects of grazing by black brant geese (Branta bernicla nigricans) on Carex subspathacea lawns. Results showed no effect of grazing on net above-ground primary productivity over a wide range of natural grazing intensities at the landscape level. No differences in forage quality, net primary productivity, or response of C. subspathacea growth rates to grazing pressures could be detected between colonies. This suggests that goose grazing does not have deleterious effects on C. subspathacea in this ecosystem. Spatial variation in N concentrations, availability of forage per sampled area, and quality of vegetation was greater than seasonal variation in these forage characteristics. According to Person et al. this finding is profound, given gosling growth and recruitment rates have been shown to be sensitive to relatively minor seasonal decreases in forage quality and availability, and it is likely that gosling growth rates vary spatially.

This study investigated the effects of grazing by black brant geese (Branta bernicla nigricans) on Carex subspathacea lawns on the Yukon-Kuskokwim delta, Alaska. Variations in growth and forage quality in both grazed and temporarily exclosed sites were compared to determine responses of Carex subspathacea at landscape scales, within two nesting colonies of different population dynamics. Landscapes differed in forage quality, grazing patterns, and in the effect grazing had on Carex forage characteristics. Grazing had no affect on net above-ground primary production (NAPP). There was no difference between the two colonies with respect to the response of Carex growth rates, NAPP, or forage quality in response to grazing pressures. Geese grazing apparently does not have deleterious effects on the Carex subspathacea ecosystem.