Foraging intensity and faecal inputs are important determinants of plant community response to herbivory. We used captive adult lesser snow geese (Anser caerulescens caerulescens), which feed on both above- and below-ground plant tissues, to manipulate foraging intensity and faecal inputs to plots in a sedge meadow in spring, 1996. We measured plant and soil characteristics throughout the growing season of 1996 and in August 1997. We analysed three contrasts: grazed plots versus ungrazed controls, plots with a short period of feeding (3 goose-hours) versus plots with a long period of feeding (6 goose-hours), and grazed plots with faeces versus grazed plots without faeces. Although grazed plots had an order of magnitude higher foraging intensity than that imposed by wild geese in the marsh, there was no effect of feeding on biomass or nitrogen concentration in the dominant species, Carex ramenskii and Triglochin maritimum, after one and two growing seasons. The amount of forage removed by geese did not differ between plots grazed for long and short periods, indicating that geese were able to remove little additional biomass after 3 hours due to low availability. Therefore, the amount of biomass removed by geese was a better indicator of foraging intensity than the time geese fed on plots. The presence of faeces had no effect on biomass or nitrogen concentration in Carex ramenskii or Triglochin maritimum, or on rates of net nitrogen mineralization in soils. Thus, faeces did not appear to increase nitrogen availability for plants in this marsh, probably because faecal density was low.
|Title||Response of a subarctic salt marsh plant community to grubbing and grazing by captive lesser snow geese|
|Authors||Amy B. Zacheis, Jerry W. Hupp, Roger W. Ruess|
|Publication Subtype||Journal Article|
|Record Source||USGS Publications Warehouse|
|USGS Organization||Alaska Science Center|