Herbivore-mediated effects on ecosystem processes in a near-Arctic salt marsh
dc.contributor.author | Person, Brian Thomas | |
dc.date.accessioned | 2015-03-02T23:22:25Z | |
dc.date.available | 2015-03-02T23:22:25Z | |
dc.date.issued | 2001-12 | |
dc.identifier.uri | http://hdl.handle.net/11122/5033 | |
dc.description | Dissertation (Ph.D.) University of Alaska Fairbanks, 2001 | en_US |
dc.description.abstract | Herbivores influence, and often regulate energy flow. I investigated interactions between herbivory and the foods on which geese rely while nesting and rearing their broods on the Yukon-Kuskokwim Delta in southwestern Alaska. In a captive Cackling Canada gosling (Branta Canadensis minima) experiment I decoupled the effects of seasonal declines in forage quality and availability on gosling development. An 11% decline in forage quality translated to goslings that were structurally smaller and 100 g lighter at 31 days of age. Forage availability had similar effects on gosling size, and the combined magnitude of these effects are similar to those observed in wild populations. I manipulated within-season grazing history of 'Carex subspathacea' swards within brood-rearing areas used by Black Brant geese (Branta bernicla nigricans). Spatial variation in forage quality and availability exceeded seasonal variation. Brant consumed over 95% of the annual aboveground production of these swards without any short- or apparent long-term effects on aboveground growth. Adding grazing pressure to 'C. ramenskii, ' or removing grazing pressure from 'C. subspathacea, ' resulted in a bi-directional shift in the morphology and nutritional characteristics of these sedges. The areal extent of 'C. subspathacea' increased 2 to 8% of the Tutakoke landscape with a concomitant decrease in 'C. ramenskii' meadows between 1991-1998. Brant have been increasing the carrying capacity of the Tutakoke River colony following a population decline in the early 1980's. The population has increased beginning in 1988, yet remains below historic numbers. Density-dependent effects on gosling growth accompanied the population increase initially. However, gosling mass has increased over the past decade due to herbivore-mediated increases in the areal extent of grazing lawns. | en_US |
dc.description.tableofcontents | Ch. 1. Cackling Canada gosling growth: separating variation in food quality from availability -- Ch. 2. Forage variation in brood-rearing areas used by pacific black brant geese on the Yukon-Kuskokwim delta, Alaska -- Ch. 3. Feedback dynamics of grazing lawns: coupling vegetation change with animal growth -- Ch. 4. Stability of a near-arctic saltmarsh: community resistance to tidal disturbance -- Conclusions -- Literature cited. | en_US |
dc.language.iso | en_US | en_US |
dc.title | Herbivore-mediated effects on ecosystem processes in a near-Arctic salt marsh | en_US |
dc.type | Dissertation | en_US |
dc.type.degree | phd | en_US |
dc.identifier.department | Department of Biology and Wildlife | en_US |
refterms.dateFOA | 2020-03-13T01:12:05Z |
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Biological Sciences
Includes WIldlife Biology and other Biological Sciences. For Marine Biology see the Marine Sciences collection.