The snowshoe hare filter to spruce establishment in boreal Alaska

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Show simple item record Olnes, Justin 2018-06-26T23:30:20Z 2018-06-26T23:30:20Z 2018-05
dc.description Thesis (Ph.D.) University of Alaska Fairbanks, 2018 en_US
dc.description.abstract Interior Alaska is a heterogeneous landscape within the circumpolar boreal forest and is largely composed of black and white spruce (Picea mariana and P. glauca). Improving our understanding of the factors affecting patterns in spruce regeneration is particularly important because these factors ultimately contribute to shaping the boreal forest vegetation mosaic. Herbivory by snowshoe hares (Lepus americanus) is one factor that likely drives patterns in spruce establishment. The interaction between spruce and snowshoe hares provides an opportunity to study how plant-herbivore interactions can affect succession, vegetation community composition, and consequently, how herbivory influences landscape heterogeneity. I explored how herbivory by snowshoe hares alters the survival and growth of spruce seedlings across Interior Alaska's boreal forest. I hypothesized that the survival and growth rate of regenerating spruce is significantly reduced by snowshoe hare herbivory and that snowshoe hare herbivory influences the pattern of spruce establishment across time and space. To address this hypothesis, I conducted research in three distinct vegetation communities across the region: productive lowland floodplains (Chapters 1 and 2), treeline (Chapters 3 and 4), and recently burned stands of black spruce (Chapter 5). Together these five chapters reveal that snowshoe hares affect spruce establishment across much of boreal Alaska. Where and when hares are abundant, spruce can be heavily browsed, resulting in suppressed seedling growth and increased seedling mortality. The results of these studies also reveal a consistent and predictable pattern in which this plant-herbivore interaction takes place. The snowshoe hare filter acts as a 'spatially aggregating force' to spruce establishment, where the potential for optimal regeneration is highest during periods of low hare abundance and where hares are absent from the landscape. en_US
dc.description.tableofcontents Introduction -- Chapter 1. Stage-dependent effects of browsing by snowshoe hares on successional dynamics in a boreal forest ecosystem -- Chapter 2. Asynchronous recruitment dynamics of snowshoe hares and white spruce in a boreal forest -- Chapter 3. Can snowshoe hares control treeline expansions? -- Chapter 4. Functional responses of white spruce to snowshoe hare herbivory at treeline -- Chapter 5. Herbivory by snowshoe hares on regenerating black spruce foreshadows future capacity to influence postfire succession -- Conclusion. en_US
dc.language.iso en_US en_US
dc.subject Spruce en_US
dc.subject Seedlings en_US
dc.subject Effect of browsing on en_US
dc.subject Alaska en_US
dc.subject Interior Alaska en_US
dc.subject Growth en_US
dc.subject Diseases and pests en_US
dc.subject Mortality en_US
dc.subject Black spruce en_US
dc.subject Regeneration en_US
dc.subject Taigas en_US
dc.subject Ecology en_US
dc.subject Snowshoe rabbit en_US
dc.subject Food en_US
dc.title The snowshoe hare filter to spruce establishment in boreal Alaska en_US
dc.type Thesis en_US phd en_US
dc.identifier.department Department of Biology and Wildlife en_US
dc.contributor.chair Kielland, Knut
dc.contributor.committee Ruess, Roger
dc.contributor.committee Juday, Glenn
dc.contributor.committee Genet, Helene
dc.contributor.committee Mann, Daniel

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