Life's more than one niche: demographic constraints on northern black spruce range expansion in Yukon, Canada

Goodwin, Katie (2019) Life's more than one niche: demographic constraints on northern black spruce range expansion in Yukon, Canada. Masters thesis, Memorial University of Newfoundland.

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Species’ distributions are often characterized by the species’ niche represented in geographic space. Species’ niches can be divided demographically, resulting in multiple demographic niches with unique dimensions. This approach determines which life stages have either the narrowest niche breadth or the least available niche space at the range edge, and thus act as key demographic hurdles on range expansion. We quantified microsites inhabited by different life stages of black spruce (Picea mariana) at subarctic treeline in Yukon, Canada to characterize demographic niche breadth and assess how available niche space changed towards the range edge. We found that restricted suitable emergent niche space and viable seed availability towards the range limit were the overwhelmingly main limiting demographic bottlenecks on northern range expansion. Our findings suggest that demographic niches can identify life stage specific hurdles to range expansion, contributing to our understanding of how species’ distributions will respond to climate change.

Item Type: Thesis (Masters)
Item ID: 14089
Additional Information: Includes bibliographical references.
Keywords: species’ distributions; treeline; demographic niches; ontogenetic niche shifts; seed production; seedling emergence; microsite suitability; subarctic; regeneration niche; Picea mariana
Department(s): Humanities and Social Sciences, Faculty of > Geography
Date: October 2019
Date Type: Submission
Library of Congress Subject Heading: Black spruce--Yukon--Geographical distribution.

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