The influence of geomorphology and flow regulation on riparian cottonwoods

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Willms, Chad Ryan
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005
This study investigated the influence of geomorphic context and flow regulation on cottonwood (Populus) age structure, stand size, recruitment rates, and annual radial growth patterns along the Oldman River in southern Alberta. Dendrochronological techniques were used to age trees, establish population structures, and measure annual radial growth on three reaches in differing geomorphic contexts. Cottonwoods within a narrow, 'constrained' reach were more negatively impacted by partial dewatering of the river, but responded more favorably to increased late-summer flows combined with suitable recruitment conditions than the trees within a wide, 'alluvial' reach. A positive linear relationship between early-summer peak discharge and annual radial growth was found only on the alluvial reach. However, these trees also had the slowest growth rates, likely due to competition between trees because alluvial reaches often support large, dense stands of cottonwoods. This study demonstrates the need to consider the geomorphic context when studying cottonwood responses to river regulation.
xvi, 141 leaves : ill. ; 29 cm.
Dissertations, Academic , Cottonwood -- Alberta -- Oldman River Basin , Oldman River, Alta. -- Regulation