Evaluation of instream flow management for riparian restoration along the St. Mary River, Alberta

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Gill, Karen M.
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2007
River damming and offstream water diversion have led to the severe collapse of riparian cottonwoods along the St. Mary River. To promote cottonwood recovery, a systemic restoration approach was applied by improving critical components of the flow regime, and initial assessments showed successful seedling recruitment. This research provides a longer-term assessment by comparing sapling distribution and growth among six regulated and free-flowing river reaches. Sapling patches along the lower St. Mary were very sparse (14% of reach) compared to those along the similarly-regulated Waterton River (82%). This disparity highlighted different conceptual models of degradation and restoration trajectories. Reach mean sapling diameters were strongly positively related to average spring river levels (R2 = 0.987), indicating that growth along the lower St. Mary may be hindered by low flows. However, more variation in sapling size occurred at smaller spatial scales indicating that site-level factors like density are also important determinants of growth.
Cottonwood -- Ecology -- Alberta -- St. Mary River , Riparian restoration -- Alberta -- St. Mary River , Riparian ecology -- Alberta -- St. Mary River , St. Mary River (Alta.) , Streamflow -- Alberta -- St. Mary River , Riparian areas -- Alberta -- St. Mary River