Functional flows: an environmental flow regime benefits riparian cottonwoods along the Waterton River, Alberta

An environmental flow regime implemented in the Waterton River, Alberta, significantly benefited riparian cottonwoods (Populus trichocarpa and P. angustifolia) by increasing minimum flows and introducing gradual recession after spring peaks. The study found that these 'functional flows' enhanced tree growth and colonization, particularly by raising the minimum discharge from 0.93 to 2.27 m³/s. Tree ring analyses revealed improved growth patterns in established trees, while spatial distributions indicated that cottonwood colonization elevated with increased flow. Historical comparisons across four dam operation intervals—pre-dam, early post-dam, drought period, and environmental flow regime—highlighted the ecological benefits of regulated flows for riparian ecosystems.

Foster, S. G., Mahoney, J. M., & Rood, S. B. (2017). Functional flows: an environmental flow regime benefits riparian cottonwoods along the Waterton River, Alberta. Restoration Ecology, 26(5), 921–932. Portico. https://doi.org/10.1111/rec.12654