Study

Increasing river flow expands riparian habitat: influences of flow augmentation on channel form, riparian vegetation and birds along the Little Bow River, Alberta

  • Published source details Hillman E.J., Bigelow S.G., Samuelson G.M., Herzog P.W., Hurly T.A. & Rood S.B. (2016) Increasing river flow expands riparian habitat: influences of flow augmentation on channel form, riparian vegetation and birds along the Little Bow River, Alberta. River Research and Applications, 32, 1687-1697.

Actions

This study is summarised as evidence for the following.

Action Category

Raise water level to restore/create freshwater marshes from other land uses

Action Link
Marsh and Swamp Conservation
  1. Raise water level to restore/create freshwater marshes from other land uses

    A before-and-after study in 2000–2010 along a river in Alberta, Canada (Hillman et al. 2016) found that artificially increasing flow by diverting water from another river had no significant effect on the coverage of broadleaf cattail Typha latifolia beds, but reduced the coverage of grass-like plants and increased coverage of shrubs across the whole riparian zone. For all data and statistical models, see original paper. After six years of increased flows, the proportion of the riparian zone covered by cattail beds was not significantly different to the proportion four years before flows were increased – although there was a trend towards higher cattail coverage. Across the entire riparian zone (i.e. including wetland and upland areas), coverage of other grass-like plants (grasses, sedges and rushes) was significantly lower after flows were increased than before. Coverage of woody plants (true willows Salix spp. and wolf willow Eleagnus commutata) was significantly higher after flows were increased than before. Methods: In 2004, a canal linking the Highwood River to the Little Bow River was upgraded to increase its flow capacity. This increased summer discharge in the Little Bow River. Broad riparian vegetation types were mapped using aerial photographs taken in 2000 and 2010. Cattle grazing was locally intensive.

    (Summarised by: Nigel Taylor)

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