WWRC 91-02
Response of Montane Meadow Vegetation after Two Years of Streamflow Augmentations
Abstract
Changes in montane meadow vegetation were examined in a previously ephemeral drainage that received flow
augmentation as a mitigation measure for a transbasin diversion in southeastern Wyoming. After two years of elevated
surface and groundwater levels, the herbaceous vegetation shifted toward more water-tolerant species. Dry meadows
became like moist meadows, moist meadows became more like moist-wet meadows, and moist-wet meadows became
more like wet meadows. Sedge (Carex spp.) biomass increased from 337 to 456 g m-1 in the wet meadows, while tufted
hairgrass (Deschampsia cespitosa) biomass decreased from 18 to 3 g m-2 in the moist-wet meadows. Slimstem reedgrass
(Calamagrostis neglecta) remained unchanged in the meadows with shallow standing water, but increased from 17 to 88
stems m-2 in the dry meadows with an elevated water table. Bare ground also increased as much as 31 per cent in the
meadows without a defined drainage channel.
KEY WORDS Flow augmentation Riparian vegetation Mitigation Flooding Carex Deschampsia Calamagrostis
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