Elwha River Revegetation 2013: A Plant Performance Study

Calimpong, Crescent

Research on vegetation response post dam removal is an emerging science. Dam removal is becoming increasingly common as dams begin to become structurally unsound and reach their life capacity. This study is part of a larger plant monitoring project examining revegetation efforts following the removal of two large dams on the Elwha River in Olympic National Park. It is intended to provide project managers with data on species-specific performance in a unique environment. The data will be used to improve future restoration techniques in the newly exposed substrates. Revegetation of native woody vegetation is a key component to ecosystem restoration in the Elwha River watershed. This project will investigate plant performance of five woody species planted in the former Lake Mills reservoir. In 2013, seedlings from five woody-species were tagged and monitored over three sites between June-September 2013. Although overall plant survivorship was found to be high, survivorship was lowest in substrates made up of sand, gravel and cobble and was higher on substrates made up of silt and clay. Survivorship was affected by site and sediment moisture content. In general it was found that low gravel content at the sites related to high survivorship. Site prescription also had an effect on survivorship. Only Salix scouleriana was below 90% and the four other species all had survivorship rates over 90% across the three sites in the first year. Pinus monticola had the highest average survivorship at 98%. High overall survivorship of the plants tagged in the study show potential for the use of all five woody species in future restoration plantings in the Elwha River Watershed.

Elwha River Revegetation 2013: A Plant Performance Study

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