Reintroduction of Lupinus sulphureus ssp. kincaidii (Kincaid’s lupine) to Dragonfly Bend in the West Eugene Wetlands
In the Willamette Valley, Kincaid’s lupine serves as the primary larval host plant for the endangered Fender’s blue butterfly, making conservation of the lupine a common strategy for the success
In the Willamette Valley, Kincaid’s lupine serves as the primary larval host plant for the endangered Fender’s blue butterfly, making conservation of the lupine a common strategy for the success of both species. The objective of this project was to introduce Kincaid’s lupine to Dragonfly Bend, a wetland mitigation site located in the West Eugene Wetlands, and managed by the City of Eugene and Eugene District Bureau of Land Management. This report summarizes the results of three years of reintroduction efforts at this site.
Survival of both transplanted and seeded lupine were very low at Dragonfly Bend. In 2007 10.3 and 2.5% (north and south areas, respectively) of transplanted individuals and 1.2% of seeds survived (no difference between areas was found in seed plots). By 2008 no transplants or seedlings could be found. However, in 2009, we found four individuals in the seeded plots.
There are two primary issues that may affect the long-term success of Kincaid’s lupine reintroduction at Dragonfly Bend. The first is the heavy clay that is present below the compost in the mounded habitat. Due to their long taproots, lupine plugs must be planted relatively deep in the soil. It is possible that the roots of the plugs planted in 2007 were damaged as the clay dried, causing high mortality. In contrast, it is possible that as the roots of seeded plants grew, they were able to find more habitable cracks and pockets as they reached the clay layer. We recommend that all future reintroduction efforts use seeds instead of transplants. The second management issue at this site is competition by other seeded native plants. Although areas around lupine plants were weeded in spring 2009, there was still significant shading by neighboring plants. The level of underground competition is unknown, but based on the high amount of aboveground biomass, we expect that it is high. Continued weeding will be necessary for the survival of lupine at this site.