Population dynamics and conservation biology of Lupinus sulphureus ssp. kincaidii (Fabaceae)

Kincaid's lupine (Lupinus sulphureus ssp. kincaidii [Smith] Phillips) is a federally listed Threatened plant of Willamette Valley prairies. Both low reproduction, due to seed coat dormancy, and competition from invasive plants may threaten the longterm viability of this species. In separate studies, I investigated seed germination and an invasive species control technique. My objectives in the seed germination study were to test for a seed scarification requirement for germination and to identify an effective scarification treatment. I tested the effects of various durations of sulfuric acid immersion on rates of seed water imbibition, germination and emergence in three experiments, and found that sulfuric acid immersion increased germination and emergence rates and 20 min of immersion yielded optimal results. This indicated that Kincaid's lupine seeds have seed coat dormancy effectively broken by a short duration of acid scarification. My objective for the invasive plant control study was to evaluate the effects of growing season mowing on Kincaid's lupine growth and reproduction. This technique was shown effective in reducing cover of the dominant invasive plant in the studied population, tall oatgrass, but its effects on Kincaid's lupine were unknown. I tested the effects of mid-June mowing on the change in numbers of Kincaid's lupine racemes and leaves in permanent plots over one year following treatment. I found that mowing reduced the number of leaves and racemes produced the year following mowing, indicating that growing season mowing may not be a safe control for invasive species in Kincaid's lupine populations