Counting growing individuals of an annual or biennial plant to assess long-term population dynamics without considering the seed bank may not provide an adequate assessment of a species' viability. To support the understanding of the viability and population dynamics of Lepidium papilliferum (A. Nelson & Macbride) (slickspot peppergrass), a field and greenhouse study was undertaken. Lepidium papilliferum grows primarily in slick spots in southwestern Idaho. Slick spots are small, moist, crusted or smooth-surfaced areas of western United States basins. The slick spots sampled contained both seed-producing flowering plants and biennial rosettes. In the seed bank, seeds were found in the soil profile to a depth of 15 cm both within and outside the slick spots. In most locations, seeds were more abundant in the upper 5 cm of soil, and those seeds had a greater germination percentage and rate than those from lower depths. Knowledge about the viability of the seed bank allows for assessing the fluctuations in annual plant-count numbers. The plant counts from 5 years of data were found to be strongly correlated to spring climatic conditions. These correlations help explain seasonal expansion and contraction of population numbers. This ability to assess annual population data counts provides better insight into long-term increases or decreases of population numbers and species stability.
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