Seed Bank, Survivorship, and Size Distribution of a Nebraska Population of Impatiens capensis (Balsaminaceae)

The growth and survivorship of a population of Impatiens capensis were followed in eastern Nebraska. Soil cores were taken within the population to estimate the size of the seed bank. The number of seeds in the soil remained relatively constant from April through October, with a mean of 200 seeds/m2. The seed bank size corresponded to observed seedling densities in the following years. Twenty permanent plots were established within the population and censused for three years, 1983–1985. Seedling recruitment to the population was similar in 1983 and 1984 but 30% higher in 1985. The seedling densities of plots were uncorrelated from year to year. Survivorship in 1983 followed a Deevey Type I pattern. Almost one-third of the population survived until chasmogamous reproduction. Plant size (stem height) was measured monthly on all individuals during 1983. The frequency distribution of stem height was positively skewed as long as growth was exponential. When the growth rate slowed, the distribution became more normal.