Germination Ecology of Some Common Forest Herbs in Yellowstone National Park, Wyoming, U.S.A.

Abstract

Seed viability and dormancy mechanisms were investigated in seven herbaceous plant species and one low shrub species common in the first few years of postfire succession in subalpine forests of Yellowstone National Park, Wyoming, U.S.A. Seeds of Epilobium angustifolium (fireweed) had rapid and high percent germination in both the fall and spring after seeds were collected. Seeds of Lupinus argenteus (lupine) germinated well after several months of warm or cold storage, and the rate of germination but not the final percent germination was increased by scarification. Seeds of Arnica cordifolia (heartleaf arnica) were nearly all nonviable; only one seed germinated out of 650 tested, and no seedlings were observed in the field. Small sample sizes limited the scope of testing of the other species, but both Cirsium arvense (Canada thistle) and Epilobium ciliatum (willow-herb) showed moderate to high germination in the spring after several months of storage, Hieracium albiflorum (hawkweed) germinated better in the fall than in the following spring, Vaccinium scoparium (dwarf huckleberry) seeds germinated in the fall 1 mo after collection, and seeds of Antennaria racemosa (pussytoes) failed to germinate when tested in the fall 1 mo after collection. These results, combined with field studies, indicate that large-scale fires provide opportunities for recruitment of new genetic individuals, increased genetic diversity, and colonization of new patches on the forest floor in several species, including Epilobium angustifolium, Lupinus argenteus, Hieracium albiflorum, and Cirsium arvense. These effects are likely to persist for many decades in these long-lived perennial plant species.