The effect of environmental variation on the distribution, reproduction, and demography of a rare understory plant.

Conservation decisions rely on accurate information about the environmental requirements, distribution, and demography of endangered species. Actaea elata is a globally rare, perennial herb found in a range of forest stand types. I assessed the effects of microhabitat and habitat variation on the distribution and reproduction of A. elata individuals from populations in contrasting forest stands, and investigated their demography. Reproduction was more likely to occur in higher light conditions, such as canopy gaps or broadleaved (vs. coniferous) stands. All populations of A. elata were either stable or in decline; however the causes varied. Specifically, low recruitment occurred in the low-light, coniferous stand, while higher mortality and retrogression to previous stages occurred in the open broadleaved stand where herbivory was common. Thus, conservation decisions for A. elata should be tailored to differing habitats, and might include prescriptions to increase light to some degree and recruitment or exclude herbivores.