White-tailed deer florivory influences the population demography of Polemonium vanbruntiae

Abstract

White-tailed deer (Odocoileus virginianus Zimm.) may influence reproduction and dispersal of plant species through herbivory of flowering stems. We examined the effects of white-tailed deer herbivory on the seed production of Bog Jacob’s-ladder (Polemonium vanbruntiae Britt.), a facultative wetland plant considered rare throughout its range. We monitored life-stage transitions in 10 local populations in Canaan Valley, West Virginia, from 2005–2007, modeled the population growth rates, and estimated extinction rates for each population accounting for the loss of seeds due to white-tailed deer florivory. Seed loss due to consumption of flowering stems ranged between 0 and 96% within individual populations ( = 52 ± 4.5%). A significant difference in seed production occurred between browsed ( = 0.6 ± 0.18) and unbrowsed ( = 24 ± 1.43) plants. Predicted seed loss was significantly higher ( = 57 ± 19%), where no hunting was allowed, than where deer hunting occurred ( = 40 ± 18%). The observed levels of white-tailed deer florivory have the potential to significantly reduce population growth rates (p < 0.0001). Although white-tailed deer florivory may not increase local population extinction rates, loss of seed production may result in a loss of the potential for colonization of new patches.