The effects of elk (Cervus elaphus) browsing on plant growth and nitrogen (N) cycling were measured in short willow and tall willow (Salix spp.), aspen (Populus tremuloides), and upland grass/shrub in Rocky Mountain National Park using 35-year and 4-year ungulate exclosures. The effects of elk herbivory were most evident in the willow and aspen vegetation associations where browsing decreased plant height, volume, stem density, biomass of fine roots, above- and below-ground N yield, and litterfall. Direct observations and fecal pellet analysis revealed that elk were consuming N in the willow and aspen vegetation associations, where they browsed the most, and depositing that N in the conifer associations, where they rested/bedded and deposited more feces and urine. The results of this study suggest that elk have the ability to alter not only above-ground plant production but also nutrient cycling dynamics and that elk management in Rocky Mountain National Park should focus on the control of elk in the willow and aspen vegetation associations that are most impacted by browsing.
Effects of elk herbivory on vegetation and nitrogen processes
Rocky Mountain National Park