In forests, the kind and amount of overstory vegetation is influenced by both the tree canopy and the season and intensity of ungulate herbivory. As tree canopy increases, the trees are able to outcompete understory vegetation for available moisture and soil nutrients. Shading is also important in thicker overstories. Additionally, grazing animals like mule deer, elk and cattle consume understory vegetation, sometimes to the extent that the plants drop out of the understory. This understory vegetation is important to a variety of small mammals and birds. Therefore, the interaction of overstory density and grazing pressure is important to maintaining biodiversity at the landscape level in forested ecosystems.
This research project is just beginning. We will be observing and evaluating the influence of various logging methods and the influence of grazing animals on the composition and production of forest understory vegetation.
For more information about this research contact Marty Vavra.