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Abstract
A controlled, manipulative study utilizing exclosures was initiated in 1994 by Zeigenfuss and others (2002) to assess the effects of prescribed fire and ungulate herbivory in the bitterbrush communities of Rocky Mountain National Park (RMNP). Four sites were chosen randomly from all available bitterbrush communities in RMNP wherein exclosures were erected (March/May 1995) and paired grazed plots established. Prescribed burns were performed on half of each exclosed and grazed area in 1995 and 1996. Using the sites and exclosures already present in the bitterbrush communities, additional data were collected from July 2001 to August 2002 to determine the communities’ responses to prescribed fire and herbivory 6 and 7 yr post-burn. Bitterbrush canopy volume and estimated annual production remain lower 6 and 7 yr post-burn in burned treatments as compared to their corresponding unburned treatments. Total shrub canopy area, volume, and estimated annual production did not significantly differ due to burning, but differed due to grazing at least 1 yr of the study (p <0.10). Data support that the ambient level of herbivory present in RMNP is affecting postburn successional patterns by impeding shrub regeneration. We caution against the use of any type of prescribed fire that would burn a substantial portion of the shrub component in these communities while ungulate herbivory remains high due to the alteration of post-fire successional patterns that could result in the loss of a major component of the community.
Parent Publication
Citation
Nesvacil, Kelly; Olmsted, Charles E. 2008. The effects of prescribed fire and ungulate herbivory and 7 years postburn in the upland bitterbrush (Purshia tridentata) communities of Rocky Mountain National Park, Colorado. In: Narog, Marcia G., tech. coord. 2008. Proceedings of the 2002 Fire Conference: Managing fire and fuels in the remaining wildlands and open spaces of the Southwestern United States. Gen. Tech. Rep. PSW-GTR-189. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. p. 83-90
