Aspen Response to Prescribed Fire under Managed Cattle Grazing and Low Elk Densities in Southwest Montana
The Whitetail Watershed Restoration Project used prescribed fire in 2005 and 2006 to address quaking aspen (Populus tremuloidesMichx.) decline, conifer encroachment and altered hydrologic function in a forested watershed in southwest Montana. As part of this effort, we evaluated aspen response to fire in two sub-drainages of the Whitetail Basin three years after treatment. Unburned stands were surveyed to determine whether aspen regeneration was occurring following long term disruption of historical fire return intervals. This information was compared to stem response in nearby burned stands. Regeneration was noted in only one of 40 unburned stands, suggesting aspen stands were declining in this area. Three years after prescribed fire sucker density was significantly higher in the burned stands. This increased the likelihood that stands could regenerate. Based on earlier studies describing suppression of stand regeneration by cattle (Bos taurus) and elk (Cervus elaphus nelsoni) browsing impacts on aspen sucker height and density were measured in a sub-sample of burned stands. Within the first three years post-fire big game and the combination of big game and cattle did not affect sucker density in the burned stands. Although sucker height was significantly less in plots used by ungulates it may not be high enough to prevent regeneration. This assertion was supported by sufficient annual growth rates and the recruitment of individual regeneration stems into burned stands. Results from this study indicate that aspen stands can be successfully regenerated in areas where elk numbers are less than 1 animal/km2 and cattle grazing is closely managed. Monitoring will continue to learn if stand regeneration does occur.
Durham, D.A.; Marlow, C.B. 2010. Aspen response to prescribed fire under managed cattle grazing and low elk densities in southwest Montana. Northwest Science 84(1):141-150.