Aspen response to prescribed fire in Southwest Montana

Abstract

A collaborative effort by the BLM, MAES and MFWP, the Whitetail Watershed Restoration Project used prescribed fire in 2005 and 2006 to address aspen decline, conifer encroachment and altered hydrologic function in a forested watershed within Jefferson County, MT. As part of this effort quaking aspen response to fire was evaluated in two sub-drainages of the Whitetail Basin three years after treatment. Unburned stands were first surveyed to determine whether regeneration was occurring and to measure the distribution of aspen stems by size class. This information was then compared to stem response in burned stands. Big game and cattle impacts on aspen sucker height and density were measured using a series of 3-part ungulate exclosures in a sub-sample of burned stands. Regeneration was occurring in only1 of 40 unburned stands suggesting aspen was declining in this area. Sucker density increased dramatically in the burned stands after three years increasing the likelihood for regeneration. 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 we did not feel it was enough to prevent regeneration. This assertion was supported by sufficient annual growth rates and the recruitment of individual regeneration stems into stands outside of protected plots. While it appears fire has increased the potential for aspen regeneration in the Whitetail Basin, early growth rates have allowed for some individual stem to surpass browse height to date, suggesting future monitoring will be necessary to learn if the current recruitment levels are sufficient to regenerate the majority of stands.