Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Wildland Resources

Department name when degree awarded

Range Science

Committee Chair(s)

Laurens Smith


Laurens Smith


Western forests dominated by aspen (Populus tremuloides Michx.) are highly regarded by most resource managers for their ability to provide a variety of benefits (Bartos and Mueggler 1982, Mueggler 1988). They noted aspen to be beneficial for production of livestock forage, wildlife habitat, and scenic beauty, and they are a potentially valuable source of wood products. However, in the West, communities are concerned about the dwindling acreage of aspen. The decline of aspen has been partly attributed to excessive ungulate browsing (Smith et al. 1972, Collins and Urness 1983, Bartos and Campbell 1998). Long-term grazing exclosures have also revealed that browsing by native and domestic ungulates hindered aspen regeneration throughout south-central Utah, including changes in understory species composition (e.g. Kay and Bartos 2000). However, though ungulate browsing is an established cause of poor success in aspen regeneration, beyond that fact, very little is known about the particulars of the response, especially how it is affected by time and intensity of browsing.