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Abstract
Ponderosa pine ecosystems provide important foraging habitats for both wild and domestic ungulates. Livestock typically graze ponderosa pine ecosystems from May through October. Mule deer and elk may utilize these habitats on a yearlong basis in some areas. Stand density has a significant effect on understory production. Competition for soil moisture and nitrogen limit understory production. Since these systems typically exist at lower elevations, south aspects and on rather shallow soils, soil moisture is usually unavailable to understory species by mid summer. Optimal forage quality, therefore, occurs from late spring through mid-summer. Livestock use for optimal production should occur during this time frame. Herbivory by both native and wild ungulates can influence the structure and composition of understory vegetation. Ungulates, through the act of selective foraging influence the competitive ability of understory plants utilized. Ungulates can by considered agents of change in ecosystems by three processes: the regulation of process rates, modification of spatial mosaics, and action as switches controlling transitions between alternative ecosystem states. These understory composition and structure changes may have important implications to such diverse attributes as nutrient cycling, energy flow, biodiversity, stand density, fire type and interval, forest productivity, and ungulate productivity.
Parent Publication
Citation
Vavra, Martin; Walburger, Kenric; DelCurto, Timothy. 2005. Ungulate ecology of ponderosa pine ecosystems in the northwest. In: Ritchie, Martin W.; Maguire, Douglas A.; Youngblood, Andrew, tech. coordinators. Proceedings of the Symposium on Ponderosa Pine: Issues, Trends, and Management, 2004 October 18-21, Klamath Falls, OR. Gen. Tech. Rep PSW-GTR-198. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 145-158
