EFFECTS OF SIMULATED ELK GRAZING AND TRAMPLING (I): INTENSITY

Abstract

Vegetative impacts caused by Rocky Mountain elk (Cervus elaphus nelsoni) grazing and trampling have been a growing concern for natural resource managers. The threat the archeological resources and naturally functioning ecosystems as a result of excessive elk trampling and grazing now rank as the highest management priority at Bandelier National Monument (BAND), New Mexico. In summer 1998, BAND erected a series of ungulate exclosures and paired reference areas to evaluate elk impacts on the vegetative community in piñon-juniper (Pinus edulis – Juniperus spp. [PJ]), ponderosa (Pinus ponderosa) grassland, and mixed-conifer (MC) habitat types. We evaluated simulated grazing/trampling treatment combinations applied at different intensities from January through May of 1999 and 2000. Litter cover was negatively correlated with clipping intensity in PJ and MC sites. Trampling more consistently impacted parameters and may stimulate plant productivity at an intermediate intensity, especially in terms of forb response. Longer time periods may be needed to detect vegetative responses to changes in grazing pressure especially in ecosystems that have developed with a history of grazing pressure.