FIELD GUIDE TO INSECTS AND DISEASES OF ARIZONA AND NEW MEXICO FORESTS
Ungulates

Domestic livestock and wild ungulate browsing can cause severe damage to forest regeneration. Aspen forests in particular have suffered extreme damage. Rocky mountain elk are considered the primary threat to the long-term survivability of aspen, because they impact aspen in so many ways. Elk have a height advantage over other ungulates and are able to reach higher in the crowns of saplings, often snapping the main bole and killing it. Elk rub antlers on small diameter trees (7 to 15 cm), creating wounds that allow entry for canker and wood decay fungi. Elk also gnaw or strip the bark (a.k.a. barking) of larger trees, allowing the entry of insects such as the bronze poplar borer.

References:  39, 92

Figure 296. Figure 296. Aspen suckers are heavily browsed by ungulates, especially elk.
Figure 297. Figure 297. Elk "bark" mature trees with their teeth.
Figure 298. Figure 298. Elk snapped these saplings while feeding on foliage after a protective fence was removed.
Figure 299. Figure 299. Ponderosa pine browsed by ungulates.