Understanding the state of curl-leaf mountain mahogany

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Bighorn Canyon¿s Natural Resource Condition Assessment (Komp et al. 2012) identified the need to understand the state of curl-leaf mountain mahogany (Cercocarpus ledifolius) and change in Utah juniper (Juniperus osteosperma) cover with a focus on bighorn sheep (Ovis Canadensis) habitat. Bighorn sheep rely on curl-leaf mountain mahogany as a staple dietary item. Curl-leaf mountain mahogany occurs across approximately 40% of Bighorn Canyon. In 2011, large areas of mountain mahogany were recorded as dying from unknown causes. In addition, Utah juniper has been documented to be invading areas occupied by mountain mahogany. While bighorn sheep populations have been steady, there is concern that the decrease in available mountain mahogany, a species sheep rely upon throughout the year, may have a direct impact on the bighorn sheep population. Once widely distributed across the West, bighorn sheep persist chiefly in small, fragmented populations that are at ongoing risk of decline as a result of disease, forest encroachment, and primary forage depletion. Continued loss of the curl-leaf mountain mahogany due to unknown causes that may include long-term drought, increase in pest species presence (e.g. tent caterpillars), or juniper encroachment could lead to an eventual decline in the overall bighorn sheep population in the park. This focused condition assessment will allow the park to effectively enact a restoration strategy for mountain mahogany that would ensure that this critical forage species for bighorn sheep is present long into the future.

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