The Tushar mountains provide critical alpine habitat for a variety of flora and fauna, including 27 endemic plant species. The Tushar Indian-paintbrush (Castilleja parvula var. parvula) is one of five taxa listed as high-priority for conservation and most likely to be impacted by herbivory. Mule deer (Odocoileus hemionus) and elk (Cervus canadensis) inhabit these mountains, and mountain goats (Oreamnos americanus) were introduced in 1986. Since then, controversy has persisted concerning potential detrimental effects of introduced goats on alpine plant communities; however, little data existed to support or negate such claims. Our objectives were to: 1) monitor growth and fitness of individual Tushar paintbrushes and 2) identify feeding preferences and quantify grazing pressure of ungulates within the study area. In 2018, we established long-term monitoring plots in three Tushar paintbrush populations (100 individuals tagged per population) and recorded utilization and reproductive/vegetative measurements for each tagged plant. Plots were revisited and reassessed in 2019. We monitored and assessed ungulate grazing within the study area via centroid sampling at observed feeding sites. Centroid sampling consisted of four perpendicular 25 m transects with Daubenmire frames placed every 5 m from which species composition, percent cover, and percent utilization were recorded.
Results/Conclusions
We collected data on plant abundances and ungulate foraging preferences from 148 feeding centroids. Preliminary results show a mean utilization of 30.2% when it appeared in feeding centroids for mountain goats and 31.5% in deer feeding centroids. In comparison, randomly placed centroid samples showed a mean utilization of 1.3% for the Tushar paintbrush. Thus, ungulates may be seeking out the Tushar paintbrush as a forage species. It was among the top 10 most-utilized plant species found within the mountain goat feeding centroids and the top 10 most-utilized plants in the deer feeding centroids. In addition, we found a mean utilization of 27.3% at our long-term monitoring plots within Tushar paintbrush populations. Therefore, it is important that continued monitoring take place to determine the long-term impact of ungulate foraging on the stability of Tushar paintbrush populations. Given time, the long-term monitoring plots will allow us to better identify trends in the Tushar paintbrush populations. This research will help inform land managers of the status of the Tushar paintbrush and provide insight regarding the relationship between the ungulates and alpine plant communities of the Tushar Mountains.