Cooperating Agencies:

• Coconino National Forest

Location:

25 miles (40 km) northeast of Flagstaff, AZ, in the Sunset Crater volcanic field.

Date Initiated:

1994

Description:

Penstemon clutei (Sunset Crater Beardtongue) is a rare species endemic to the volcanic cinder hills and fields to the north and east of Flagstaff, Arizona. Dramatic plant regeneration after a 1973 wildfire suggested that fire disturbance plays a valuable role in the ecology of the species. Building on previous Coconino National Forest studies, the ERI initiated a series of research projects to explore factors affecting seed germination of the species, and to test the effects of prescribed burning and reduced competition (tree root trenching) on individuals of P. clutei.

The seeding study utilized seed collections made in the spring and fall of 1993, at both higher and lower elevations within the species’ range. Seeds were tested in the lab and field under a variety of environmental conditions to address factors which may affect germination rates for the species. Results overall from the seeding study were inconclusive, except to indicate that P. clutei has no apparent winter dormancy requirement.

Since recurrent, low-intensity fire was historically present in the ponderosa pine forests of the study site, and many herbaceous plants have declined in these forests during the era of fire exclusion, prescribed burning was expected to increase the density and vigor of P. clutei plants. Experimental burns were conducted on a series of plant-centered measurement plots across the study site, with some plots burned in the fall and others in the spring. Another factor which may affect growth and reproduction of the species is root competition from surrounding trees. To examine whether this was the case, we dug 1 m deep trenches around a subset of the burn and control plots, lining them with heavy plastic sheeting before backfilling them. P. clutei responded poorly to prescribed fire alone, but seedling recruitment was found to be significantly higher after trenching, which indicates that tree mortality from wind-throw or from flare-ups during otherwise low-intensity wildfires may be more important in the regeneration of the species than fire alone.

Project Status:

Information gained from these studies can increase our knowledge of the ecology of P. clutei and assist in integrating rare plant management plans into the context of ecological restoration.The plots established in the course of our experiments were permanently marked, and may be revisited in the future to investigate longer-term trends in the ecology of this beautiful, rare plant.

For More Information:

• Contact Judy Springer, at
• Penstemon website

Publications:

• Fulé, P.Z., J.D. Springer, D.W. Huffman, and W.W. Covington. 2001. Response of a rare endemic, Penstemon clutei, to burning and reduced below ground competition. Southwestern rare and endangered plants: proceedings of the third conference. USDA Forest Service Proceedings RMRS-P-23:139-152.