Dune Habitat Trends of an Endangered Species,Penstemon haydeniiWats. (blowout penstemon), in Carbon County, Wyoming

Abstract

Penstemon haydenii Wats. (blowout penstemon, blowout beardtongue) is an early-succession plant species that is adapted to the dynamic habitats found in sand dunes. Following widespread habitat loss, the species was thought to be extinct from 1940 until it was rediscovered in 1968. It was listed as endangered in 1987 under the Endangered Species Act. At the time, it was only known from the Nebraska Sandhills, where its low numbers were ascribed to habitat loss. It was first discovered in Wyoming in 1996, in the Ferris Dunes of Carbon County. To develop a proxy for historic Wyoming habitat trends and a context for current conditions, we reconstructed the history of dunes where P. haydenii is presently located. Twelve georeferenced aerial photograph sets and digital imagery from 1946 to 2015 were analyzed to trace currently occupied dune areas back over the 70-year period. All currently occupied dunes were continuously present as areas of active sand over the 70-year timespan. Dune migration averaged 2.9 m/year. Dune extent declined 16.1% (2015 compared to the average). The continuity of active sand dune habitat and asynchronous trends in migration and in aerial extent between dunes and over time indicate a dynamic dune system maintained by wind erosion. These results provide critical context for population and habitat data of P. haydenii in Wyoming.