United States Department of Agriculture Conservation Assessment Forest Service Rocky of the Variegated Mountain Region Black Hills Scouring Rush in the National Forest Custer, Black Hills National Forest, South Dakota May 2003 South Dakota and Wyoming Bruce T. Glisson Conservation Assessment of Variegated Scouring Rush in the Black Hills National Forest, South Dakota and Wyoming Bruce T. Glisson, Ph.D. 315 Matterhorn Drive Park City, UT 84098 email:
[email protected] Bruce T. Glisson is a botanist and ecologist with over 10 years of consulting experience, located in Park City, Utah. He has earned a B.S. in Biology from Towson State University, an M.S. in Public Health from the University of Utah, and a Ph.D. in Botany from Brigham Young University EXECUTIVE SUMMARY Variegated scouring rush, Equisetum variegatum Schleich. ex F.Weber & D.M.H. Mohr, is a circumboreal, early seral, herbaceous facultative wetland species that occurs along streambanks, lake shores and in wetlands across the northern United States, Canada, and Alaska (USDA NRCS 2001; NatureServe 2001). Disjunct, isolated occurrences of variegated scouring rush in South Dakota, Utah, and Colorado may be relicts from the last Pleistocene glaciations. In Black Hills National Forest, variegated scouring rush is known only from Beaver Gulch in the Bear/Beaver Gulch Botanical Area. As a regional disjunct, boreal species, the Black Hills population is inherently less secure than populations in the core range of the species and may not be able to persist under warmer, drier climatic conditions in Black Hills National Forest. There do not appear to be any immediate risks to the currently known locations of the species, but their small populations and limited microsite habitats may make the species vulnerable to random stochastic events and human-caused disturbances.