Vascular plant species checklist of Bighorn Canyon National Recreation Area, Montana and Wyoming

Heidel, Bonnie; Fertig, Walter

Under congressional mandate, each unit of the National Park Service is required to develop comprehensive species lists that capture at least 90% of their total flora and fauna. Bighorn Canyon National Recreation Area was surveyed extensively from 1976-1984, resulting in the documentation of over 650 vascular plant taxa for the park. Rare plant surveys in 1998-99, however, resulted in the discovery of 60 additional species, calling into question whether Bighorn Canyon NRA had achieved the 90% threshold. In 2001 we were contracted to revise the existing checklist of the park’s flora and conduct field surveys in under-sampled habitats to identify potentially missing species. After extensive review of the existing literature and herbarium collections at Bighorn Canyon and the Rocky Mountain Herbarium, we identified 81 species that had been falsely reported for the park and 45 additional taxa that could not be verified. Our herbarium search and fieldwork also identified over 120 additional species that had not previously been identified for Bighorn Canyon, including 22 additional weed species. Our revised checklist now contains 739 vascular plant taxa, all of which have been verified with voucher specimens or reliable observation data. We also compiled a list of 148 potential species that could occur in the study area due to the presence of suitable habitat. If we add the 44 potential species with the highest probability of occurring in the park, the current checklist would still represent over 94% of the total flora. Some relatively inaccessible areas of the National Recreation Area and cryptic or taxonomically difficult species groups remain undersampled, but overall, the known flora of Bighorn Canyon is probably at or near the 90% target level. (Abstract as submitted by authors)

Vascular plant species checklist of Bighorn Canyon National Recreation Area, Montana and Wyoming

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