Special status vascular plant surveys and habitat modeling in Yosemite National Park, 2003–2004

Moore, Peggy; Colwell, Alison; Coulter, Charlotte

The objectives of this project were to update information on listed species occurring in the park, to determine population status of the highest priority species, and to create predicted habitat models for a subset of those. USGS worked with the park botanist to revise the park’s special-status plant list, adding species newly documented in the park, those for which we uncovered evidence of occurrence, and new species listings. For each taxon, we provided information on listing status, distribution, habitat, elevation range, flowering period, and rationale for inclusion on the list. Following survey work in 2003 and 2004, we proposed additional candidates for the park list. These were compiled using the same procedure of evaluating evidence of occurrence, distribution, and listing information. The result is a list composed of 151 taxa that includes four state-listed species, 13 Forest Service Sensitive taxa, and 62 taxa listed by the California Native Plant Society (CNPS). The remaining species on the park list are included for reasons of distribution and their contribution to the biological diversity of Yosemite. Subsequent to the list revision, USGS used hand-drawn maps from the 1980s converted to digital format, available references, and herbarium specimen records, both recent and historic, as guides for surveying listed plant populations throughout the park in 2003 and 2004. We surveyed species according to a priority order established in consultation with the NPS, beginning with the four California State Rare species. We then proceeded through species listed by other federal agencies and CNPS, completing 163 surveys among 39 plant species during the two field seasons. We collected detailed information on population size, location, and habitat at each of 127 populations. We collected specimens of plants underrepresented in the park herbarium and photographed each species along with its habitat. We documented nine species not previously known from the park and found a species of bog-orchid new to science.Concurrently with field surveys to determine population status, USGS used mapped population perimeters and thematic data themes in a GIS environment (e.g., geology, vegetation, fire history) to map potential habitat for seven of the rare plant species we surveyed. Field verification ascertained that model accuracy ranged from 17% to 73%, depending on the species. Results served to increase the known distribution of short-leaved hulsea by 133% and mountain lady’s slipper by 50%.

Special status vascular plant surveys and habitat modeling in Yosemite National Park, 2003–2004

Series