Restoring Populations of Threatened Physaria Species in the Piceance Basin

Location: Piceance basin, western Colorado

Two federally threatened plant species are endemic to the Piceance Basin of Northwestern Colorado: Dudley Bluffs bladderpod (Physaria congesta) and Dudley Bluffs twinpod (Physaria obcordata). These two wild mustards are found exclusively in Rio Blanco County, Colorado, and lie in the heart of an ongoing natural gas field expansion. Because their habitats occur only in a very restricted range on specific and highly fragmented substrates, these species are limited in their ability to expand their range, or withstand stochastic events. Both species have not shown an ability to occupy or re-occupy habitats in disturbed or reclaimed suitable hPhysaria congestaabitats, with the exception of one population at the edge of the Piceance Basin on Calamity Ridge, where substrate characteristics display important differences from populations found in the central portion of the Basin. The 1997 White River Resource Management Plan (RMP) designated four Areas of Critical Environmental Concern (ACEC) for Dudley Bluffs twinpod and bladderpod occupied habitats, as they were then known. Since this time, survey work has increased the known distribution and abundance of both species and potentially suitable habitats within and external to the ACECs. Approximately 54 percent of both Dudley Bluffs twinpod and bladderpod populations occur within these ACECs.

Efforts to preserve these species to date have focused on protecting critical habitats. The purpose of the proposed research project is to explore possible approaches for establishing new populations of these species in suitable areas not needed for energy development in order to increase their overall abundance in the region.  The primary objective of the proposed research is to determine the best approach for establishing new populations of P. congesta and P. obcordata in suitable habitats of the Piceance Basin in Northwestern Colorado.
Supporting research objectives include:

  • Identify soil moisture limitations to the establishment of new recruits of P. congesta and P. obcordata.
  • Identify soil nutrient limitations to the establishment of new recruits of P. congesta and P. obcordata.
  • Identify soil biological feedbacks that limit or promote the establishment of new recruits of P. congesta and P. obcordata in the Piceance Basin.
  • Determine if the promotion of pollinators via increased local nectar sources can increase fecundity of P. congesta and P. obcordata.

We propose a mixture of laboratory, greenhouse and field studies to meet these research objectives.  Results from this work could be used by land managers to mitigate concerns regarding threats to these species. The ultimate goal of this work would be to provide a means for delisting these threatened species.  REL grad student Sasha Victor will be conducting the bulk of this research as part of her Master’s degree thesis research.