English: A typical Dudley Bluffs bladderpod in full bloom during early May.

Photo credit: USFWS ...........................................................................

BACKGROUND: The Dudley Bluffs bladderpod (bladderpod - Physaria congesta) and the Dudley Bluffs twinpod (twinpod - Physaria obcordata) are limited or endemic to barren white shale outcrops and specific soil tongues in the Piceance Basin of Rio Blanco County, Colorado. The bladderpod is known from eight populations, consisting of roughly 546,000 plants across an estimated 930 acres, while the twinpod is known from 11 populations, consisting of roughly 25,000 plants across an estimated 318 acres. Approximately 88% of the total occupied bladderpod and twinpod habitat occurs on public lands managed by the Bureau of Land Management. All known populations occur within a 20 square mile area.

When these two species were listed in 1990, natural gas drilling was not considered a threat. Previously considered inaccessible, these two species sit atop the nation’s biggest reservoir of natural gas. Fracturing technique advancements, however, have recently made these natural gas deposits accessible with 95 percent of the development near these rare plant populations. Rio Blanco County currently has over 2,600 natural gas wells, but predictions estimate there may be as many as 19,000 wells within 15 years, more than any other Colorado county. These wells and their associated infrastructure (pads, pipelines, roads, and traffic) are impacting populations and habitat of both the bladderpod and the twinpod. The Bureau of Land Management, the Colorado Natural Areas Program, the U.S. Fish and Wildlife Service (Service), and other partners have been working together to better document and study these impacts to the bladderpod and the twinpod.

Oftentimes management for rare plant species does not adequately consider impacts outside of the immediate area where a plant is found. For example, ecological effects from dust generated by heavy traffic on dirt or gravel roads can extend more than 300 feet from the road. Or, for every vehicle traveling one mile of unpaved roadway once a day, every day for a year, 2.5 tons of dust can be deposited. Effects to plants from dust can be numerous, including changes to a plant’s photosynthesis, respiration, transpiration, water use efficiency, leaf conductance, growth rate, plant vigor, and gas exchange rates. Changes to plant communities and species’ abundances within these communities have also been linked to dust deposition. Aside from dust, roads themselves alter ecosystems by importing invasive nonnative species, altering hydrology, and changing sedimentation patterns. In addition, both the twinpod and the bladderpod require pollinators for reproduction. Impacts to these solitary ground or twig nesting bees (especially their nesting habitats) may impact these species’ reproduction. We consider all of these effects to be part of “dispersed development” impacts. Our research hopes to address impacts to these two species, their associated plant communities and their pollinators. We are hopeful this research will allow land managers to better evaluate and address threats from this dispersed development.