The White Bluffs bladder-pod (Physaria tuplashensis)is a Candidate species for federal listing under the Endangered Species Act and is considered Threatened in Washington. Studies of this species began in 1997 on the only known population of P. tuplashensis, a species that is endemic to the Hanford Reach National Monument. The species occurs as a single population in a narrow 17 km long band along the top of the White Bluffs of the Columbia River.
On May 24, Service biologists from the Mid-Columbia River National Wildlife Refuge Complex and from the Ecological Services office in Spokane, Washington partnered with botanists from Washington State Department of Natural Resources Natural heritage program, University of Washington’s Rare Care program and local members of the Columbia Basin Chapter of the Washington Native Plant Society to complete monitoring of the White-bluffs bladder-pod.
Although the area where the bladderpod grows is in conservation status as part of the Hanford Reach National Monument, wildfire and invasion of non-native species continue to be threats to the existing population. The population monitoring transects were monitored annually from 1997-99, in 2002, and were revisited and counted again in 2007, following a recommended interval for monitoring. Subsequent to the monitoring effort in 2007, a large wildfire known as the “Overlook fire” burned through the northern portion of the Physaria population. Therefore, the population monitoring was conducted again from 2008-2011 to assess whether or not the fire had an effect on the Physaria population. The population declined annually post-fire, until this season when a combination of moist fall, mild winter and wet spring allowed the population to rebound to record high numbers of plants. Monitoring revealed a population estimate of nearly 59,000 plants! Monitoring results will be further analyzed to determine population stability over time and to adjust monitoring intervals for this rare species.
By Heidi Newsome, Wildlife Biologist, Mid-Columbia River National Wildlife Refuge Complex