Rare Plant Monitoring
Report Section 10.10.1.2)J. L. Downs
More than 100 plant populations of 47 different taxa listed
by the Washington Natural Heritage program as endangered,
threatened, sensitive, review, or watch list are found at the
Hanford Site (http://www.pnl.gov/ecomon/Veg/Habitat.asp;
PNNL-13688).
The U.S. Fish and Wildlife Service
has designated 5 of these 47 taxa (including the two species,
Umtanum buckwheat [Eriogonum codium] and White Bluffs
bladderpod [Lesquerella tuplashensis]) as species of concern in
the Columbia River Basin ecoregion (http://www.dnr.wa.gov/nhp/refdesk/lists/plantrnk.html).
These two species
are proposed as candidates for federal listing. In addition to
the rare plant populations, several areas on the Hanford Site
are designated as special habitat types with regard to potential
occurrence of plant species of concern listed by Washington
State. These are areas that potentially support populations
of rare annual forbs that have been documented in adjacent
habitats.
In June 2004, a population of coyote tobacco, Nicotiana attenuata, was discovered in a disturbed, open sand dune adjacent to the 618-10 burial ground, approximately 3.2 kilometers (2 miles) southeast of the 400 Area. A total of approximately 30 individual plants were found at that time, and the habitat in the vicinity of the population was designated a rare plant protection area to help conserve the population while cleanup of the 618-10 burial ground proceeds. The site was inspected several times during 2005 and no living plants were found. The disappearance of coyote tobacco from this area is presumably due to below normal rainfall during the year. Between January and May 2005, there were 5.9 centimeters (2.33 inches) of precipitation compared to 11.4 centimeters (4.5 inches) between January and May 2004 (normal for that period is 5.9 centimeters [3.12 inches]).
During September 2005, monitoring transects originally established to examine the condition and status of persistent sepal yellowcress (Rorippa columbiae) were revisited along the Columbia River shoreline near the 100-F Area. No specimens were located along the original transects. However, nearly 130 individual plants, in clumps of 5 to 40 individuals, were found nearby and up the river bank from the original population. Data that describe trends in plant numbers and the timing of growth for this species are of interest because large variations in population numbers have been observed. These variations are believed to be related to river-level fluctuations that inundate habitat for this species during a large part of the growing season. Additional data were gathered in 2005 to investigate this relationship by employing a survey grade real-time global positioning system to map the location and elevation of each plant clump found along the Columbia River shoreline near the 100-F Area.