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Reintroducing northern wormwood to Oregon
Promoting wormwood recovery
Northern wormwood plant in greenhouse
ODA staff outplanting northern wormwood
Potential northern wormwood habitat
Northern wormwood plants grown in the greenhouse (left – photo by Kelly Amsberry) were used to augment an existing population of this species in Washington (center – photo by Melissa Carr). The photo on the right depicts an outplanting site along the Columbia River in Oregon (photo by Rebecca Currin). If downloading images from this website, please credit the photographer.

Project Goal
To promote recovery of northern wormwood by reintroducing populations of greenhouse grown transplants into managed sites within the plant’s historic range.

Project Duration
2005 - present

Background
Northern wormwood (Artemisia campestris var. wormskioldii), a northwest endemic, occurs only in sand and pebble soils on the banks of the Columbia River. The construction of a series of dams on the Columbia beginning in the early 1900s resulted in the disappearance of many of the ‘cobble bars’ that previously supported this rare species. This extirpation of many populations prompted ODA to list northern wormwood as endangered in 1995.

Summary
  • To ascertain the current status of this rare endemic, a survey of all accessible historic locations in Oregon was completed by the Native Plant Conservation Program in 2005. Additionally, areas that contained potentially suitable habitat, but were not currently occupied, were identified. Although no plants were found in historic sites on the Oregon side of the river, several sites that both contained potentially suitable habitat and occurred on administratively protected, publicly owned land were located.
  • Working with the Washington Public Utilities Department and the Washington Natural Heritage Program, NPCP staff collected seed from plants at one of the two currently extant sites (both of which occur in Washington). To determine the feasibility of creating new populations of this rare species, a germination study using these seeds was completed, and the resulting plants were transplanted back out at the Washington site. The growth and reproduction of these transplants will be monitored for several years to determine their potential for successful establishment.
  • In 2008, an initial introduction of 359 northern wormwood plants were transplanted out at Squally Point, an Oregon Parks and Recreation-managed property along the Oregon side of the Columbia River. Initially, 127 plants were planted in an experimental array in the spring of 2008, then in the subsequent fall an additional 232 plants were outplanted in the areas within the site shown to be most likely to be successful (using a model developed from the survival and reproduction of the spring transplants). Survival of the transplants was high, and many of them produced flowers the first year. However, recruitment did not appear to occur from seed dispersed by transplants in the first year of monitoring.
  • In October 2011, a large-scale reintroduction project was completed in order to promote the recovery of northern wormwood. A total of 2,091 plants were planted on Rufus Island, an island on the Columbia River. This project will observe the effects of three environmental factors on plant survival in order to gain information on transplant success. The three factors considered are substrate type, distance from the water line, and presence or absence of false indigo, an invasive species found on the site. Transplants were arrayed in four sub-populations in order to maximize the potential of creating a viable population.

Future Work
Based on the results of the large-scale project, information on transplant success should be used to guide further reintroduction of northern wormwood, as well as the protocol used in growing plants in the greenhouse. As transplants of this species have so far demonstrated little to no recruitment, additional research in this area may be a potential next step in order to further the recovery of this species. Recommended studies include testing seed viability in the wild and creating safe sites for seedling establishment.
 
For more information about this species, visit the northern wormwood plant profile.