September 16, 2009

Northwest U.S. may face more tamarisk

The U.S. Forest Service says computer models suggest tamarisk -- an aggressive invasive plant -- will likely expand its habitat if the climate changes.

Scientists at the Forest Service's Pacific Northwest Research Station say if projected warming trends are realized, one of the nation's most aggressive exotic plants will invade more U.S. land area.

Results of our study suggest that a little over 20 percent of the Northwest east of the Cascade Mountains supports suitable tamarisk habitat, but less than 1 percent of these areas is currently occupied by the species, said Becky Kerns, a research ecologist with the Western Wildland Environmental Threat Assessment Center who led the study. That means the remainder is highly vulnerable to invasion right now with the situation potentially getting worse as favorable conditions for tamarisk may expand under climate change.

She said the study's findings translate into a 2- to 10-fold increase in highly suitable tamarisk habitat in Oregon, Washington and Idaho by the end of the century.

Tamarisk, also known as saltcedar, is a deciduous shrub or small tree that grows quickly, reproduces profusely and tolerates drought and salty conditions, making it capable of easily displacing native species, the forest service said. It also sheds leaves that serve as potential fuel, significantly increasing an area's wildfire risk.

The research appears in the journal Invasive Plant Science and Management.