Russian Olives and Tamarisk Get A Little Federal Love

Tamarisk trees (also called saltcedar) and Russian olives are widely considered to be water-hogging, wildlife-hostile, invasive scourges in watersheds in at least 17 western states. As a result, many communities and organizations have devoted a great deal of time and money in difficult efforts to restore areas dominated by these trees to a more naturalistic vegetative mix.

To find out if those groups are going in the right direction, Congress asked in 2006 for an overview of the available science. On April 28, 2010, the US Geological Survey, the Bureau of Reclamation, the US Forest Service, other federal agencies, and university experts released a report that said the water-hogging assumption has little merit. They found that effects on wildlife are mixed — some native species leave, but many animals still use the habitats, including some endangered species. They did note, though, that dense stands of tamarisk tend to provide reduced wildlife habitat, and that such areas can also impede recreational access to waterways, pose a wildfire hazard, and damage irrigation canals.

• "Saltcedar and Russian Olive Control Demonstration Act Science Assessment," U.S. Geological Survey Scientific Investigations Report 2009-5247; press release.

These findings offer a good hook to revisit these programs, sound out local reactions, and see if the eradication programs will continue.

When communities try to eradicate either of the trees, they find that it is difficult to destroy them, requiring a mix of mechanical removal, burning, pesticide spraying, introduction of bugs that feed on the trees, and other disruptive and potentially damaging actions. Restoring a beneficial mix of vegetation is also very difficult, since the two trees and other invasive species tend to have biological advantages in these wounded ecosystems, and because other difficult efforts to restore natural waterway flow patterns may be needed to help native species re-establish themselves.

If there is little advantage in undertaking these campaigns, communities may want to review their assumptions and priorities. At the same time, if there are local experts who consider the new report bogus, and urge their community to continue its eradication efforts, there will be stories as the local figures defend their opinion against the federal findings.