Be(etle) Careful What you Ask For

Tamarisk along the Colorado River | Photo by Mike BuchheitFor more than a decade, land managers across the Southwest have been battling the spread of the highly invasive tamarisk tree. This pernicious plant, native to Eurasia, has elbowed out indigenous plants along the banks of the Colorado River and other desert streams and riparian areas. In Grand Canyon National Park, vegetation specialists have eradicated over a quarter million tamarisk trees in their attempt to preserve the integrity of the ecosystem.

In other parts of the Southwest, the tamarisk leaf beetle (Diorhabda spp.) was introduced to help destroy the trees. Unfortunately the beetle has migrated to the upper stretches of the Grand Canyon—well south of its anticipated range. The spread of the beetle in the canyon would likely result in a rapid reduction in the tamarisk population. This sounds good at a glance, but unwelcome consequences include increased wildfire risk in dense stands, and the destruction of habitat for the Southwestern willow flycatcher, an endangered species of bird that nests in isolated tamarisk thickets near the canyon floor.

The National Park Service is monitoring the situation, and exploring contingency plans should the beetle migration continue downstream. Follow this link for more on this unfolding botanical drama whose last chapter is far from written. Read more…