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Saying So Long to Salt Cedar

June 23, 2010

Bluff is a quiet town on the banks of the San Juan River. Sandstone cliffs rise up on either side, isolating and inspiring the small community of farmers, ranchers, and artists that make Bluff their home. Tall cottonwood trees outline the river’s progress as it flow west, through town, toward its junction with the Colorado River some miles distant. Thick stands of salt cedar, also known as tamarisk, provide an almost impenetrably dense understory to Bluff’s cottonwood groves. Or at least, it did.

Tamarisk is a nonnative plant, an invader from the central Asian steppes and about as welcome as the Mongol hordes. Introduced in the eastern United States in 1823 as an ornamental, it soon escaped cultivation and began to work its way west along the country’s waterways. By 1900 it was being used to stabilize river banks along the Colorado and Rio Grande rivers at which it excelled, but a bit too well. By 1998 tamarisk stands covered in excess of a million acres along nearly every desert river, stream, lake, and pond in the southwestern United States, choking out willow and other native trees, grasses, and shrubs. While a few native animal species adapted to the new plant, most did not and the biodiversity of areas infested with the invasive plummeted. Unimaginably fecund, resistant to drought and floods, quick to regrow after fire, rapaciously thirsty, ultimately impossible to control, it was the western land manger’s worst nightmare for decades.

The secret to tamarisk’s control was not with chainsaws, bulldozers, fire, and chemicals. Tamarisk leaf beetle, a tiny Asian insect roughly the size of a ladybug, feeds exclusively on tamarisk leaves. A fastidious feeder, it will starve itself to death before it will touch native plants and crops. After careful and extensive testing, the beetle was released in 2001 in ten western states and the results were slow but astonishing. The beetles descend on living tamarisk and strip them of leaves, often in just a few days. Deprived of the ability to perform photosynthesis, the plant’s root mass decreases. As the cycle of leafing and being stripped of leaves continues over several years, root mass eventually decreases to the point at which the plant dies.

The beetle has been at work in Bluff for several years and has done its job well. But the dead and dying tamarisk present a new problem. A single errant spark during Bluff’s long, hot summer could result in a catastrophic fire. To forestall disaster, Bureau of Land Management work crews spent much of May clearing the dead trees in Bluff with chainsaws and mulching them with wood chippers. It also conducted restoration projects by planting Fremont cottonwood trees, coyote willow, and other native plants in the newly cleared areas. The area along the river bank currently looks like a war zone, scarred and raw beneath the cottonwood canopy. But my fingers are crossed as I hope that, within my lifetime, the river will begin to look again as once it did.

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