From the Albuquerque Journal (John Fleck):
Introduced in the 19th century to protect railroad bridge abutments, praised for its ability to protect riverbanks from erosion, vilified for alleged water-sucking ways while simultaneously defended as wildlife habitat, the story of the Eurasian tamarisk – also known as salt cedar – is a textbook example of unintended consequences.
The beetle, introduced in small populations in an attempt to control the tamarisk, is the latest example. Brought from Europe to Utah and Colorado a decade ago, along with small populations in Texas, the beetle has run amok, spreading far beyond the narrow range biologists predicted.
After initial beetle arrival in 2012, the beetle rapidly spread uninvited up and down New Mexico’s rivers.
“Last year was really the year of the beetle,” said Oglesby, an attorney at a University of New Mexico water policy think tank and board member of the Tamarisk Coalition, a nonprofit tracking the beetle’s spread. “It came charging down the Jemez. It came charging down the Rio Grande, and now it’s charging up the Pecos as well.”
The beetles lay their eggs on tamarisks, with their larval offspring eating the leaves, quickly turning green patches of trees brown. Depending on local conditions, they often do not kill the tree outright, leaving it bristling with dead growth that nevertheless can sprout new leaves the following year.
Getting rid of tamarisk always has been an article of faith along Western rivers, but the dying trees along rivers’ edges in New Mexico and around the West are raising new questions – about fire risk and lost habitat for birds and other creatures that have made their homes in the artificial forests…
Oglesby saw the entire panoply of the tree’s history on display as he and a group of colleagues kayaked down the Rio Grande north of Albuquerque one recent fall afternoon.
Tamarisk swarmed over the river’s banks, crowding out native vegetation. In some areas, humans had intervened at great expense to clear them, creating an open bosque cottonwood forest.
But everywhere the scrubby tamarisk remained, there were signs of beetles chomping their way through them.
Formed to pursue habitat restoration along Western rivers, the Colorado-based Tamarisk Coalition now has become the de facto chronicler of the beetle’s spread. The group’s 2014 monitoring efforts are not yet complete, said Ben Bloodworth, who is overseeing the effort for the group.
But preliminary reports suggest that the beetle has become firmly established in Bernalillo and Valencia counties, and that a second population of beetles introduced in Texas has made its way through Las Cruces and is moving north up the Rio Grande.
The first beetle introductions, in Colorado and Utah, were approved by the U.S. Department of Agriculture, with the belief that the beetle’s impacts would be local.
Once it became clear the beetle was spreading much farther than expected, the agency stopped the program, but the beetle has continued to spread, undeterred…
For now, action in the middle Rio Grande is limited to monitoring the beetle’s progress. “People are just waiting and watching,” Oglesby said.