It’s been more than 80 years since the tamarisk, also known as the Saltcedar, took root along the Little Colorado River that winds through the communities of Winslow and Holbrook.
The non-indigenous shrubs and trees were introduced to the area after settlers who came to the area needed access to water. They built dams and dug deep wells to reach the aquifer. Clearing the land destroyed many of the local cottonwoods and willows that lined the waterways, so tamarisks were brought in to stabilize the eroding soil and silt of fragile stream banks.
The hearty bushes and trees were imported as ornamental plants from Asia to the East Coast years before and brought west to be used as windbreaks and provide much needed shade over easily evaporative waterways.
What wasn’t anticipated was how invasive the tamarisk would become. Over the years, the tamarisk crowded out any indigenous plant species that would have normally grown along the waterways and affected the habitats of wildlife in the area.
The thirsty tamarisk posed another problem, as well. According to the U.S Department of Agriculture Animal and Plant Inspection Service (APHIS), water use by tamarisk is among the highest of all stream bank species. APHIS notes that the plant can lower water tables, reduce stream flow, dry up desert springs, and reduce availability of water for agriculture, municipalities, native plants and wildlife. It is estimated by APHIS that the cost of water lost to tamarisk is $133 million to $285 million annually.
To battle the problem, in 2005 APHIS introduced a program to control the continued expansion of the tamarisk in 14 states. A leaf beetle from central Asia called Diorhabda elongate was introduced into the tamarisk environment. The small brownish striped beetle is host specific to the tamarisk and defoliates the tree, eventually causing it to die. Scientists didn’t anticipate that the beetle would eliminate the tamarisk entirely, but would thin the herd, so to speak, allowing for the return growth of indigenous plant life.
When the concept of introducing the beetle first arose, concerns were raised by groups such as the Center for Biological Diversity (CBD), which believed the introduction of the beetle could endanger species such as the southwestern willow flycatcher, a bird listed as endangered under the Endangered Species Act in 1995 that nests in tamarisk near the Rio Grande in New Mexico.
To address the concern, APHIS released the beetle away from such habitats, believing that the beetle would remain in controlled regions and thus protect those birds.
Such efforts failed as the beetles traveled along the Colorado River and quickly expanded their range of defoliation, rapidly killing the tamarisk in larger quantities than anticipated.
According to the CBD, the rapid advancement of the beetle has not only decreased nest cover for the flycatcher, it has led to increased predation risk and altered microclimate, having dramatic effects on chick survival for the endangered bird.
Other issues arising from the introduction of the beetle include the biomass left behind by the dead tamarisk and the inability to restore the natural vegetation before erosion occurs.
APHIS made the decision in 2010 to discontinue the program, but now the CBD is seeking to hold the agency accountable for its actions.
Last year the CBD, Maricopa Audubon Society and Dr. Robin Silver of the CBD filed a lawsuit against APHIS, the Agricultural Research Service (ARS), the U.S. Department of the Interior, and the U.S. Fish and Wildlife Service claiming that the agency authorized the wide-scale release of an invasive species that is having, and will continue to have, devastating effects on the swallow, as well as facilitating an ecological disaster.
According to Silver, the lawsuit is waiting on a ruling in the U.S. District Court of Nevada.
“The lawsuit is about accountability. This involves hundreds of millions of dollars in damages. What they did (APHIS and ARS) is release an invasive species and when it didn’t work out, they cancelled the program without any compensation for damages. When the feds looked at it they said there’s no program to consult on, so we can’t do anything,” explained Silver.
This year is the first that the destruction of the tamarisk has become apparent along the Little Colorado River that runs through local communities. While the flycatcher is no longer in this region, there is concern that erosion and other habitat preservation can become a problem as there are no remedial plans in place to clear out debris or support the soil along the riverbanks, the same concern that brought the tamarisk to the area all those years ago.
Ben Bloodworth, program coordinator for tamarisk beetle education with the Tamarisk Coalition, noted that his organization provides referrals for assistance when it comes to restoration of indigenous plant life to the area.
“The beetle that’s in Holbrook is likely the northern tamarisk beetle and while it will defoliate the tamarisk, it’ll be several years before the root system will lose its ability to hold soil,” stated Bloodworth.
He explained that there are resources that can assist landowners in restoring the cottonwoods or willows that originally thrived in the region before erosion occurs due to the loss of the tamarisk. “Landowners or tribes will need to reach out and identify what is the best restoration plan for their part of the state. There may be grants or funds available for the process,” Bloodworth said.
The Tamarisk Coalition is located in Colorado, but has a field office in Flagstaff. “There are other habitats that may not be utilizing the tamarisk, but a program for restoring the area may impact them. It would be best for landowners to reach out to organizations that can offer the right kind of information,” Bloodworth concluded. For more information visit tamariskcoalition.org.
A representative of APHIS stated that they were unable to comment at this time due to the ongoing litigation.
