This native riparian bosque (forest) has been restored at Bosque del Apache National Wildlife Refuge, NM, after the removal of invasive salt cedar. (Gina Dello Russo/USFWS)
An invasive species strike team is helping three national wildlife refuges in New Mexico eradicate salt cedar within their boundaries. The team hopes to accomplish its goal within three to five years, possibly sooner.
Gina Dello Russo, New Mexico invasive species strike team coordinator and ecologist at Bosque del Apache National Wildlife Refuge, credits the particular topography and the dedication of refuge staff for the imminent success at Maxwell, Las Vegas and San Andres Refuges.
Maxwell and Las Vegas are small refuges characterized by short-grass prairie uplands. San Andres Refuge is remote upland terrain, with limited surface water and few avenues for salt cedar to become established. So eradication is within the realm of possibility at these refuges.
The strike team is also working to control salt cedar at Bosque del Apache, Bitter Lake and Sevilleta Refuges in New Mexico. These three refuges are on floodplains where the moist soil welcomes salt cedar, making complete eradication virtually impossible. By the 1980s, salt cedar had taken over nearly half the riparian floodplain in Bosque del Apache Refuge, threatening the habitat for such species as the endangered Southwestern willow flycatcher and the yellow-billed cuckoo.
Salt cedar, originally imported to the Southwest for decoration and erosion-prevention, can grow to 26 feet, rob arid landscapes of precious water and cause soil to become saline. Resistant to drought and producing 600,000 seeds a year, salt cedar can quickly become a monoculture and displace native birds and animals.
Eradicating or controlling salt cedar is very labor intensive. "Its a lot of chain saw work in these isolated areas," says Dello Russo, followed by treating stumps with chemicals and re-treating sprouts the next year. At Bosque del Apache Refuge, the stumps are removed so the area can be flooded during native tree seed dispersal and planted or reseeded with other native plants.
An estimated 3,500 acres of salt cedar have been removed at Bosque del Apache Refuge with 3,000 acres restored to native riparian plant communities.
"A native bosque," explains Dello Russo, "includes dense trees but also smaller stands of willows, plus openings of grasslands and wetlands. The patchiness within a native riparian forest is what brings in bird diversity, with the varied light penetration, moisture gradients, food resources, forest structure, and plant variation. Its a beautiful thing to see."
There are still approximately 3,000 acres infested with salt cedar left on Bosque del Apache Refuge, with progress dependent largely on funding.
Strike Teams on the Attack
The Refuge System initiated the Invasive Species Strike Team program in 2004. Teams operate in the Southwest (New Mexico and Arizona), the Florida Everglades, North Dakota, Hawaii and the Pacific Islands, and the Upper Missouri/Yellowstone/Upper Columbia River area.
The 2010 Southwest strike teams mapped 1,503 acres and cut down and treated young and mature salt cedar on 597 acres; youth conservation crews pulled more than 300,000 invasive salt cedar seedlings. This summer, the New Mexico strike team also partially funded a biological technician who is organizing existing mapping and treatment information into a comprehensive geo-database for all six New Mexico refuges.
Dello Russo expects the New Mexico strike team to assist refuges in building partnerships with surrounding landowners to address salt cedar and other invasives on a landscape level. "San Andres Refuge has established partnerships with White Sands Missile Range and National Monument. The strike team can support mapping and monitoring, so that we move beyond protecting the refuge to working on the landscape around us."
Controlling invasives is a never-ending process. Even when Maxwell, Las Vegas and San Andres Refuges succeed in eradicating salt cedar, there will have to be regular monitoring to catch any new arrivals. The primary objective of all Service strike teams is early detection, rapid responseEDRR.
Karen Leggett is a writer-editor in the Refuge System Branch of Communications.