Contacts (../files/az_wipwg.pdf) The Nature Conservancy in Arizona Press Releases Search All Press Releases Tamera Skrovan Tamera Skrovan Phone: (602) 322-6996 (480) 415-3933 (Cell) E-Mail: tskrovan@tnc.org

Working Group Releases List of 71 Invasive Plants Threatening Arizona's Wildlands

List to be advisory and non-regulatory

Phoenix, AZ—November 3, 2005—A group of more than 25 organizations assessing the impacts of non-native invasive plants on Arizona’s natural resources today released a list of 71 plants threatening the state’s wildlands.  The categorized information—available in a spiral-bound booklet or electronically—will help everyone from landscape architects to state and federal land managers identify and take steps to manage plants that in a worst-case scenario can alter natural fire and water processes within Arizona.  The majority of plants on the list are not regulated by state and federal law.  The list is intended to be advisory and non-regulatory.

“Southern Arizona’s experience with wildland fires this past winter and spring illustrates the threat posed by these invasive non-native plants,” said John Hall, Sonoran Desert program manager for The Nature Conservancy in Arizona.  “Most native desert plants are not adapted to fire.  The relatively wet winter enabled invasive plants to multiply and fuel destructive wildfires in our desert landscapes that rarely, if ever, burned.”

“Similarly, invasive non-native plants—which are increasing in number and area they affect annually in Arizona and throughout the Southwest—are crowding out native vegetation along the state’s streams and rivers,” said Mark Dimmitt, director of natural history at the Arizona-Sonora Desert Museum.  “Over time, the effect of these invasives is to alter natural flow patterns and damage streamside environments and aquatic habitats.”

Larry Riley, fisheries chief at Arizona Game and Fish Department, added that such changes in natural water behavior, as with wildfires, also can lead to damage to wildlife habitats and economic and human health hardships for public, private and tribal interests.

The group evaluated a total of 74 invasive non-native plants (three did not make the list) using regionally developed criteria and a comprehensive review and oversight process to ensure consistent findings.  To be evaluated, a non-native plant had to be established in Arizona’s wildlands, that is, outside of human cultivation and management.

Patti Fenner, president of Southwest Vegetation Management Association, which sponsored the list development, explained that clarification was needed about which plants are the culprits:  “Problematic invasive non-native plants are not limited to regulated noxious weeds, which are primarily agricultural pests. Nor do all non-native plants in Arizona pose a threat to our state’s wildlands.  We needed to know which plants warranted our concern.”

The list groups the 71 invasive non-natives according to how severely they impact plant and animal communities, how quickly they disperse and take hold, and how widely they currently are distributed in Arizona.  Among those categorized with the highest impact are such familiar plants as red brome, Russian olive, buffelgrass, fountain grass, saltcedar, and giant salvinia—a water fern that infests portions of the Colorado River below Parker Dam.

Hall said that initially, the information is expected to be most useful to land managers working with state, federal and private lands, as well as to the nursery and landscaping industries involved in the commercial sale and use of plants.

“A critical next step is to work with industry to find non-invasive alternatives to commercially sold plants on the list,” he said.  “The ideal situation will be for the industry eventually to take a leadership role and direct retailers and buyers toward native plants or non-invasive non-natives.”

As for new biological invaders, Ed Northam, a consulting weed biologist and working group coordinator, said that prevention, early detection, rapid response, and local eradication are the most effective and least costly strategies to combat them before they expand beyond control.

The working group includes more than 25 state and federal agencies, academic institutions, and private conservation, professional and commercial organizations from throughout Arizona that joined together to form the Arizona Wildlands Invasive Plant Working Group (AZ-WIPWG). 

“The AZ-WIPWG was truly an example of multiple organizations partnering and sharing resources to accomplish a mutual goal,” said Rebecca de la Torre, deputy director of Southwest Strategy, a forum for government executives to exchange information and resolve resource and management issues in Arizona and New Mexico.  In addition, 24 organizations showed their support for the listing process and list uses by allowing their name to appear in association with the published list (see lists of participants, supporters and contact information attached.)

Lori Faeth, policy advisor for natural resources and environment for Governor Janet Napolitano, applauded the efforts of the working group.  She noted the importance of bringing the list to the Invasive Species Advisory Council for consideration as a working list of invasive non-native plants that threaten Arizona’s wildlands.  The council, established by Executive Order #2005-09, is charged with the development of recommendations to address invasive species in Arizona.  The recommendations are due to Governor Napolitano on June 30, 2006.

To view the plant list and find out more about AZ-WIPWG, visit the U.S. Geological Survey’s Southwest Exotic Plant Information Clearinghouse website.  Go to the “AZ-WIP” link.

(For hi-resolution images of some plants, contact Christine Conte, Arizona-Sonora Desert Museum, at (520) 883-3005 ext. 105 or cconte@desertmuseum.org.  To view images, visit www.desertmuseum.org and click on “Invaders of the Sonoran Desert Region,” then “project species.”)

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