Management Strategies at Saguaro National Park

Invasive Plant Management

The methods that we use are chiefly manual removal and chemical control. You may have seen teams of hardy buffelgrass removal volunteers, with gloves and tools, digging out the plants. Park Service staff and interns also apply an herbicide containing glyphosate during the growing season, when plants are over 50% green.

Prescribed fire is successfully used in other National Parks to control some of the same invasive plants. However, in desert areas of Saguaro National Park, where the native plants are not fire-adapted but the non-natives are, fire is less appropriate as a method of control. Biological controls, introducing another exotic species to control the invasive plant, such as goats to eat the grasses or insects to destroy the seeds, are not in current use.

 

NPS photo

Species-Specific Management

It is not a one-size-fits-all type of effort! For our efforts to succeed, we implement species-specific management strategies. We implement the most appropriate control technique for each species and site, considering the extent of the invasion and the threat it represents. We ensure that the control is environmentally safe and supported by research. Species-specific management strategies include:

• Preventing new invasions through washing of contractor vehicles, use of certified weed-free hay for stock, and use of weed-free soil and rock for construction projects.
• Performing early detection and rapid response. Volunteers in the Weed Free Trails program augment Park Service efforts in this area by monitoring trails, removing small infestations, reporting larger infestations, and revisiting cleared sites for regrowth. Get involved in Weed Free Trails.
• Eradicating existing infestations where possible to prevent fire, minimize ecological impact, and reduce their spread.
• Controlling the spread of infestations that cannot be eradicated.
• Promoting restoration of native species and habitats in ecosystems degraded by invasive plants.
• Cooperating and collaborating with neighbors to prevent potential re-infestations across park boundaries.
• Taking inventory and monitoring invasive plants to support analysis, to identify trends, and to develop management strategies.
• Researching new ways to improve our control techniques, such as helicopter delivery of herbicide in rugged, unstable, or hard-to-access terrain, and implement adaptive management strategies.

 

Early Detection Rapid Response

One of the most important aspects of invasive species management is early detection and rapid response (EDRR). This refers to the practice of surveying and identifying invasive species and reacting to such identification in a speedy manner so as to combat the infestation as early as possible.

Stinknet

Stinknet is a recently-arrived highly invasive annual plant that has been located in limited areas of the park, but more widely in and around Tucson. Since its arrival in Arizona, stinknet (Oncosiphon pilulifer), a native of southern Africa, has taken over open spaces throughout the Phoenix metro area, quickly overtaking native wildflowers and forming dense stands that become major fire risks when they dry out. While stinknet is relatively new to Tucson and Pima County, local biologists are concerned about its rapid rate of spread and consider it to be the most dangerous invasive plant since buffelgrass was introduced in the 1930s.

As stinknet spreads, it is important that we practice early detection and rapid response in our management strategies for this species. Learn more about stinknet and how to report it in southern Arizona here. For more detailed information on the plant and its management, check out this article.