Aerial treatment of buffelgrass is concluded for 2014:
Between August 19 and 24, approximately 250 acres of dense buffelgrass were treated using a helicopter. Ninety vegetation monitoring plots were installed prior to the aerial treatments. Park scientists are monitoring the impacts to buffelgrass as well as to native vegetation. The results from the first year of monitoring data will inform decision makers as they adapt and update the planned actions for future years.
The Plan to Fight Buffelgrass and Restore Native Habitat
The Restoration Plan is part of the environmental compliance required for restoration activities within park boundaries, and outlines the recommended action to reduce the threat of invasive plants, as well as recommended actions to restore park land in case of floods, fire, or other large scale changes to the landscape which require mitigation against further damage.
After an experimental demonstration project in 2010, the park initiated the process to conduct helicopter application of herbicides. The compliance process took several years of research, public meetings, and interviews. The Restoration Plan and Environmental Assessment was approved with a Finding of No Significant Impact (FONSI) and signed by Sue E. Masica, Regional Director for the Intermountain Region of the National Park Service.
2014 was the first year that aerial treatment of buffelgrass took place, during the week of August 18. Over 250 acres of buffelgrass infested land were treated. There was evidence of die back within a few days of treatment, and monitoring will continue to inform future park decisions regarding aerial treatments. It is expected that some areas will take years of retreating to restore native vegetation and improve wildlife habitat.
What is the Restoration Plan?
The Restoration Plan describes management actions to restore native vegetation and mitigate negative impacts to park lands from damage caused by fire, flood, invasive species, or other human causes. The EA, which was available for public review and comment for 30 days, included an analysis of the proposed alternatives, and identified and compared their potential environmental impacts. The FONSI took this assessment and public comments into account, and accepted the preferred alternative, which includes all of the techniques the park has been using to date, and allows for aerial (helicopter) delivery of restoration treatments to sites that are not accessible by ground crews.
You can review the Restoration Plan, Environmental Assessment and FONSI by clicking the links below.
Visitors from around the world arrive at Saguaro National Park anticipating a breath-taking view of giant cacti and a prime example of Sonoran desert plants and animals. This splendid landscape is threatened by invasive plants, like buffelgrass (Pennisetum ciliare). Buffelgrass, native to Africa, was brought to the U.S. for cattle forage and erosion control in the 1930s. Its rapid and aggressive growth crowds out native plants, alters wildlife habitat, and increases the risk of wildfires. Buffelgrass-fueled wildfires burn very hot, spread rapidly, and are capable of destroying cactus and wildlife alike, changing the Sonoran Desert as we know it.
Buffelgrass in Saguaro National Park
Buffelgrass was first noted in the park 1989; and hand removal of this weed began in the early 1990s. Manual removal is very labor intensive, and the rapid growth and spread of buffelgrass quickly outpaced our efforts. The Park's 2004 Exotic Plant Management and Environmental Assessment Plan authorized the use of herbicides to treat invasive non-native plant species based on cost, effectiveness, and Park Service regulations. Herbicide selection is based on effectiveness versus potential impacts of the environment and non-target species. Herbicides with the active ingredient of glyphosate are very effective at killing buffelgrass, virtually non-toxic to wildlife, and do not accumulate in water or soils. However, they must by applied when plants are actively growing, which limits treatments to the monsoon season. The disadvantage of some herbicides like glyphosate are that they are non-selective, and impact non-target plants.
Success - at a Small Scale
Our current ground-based control efforts include manual pulling of plants, and spraying herbicides with backpack or truck-mounted sprayers in areas accessed on foot or by road. Through a process called adaptive management (assessing the results of our actions to ensure that our goals are met without unacceptable side effects, and adjusting our strategies accordingly), we've learned that to successfully control buffelgrass, treatments need to occur several times a year for up to five years.
If we remain constrained by factors such as inaccessibility, limited treatment window, and the need for repeated treatments, there is little hope of removing the estimated 2,000 acres of buffelgrass growing throughout the park. At a predicted spread rate of 10% - 35% annually, we simply cannot keep up with the growth of buffelgrass.
Next Step in Reducing the Threat
In 2010, we partnered with other local, state, and federal agencies to evaluate the use of helicopters to deliver herbicides for buffelgrass control. Both a boom mounted to the underside of a helicopter, or a "spray ball" tethered from a helicopter, proved to be effective delivery mechanisms. The boom application is proposed for treating large infestations that no longer support native plant communities; and because of its precision, the spray ball is proposed for treating small infestations. Follow-up studies of this treatment found that many native species, particularly cacti and trees, were largely unaffected by glyphosate.
Only remote and difficult to access sites that are dominated by buffelgrass are proposed for aerial herbicide treatment. Spraying of herbicides would not occur within a quarter-mile of occupied private property, one hundred and sixty-five feet of a spring or other water source, or above six thousand feet elevation. Click on the district name to see a map of the treatment exclusion zones.
We will continue to monitor treated areas to evaluate effectiveness and to identify and mitigate any potential negative impacts.
At Saguaro National Park we are committed to evaluating the effectiveness and costs of different methods of buffelgrass control. Our research includes studies on herbicides efficacy and toxicity on both buffelgrass and non-target native vegetation and wildlife, such as desert tortoise. The Park has funded studies on the use of remote sensing techniques, such as satellite photography, to identify and monitor buffelgrass and its fuel loads. We are also developing computer models to predict buffelgrass spread and buffelgrass-fueled fire behavior.
What do you think?
Your national parks are created to preserve and protect special resources for the enjoyment of future generations. To honor that commitment, we must consider the current and future impacts of threats such as buffelgrass and how to control them. National Park Service staff have written a draft Environmental Assessment for this Restoration Plan.
Please stay involved with this process by checking for updates on this website.
For more information on buffelgrass, please visit the links and video below.
Video - Welcome to the Buffelgrass Patch
Video - Buffelgrass! The Epic!
Did You Know?
The average life span of a saguaro cactus is 150 years, but some plants may live more than 200 years. A 20 foot tall saguaro weighs approximately 1 ton (2000 pounds).