Delays expected along Picture Rocks Road
Commuters could face minor delays due to road construction starting on November 20. Workers will be out along the road shoulders trimming brush and salvaging sensitive plant species located along road shoulders, to improve safety along the roadway. More »
Environmental Assessment (EA)
Saguaro National Park is evaluating restoration treatment activities to address natural and human-caused ecological disturbances. These disturbances range in scale from very small to hundreds of acres, and include impacts from events such as fire, non-native plant invasions, off-trail human use, and off-road vehicle use. The primary disturbance of concern to the park is the invasion of buffelgrass. Current efforts to restore these disturbances are all ground-based treatments and limited to areas that can be accessible for field crews. Restoration treatments proposed to address these disturbances include aerial application of herbicides, aerial seeding, and aerial mulching in remote inaccessible areas of the park.
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 US 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 fires 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 here in 1989; hand removal of this weed began in the early 1990s. Manual removal is labor intensive, and the rapid growth and spread of buffelgrass outpaces our efforts. The Park's 2004 Exotic Plant Management and Environmental Assessment Plan authorized the use of herbicides based on cost, effectiveness, and Park Service regulations. The choice of herbicide is based on effectiveness versus potential impacts to the environment and non-target species. Herbicides with the active ingredient glyphosate are very effective at killing buffelgrass, virtually nontoxic to wildlife, and do not accumulate in water or soils. However, they must be applied when plants are actively growing, which is 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 ground-based control efforts include manual pulling of plants, and spraying herbicides with backpack or truck-mounted sprayers in areas reached 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.
Despite the challenges of controlling buffelgrass, we are encouraged by our successes, but they have been at a small scale. If we remain constrainted 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 the spray ball is proposed for treating small infestations, because of it precision. Studies found that many native species, including cacti, were largely unaffected by glyphosate.
Only remote and difficult to access sites that are dominated by buffelgrass would be treated using the aerial application of herbicides. No spraying would be allowed within a quarter-mile of occupied private property, one hundred and sixty-five feet of a water source or drainage, or above six thousand feet elevation. We will continue to monitor treated areas to evaluate effectiveness and negative impacts. Click on the district name to see a map of the treatment exclusion zones.
At Saguaro National Park we are evaluating the effectiveness and costs of different methods of buffelgrass. Our research includes studies on herbicide efficacy and toxicity on both buffelgrass and non-target native vegetation. 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. In partnership with the University of Arizona, we are also conducting research to determine the effects of buffelgrass on desert tortoises and other wildlife.
What do you think?
Your national parks are meant 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 buffelgrass and how to control it. In the coming months, park staff will be writing a draft Environmental Assessment, taking into consideration all public comments. When completed in early 2013, there will be further public review and additional opportunities to comment.
You may send initial thoughts and concerns to guide our planning. Comments can be submitted to the NPS's environmental planning analysis program: http://parkplanning.nps.gov/commentForm.cfm?documentID=50587; OR by email: SAGU_Planning@nps.gov; OR by mail to: Superintendent, Saguaro National. Park, 3693 S. Old Spanish Trail, Tucson, AZ 85730.
Please stay involved with this process by checking for updates on this website. For more information please visit the links and video below.
Did You Know?
"Don't call ME pig!" Javelinas are able to eat spiny prickly pear pads with no obvious harm to their mouths, stomachs or intestinal tracts due to an enzyme in their saliva. Javelinas are not true pigs, they are peccaries, which are native to the Americas. True pigs are native to Europe and Asia. Wild pigs and boars are descended from true pigs brought over on boats to the new world.