Effort to curb invasive desert plant species underway

By Bob Burns
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A few more than a dozen gathered for the meeting. Mostly middle aged or older, appearing to be an unlikely group to be planning an attack on invaders, but that is their objective.

The Sonoran Conservancy of Fountain Hills is organizing some of its volunteers to address invasive plant species that can take over the town’s desert preserve, Desert Botanical Garden and other open spaces around the community.

Toni Vallee speaks to the group spreading her enthusiasm for the project, much like the plants they are seeking to remove. Teams are already moving about the preserve and garden, identifying invasive species and mapping locations for removal efforts. It is known as the Non-Native Invasive Plant Project (NNIPP).

Paul Staker, a volunteer with the McDowell Sonoran Conservancy in Scottsdale, is a veteran of a decade or more in the efforts to remove non-native plants from the desert. He said there are many non-native species of plants that have found their way into the desert, but the ones that are of most concern have probably been around for 100 to 150 years – a relatively recent introduction.

Generally, they arrived in the desert for practical purposes, feed for cattle, ornamental for landscaping, even hitching a ride into the state in decorative bouquets, as did the globe chamomile that took over large swaths of desert last spring.

Once they are introduced into an environment conducive to their growth, invasive plants will spread very quickly, Staker said. They choke out or deprive native species of scarce water. They also dry out in the heat and become flash fuel for wildfires with those incidents increasing over recent years.

The local effort to reduce invasive species is focusing on four plants, and Staker provided a primer of information about them.

Fountain grass was brought into the desert as an ornamental plant for landscaping and is used relatively extensively as such. That use is not so much a problem, according to Staker. Thousands of seeds can come from a single stalk of the grass, and they spread quickly settling mostly near washes for the moisture or water.

Buffelgrass has a similar look to fountain grass, but it is not used for ornamental landscaping. It was introduced to Arizona in the Tucson area for erosion control, so it tends to take over where it gets entrenched, according to Staker. He said there has been some success in the Scottsdale preserve against buffelgrass using herbicide, but that requires certified applicators and is indiscriminate in what it kills.

The globe chamomile, commonly known as stinknet, is another very invasive species. It is characterized by its yellow globe flowers, which contain hundreds of seeds ready to spread quickly. It will feed a fire as fuel, but not as hot as the grasses, Staker said. It is removed easily by hand and bagged to prevent seeds from spreading. An effort to remove the stinknet in Fountain Hills last spring appears to have been fairly successful, but it is an annual, and it is not certain how many seeds were spread.

Red Broome is the fourth target for the removal effort. It is similar to the other grasses mentioned, although it does not grow as thick. It is everywhere, according to Staker, and it is carpet-like and can grow to two or more feet tall. A key concern is fire hazard, broome burns quickly, but not as hot as the other grasses. Much of the time in desert burn scars the invasive species are the first plants to return.

Staker said the City of Scottsdale is moving its mitigation efforts toward a professional attack rather than using so many volunteers. He said experience has shown him that total elimination will not be achieved. Strategic removal is an objective by creating fire breaks to slow fire spread. 

The Times Independent invites readers to submit their civil comments on this issue. Email AZOpinions@iniusa.org. Bob Burns can be reached at bburns@iniusa.org.