By Melissa Fratello and Aaron Mrotek, on behalf of Tucson Audubon Society and The Nature Conservancy, respectively
One of the most pernicious threats to biodiversity and the resilience of our watershed is the ever-growing impact of aggressive invasive vegetative species. Invasive species can be defined as non-native plants that have the ability to outcompete native vegetation, usually due to a lack of endemic biocontrols, or “checks and balances.” The presence of aggressive invasive species often results in decreased vegetative biodiversity and the establishment of single-species monocultures, which have compounding negative consequences. These consequences pose a significant, imminent threat to the health of the Sonoita Creek watershed.
Tucson Audubon Society (TAS) and The Nature Conservancy (TNC) are working together to address this threat. This work requires scientific know-how, strategic planning, and thousands of hours on the ground. It is crucial, too, that we share with our community our gratitude for support as we work to employ best practices and endeavor to manage and minimize invasives, to reach the watershed restoration goals we all share.
When tackling invasives, TAS and TNC employ a balanced, tactical approach called integrated pest management (IPM). It involves anticipating invasive infestations and preventing potential damage using strategies that implement a wide range of vegetation control methods, including but not limited to mechanical removal, cultural controls (altering the physical environment to make a target species less likely to survive, grow, or reproduce), and chemical controls to keep the ecosystem in balance while promoting a healthy environment.
For several years, Patagonia residents and eco-tourists have witnessed the results of IPM work done by TAS and TNC. We have tackled Arundo (giant reed) by spending hundreds of hours painstakingly removing root balls from the banks of Sonoita Creek. Our highly trained sawyers have cut out tree-of-heaven and Russian elm, creating space for native revegetation. And we have planted dense pockets of native grasses, plants, and trees to hold ground in spaces once occupied by Johnsongrass.
As for using herbicides, we carefully weigh benefits and risks before deciding to employ this tactic, which is rarely the first choice in IPM. In some cases, it is the only viable and lasting removal method given the resources at hand. Such is the case with highly aggressive invasive species like buffelgrass, stinknet, and vinca. When used appropriately, herbicides can be low-cost, effective, and have virtually no impact on native flora and fauna.
Even so, aversion to herbicide use is understandable. Spraying entire fields of GMO crops using boom sprayers or aerial application is commonplace in industrial agriculture. On a smaller but still harmful scale, individual consumers often overuse or misuse herbicides.
In contrast, TAS and TNC use targeted “spot spraying” by fully trained and licensed professionals, which is the safest method for effectively controlling the most aggressive and wide-spread invasive plants damaging the ecosystems of the Sonoita Creek floodplain. Individuals conducting spot spraying are well-trained in plant identification and safe handling practices to avoid affecting non-target species.
We share with this community a passion and concern for the well-being of the Sonoita Creek watershed. TAS and TNC are meticulous in selecting the safest chemical applications for restoration purposes. We exclusively choose and apply treatments that readily break down into non-toxic components within a short period. The seasonal timing of our applications minimizes risk to native vegetation, and our herbicides do not affect native seed germination.
Herbicides are a tool. And like any other tool (power equipment, hand tools, chainsaws), there are risks associated with use. The more you know, the more you are able to manage risk. TAS and TNC restoration practitioners have taken extensive care to minimize risks to the environment while maximizing benefits for our ecosystem, which is ultimately the shared goal of our organizations.
These efforts are critical for the larger restoration efforts being pursued by several local organizations as well as dedicated, individual community members, and will result in a healthier, more resilient watershed. Not taking action means giving up on birds, wildlife, and the diversity of life that makes the Sonoita Creek watershed so special, and that so direly needs us to make swift progress.