Southern Arizona's wetlands considered crucial for desert life
By Jesus Antonio Gonzalez
The drive to Parker Canyon Lake,about an hour and a half south of Tucson, shows the diversity of vegetation in southern Arizona. The vegetation changes from cactus to desert brush around Tucson to alligator juniper as the car reaches the higher elevations around Patagonia.
After another half hour of driving through windy dirt roads, Trevor Hare goes through the U.S. Forest Service entrance gate and parks in the dirt lot. A hike down the sunny side of the hill on an April morning makes a person sweat. In the riparian area, the cottonwood trees are big enough to provide shade from the scorching sun. An emerald green pool of water attracted a gathering of chirping birds.
"Water is really the limiting factor for wildlife species and vegetation," said Hare, a landscape restoration program manager for the Sky Island Alliance, a Tucson-based environmental non-governmental organization. Most wildlife in Arizona depends on riparian areas to fulfill some part of their life history, noted Trevor.
Although they make up a relatively small proportion of the landscape, wetlands and riparian areas provide many services to both wildlife and people. They offer unique and critical habitat for wildlife, such as the endangered Chiricuahua leopard frog, and trees, such as the native cottonwoods and willows. Not only do these types of environments provide benefits to wildlife, they also offer services to society, such as fishing, hiking and bird-watching.
"Riparian vegetation is important for migratory bird species,” said Laura López- Hoffman, an assistant professor in the School of Natural Resources and the Environment at the University of Arizona.
Riparian and wetland areas offer critical habitat for both native and visiting species in southern Arizona. The Patagonia area is known for birding, with organizations including The Nature Conservancy providing the opportunity to view birds on tours or on the reserves. The TNC noted that the species include types of hawks, American vultures, hummingbirds, kingfishers, and flycatchers, among about 100 others on their checklist of birds.
When asked what is important about riparian communities in the desert, William Shaw, a University of Arizona professor of Wildlife and Fisheries Science, responded, “First, because of the availability of more water compared with uplands, the primary productivity of these systems is much higher than adjacent upland. As a result, they tend to be areas with greater species diversity and plant structural diversity. This means more food and more habitat type to support more diverse wildlife communities.”
Water in the West is scarce compared to the availability of the resource in the eastern part of the country. In Arizona, many riverbeds are dry for most of the year. The rivers that do flow are manipulated to sustain society.
"Water is typically allocated for human needs, and little to no water is left for the wildlife and the environment," said López-Hoffman.
López-Hoffman and others view efforts to leave some water in riverbeds for wildlife and also as a way to provide “ecosystem services” to society. She noted the Millennium Assessment identified four different types of ecosystem services: regulating, provisioning, cultural and supporting.
These services include natural processes such as the mitigation and filtering of harmful chemicals in water flowing through vegetated areas. They also include the production of food, fiber and forage that comes from hunting, ranches, and agricultural lands. The recreational opportunities that nature provides through its landscape and scenic beauty are another service.
All of these services can be found in riparian areas. Ranchers can use the water for livestock production, and farmers for agricultural purposes. Riparian areas offer opportunities in recreation through hiking, swimming, meditation and other activities that can improve physical health.
Riparian areas can also be a defense against floods.
"Vegetation in riparian areas can act as a buffer against flooding," said López-Hoffman. This has economic implications that can save a town, rancher or farmer money when flooding occurs.
Ecosystem services "is an additional communication tool to reach a broader audience," said López-Hoffman. By seeking and identifying the benefits nature provides, scientists can identify critical areas that are essential to the sustainability of resources.
Ecosystem services promotes conservation – not only because a species is threatened or endangered, she said, but also because the area provides services essential for human lifestyles and health.
Water might seem abundant in the desert city, where one easy twist of the wrist can bring water pouring out of a faucet. A trip to Parker Canyon Lake can enlighten the hiker, visitor, or recreationist about how much riparian areas provide an essential component to hobbies, health, food, water, and wildlife and plants of southern Arizona. In addition, it humbles the visitor that such a place exists in the scorching desert land.
Jesus Antonio Gonzalez is a Tucson native studying wildlife conservation and management at the University of Arizona.
Related story on ecosystem services: A closer look at ecosystem services
Adapted by Jesus Antonio Gonzalez from the Ecosystem Services Project website
Birding opportunities in the Patagonia area
Laura López-Hoffman on Ecosystem Services