ASU Research E-Magazine: Spreading the Seeds of Knowledge

“The rivers where I come from are very different from the Southwest,” says Joelle Don de’Ville, as she leads me along the edge of the empty Salt River basin just north of Arizona State University.

A Missouri native, Don de’Ville left the abundance of the Mississippi to come to ASU, where she is pursuing a master’s degree in education. Don de’Ville studies Southwestern river ecosystems. She hopes one day to share her fascination with the environment with high school biology students.

Don de’Ville was awestruck by the desert landscape upon arriving in Arizona. She set out to learn as much as she could.

“I just picked up all these little brochures and pamphlets about [Arizona] plant life. That’s how I started. I was so amazed, it was such a new experience,” she says.

“Then I encountered some ASU students. They clued me in to the Center [for Environmental Studies],” she continues.

Don de’Ville is participating in a research project that will help the Arizona Department of Transportation (ADOT) revegetate the Salt River area in Tempe. The study is part of ADOT’s mitigation program, designed to make up for damage caused to the river area by freeway construction.

Don de’Ville points out a lone cottonwood tree, sole survivor from the days before the highway. Everything around it was bulldozed to make way for the Route 202. Much was already dead. Dams upstream along the Salt River effectively wiped out riparian habitats downstream. Now, ADOT, the City of Tempe, and the Southwestern Center for Education and the Natural Environment are trying to reconstruct the riparian ecosystem along drip lines that follow the riverbed.

Recreating a riparian ecosystem is much more difficult than preserving an existing area, according to Don de’Ville. For example, new seedlings do not have the cover of larger plants to protect them from the elements. They do in natural systems.

“The dynamics of the system are completely different,” she says. “Some of the plants don’t adjust as well. They’re not used to the full, direct sunlight.”

Despite these difficulties, Don de’Ville and her colleagues are not alone in their efforts. The ecosystem itself lends a hand. As we walked along the canal that flows beside the river, Ron Tiller, a doctoral candidate in the botany department, called out to us.

“Look at this!” he yelled, pointing down at the canal banks. There, a tiny forest of baby mesquite trees was pushing up through the gravel. These trees were not planted by human volunteers. They were volunteers donated by Mother Nature herself. In eco-speak, volunteers are plants that grow naturally without human instigation.

Don de’Ville’s job is to find out why some plants, like the tiny mesquite trees, survive, while others do not. To do this, she spends a great deal of time monitoring the plots, taking measurements from every angle. She measures diameter, height, canopy area, and stem density, to name a few.

She also looks at the “leaf area index,” which measures the canopy area and the amount of light that penetrates through it. Data in hand, she makes recommendations to the City of Tempe that will help increase plant survival. Her recommendations might involve the need to provide more water from the drip lines or to relocate certain species.

There are certain plants that Don de’Ville does not want to survive, however. These are the “exotics,” plants not native to this area and plants that, in many cases, kill the native species.

The most common exotic is salt cedar, an aggressive immigrant that was brought to Arizona from Eurasia.

I asked Don de’Ville to point out a salt cedar to me. She swept her arm out towards a large collection of familiar-looking trees, trees that I had always taken for Arizona natives.

“You see it so often, it becomes part of what you think is supposed to be there, and it’s really not,” she says.

Don de’Ville hopes to educate her future students about what is supposed to be there. She also wants to teach them how to protect it.

“Future generations are going to be the stewards of the land. If I can incorporate some of my fascination and pass off the knowledge that I’ve acquired so that the decisions they make will be informed, conscientious decisions, that will be wonderful,” she says with a smile.

“Plus, biology is the study of life. How can you go wrong with that?” —Diane Boudreau