George Frisvold: A dynamic defense against buffelgrass

By Stephanie Doster | July 12, 2007

Imagine that a pesky, if not down-right dangerous, invasive plant has infiltrated your yard, threatening to squeeze out your favorite cacti and other native plants. You yank out the unsightly intruder, only to find it thriving in your neighbors’ yards, unchecked and poised to strike your property once again. What do you do?

That is exactly the type of question that University of Arizona Agricultural and Resource Economics Professor George Frisvold is tackling, only on a larger scale.

Armed with a U.S. Department of Agriculture grant and an impressive background in economics and agriculture, Frisvold is hoping to develop a tool that land managers can use to collectively attack one tough invasive plant: buffelgrass.

That tool, a web-based decision support system, would allow government agencies and private land managers to provide information to each other about buffelgrass and map out cost-effective strategies for managing the pest in Arizona, especially in areas where the desert and cities meet.

“The decision model will illustrate to people that if they cooperate, controlling buffelgrass could be a lot more effective,” Frisvold said.

Buffelgrass is a non-native perennial grass that is spreading rapidly into desert ecosystems, where it can out-compete and potentially wipe out native vegetation, like the iconic saguaro cactus. The flammable grass also can contribute to fire hazards, threatening houses, buildings, and desert plants that are ill-adapted to survive fire. With climate change and warmer temperatures, buffelgrass could grow at higher elevations, increasing fire risk in the mountains, researchers say.

A number of efforts are underway to manage buffelgrass; spraying it with herbicides and wrenching it out of the ground manually are two treatment options, but steep terrain, location, weather and climate conditions, and other factors can limit where and when they are used.  

The decision tool is important in the buffelgrass battle because a number of economic models assume that a single resource manager decides the costs and benefits of controlling the invasive species, Frisvold explained. While useful, those models don’t take into account the coordination problems that arise between multiple jurisdictions. With user-friendly displays and maps, the tool is designed to fix that.

“With something like buffelgrass, you have the Park Service, hotel resources, county land, city land, national parks, the Forest Service, Bureau of Land Management land, and tribal lands,” Frisvold said. “Everyone is trying to control their own plot, and they might care about different things, like reducing fire risk or protecting endangered species. The basic problem is that this can defeat what they’re each trying to do. Luckily, many agencies realize this and are starting to coordinate their buffelgrass control activities.”

Frisvold, the principal investigator, is modeling the project on the Fire-Climate-Society decision support tool created by the Wildfire Alternatives (WALTER) research initiative housed at the UA’s Institute for the Study of Planet Earth. For the buffelgrass tool, users would enter a number of factors, such as their jurisdiction, resources that are most important to them—fire risk or endangered species, for example—and how much money and labor they have to attack the problem. Drawing on buffelgrass information from natural and social sciences, the tool would help steer the user toward a management plan.

“The model tells you what the best thing to do is given your budget and what you care about most,” Frisvold said. “For example, some people don’t like the idea of applying herbicides. In the model, you can say, ‘I don’t want to spray. Let’s take that option away and see what happens if we don’t spray.’ Without spraying, though, you need a lot more labor. It will lay out the trade-offs for people so that they have to decide what to do, rather than us telling them. People can consider different scenarios themselves.”

In addition to Frisvold, other Institute for the Study of Planet Earth (ISPE) scientists involved in the project include Barron Orr, assistant professor in the Office of Arid Lands Studies; Stuart Marsh, professor of Arid Lands Resource Sciences and Geography; and Julio Betancourt, adjunct professor in Geosciences, Geography and Regional Development, and the Laboratory of Tree Ring Research with The University of Arizona Desert Laboratory on Tumamoc Hill in Tucson. Travis Bean, coordinator for the buffelgrass education and control project at the Desert Laboratory, is another member of the team.

In the future, Frisvold envisions enhancing the tool with another variable: climate change.

“If climate were to change, how does that make managing buffelgrass more difficult?” Frisvold said. “For example, climate affects where buffelgrass can spread and thrive. It affects when and how well using herbicides work, so it  affects both the scope of the problem—at what elevations or latitudes buffelgrass can grow—and how effective your treatment options will be.”

When he isn’t bending his mind around economic equations that measure the costs of buffelgrass, Frisvold is busy on a number of other projects related to climate change. One project involves exploring to what extent temperature and rainfall affect irrigation water use. In the Southwest, agriculture uses far more water than any other sector. This study is designed to help identify agricultural water demand under future climate conditions, as well as how climate variability influences water use.

“We’re finding that farmers do take advantage of rainfall when they can to conserve irrigation water. We’re also estimating just how much more water they use when weather is hotter and dryer than normal. Agriculture uses a lot of water, so even subtle responses to changes in temperature and rainfall have a big impact,” Frisvold explained.

Those findings are important, he said, because one way municipalities might respond to an extended, extreme drought is to buy water from farmers.

“Just at the time when municipalities want more water, farmers need more water to grow their crops,” Frisvold noted. “Cities may find that acquiring water will be more expensive than they expect.”