Economic Costs and Invasive Species

Sean D’Evelyn, assistant professor of economics, studies efficient invasive species management and on environmental public goods. Here he talks about economics and ecosystems.

How does one apply economics to the issue of dealing with invasive species?
Economics as a discipline is primarily about what you do when you can’t have everything. You’ve got to make important trade-offs. So, applying economic principles to specific environmental topics, like invasive species, is not so surprising: How much effort do we spend trying to prevent the arrival of an invasive species? What are effective tools to help protect the environment that are also cost-effective? At what point is a quarantine policy too burdensome? What is the best way to weigh prevention vs. control. Good data and good analytics can help people make the right policy for all of us.

What is the greatest cause of non-native plant and animal species invading other ecosystems?
People have assumed that human activities are one of the large drivers of species movements. There have been plenty of examples of invasive species being transported accidentally as part of trade or migrations. I have a paper in which I look at introduction of non-native species over time across the entire world. This paper shows that people, indeed, are a huge driver of species movements. There is some hope. Even though things like Gross National Product and population growth tend to be very strong predictors of species movement, people work to mitigate the impacts of non-native introductions when they get to a certain level of affluence or become aware of the environmental impacts.

How can your research help a policy maker with a specific problem?
In 2005, the state of Hawaii was trying to decide whether to implement a ban on a particular plant species because a rust fungus seemed to be spreading on the plants. They were worried that it could wipe out a large section of forest. We realized that the primary plant in question was actually being used as a filler green for bouquets. Restrictions would be an inconvenience for florists, who would have to re-source some of their materials. We surveyed perhaps a dozen florists and realized this was a temporary problem. They’d need to spend a little time re-sourcing things. We tried to gauge how much time would be lost in that effort, but ultimately we suggested that a ban was the right policy. It would be the easiest and most effective response, and losses were small enough to make it worthwhile. The net benefits were greater than quarantining or any other policy we could come up with.

Why is Hawaii an interesting place for your studies?
Hawaii is interesting because, in many ways, the ecosystems are so fragile. There are species with no natural predators — some plants have no thorns, for example. There are essentially zero snakes or other predatory species that could be harmful to humans. So the tourism industry is very aware of the potential impact of invasive species, as is the agricultural industry. Also, there are clear pathways by which invasive species can come into Hawaii, whether it be on planes or boats. On the other hand, you can regulate what happens at those points of introduction.

How does your work apply to similar issues that exist in California?
The lessons we learn about Hawaii can be applied to California. California has vulnerable ecosystems, including the Ballona Wetlands. California’s agricultural sector is much larger than Hawaii’s, so invasive species are a serious concern. How do we prevent invasive species from coming to the area and how do we deal with them when they do? Recognizing the trade-offs between different policy tools is very appropriate here as well. There are differences, because snakes and plant fungi are different from insects and beetles that we’re particularly worried about. But, at the end of the day, it’s still a population that if left unchecked can cause great damage to ecosystems and agriculture. We need to mitigate those potential risks.

Sean D’Evelyn
Photo by Jon Rou
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