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November 2009 UWM Report article

Grad student’s forest research featured in Nature

By Laura L. Hunt

Joe Mascaro, a former National Science Foundation Graduate Research Fellow, is perturbing some long-held ecological beliefs about biodiversity in the plant kingdom.

When biology graduate student Joe Mascaro began his research into the effects of exotic plants on forest dynamics, he had no way to know that the work would end up featured in the prestigious journal Nature—a feat that not even many faculty have achieved.

But then again, the work of Mascaro, who is finishing his Ph.D. at UWM, is perturbing some long-held ecological beliefs about biodiversity in the plant kingdom, namely that heavily “invaded” environments, also called “novel ecosystems,” are of little value.

Hawaii has a lot of such forests—a hodgepodge of nonnative plants in a geographic area that is not managed or no longer managed by humans. Such ecosystems have traditionally been considered something to be avoided in favor of forests of native species. There is very little data on the issue, but Mascaro has stepped in to fill the void.

He is finding that novel forests have unique ecological benefits. In fact, he recently found that in some areas novel forests can store more carbon than native forests. And that’s not all.

Mascaro, who came to UWM specifically to work with Associate Professor Stefan Schnitzer, recently responded to questions about the research and where it will lead.

Q. Did you choose Hawaii for fieldwork because of the novel ecosystems there?

A. Yeah. I was an intern for a project funded by the USGS [U.S. Geological Survey] and looking at avian malaria on the Big Island in 2003. We had a lot of field sites in heavily invaded forests, and I was really intrigued by the idea of a global suite of species suddenly thrown together, where a new set of interactions were developing, and where ecosystem properties and functioning seemed to be more or less maintained.

Q. What have you found? And why are these results important?

A. The novel forests have higher tree-species diversity. In addition, ecosystem productivity and nutrient turnover are higher in the novel forests compared to the native forests. This is very important. The general view is that ecosystems experiencing such a great transition of species will collapse in a way that could negatively impact human welfare. We’ve found that rather than collapsing, the Hawaiian forests become more productive as they are altered by species introductions.

Q. Your point about the unexpected benefits in novel ecosystems is interesting. But what about biodiversity that depends on specific native species?

A. There is no doubt that the reorganization of species that will create novel ecosystems is bad for a lot of species. However, when we look at plants, we find that competition from introduced plants has not been a strong driver of extinction in native plants. This means that regional plant diversity is actually increasing worldwide due to species introductions. The story is different for diseases or parasites, such as ash borer, and predatory interactions, such as the introduction of the brown tree snake to Guam that led to all the native birds going extinct.

Q. Where do we draw the line in either letting go or managing human influences in these ecosystems?

A. I think we have to manage in context. If we are dealing with endangered species or vast tracks of virgin rain forest—we need to protect them at all costs. However, if we are managing an abandoned parking lot in a tropical country, we might be better served by allowing natural processes to run their course. The ecosystem that is assembled as a result will probably surprise us in its diversity and complexity.

Q. What are your future plans?

A. I expect to graduate this spring, and am looking for postdoctoral opportunities. I hope to keep working on novel ecosystems and climate change. Ultimately, I plan to apply for an AAAS [American Association for the Advancement of Science] fellowship that may enable me to have an influence on policy development.  


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