Vine invasion? UWM ecologist looks at coexistence of trees ...( Among the hundreds of species of woo...)

Among the hundreds of species of woody vines that University of WisconsinMilwaukee ecologist Stefan Schnitzer has encountered in the tropical forests of Panama, the largest has a stalk nearly 20 inches in circumference.

"That's like a large tree," says Schnitzer. "And because it winds itself up to the forest canopy and spreads, it can cover as much canopy area as a community of trees."

Such vines, called lianas, concentrate their energy on extending high and wide, and plunging their roots deep into the earth, rather than on building a thick trunk, says Schnitzer, an assistant professor of biological sciences at UWM who specializes in the vines and forest diversity.

They are essentially structural parasites, he says. But tropical lianas, even more so than their temperate counterparts (like kudzu, grapevine and poison ivy), are important players in tropical forest dynamics.

Growing evidence suggests that lianas are becoming more abundant with rising levels of carbon dioxide (C02) in the atmosphere, choking out trees. While all plants remove C02 from the atmosphere and store it, vines do not sequester as much as trees do so vines may cause a net forest-wide loss in carbon.

Scientists would like to know if lianas really are becoming more numerous in tropical forests and what if any effects that would have on C02 and climate change.

One problem in testing the theory of lianas on climate change, says Schnitzer, is that scientists aren't sure whether C02 is acting on lianas or the other way around. To find out more, he is involved in one of the most comprehensive community-level studies on liana-tree interactions ever conducted.

Lianas vs. trees

Schnitzer's study in central Panama aims to better understand the impact of lianas on forest regeneration by first looking at the abundance and distribution of the vines.

The project is backed by the Smithsonian Tropical Research In
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