BURLINGTON, Vt., Oct. 29 (UPI) — U.S. biologists say they found some savanna trees may contribute to the likelihood of wildfires to promote their own abundance at the expense of competitors.
University of Vermont Associate Professor Brian Beckage, the study’s lead author, said positive feedback loops between fire and trees associated with savannas can make fires more likely in such ecosystems.
“We used a mathematical model to show that positive feedback loops between fire frequency and savanna trees, alone or together with grasses, can stabilize ecological communities in a savanna state, blocking conversion of savannas to forest,” Beckage said.
The researchers said their findings suggest some trees might modify or “engineer” their environment, including the characteristic fire frequencies in a landscape, to facilitate their own persistence at the expense of their competitors, Beckage said.
Examples of savanna trees that facilitate frequent low-intensity fires include the longleaf pine and the south Florida slash pine, both of which frequently shed their needles providing fodder for wildfires, the researchers said. The savanna tree initially invades grassland, but by facilitating frequent fires, it limits its own density and thus prevents conversion to a forest.
The study that included Louisiana State University Professor William Platt and Louis Gross, director of the National Institute for Mathematical and Biological Synthesis, appears in the December issue of the journal American Naturalist.
Copyright 2009 by United Press International