YORK, England, July 22 (UPI) -- For tropical forests attempting to recover from felling and other forms of deforestation, regrowth is taking longer than expected. New research suggests woody climbing vines called lianas are to blame.
Researchers at the University of York calculated that recovery of felled forests may take centuries, not decades. Though scientists focused mostly on tropical forests in Africa, a survey of similar studies from around the globe suggests vines are having similar effects on tropical tree growth in Asia and South America.
In tropical forests around the world, lianas have curbed regrowth by as much as 50 percent. The implications for carbon cycles are significant, researchers say. If forests are unable to rebound, their role as a carbon sink will be diminished.
The data suggests tropical forests are already storing less carbon than before. Accounting for tree mortality and slowed growth, researchers calculated a seven-fold decrease in the total rate of biomass accumulation.
Researchers shared their findings in the African Journal of Ecology.
"No-one has until now compiled data from all over the world to see what the general trend is," lead study author Andrew Marshall, director of conservation science at Flamingo Land, said in a news release. "What this study suggests is a trend; that lianas are impacting on the tropics but not just in selected sites."
Scientists acknowledge that lianas aren't entirely bad. They are a natural part of forests and provide bridges through the forest canopy that sustain a diversity of plants and animals.
But commercial logging has allowed for an unnatural proliferation of lianas, a phenomenon that threatens the vitality of tropical forests.
"We don't want to advocate taking all the lianas out of the forest, that would be terrible," Marshall said. "But a temporary removal in some places will help forests grow back."