Source: mongabay.com
For years tropical scientists have anecdotally reported an increase in vines in the Amazon and other American tropical forests, but now a number of studies have confirmed such reports: vines are on the rise in Neotropical rainforests.
"In 2002, Oliver Phillips, a professor at the University of Leeds in the U.K., published a controversial study claiming that vines were becoming more common in the Amazon," explains Stefan Schnitzer, research associate at the Smithsonian Tropical Research Institute (STRI) in Panama and associate professor at the University of Wisconsin at Milwaukee, in a press release. "By pulling together data from eight different studies, we now have irrefutable evidence that vines are on the rise not only in the Amazon, but throughout the American tropics."
Studies have shown that on Barro Colorado Island in Panama, one of the best-studied tropical forests in the world, vines growing in tree crowns have doubled over the past four decades. Also, in French Guiana researchers have found that lianas, which are woody vines, have increased 60% faster than trees from 1992 to 2002. So far, the increase has only been seen in the Americas; studies in Africa have not found the same trend.Now that researchers have confirmed that vines are increasing, they have two questions: why are vines becoming more common and what does it mean for the future of the American tropics? To help answer these questions, Schnitze—and other researchers with STRI and the University of Wisconsin at Milwaukee—have been granted over $1 million to study the disconcerting trend by the US National Science Foundation (NSF).
The impact of vines is unknown, however, given that many vine species compete with trees for light and nutrients, a rise in vines could change the forests' carbon sequestration, water cycle, and biodiversity.
"We are witnessing a fundamental structural change in the physical make-up of forests that will have a profound impact on the animals, human communities and businesses that depend on them for their livelihoods," says Schnitze.
Researchers have come up with a number of possible theories to explain the rise of vines in the American tropics. Vines may be able to survive the increasingly common droughts in the tropics or they may recover quickly from human impact such as logging and clearing. In addition, studies have shown that lianas grow faster than trees when atmospheric carbon is higher.
