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.”
 Bauhinia is a common tropical vine. Photo by: STRI. |
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.
CITATION: Schnitzer, S.A. and Bongers, F. 2011. Increasing liana abundance and biomass in tropical forests: emerging patterns and putative mechanisms. Ecology Letters. Doi: 10.1111/j.1461-0248.2011.01890.x
Related articles
From Cambodia to California: the world’s top 10 most threatened forests
(02/02/2011) Growing populations, expanding agriculture, commodities such as palm oil and paper, logging, urban sprawl, mining, and other human impacts have pushed many of the world’s great forests to the brink. Yet scientists, environmentalists, and even some policymakers increasingly warn that forests are worth more standing than felled. They argue that by safeguarding vulnerable biodiversity, sequestering carbon, controlling erosion, and providing fresh water, forests provide services to humanity, not to mention the unquantifiable importance of having wild places in an increasingly human-modified world. Still, the decline of the world’s forests continues: the FAO estimating that around 10 million hectares of tropical forest are lost every year. Of course, some of these forests are more imperiled than others, and a new analysis by Conservation International (CI) has catalogued the world’s 10 most threatened forests.
Losing nature’s medicine cabinet
(10/04/2010) In all the discussions of saving the world’s biodiversity from extinction, one point is often and surprisingly forgotten: the importance of the world’s species in providing humankind with a multitude of life-saving medicines so far, as well as the certainty that more vital medications are out there if only we save the unheralded animals and plants that contain cures unknown. Already, species have provided humankind everything from quinine to aspirin, from morphine to numerous cancer and HIV-fighting drugs. “As the ethnobotanist Dr. Mark Plotkin commented, the history of medicine can be written in terms of its reliance on and utilization of natural products,” physician Christopher Herndon told mongabay.com. Herndon is co-author of a recent paper in the journal Biotropica, which calls for policy-makers and the public to recognize how biodiversity underpins not only ecosystems, but medicine.
Mass extinction fears widen: 22 percent of world’s plants endangered
(09/28/2010) Scientific warnings that the world is in the midst of a mass extinction were bolstered today by the release of a new study that shows just over a fifth of the world’s known plants are threatened with extinction—levels comparable to the Earth’s mammals and greater than birds. Conducted by the Royal Botanic Gardens, Kew; the Natural History Museum, London; and the International Union for the Conservation of Nature (IUCN), the study is the first time researchers have outlined the full threat level to the world’s plant species. In order to estimate overall threat levels, researchers created a Sampled Red List Index for Plants, analyzing 7,000 representative species, including both common and rare plants.
