Why are vines overtaking the American tropics?

Feb 14, 2011

(PhysOrg.com) -- Sleeping Beauty's kingdom was overgrown by vines when she fell into a deep sleep. Researchers at the Smithsonian in Panama and the University of Wisconsin at Milwaukee received more than a million dollars from the U.S. National Science Foundation to discover why real vines are overtaking the American tropics. Data from eight sites show that vines are overgrowing trees in all cases.

"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," said Stefan Schnitzer, research associate at the Smithsonian Tropical Research Institute in Panama and associate professor at the University of Wisconsin at Milwaukee.

Tropical forests hold more than half of the Earth's terrestrial species and much of the planet's carbon. If vines take over tropical forests the rules used to model ecosystem services, such as regulation of the water cycle and carbon storage may no longer apply.

"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," said Schnitzer. "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."

On Barro Colorado Island in Panama, the proportion of vines in tree crowns has more than doubled over the past 40 years. In French Guiana, liana vines increased 60 percent faster than trees from 1992 to 2002. Similar reports from Brazil, the Bolivian Amazon and subtropical forests in South Carolina in the United States confirm that vines are becoming more common and represent more of the total .

Trees have huge woody trunks that take a lot of time and energy to produce. Vines take advantage of trees, growing quickly on slender stems up into the forest canopy, where their leaves may compete for light with the leaves of the trees that support them.

There is still no consensus as to why lianas are gaining the upper hand. They may survive seasonal droughts that are becoming more common as climate becomes more variable. They may recover more quickly from natural disturbances such as hurricanes and El Niño events and from human disturbances like logging, clearing land for agriculture and road building. Lianas respond quickly to an increase in atmospheric carbon dioxide—growing faster than associated tree species in several experiments.

In North American forests, invasive vines such as kudzu, oriental bittersweet, English ivy and Japanese honeysuckle often reduce native tree regeneration and survival, although there is no obvious trend as there is in the American tropics. In contrast, two studies of forests in tropical Africa did not detect vine overgrowth.

To understand the nature of this contemporary spell that has been cast on the tropical forests of the Americas, the authors propose to take advantage of the widespread network of large-scale,
long-term monitoring plots—the Smithsonian Institution Global Earth Observatory network coordinated by the Center for Tropical Forest Science—combined with experiments to reveal what gives vines a competitive edge over trees.

Business models for investment in climate-mitigation schemes through carbon storage, climate models and water availability all rely upon accurate information about tree growth and cover in . The major physical transformations indicated by this research call the reliability of such models into question.

Explore further: Scientists tether lionfish to Cayman reefs

More information: 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 For online publication on 14 Feb. 2011.

Provided by Smithsonian Tropical Research Institute

4.7 /5 (11 votes)

Related Stories

Seeing The Forest And The Trees

Oct 24, 2005

With human emissions of carbon dioxide on the rise, there is growing interest in maintaining the Earth's natural mechanisms that absorb and store carbon.

Amazon carbon sink threatened by drought

Mar 05, 2009

The Amazon is surprisingly sensitive to drought, according to new research conducted throughout the world's largest tropical forest. The 30-year study, published today in Science, provides the first solid evidence that d ...

Recommended for you

Plants with dormant seeds give rise to more species

13 hours ago

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Scientists tether lionfish to Cayman reefs

23 hours ago

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Impact glass stores biodata for millions of years

(Phys.org) —Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists ...