Kudzu, the plant scourge of the U.S. Southeast. The long tendrils of this woody vine, or liana, are on the move north with a warming climate.
But kudzu may be no match for the lianas of the tropics, scientists have found. Data from sites in eight studies show that lianas are overgrowing trees in every instance.
If the trend continues, these "stranglers-of-the-tropics" may suffocate equatorial forest ecosystems.
Tropical forests contain more than half of Earth's terrestrial species, and contribute more than a third of global terrestrial carbon and a third of terrestrial net primary productivity, says ecologist Stefan Schnitzer of the University of Wisconsin-Milwaukee.
Schnitzer is co-author with Frans Bongers of Wageningen University in the Netherlands of a paper on lianas in the current issue of the journal Ecology Letters.
"Any alteration of tropical forests has important ramifications for species diversity, productivity--and ultimately the global carbon cycle," says Schnitzer.
Tropical forests are indeed experiencing large-scale structural changes, the most obvious of which may be the increase in lianas, according to Robert Sanford, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research.
Lianas are found in most tropical lowland forests. The woody vines are "non-self-supporting structural parasites that use the architecture of trees to ascend to the forest canopy," says Schnitzer.
In tropical forests, lianas can make up some 40 percent of the woody stems and more than 25 percent of the overall woody species.
Lianas usually have a high canopy-to-stem ratio, says Schnitzer, "which allows them to deploy a large canopy of leaves above those of the host tree, competing aggressively with their hosts for sunlight, water and nutrients."
Intense competition from lianas for above- and below-ground resources limits
|Contact: Cheryl Dybas|
National Science Foundation