ATHENS, Ga.--Tropical forests have been disappearing at alarming rates for the past three decades. Farmers, ranchers and timber industries have cut millions of acres, and only in the past few years has the ecosystem damage become clear.
A new study by botanists at the University of Georgia now shows for the first time that trees left standing in pastures can actually dominate the reproduction in nearby remnant forests, creating a "genetic bottleneck." The research indicates that the survival of tropical forests could be far more complex than was known before and that new approaches to conservation strategies may be needed.
"The key is to understand how much genetic movement there is between fragments of forest," said Dr. James Hamrick. "When we lose fragments of forest, we lose genetic diversity. Gene exchange between fragments helps to maintain this diversity."
The study, by Hamrick and his graduate student Preston Aldrich, was published today in the journal Science.
Genetic diversity is vital in both plant and animal communities. Farmers have, for hundreds of years, bred crop plants and farm animals to maintain a healthy diversity of what were, before the 20th century, called traits. Now, with advanced techniques to determine the exact genetic makeup of individuals, scientists understand considerably more about how genes drift through populations.
Aldrich and Hamrick studied a tree species called Symphonia globulifera
in a little-examined premontane rain forest area in southern Costa Rica. S.
globulifera is a shade-tolerant canopy tree with bright red flowers that are
pollinated primarily by hummingbirds. Bats disperse the seeds by eating fruits
and then passing seeds on through guano at their resting sites. Like many areas
in the tropics, the study area consisted of an area of fragmented forest with a
number of large nearby members of the species standing alone in open pasture
land. There were neit
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Contact: Phil Williams
philwpio@arches.uga.edu
706/542-8501
University of Georgia
3-Jul-1998