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UI researcher finds wide buffer zones needed to ensure tropical forest
IOWA CITY, Iowa -- Tropical parks and forest preserves may require buffer
zones extending more than eight miles beyond their boundaries in order
to ensure the survival of their rich diversity of plant and animal life,
according to research findings published by a University of Iowa biologist
in the Wednesday, Feb. 11 issue of the British journal Nature.
John D. Nason, associate professor in the UI department of biological
sciences, bases his conclusion on his study of the pollination patterns
of several species of fig trees in the vicinity of Barro Colorado Island,
Panama. Figs were chosen for the study because their populations bear fruit
year round and are key to the survival of many animal species. Nason says
that although their importance in the New World tropics and in Asia is
well recognized, the question of how large biological reserves must be
to preserve fig populations had never been adequately answered.
Nason found that fig trees, which are pollinated by species-specific
wasps, are routinely pollinated at distances of about 3.5 to 8.5 miles
between host trees. Because of such wide pollen movement, breeding groups
of fig trees can exist over areas as large as 225 square miles, an order
of magnitude larger than for any other plant species. Moreover, he found
his results likely can be applied to the roughly 350 species of fig trees
that share similar pollination systems.
Nason says that fig populations in South Africa and in the Krakatau
Islands are currently being studied to test his results, and the need for
further information seems clear.
"Information guiding the establishment of reserve areas sufficient
for the long-term preservation of fig populations is of vital importance
to the management of tropical biodiversity, particularly as large areas
of continuous tropical forest become increasingly fragmented by human activities,"
Nason says. "The results of fig research stress the importance of
preserving fig trees, even at low densities and great distances, in surrounding
Nason's co-authors are: E. Allen Herre of the Smithsonian Tropical Research
Institute, Balboa, Ancon, Republic of Panama; and J.L Hamrick, departments
of botany and genetics, University of Georgia, Athens, Georgia.