An international research team has discovered that the size of Amazon forest reserves is yet more important than previously thought. Their findings, to be published this week (January 12th) in the journal Science, underscore the importance of protecting the Amazon in large stretches of primary forest.
The article summarizes bird survey results from the world's largest and longest running experimental study of forest fragmentation the Biological Dynamics of Forest Fragments Project, sponsored by the Smithsonian Tropical Research Institute, the Smithsonian Institution and the National Institute for Amazon Research, in Brazil.
Fragmentation shrinks the Amazon forest by thousands of square kilometers every year, leaving a trail of small forest fragments isolated by cleared land. Many species that occur in intact forest prior to destruction will not be present in a small fragment, but would they be found in an equally small plot surrounded by untouched forest? The answer to this question has profound management implications because it weights the relative importance of area and isolation in the design of forest reserves.
The team, headed by Gonalo Ferraz from the National Institute for Amazon Research in Brazil, has been studying a 13-year data set of more than 40,000 bird captures in 23 isolated and non-isolated plots of forest, ranging from 1 to 600 hectares. Richard Bierregaard, Jr. and Philip Stouffer led the data collection as part of the experimental study founded by Thomas Lovejoy and his Brazilian colleagues. The most striking result is that the effects of area on the occurrence of bird species are much stronger than the effects of isolation.
"It is no surprise that small isolated fragments lack many species" said Ferraz. "Many birds are so uncommon that they will rarely occur in small plots even in the middle of vast undisturbed forest." The question is, does isolation aggravate this pervasive effect of size. It doe
Contact: Gonalo Ferraz
Smithsonian Tropical Research Institute