Large Amazon Forest Reserves Crucial for Species Survival

WASHINGTON, DC, January 11, 2007 (ENS) - Conservation of extensive Amazon forest reserves is even more important than previously thought, according to a new study by an international scientific team. The research, to be published in tomorrow's issue of the journal "Science," spotlights the importance of protecting the Amazon from fragmentation.

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 at the National Institute for Amazonian Research.

Between May 2000 and August 2006, Brazil lost nearly 150,000 square kilometers (57,915 square miles) of forest - an area larger than Greece. Across the entire Amazon since 1970, an area four times that size has been destroyed.


Poor farmers use fire for clearing land in the Brazilian Amazon. (Photo M.O. Andreae courtesy Max-Planck Institute)
Every year, land clearing for agriculture, ranching and logging - both legal and illegal - shrinks the Amazon forest by thousands of square kilometers, leaving small forest fragments isolated from one another by cleared land.

Many species that occur in intact forests prior to destruction will not be present in a small fragment. But the scientists wanted to learn if these same species would be found in an equally small plot surrounded by untouched forest.

They say 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 study is sponsored by the Smithsonian Tropical Research Institute in Panama, the Smithsonian Institution in Washington, DC, and the National Institute for Amazon Research in Brazil.

The scientific team, headed by Gonçalo Ferraz from the National Institute for Amazon Research, studied a 13 year data set of more than 40,000 bird captures in 23 isolated and non-isolated plots of forest, ranging from one to 600 hectares.

Richard Bierregaard, Jr. and Philip Stouffer with the Biological Dynamics of Forest Fragments Project led the data collection as part of the experimental study founded by Thomas Lovejoy and his Brazilian colleagues.


Forest view from tower in Manaus, Brazil (Photo by M.O. Andreae courtesy Max-Planck Institute)
The scientists found that conservation of large areas is important because the forest is diverse.

"What might look like a vast mantle of homogeneous green is actually a multicolored mosaic," said Lovejoy, who is president of the The H. John Heinz III Center for Science, Economics and the Environment in Washington, DC, and the founder of the public television series "Nature."

"Species that occur throughout the forest at the large scale actually may have very specific requirements at the fine scale," he said.

This detailed look at the dynamics of 55 bird species allowed an unprecedented test of theories about the effects of reserve size and isolation on the local extinction and colonization of species.

The study shows that some species vanish because they do not survive in a given site, others because they do not colonize new sites that become available. The two processes may also act in combination.

The effects of area size on the occurrence of bird species are much stronger than the effects of isolation, the scientists concluded.

"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."

But large areas of forest encompass a wide enough variety of local conditions and species, to ensure the survival of the Amazon and its inhabitants, said Ferraz and his team.


Hyacinth macaws inhabit the Brazilian Amazon. Recent estimates of the number surviving in the wild have ranged from 2,500 to 5,000. (Photo courtesy Amazon Image)
The Amazon rainforest holds one fifth of the planet’s plant and animal species, more than 200 indigenous cultures, and 30 million people in search of sustenance and wealth.

In the past four years, under the administration of President Luiz Inácio Lula da Silva, Brazil has set aside more than 20 million hectares of the Amazon basin from development, giving the country the largest protected areas system in the world.

Brazil now has some 110 million hectares, an area twice the size of France, under some form of protection.

In December, the government of the Brazilian state of Pará established the largest protected area ever, 15 million hectares in northern Brazil.

Stretching from the border of Guyana and Suriname in the north to south of the Amazon River, the seven new protected areas created by Pará Governor Simão Jatene include the world’s largest tropical forest reserve.

The scientists say their findings confirm the importance of this action and other similar efforts to conserve extensive forested regions.