Longest-running Amazon rainforest experiment imperiled by colonization plan

Longest-running Amazon rainforest experiment imperiled by colonization
Rhett A. Butler, mongabay.com
July 25, 2007

One of the world's most important and longest-running scientific experiments is under threat by new colonization proposed by the Brazilian government, warn researchers writing in the journal Nature.

The Biological Dynamics of Forest Fragments Project, an experiment launched outside the Brazilian city of Manaus more than 25 years, has helped researchers understand the impacts of deforestation and fragmentation on the complex ecology of the world's largest and most biodiverse rainforest: the Amazon. But now a colonization scheme sanctioned by the Brazilian federal agency SUFRAMA threatens to undermine the basis for decades of critical research.

"The stakes are very high," said William Laurance [interview with Laurance] of the Smithsonian Tropical Research (STRI) and a co-author of the paper. "It's not just the fragmentation project that's threatened but also other scientific sites operated by Brazilian and other organizations, as well as critical conservation areas in the region."

The Amazon is increasingly fragmented in colonized areas. Image courtesy of Google Earth

SUFRAMA (Superintendencia da Zona Franca de Manaus, the Manaus duty free zone oversight commission), which manages a large expanse of the central Amazon, plans to settle "many thousands" of people both inside the study area and across the region, in areas that are presently rainforest. These areas are home to animals like jaguar, puma, tapir and the harpy eagle -- species which have gone extinct in unprotected forests.

Laurance and his colleague Regina Luizão of Brazil's National Institute for Amazonian Research warn that hunters have already invaded the area and research camps have been raided and equipment has been stolen. Several study sites were burned by colonists last year.

"There is really not much to be gained economically from these colonization projects, and there is so much to lose," said Thomas Lovejoy, President of the Heinz Center for Science, Economics and the Environment in Washington, D.C., who conceived and helped to establish the fragmentation project more than 25 years ago. "In fact, the results of the science we're doing could be more profitable for Brazil. Intact forests could have great economic value in the long term for the purpose of stabilizing global climate and for conserving biodiversity."

A fragment of forest surrounded by cleared areas in the Amazon near Manaus. Image courtesy of Google Earth

The scientists say Brazil's Ministry for the Environment and IBAMA, the national environmental agency, have been helpful and sympathetic to the plight of the project, but "they have struggled to get the attention of SUFRAMA, despite years of behind-the-scenes negotiations," according to a statement from STRI.

"We appreciate that SUFRAMA is mainly concerned with economic development," said Laurance, "but the economic benefit of the colonization projects is very low. The forest is just being burned to make charcoal or low-quality cattle pasture. And it's a notoriously hard life for the colonists, who struggle to eke out a living in an area with many diseases but far from any medical services."

"We are hoping that SUFRAMA can partner with us to help promote a real vision for sustainable development in the central Amazon," added Luizão. "We believe that economic progress can proceed without causing irreversible harm to science and the environment. Our goal is not to confront SUFRAMA, but we are desperate. This is a cry for help."

The Biological Dynamics of Forest Fragments Project (BDFFP). Image courtesy of STRI

The Biological Dynamics of Forest Fragments Project

During the late 1970s the Brazilian government was encouraging widespread clearing of rainforest by offering tax incentives to landowners. However, in an area known as the Manaus Free Zone, just north of the Amazonian city of Manaus, the government required that 50 percent of the forest on a developed area must be saved. Lovejoy used this stipulation for his experiment, convincing landowners to leave their required forest patches in neatly cut squares, ranging in size from 2.5 acres (1 hectare) to 2,500 acres (1,000 hectares).

Deforestation in the Amazon. Photo by Rhett A. Butler

The experiment found that the most seriously degraded forest with the least diversity were the smallest, one-hectare reserves, while the reserves that retained the most diversity were the ones of the largest area. In the smaller reserves, drying winds reached the interior, affecting tree species and resulting in more tree falls. Gaps in the canopy allowed more sunlight to reach the forest floor, further altering the understory microclimate and causing changes in the makeup of resident species. Larger herbivores left the patches since the limited number of trees could not provide sustenance, soon followed by predators, which could not cope with the loss of prey. The loss of predators caused an imbalance in the food chain, and the populations of small herbivores and omnivores increased, adding pressure on forest seed banks and impairing the reproducing ability of forest trees. Troops of army ants could not be supported by meager forest patches and they too left, along with the bird, butterfly, and other insect species that depended on the troop. Shade-loving plants and animal species died off as more sunlight penetrated the diminished canopy, and "gap" species, like vines and certain bird and insect species, proliferated. These losses continued to set off a chain reaction that caused profound changes in the system, eventually resulting in its collapse.

Aerial photo of the BDFFP, taken by Dr. Rob Bierregaard

Similar experiments carried out around the world have yielded similar results. The colonization of forest patches by forest-edge species, light-gap specialists, and savanna species can counter the loss of species less tolerant of the changed forest and maintain the diversity of the patch. In some cases, forest fragment diversity may hold steady, but overall (global) diversity declines as some unique species lost from the forest patch are not replaced. Declining biodiversity in accordance with decreasing land area is an important trend to consider for conservation.

In global studies, larger forest patches lost fewer of their species. Diversity declined but at a rate and to a degree inversely proportional to the size of the patch. In other words, the larger the patch, the more organisms survived and were successful in reproducing. Thus these experiments demonstrated that the area of an ecosystem directly affects biodiversity.

Researchers have used experiments like the Biological Dynamics of Forest Fragments Project to help plan protected areas and conservation strategies. The loss of this Amazon project will be seen by scientists as a significant set back to tropical forest research efforts around the world.

Comments?

News options News index | RSS | Add to MyYahoo!

Advertisements:

Organic Apparel from Patagonia | Insect-repelling clothing

MONGABAY.COM
Mongabay.com seeks to raise interest in and appreciation of wild lands and wildlife, while examining the impact of emerging trends in climate, technology, economics, and finance on conservation and development (more)

CONTENTS

Rainforests
Tropical Fish
News
Madagascar
Pictures
Kids' Site
Languages
Blog
T-shirts
Newsletter
About
Contact
Archives
Interns
Help