CHARLES BURESS – SAN FRANCISCO CHRONICLE
The world’s rain forests hold many promises.
They help store greenhouse gases that would otherwise contribute to global warming. They provide habitat for thousands of species and homes for indigenous people.
Yet rain forests are still being destroyed despite decades of work to prevent deforestation. The economic pressures are great: a desire to expand cropland, the need for more cattle-grazing pastures and the production of timber, to name a few.
It’s unclear how much the destruction of rain forests is offset by reforestation in areas where forests were cut down and by natural expansion of forests and planting of trees on nonforest land.
Alan Grainger, a University of Leeds geographer and editor of the Journal of World Forest Resource Management, has found that estimates of rain forest destruction between 1973 and 2000 vary widely. In a report published last month in the Proceedings of the National Academy of Sciences, he concluded that existing data make it difficult to conclusively prove overall tropical forest decline.
However, the main source used by most researchers, the U.N. Food and Agriculture Organization’s Forest Resources Assessments, indicates a net decline in tropical forests from 1990 to 2005. The agency’s data for the size of natural forest in 90 tropical countries showed 4.37 billion acres in 2005, down 9.3 percent from 4.81 billion acres in 1990.
“Deforestation is real,” said Lars Laestadius of the World Resources Institute, a nonprofit environmental think tank. “We can see it on the ground and in satellites.”
However, even if the loss of some rain forests is made up by regrowth, problems with deforestation remain.
Richard Houghton, a senior scientist at the Woods Hole Research Center of Falmouth, Mass., estimates that tropical deforestation releases about 1.5 billion metric tons of carbon into the atmosphere each year as the trees that store the greenhouse gas are cut. The burning of fossil fuels, by comparison, produces about 7 billion tons, according to some estimates.
Data from the World Resources Institute indicate that deforestation accounts for about 18 percent of human-caused greenhouse gases, compared with nearly 10 percent for road vehicles.
A recent U.N. meeting on climate change focused on deforestation. The December conference in Bali produced an international agreement that pledges a global effort to reduce tropical deforestation because of its impact on climate change. A plan to do that is expected by next year.
While some critics said the effort is not ambitious enough, it is still “great progress,” said Frank Merry, a scientist at Woods Hole. Other environmentalists have praised the attention to the issue.
Solving the problem of deforestation takes a country-by-country approach, many experts agree.
The Amazonian and other tropical forests of South America are losing about 8.6 million acres a year, from a total estimated at about 1.7 billion acres in 1999, said Rodolfo Dirzo, a Stanford biology professor who studies deforestation’s impact on biodiversity.
The primary cause, he said, is conversion of the land to agricultural uses such as cattle grazing and crops, followed by logging for timber.
The World Wildlife Fund estimates that 17 percent of the Brazilian Amazon has been deforested. That’s an area about the size of Texas.
The main drivers of the Brazilian deforestation, according to the group, are agricultural expansion for soybeans and other crops, cattle ranching, roads and dams for resource access and for energy exploration, illegal logging, forest fires and drought.
Meanwhile, in Paraguay, the rate of deforestation has dropped sharply, largely because most of the easily accessible forest has already been cut down, said Richard Reed, chair of the Sociology and Anthropology Department at Trinity University in San Antonio. That country’s forests are now one-tenth of what they were when he first went there 25 years ago, he said.
The loss has had a “devastating effect” on the Guarani Indians, who lived in the forest and whom Reed has studied for the past quarter century.
“The Indians are forced onto little packets of land that are left over once all the land is sold off,” he said. Largely gone is their hunting, fishing and foraging life, replaced by being “forced to work for wages, and hanging out on the edges of towns and farms,” he said. They live like day laborers, while the suicide rates for teenagers are astronomical, he said.
Southeast Asia also is seeing significant deforestation, particularly to plantations for palm oil, which is used in a wide range of snacks and foods. Indonesia has seen more than 182 million acres of its forest destroyed in the past 50 years, according to Greenpeace.
And in Mexico, only about 17 percent of the original forests remain, Stanford’s Dirzo said. There, about 10 percent of species have been wiped out, meaning the potential loss of unique chemical compounds that could have life-saving value as medicines, Dirzo said.
Those who want to help save rain forests have a wide range of options to choose from. Those who wish to learn more about the rain forest problem or about actions recommended by various organizations can contact a large number of groups.
Amazon Watch: www.amazonwatch.org
Center for International Forestry Research: www.cifor.cgiar.org
Friends of the Earth: www.foe.org
National Oceanic and Atmospheric Administration: www.noaa.gov
The Nature Conservancy: www.nature.org
Rainforest Action Network: www.ran.org
Union of Concerned Scientists: www.ucsusa.org
U.N. Intergovernmental Panel on Climate Change: www.ipcc.ch
U.N. Framework Convention on Climate Change: unfccc.int
Woods Hole Research Center: www.whrc.org
World Resources Institute: www.wri.org
World Wildlife Fund: www.wwf.org