Deforestation is often wrongly blamed for causing floods, like in Guatemala this month, under a myth that has skewed agricultural policies, an international report said on Thursday.
"There is no scientific evidence linking large-scale flooding to deforestation," the U.N.'s Food and Agriculture Organization (FAO) and the Indonesia-based Center for International Forestry Research (CIFOR) said in a report.
The frequency of major floods in the past 120 years, back to the late 19th century when forests were far more abundant, has been stable worldwide, it said. That implied that deforestation was not a cause of flooding.
It said devastation from Hurricane Stan in central America this month had been widely and wrongly blamed on excessive runoff caused by deforestation. The same was said about recent floods in China, Thailand and Vietnam.
The report said it was incorrect to believe that forests acted as giant sponges that soak up water and release it during dry seasons. After heavy rains, excess water runs off waterlogged forest floors like off other surfaces.
The report said tree roots were too shallow to prevent major mudslides, like those that entombed hundreds of people in Guatemalan villages this week.
"Most people automatically believe that if there's a large flood then loggers and deforestation are responsible," David Kaimowitz, director-general of CIFOR, told Reuters during a visit to Oslo. "In most cases it's not true."
Still, it said forests could play a role in minimising water runoff in some localised floods but did not have an impact on severe widespread floods.
LOGGING BANS
The report said some governments might cling to the myth that forests help prevent floods to let policymarkers blame loggers or small farmers for their own failure to anticipate the effects of heavy rains on dams or cities downstream.
Some governments, like in China and some other Asian nations, had banned logging to try to ease flooding.
"Such misguided views have in the past prompted governments to make life harder for poor farmers by driving them off their lands and away from the forests, while doing nothing to prevent future flooding," said Patrick Durst, a senior forestry officer at the FAO for Asia and the Pacific.
"There are many good reasons to manage forests well without relying on myths," said Kaimowitz. "But you can't sell conservation to the public on false premises."
Forests provide habitats for many species of birds and insects, produce oxygen and soak up heat-trapping gases as they grow, and are a source of building materials or firewood.
And floods are a part of a natural cycle, helping maintain fertility on flood plains. In some parts of the world, crops like rice and jute depend on seasonal flooding.
The report said a surge in the human death toll and mounting economic losses from floods in recent years was largely because more people lived in flood plains.
"As a result, many floods that previously would have been only minor events now become major disasters," the report said.Reuters
