August 8, 2002. Copyright 2002. Graphic News. All rights reserved.

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GN14163 -- Bird's-eye view of clearing after "slash-and-burn" has transformed the landscape from tropical humid forest to pasture. MUST CREDIT: Hugh Eva 

Tropical forest loss less than expected

LONDON, August 8, Graphic News: Scientists using the global imaging capabilities of Earth-observing satellites have collected the most accurate measurements to date confirming massive deforestation of the worldÕs humid tropical forests.

FrŽdŽric Achard and colleagues at the Joint Research Centre at Ispra in Italy used satellite imagery and new statistical techniques to estimate the amount of tropical humid forest lost between 1990 and 1997. The international team found that it was 23 percent less than previously estimated, according to a study published in the August 9 issue of the journal Science.

While that may seem like good news, the losses still amount to 5.8 million hectares -- nearly twice the area of Belgium -- each year, and an additional 2.3 million hectares per year have been visibly degraded. 

Loss of forest cover affects biodiversity, climate, and tourism benefits; as well as net revenues from the sustainable harvests of commercial timber and other forest products, says the report. The researchers collected data from 100 sites in Southeast Asia, Latin America and Africa, representing 6.5 percent of the humid tropical domain.

ÒThe three continents we examined revealed considerable differences in percentage change rates,Ó said Achard. Southeast Asia had the highest percentage deforestation rate -- up to 5.9 percent per year -- while Africa lost its forests at about half the rate of Southeast Asia. Madagascar is losing its forests at up to 4.7 percent per year. Latin America showed the lowest percentage rate.

ÒThe major forest changes were largely confined to a number of hot-spot areas where change rates were alarmingly high: annual transformation rates of more than 2.5 percent were measured at 16 sample sites,Ó Achard added.

In Indonesia, corruption and poor law enforcement have led to a spate of illegal logging, resulting in one of the highest rates of tropical forest loss in the world. Deforestation rates in the biologically rich Asian archipelago doubled between 1990 and 1997, with the country losing 2.5 million hectares of forest every year -- the same area annually as the much larger Brazilian Amazon band.

The countryÕs most biologically rich forests, known as lowland forests, are rapidly disappearing on the island of Sulawesi, and all forest could disappear from Sumatra by 2005 and from Kalimantan by 2010. Overall, Southeast Asian forest cover fell from 283 million hectares in 1990 to 270 million hectares in 1997. 

In addition to illuminating issues like tropical ecology, biodiversity, and sustainable development, these improved estimates will advance understanding of the global carbon cycle, say the researchers.

In Latin America, the transformation from forests to agriculture by "slash-and-burn" destroyed 2.5 million hectares per year. Many scientists are concerned that the Amazon jungle acts as a carbon sink, reducing global warming by absorbing more carbon dioxide than it releases into the atmosphere. Data presented at the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) in Brazil last July estimate that the Amazon absorbs between one tonne and nine tonnes of carbon dioxide per hectare.

The paper concludes that earlier estimates, which were based on surveys of forest cover made by the United Nations Food and Agricultural Organization, may have been off the mark by as much as 50 percent. 
/ENDS

Source: Science