World forest cover shrinking - report

The world's forest cover shrunk by 3.1 per cent between 2000 and 2005, according to satellite observations detailed in a study.

Hardest-hit were boreal forests - the world's far northern sub-arctic forests - which account for about one-third of this loss, said the report, published in the April 26-30 issue of the Annals of the National Academy of Sciences.

There are several causes of forest destruction, including human cutting and natural phenomena such as fires ignited by lighting, the report said. Data on changes in the world's forest cover are needed to estimate the impact of carbon dioxide emissions, one of the main greenhouse gases, and to set parameters for "global-scale biogeochemical, hydrological, biodiversity and climate models," read the report.

The total forest loss between 2000 and 2005 was estimated to be 1,011,000 square kilometres, the researchers said. Boreal forests, which account for 26.7 per cent of the world's forest cover, showed the greatest shrinkage over this period, losing four per cent, or 34.7 per cent of the total forest loss during the study period.

The report's authors, from South Dakota State University and the State University of New York, attributed two-thirds of the loss in boreal forest cover to fires. Tropical humid forests, which cover 11.5 million square kilometres and represent the world's largest forested surface, lost 2.4 per cent of their cover during the research period, or 27 per cent of the overall loss.