The destruction of forests not only reduces habitat available for wildlife but also adds to the greenhouse effect because the carbon stored in trees is released into the atmosphere.

Deforestation accounts for 18 percent of the carbon dioxide produced each year, a significant proportion of the emissions scientists say are causing global warming which also poses risks to forests via increased fires and the spread of pests.

Demand for agricultural land is one of the main reasons that forests continue to be erased at the rate of 13 million hectares a year, an area about the size of England.

However, moves by some countries to replant forests has meant the annual net loss has dropped from around 9 million hectares in the 1990s to 7.3 million, according to the "State of the World's Forests 2007" report.

A huge tree planting programme in China, for example, more than offset large-scale deforestation in other parts of Asia such as Indonesia, to produce a net increase in the amount of forested land in the Asia-Pacific region during the first five years of the decade.

China's economic boom has driven demand for wood and the country has adopted a tree planting policy, not only to reduce its reliance on imported timber, but also for soil protection, especially in areas near the Gobi desert, Killmann said.

In Africa and Latin America, there are fewer positive signs.

Forested land in Latin America -- home to the Amazon -- fell to less than half of the continent's area. By 2005, forests were estimated at 47 percent of the total land, from 51 in 1990.

More than half of global deforestation in the period 2000-2005 happened in Africa, the report said, underlining its conclusion that poverty and war are major contributors to forest destruction.

Although economic growth often contributes to illegal logging, the FAO concluded that development was, on the whole, beneficial to forests as wealthier countries were more likely to establish conservation policies.