In the last 8000 years about 45% of the Earth's original forest cover has disappeared, most of which was cleared during the past century. The Food and Agriculture Organization of the United Nations (FAO) recently estimated that about 13 million hectares of the world’s forests are lost due to deforestation each year. The annual net loss of forest area between 2000 and 2005 was 7.3 million hectares (equivalent to the net loss of 0.18 percent of the world’s forests).
The mechanisms that cause deforestation, fragmentation and degradation are varied and can be direct or indirect. However, the most important factors associated with the decline of forest biological diversity are of human origin. The conversion of forests to agricultural land, overgrazing, unmitigated shifting cultivation, unsustainable forest management, introduction of invasive alien plant and animal species, infrastructure development (e.g. road building, hydro-electrical development, urban sprawl), mining and oil exploitation, anthropogenic forest fires, pollution, and climate change are all having negative impacts on forest biological diversity. And as forests are degraded, so too is biological diversity. This degradation lowers the resilience of forest ecosystems and makes it more difficult for them to cope with changing environmental conditions.
For more information on the loss of forest biodiversity see Vital Forest Graphics