For now see Wikipedia:
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to agriculture or urban use.
The term deforestation is often misused to describe any activity where all trees in an area are removed. However in temperate mesic climates, the removal of all trees in an area—in conformance with sustainable forestry practices—is correctly described as regeneration harvest. In temperate mesic climates, natural regeneration of forest stands often will not occur in the absence of disturbance, whether natural or anthropogenic. Furthermore, biodiversity after regeneration harvest often mimics that found after natural disturbance, including biodiversity loss after naturally occurring rainforest destruction.
From a USDA blog post, “US Forest Service finds that forests play huge role in reducing carbon and higher global temps”,
One of the key findings in the study is that global forests have annually removed 2.4 billion tons of carbon which absorbs 8.8 billion tons of carbon dioxide from the atmosphere, about one-third of fossil fuel emissions annually for the period of 1990-2007.
“The new information suggests forests alone account for the most significant terrestrial carbon sink, and that non-forest lands such as agriculture, grass, desert and tundra collectively cannot be considered a major carbon absorption sink,” said Dr. Yude Pan, a U.S. Forest Service scientist and a lead author of the study.
The study reveals the dominant role of tropical forests. Tropical forests, which have not suffered from deforestation, absorb enormous amounts of carbon — more than all other northern hemisphere forests combined. The analysis also identified an additional large carbon uptake of 1.6 billion tons per year in tropical re-growth forests that are recovering from deforestation and logging, which partially compensates for a large carbon source from tropical deforestation.
The study also highlights risk of passively relying on forests to continue to remove carbon from the atmosphere. Such carbon sequestration is reversible through increased drought, wildfire and forest degradation.
Y. Pan et al., A Large and Persistent Carbon Sink in the World’s Forests, Science Express prepublication July 2011
See also Afforestation.