It's also the major building material in such places, and provides a wealth of associated products including charcoal, oil and paper. Current trends indicate we're not growing enough trees for future demands. Despite this, it's estimated that 10 times as much tropical forest is being cleared each year as is being planted. Unfortunately, the replanting of forests has not, until recently, been included in the agricultural plans of most people. However, of possibly greater consequence are the indirect benefits of trees.
Trees play an important role in sustaining a healthy environment.
The only thing working against trees is that they don't grow overnight. Plant a tree, and you won't start seeing the benefits for several years. In the meantime, the land taken up by those trees is likely to be required to grow food crops for the short term. That's the situation in many developing nations anyway. Indeed, over much of the developing world, the natural forest cover has been removed to make way for food crops, and to provide people with fuel to stay warm and cook, and timber to build.