Trees grow using photosynthesis, absorbing carbon dioxide and releasing oxygen. Therefore, the more trees that are planted, the greater the absorption of carbon dioxide, one of the major contributors to global warming. It is also known that young trees are more efficient at photosynthesis than mature ones. Thus, the constant harvesting and replanting of trees reduces the levels of carbon dioxide still further, together with increasing the supply of oxygen. As a result of greater environmental awareness, timber is starting to regain some of its traditional markets that had been lost to 'modern' materials.
Timber is the obvious alternative.