In the case of urban wood waste, leaves and branches are collected and typically ground up with other waste wood. The ground up material can be used as mulch or converted to compost. In the case of harvesting commercial timber, slash (non-marketable tree parts) is typically left on-site. Slash may be distributed throughout the harvest site or may build up in piles if trees are passed through a delimber (a machine used to remove limbs). In some cases, the whole tree is removed from the site. This FAQ was adapted from Wood to Energy and used with permission.