Forestry residues consist of slash left on the forest floor following logging operations; stems, stumps, tops, foliage, and damaged trees that are not mer­chantable; and wood and bark residues accumulated at primary wood manufac­turing plants during production of lumber. Underground tree roots can also be included in the list of forestry residues. The difficulty of accurately assessing the amounts of forestry residues that are and can be realistically collected and utilized as waste biomass for an entire country has been encountered by almost all who have embarked on the task. In the United States, many federal, state, and regional forestry offices and many of the companies in the logging and lumber manufacturing businesses do not keep and maintain detailed records of residue production and its disposition. Surveys are done only periodically and they vary widely from state to state. The survey of an entire country for a given time period is therefore subject to considerable error. Nevertheless, such assessments provide valuable information and an overall indication of the energy potential of forestry residues as waste biomass.