An Enquiry on Forest Areas Reported to the Global Forest Resources Assessment-Is Harmonization Needed?

For international reporting purposes, information on forest resources often has to be supplied according to international definitions. Nevertheless, the country reports of the Food and Agriculture Organization (FAO) Global Forest Resources Assessment 2005 indicate that countries either prefer to use their own forest definitions or use national classes of forest and other biomes as a basis for reclassification to resolve the discrepancy between national and international forest definitions. These preferences are due to the complexity encountered when dealing with the problem of transforming national estimates into estimates according to an international definition but are also due to the lack of a methodological foundation. In view of the multitude of existing national forest definitions and the increasing international reporting requirements, a thorough methodological consideration of the problem appears to be particularly necessary. Therefore, a mathematical approach for comparing national definitions to an international definition is developed. After formalization of definitions and illustration of the peculiarities in national forest definitions, the basics of set theory and simple logic are applied to derive six relevant cases that describe how national definitions of forest are distinct from that of FAO. As a result, we are able to assign each country to a specific case and thus provide a basis for further analyses. We also reflect on the reclassification problem and describe two examples that illustrate the influence of assessment methods in the aim to report according to a common definition. FOR. SEI. 58(3):201-213.