The 1998 Revision of the United Nations medium variant population projection indicates an increase of world population to about 8.9 thousand million by the year 2050 (United Nations, 1998), with a possible range of 7.3 to 10.7 thousand million. Most experts agree that through full and adequate application of modern agricultural technology, the world's land resources could provide sufficient food, fiber, animal feed, biofuel and timber for such a world population. In practice, however, there will very likely be acute land shortages in some countries, especially in several developing countries (e.g., see Fischer and Heilig, 1997).
Land is an indispensable resource for the most essential human activities: it provides the basis for agriculture and forest production, water catchment, recreation, and settlement. The range of uses that can be made of land for human needs, is limited by environmental factors including climate, topography and soil characteristics, and is to a large extent determined by demographic, socioeconomic, cultural, and political factors, such as population density, land tenure, markets, institutions, and agricultural policies.
In most developing countries, the needs and demands of rapidly increasing populations have been the principal driving force in the allocation of land resources to various kinds of uses, with food production as the primary land use. Population pressure and an increased competition among different land users have emphasized the need for more effective land-use planning and policies. Rational and sustainable land use is an issue of great concern to governments and to land users interested in preserving the land resources for the benefit of present and future populations. An integrated approach to planning and management of land resources is a key factor to implementing solutions which will ensure that land is allocated to uses providing the greatest sustainable benefit.
The increasing human population in several developing countries is placing pressure on the finite land resources, risking over-exploitation and land degradation. Sectoral and single objective approaches used to alleviate this situation have frequently not been effective. An integrated approach is required that involves all stakeholders, accommodates the qualities and limitations of each land unit, and produces viable land use options (FAO, 1995a).
The Food and Agriculture Organization of the United Nations (FAO) with the collaboration of the International Institute for Applied Systems Analysis (IIASA), has developed a system, that enables rational land use planning on the basis of an inventory of land resources and evaluation of biophysical limitations and potentials. This is referred to as the Agro-ecological Zones (AEZ) methodology.
The AEZ methodology utilizes a land resources inventory to assess, for specified management conditions and levels of inputs, all feasible agricultural land-use options and to quantify expected production of cropping activities relevant in the specific agro-ecological context. The characterization of land resources includes components of climate, soils and landform, which are basic for the supply of water, energy, nutrients and physical support to plants.
Recent availability of digital global databases of climatic parameters, topography, soil and terrain, and land cover has allowed for revisions and improvements in calculation procedures and to expand assessments of AEZ crop suitability and land productivity potentials to temperate and boreal environments. This effectively enables global coverage for assessments of agricultural potentials and has led to this Global AEZ study.