The structure and approach of AEZ is static. There is no feedback in it, so it is not suitable for simulation. Consequently environmental effects and the effects of develop ment cannot be evaluated endogenously. Instead, the climate and resource data base must be exogenously adjusted to determine the long-term outcome. This means that to introduce climate change it is necessary to redraw the climate map.
Another characteristic of AEZ is that potential production of the land resources is overestimated because areas for growing non-food crops (eg. vegetables, beverage crops, etc.) and forest (for timber, fuel wood, etc.
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except steep areas and conservation forestry) have not been considered. For this reason "the result of the study would have to be reduced by a t least one third" (Shah et al., 1985b:5). However, the LRFP Kenya Case study includes both non-food crops and forests.A third feature of AEZ is that "the study assumed average mean climatic patterns.
The effect of neither the short-term weather fluctuations nor the long-term changes in cli- mate have been considered" (Shah et al., 1985b:6). Here again, the LRFP Kenya Case study includes rainfall distribution patterns and provides production estimates for "good"
and "bad" years in addition t o the "average" years.
2.1.2.3. Sources of s u r p r i s e t o AEZ
Surprises t o the AEZ study can come from two sources: climate changes and new crop varieties. It is not easy t o assess the adaptability of present crop varieties to new cli- mate or soil conditions. Similarly the changes implied by a new crop or variety may be of a similar magnitude t o those coming from climatic shifts.
2.1.2.4. Relevance t o long-term, large-scale e n v i r o n m e n t a l s t u d i e s
AEZ is concerned with the environment only with respect to land suitability. Land suitability in turn is a function of environmental indicators such as climatic changes and soil suitability changes. The indicators are highly dependent on the technological level applied.
The AEZ study covers the environmental and development characteristics of interest t o development-environment studies only indirectly:
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Water quality and quantityWater quality can be affected through a changing soil phase (namely salinity phase), while water quantity can affect crop production. Water quantity more directly affects land area through irrigation. The extent of irrigation in AEZ comes from estimations provided by AT 2000.
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Land qualityOne of the main objectives of the AEZ study is to assess the extent of land area which are suitable for the production of the most important crops. Suita- bility is defined as meeting the climate and soil requirements of a specific crop, and is further classified into very suitable, suitable, marginally suitable and non-suitable. Soil conservation activities are needed t o maintain soil suitabil- ity.
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Land quantityOn the basis of the land suitability assessment AEZ identifies the potentially usable land area by region/country. Potential usable land area can be dimin- ished by land degradation. Total land is adjusted using a rough estimate of non-agricultural land use, namely 0.05 ha per person. Thus potentially avail- able agricultural land is also a function of population growth.
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ClimateAEZ results are highly dependent on climate. Land suitability is established on a climatic basis. It can be concluded that any climatic changes may significantly affect the land suitability evaluations and through that the poten- tial production values as well.
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Air quality, ecosystem quality and resource availability are practically not con- sidered.-
Development Characteristics:AEZ compares several different land uses, crops and levels of technology in evaluating production potentials and the costs of production.
T o summarize the appropriateness of AEZ for environmental studies: (1) The model does not deal realistically with environmental interactions, which must be introduced exo- genously. (2) In calculating net biomass production, the growth function is estimated only from climate parameters and genetic properties of the crops. All other constraints which reduce the potential production and yield are estimated by expert judgement. (3) All the model's constraints and structural elements are static (except soil loss and produc- tivity loss).
2.1.3. O t h e r r e l e v a n t publications
Higgins, G.M. and A.H. Kassam. 1980. The Agro-ecological Zone Inventory In: Report on the Second FAOIUNFPA Expert Consultation on Land Resources for Population of the Future. Rome:FAO.
Kassam, A.H., J.M. Kowal and S. Sarraf. 1977. Climatic adaptability of crops. Consul- tants' Report, Agro-ecological Zones Project. AGLS. Rome:FAO.
Kassam, A.H. 1977. Net biomass and yield of crops. Consultants' Report, Agro-ecological Zones Project. AGLS. Itome:FAO.
Kassam, A.H. 1979. Agro-climatic suitability classification of rainfed crops. Consultants' Report. AGLS. Rome:FAO.
Wood, S.R. 1980. The allocation of irrigated areas and production of agr+ecological zones. Consultants' Report. AGLS. Rome:FAO.
The following studies pertain t o the estimation of population supporting capacity in AEZ:
FAO/IIASA/UNFPA. 1983. Potential supporting capacities of lands in the developing world. Technological Report of Land Resources for Population of the Future Pro- ject, Rome:FAO.
Shah, M.M. and G. Fischer. 1980. Assessment of population supporting capacities. In:
Report on the Second FAOIUNFPA Expert Consultation on Land Resources for Population of the Future. Rome:FAO.
Shah, M.M., G. Fischer, G. Higgins, A.H. Kassam and L. Naiken. 1985b. People, land and food-production potentials in the developing world. Publication number CP-85-11.
International Institute for Applied Systems Analysis, Laxenburg, Austria.
Food and Agriculture Organization. 1984. Land, food and people. Rome: FAO.
2.2. A g r i c u l t u r e Toward 2000 ( A T 2000)
Food and Agriculture Organization of the United Nations. 1981. Agriculture Toward 2000. FAO, Economic and Social Development Series, 23. Rome.
2.2.1. D e s c r i p t i o n
Agriculture Toward 2000 (AT 2000) is the result of a four year study completed in 1981 by the Food and Agriculture Organization of the United Nations. An early draft of the work was published in July 1979 and contains an extended summary.
The study analyzes the implications for world agriculture of population and income growth up t o the year 2000. It proposes a strategy for the development of world agricul- ture t o abolish world hunger by the end of the century. It recognizes that increased food production alone will not solve the hunger problem: distribution of agricultural products also needs improvement.
2.2.1.1. S c a l e and resolution.
The unit of analysis is the individual country with 90 developing countries studied in detail (China is not included in the detailed analysis). Thirty-four developed countries are aggregated and studied in less detail. Analyses of the latter production, input and
investment requirements rely mainly on existing trends. China is examined only with respect to possible future agricultural trade.
2.2.1.2. Approach
AT 2000 sketches a global framework for future world demand, production, trade and nutrition. National and international policy actions and options which enable agri- culture to contribute to overall economic and social development are considered.
The model is normative and demand driven. Demand for food and agricultural export products is derived using socio-economic objectives as constraints. AT 2000 analyzes quantitatively three scenarios for agricultural development. Instead of producing a forecast or projection the study describes requirements for achieving development goals.
For each of the 90 developing countries the analysis covers a variety of crops, land classes, and technologies.
Food demand is projected for 27 groups of commodities for 131 countries. For each of the 90 developing countries, production is analyzed for 28 crops, 6 livestock products, 6 classes of rainfed and irrigated land, 9 levels of current inputs and 26 investment items.
Twenty four production techniques are distinguished, based on 6 landlwater resource combinations (based on the AEZ study) and 4 management levels. For each management level a production technique represents a certain yield level, and is associated with a com- bination of input factors (24 in total, i.e. 6 land types x 4 management levels).
The model first projects food demands at the national level. Then the potential agri- cultural production is assessed. Projections differentiate between developed and develop ing countries, and between crops and livestock. The estimates of country-specific produc- tion levels and required inputs are based largely on expert judgement of yield levels for each crop and land class. Both present and possible future combinations are accounted for.
The AEZ study (see section 2.1) is used to analyze the land base and production potentials. Production targets are derived taking into account total demand, self sufficiency and export targets, and the projected national production. From projected demand and input requirements, resource requirements are calculated including area of land in each class, labor, and capital inputs. This gives rise to the net trading position of each country. World trade balance is achieved by iterative output adjustments largely by the developed countries.
Three scenarios were evaluated in AT 2000:
(1) trend: production and consumption of agricultural products is extrapolated from past trends between 1963 and 1975;
(2) scenario A: an optimistic high growth scenario in which the global economy grows in accordance with the UN International Development Strategy (UN, 1980);
(3) scenario B: a moderate growth scenario in which current trends of economic growth improve.
2.2.1.3. K e y aeeumptione and exogenous variables