1. Statistical information on agricultural
performance, as on most other aspects of social and economic development, is
difficult to obtain and tends to be of poor quality. This study craws on what is
generally considered to tee the best available statistical information (see the
Statistical Appendix for data and sources).
2. The data on which estimates of food avallability and
consumption are based (such as crop acreage, yields, livestock production,
processing and storage losses) are of poor quality in most African countries.
Increasingly, it is also recognized that noncultivated plants and "bushmeat''
contribute far more to many Africans' diets, particularly in poor crop years,
than has been captured in official statistics Nevertheless, few observers are as
skeptical of the general picture of serious food deficits as Svedberg (1991).
3. Demographic modeling of the potential impact of AIDS m
extremely difficult Some simulations suggest that AIDS may reduce the population
growth rate of SSA as a whole by as much as 05 to 1.0 percentage points in the
early decades of the 21st centurythrough drastically higher mortality
rates. But higher mortality rates may delay fertility declines.
4. UNDP/World Bank (1992), Tables 14-8 rough 14-1, provides
country-specific data on energy consumption, including consumption of fuelwood.
5. The InterAfrican Committee on Medicinal Plants and African
Tropical Medicine and the Scientific, Technical and Research Commission of the
OAU fave published a pharmacopeia of African medicinal plants of proven
efficacy, African Pharmacopeia (1985), and several African countries }rave
established research institutes focusing on traditional medicine and the sources
and effects of the active ingredients in medicines administered by traditional
healers (DeJong 1991).
6. WRI/IIED estimates are even higher, suggesting that more than
80 percent of SubSaharan Africa's productive drylands, some 660 million
hectares, are affected by "desertification" (Table A-27).
7. The Sub-Saharan Africa Hydrological Assessment attempts to
meet this need by assisting countries to develop a reliable hydrological data
base (see Chapter 10, note 1).
8. In Cd'Ivoire, where deforestation has been the most
rapid, mean annual rainfall declined significantly during the 1970s and 1980s
(World Bank 1989a). Rainfall in Senegal decreased by 2.2 percent a year in the
1970s and 1980s, and there was a sharp decrease in rainfall in northern Nigeria
and Cameroon (Lele 1989c; Lele and Stone 1989). Rainfall also declined
dramatically throughout Ethiopia during that period (World Bank 1987a).
9. Cloud droplets form around aerosol particles, called cloud
condensation nuclei (CCN). Biomass burning generates and releases into the
atmosphere vast amounts of pyrogenic aerosol particles, which are very effective
as CCN. The more CCN in the atmosphere, the more droplets form, resulting in
smaller droplet size with a given amount of available water. Clouds composed of
smaller droplets are lighter in color' reflect more sunlight bade into space,
and are less likely to produce rain. Since clouds are a major regulatory and
control mechanism for the Earth's heat balance, large scale modifications in
cloud properties have a strong impact on global climate. The increasing
abundance of CCN is, therefore, likely to have potentially critical impact on
precipitation efficiencycompounding the changes in hydrological cycles in
the tropics caused by land surface changes such as deforestation (Andreae and
10 See, for example, Barnes 1990a and 1990b; Bishop and Allen
1989; Elliot 1986; Falloux and Mukendi 1988; Gorse and Steeds 1987; FAO/IBRD
Cooperative Programme 1991; Lal and Okigbo 1990; Matlon 1990; de Montalembert
and Clement 1983; Mortimore 1989a and 1989b; Nelson 1988; Stocking