ments resulting from the conversion of a tropical rain forest to different land use systems and agricultural practices. The rainfall results showed that the amount of rainfall under the forest canopy was about 12 percent less than that in cleared areas. The amount of solar radiation received in the cleared area was 25 times greater than that received under forests. On average, soil and air temperatures and evaporation rates were lower in areas under forest cover than they were in cleared areas. Relative humidities (which inversely correspond to variations in air temperature) were higher in forest areas than in cleared ones.

There are no empirical data on the extent of erosion of biodiversity because of deforestation in Côte d'Ivoire. However, forests are known to contain a wide variety of plant and animal species, many of which have not been examined by scientists. For example, they contain the gene pools of parent species from which many agricultural crops were originally bred and, therefore, may be needed for future breeding efforts if crops are devastated by new diseases or other catastrophes. Some of these species may be critically important for pest and disease resistance in agricultural crops. For example, because of a smaller gene pool, it will be harder to counteract a weakness such as reduced disease resistance in varieties of plants and animals used for economic production. Other species have important potential as pharmaceutical agents, some of which are known only to people indigenous to the forests. The erosion of the genetic base as a result of deforestation will make it increasingly difficult to maintain economic production from biologic resources.

After forests are cleared from the land, the soil's physical and chemical properties undergo significant changes, leading to nutrient losses, accelerated rates of soil erosion, and declining yields (Lal, 1981; Seubert et al., 1977). Forests protect the soil by regulating stream flows (thereby minimizing soil erosion), modulating seasonal flooding, and preventing the silting of dams and canals. Forests help to accelerate the formation of topsoil, create favorable soil structures, and store nutrients. Using data from Côte d'Ivoire, Ehui and Hertel (1989, 1992a) showed that part of the agricultural growth in Côte d'Ivoire has been accomplished at the expense of the natural resource base and is therefore unsustainable. In particular, they showed that