DETERMINANTS OF VARIATION IN TROPICAL FOREST PRIMATE BIOMASS - NEW EVIDENCE FROM WEST-AFRICA

Compared data on the soils, vegetation, and primate community at a site in West Africa (Tiwai Island, Sierra Leone) with information from other sites, especially 2 other African sites (Douala-Edea in Cameroon, and Kibale Forest in Uganda). The estimate of anthropoid biomass at Tiwai is 1229-1529 kg/km2, including 682-889 kg/km2 of colobines, one of the highest primate biomasses recorded anywhere. The soils at Tiwai were relatively high in sand content and low in pH, and had low levels of mineral nutrients. Levels of condensed tannins in the mature foliage of the trees comprising a major part of the forest canopy were higher than at other sites, but the ratio of protein to fiber in this foliage was also higher than at any other site except Kibale. A wide range of environmental factors affect primate population densities, and nutrient-poor soils and high tannin levels in tree foliage do not necessarily produce a low primate (or colobine) biomass. Seeds (an important food source for Tiwai colobines) are apparently a common part of the colobine dietary repertoire and are not consumed largely as a response to a scarcity of digestible foliage. -from Authors