Seed production by Gilbertiodendron dewevrei in the Nouabalé-Ndoki National Park, Congo, and its implications for large mammals

Abstract

A number of members of the family Caesalpiniaceae form single-speciesdominant forests in Africa (Hart 1995). Forests dominated by Gilbertiodendron dewevrei (DeWild.) Leonard cover extensive areas in the northeastern Congo basin moist forest zone (Gerard 1960, Lebrun & Gilbert 1954, Rollet 1964) and can comprise 79% of stems above 10 cm diameter at breast height and 88% of the basal area (Hart et al. 1989). In northern Republic of Congo, G. dewevrei-dominated forest is common in riparian zones (Rollet 1964). Landsat TM images, aerial videography and ground surveys of the Nouabale-Ndoki National Park reveal that G. dewevrei forest cover is extensive, particularly in uplands away from watercourses. Gilbertiodendron dewevrei exhibits synchronous, supra-annual seed crops or mast seed production (Silvertown, 1980, Hart et al. 1995). It is thought that mast fruiting may have evolved to combat seed predation through predator satiation (Augspurger 1981). In Zaire beetles may destroy over 90% of the G. dewevrei seed crop in a mast year (Hart 1995). G. dewevrei seeds are also preyed upon by a large array of mammals including rodents, duikers (Ceplhalophius spp.), pigs (Potamochoerus porcus and Hylochoerus meinertzhageni), buffalo (Syncerus caffer), elephants (Loxodonta africana cyclotis) and humans (Hart 1995). In the Central African Republic gorillas (Gorilla g. gorilla) feed heavily on G. dewevrei seeds during mast years (Fay 1989). The temporal and spatial distribution of food resources are major determinants of ranging patterns and habitat use in mammals (Leighton & Leighton 1983, MacArthur & Pianka 1966, Terborgh 1983). Fruiting phenology over a