IMPACT OF SEED DISPERSAL OF RED HOWLER MONKEYS ALOUATTA-SENICULUS ON THE SEEDLING POPULATION IN THE UNDERSTOREY OF TROPICAL RAIN-FOREST

1 Seedlings of six plant species (Parahancornia fasciculata, Virola mi chelii, Minquartia guianensis, Quiina obovata, Chrysophyllum lucentifo lium, Pouteria torta ssp. glabra), the ripe fruits of which are exploi ted by howler monkeys Alouatta seniculus, were surveyed in a primary t ropical forest at Nourague Station, French Guiana, under sleeping site s and on control plots. 2 For the six selected species, a total of 120 9 seedlings was recorded on the sleeping site plots, vs. 312 seedlings on the control plots. 3 On the sleeping site plots, seedlings of four species (V. michelii, M. guianensis, e. obovata and C. lucentifolium) showed clumped distributions. 4 Seed dispersal by red howler monkeys seems to induce heterogeneous distributions on both the large scale (s eedlings of plant species dispersed by howler monkeys are concentrated under their sleeping sites) and the small scale (seedlings on sleepin g site plots are distributed in clumps). 5 The survey clearly indicate s the important role of howler monkeys as seed dispersers of these pla nt species. The aggregative pattern of seed dispersal by howlers could contribute to the floristic spatial heterogeneity of the primary trop ical forest.