DISPERSAL OF ACACIA SEEDS BY UNGULATES AND OSTRICHES IN AN AFRICAN SAVANNA

The dispersal of African Acacia seeds in the presence and absence of l arge mammalian herbivores and ostriches was assessed in a savanna ecos ystem in South Africa. In the absence of large herbivores, A. tortilis and A. nilotica pods were mainly dispersed in the shade, directly ben eath the tree crown and seeds remained in pods for over 18 months. In the presence of large herbivores, A. tortilis, A. nilotica and A. karr oo seeds were freed from pods and were dispersed into open, non-shaded habitats. Impala dispersed most A. tortilis seeds (18,900 ha(-1)), gi raffe most A. nilotica seeds (1060 ha(-1)) and giraffe and kudu most A , karroo seeds (452 and 488 ha(-1), respectively). Seedling survival i n dung in open environments may exceed that of seedlings in soil shade d beneath the tree crown. It appears that seed dispersal by large herb ivores may be advantageous to future seedling recruitment.