Fruit consumption, seed dispersal and seed fate in the vine Strychnos erichsonii in a French Guianan forest

Fruit removal and seed dispersal of three individuals of the vine Strychnos erichsonii (Loganiaceae) were investigated in a mature forest of French Gu iana, during the season of minimal flower and fruit production. Five visito r species, birds and diurnal or nocturnal arboreal mammals, were observed, while one terrestrial rodent was collected in traps baited with S. erichson ii seeds or fruit pulp. One diurnal and one nocturnal mammal dispersed seed s at long distance. Arboreal frugivores consumed fruits as soon as they bec ame ripe and also ate unripe fruits. Fruit-traps revealed a higher fruit re moval during the night for the two more productive vines ('instantaneous' p roductivity). More than two-thirds of the seeds checked along transects unt il 30 m for the parent plant were dead or infested, without obvious relatio nship with the seed localisation (under or beyond the crown). However, the proportion of intact vs dead/infested seeds beyond the crown was higher for the more productive plant ('overall' productivity), suggesting predator sa tiation. Seed density decreased sharply in the first meters from the parent plant, but remained noticeable until 15 m after the crown on some transect s. Seedlings were very few and distributed independantly of their position under or beyond the crown. A high seed mortality, a low number and a high t urnover of seedlings under and in the vicinity of the parent plant suggest a crucial importance of long distance dispersal for the plant recruitment. Seed dispersal seems to be performed by a small number of varied species. B ased on its regular fruiting period during the season of flower and fruit s carcity, and its large place in the diet of several frugivores mammals, S. erichsonii Is probably an importante resource for these species during the season of food scarcity.