SEED TRANSPORT BY ANTS IN ANDEAN AGROECOSYSTEMS OF COLOMBIA

Abstract

Ants are important functional agents in natural ecosystems and tropical agroecosystems. Seed movement by ants may result in dispersal or post-dispersal events, affecting diaspore survival probabilities in cattle agroecosystems undergoing ecological rehabilitation. In that case, ants could be determining in the course of succession. Activity and diversity of soil foraging ants was compared in nine plots classifi ed in three land use systems: forest, treeless pasture, and intensive silvopastoril system with Leucaena leucocephala. Transects with 10 stations separated by 10m from each other were established. In each station the diversity of ants was evaluated using tuna baits, and as a separate event, deposits were offered, each one with 15 seeds from three different plant species. We found 27, 18, and 12 morphospecies of ants in forests, treeless pastures and intensive silvopastoril systems, respectively. Twentysix percent of the seeds were removed by ants in the fi rst two hours. The removal frequency was significantly lower in silvopastoril systems suggesting that the type of management of this cattle system does not promote seed movement by ants. The greatest diversity of ants transporting seeds was found in forests and in all the cases more than 50% of the arillated seeds of the native plant Siparuna aspera was removed. It is suggested that, in cattle systems where some of primary seed dispersers have been lost, ants can offer seeds movement services that might alter the survival probability of diaspores.