Survival of Swietenia macrophylla seeds sown into slash-and-burn fields in Quintana Roo, Mexico

Abstract

In tropical America, regeneration of bigleaf mahogany, Swietenia macrophylla King, the most important commercial tree species, is problematic because of its fruiting and dispersal characteristics, very low tolerance of shade and response to logging. In Quintana Roo, Mexico, abandoned slash-and-burn cropfields are excellent candidates for seedling establishment, but an efficient way to establish mahogany seedlings has not been identified. This study assessed the probability of predation on directly sown mahogany seeds, examining the effects of three treatments (four types of seed protection, two sowing methods, two times of day for sowing). The mean percentage of seeds either partially consumed or removed during a 12-hour period varied from 1.1 to 7.7% among the four seed protection treatments and did not differ between the two sowing methods. Precipitation had an important positive effect on survival, and minimum daily temperature had a marginal negative effect on survival. The Julian calendar date had a positive effect on seed survival. Seed predation did not differ among the seed protection treatments that allowed access only to rodents, only to insects, and to both types of seed predators, and predation was greater with these three treatments than with the no-access treatment. Seed predation was not influenced by the time of day of sowing. Direct sowing offers a good option for regenerating mahogany, especially if the mahogany seeds are soaked for at least 2 weeks before sowing to reduce predation risks and increase prospects for seed survival and seedling establishment.