Regeneration filters in post-agricultural fields of Puerto Rico and Ecuador

Abstract

To better understand how rainforest regenerates after agriculture I sampled the seed rain and seed bank, and set out seeds and seedlings, on microsites defined by distance to the forest in fields both in Puerto Rico and Ecuador. I found that (1) total seeds, species richness and life-form richness were twice as great in the Ecuador seed rain compared to Puerto Rico but Puerto Rico seeds were more evenly distributed among species and (2) total seedlings from the seed bank were similar between Puerto Rico and Ecuador, (3) the majority of seeds were lost to predation among all species and study sites, (4) seed disease was absent in P. aduncum and Miconia prasina, and no seeds germinated for Gonzalagunia spicata and P. riparia, (5) in Ecuador pathogenic disease claimed more seeds than germinated for all species, and Solanum ovalifolium was the only species that had seeds germinate but did not lose seeds to disease, (6) also in Ecuador, insect predation was significantly lower in the forest border for P. aduncum, and seed disease was significantly greater at the 10 m micro site for S. ovalifolium, (7) distance has a significant effect on seedling height and basal diameter, (8) losses of leaf area due to herbivory and pathogens were always low and (9) biomass and leaf specific mass were significantly reduced in the border and forest microsites. I conclude that Ecuador fields had more seeds, species, and life-forms than Puerto Rico fields, predation was the most severe post-dispersal seed filter in all fields, seeds that survived predation on Puerto Rico were lost either to disease or germination but to both mechanisms in Ecuador, all three seed mechanisms in Ecuador fields showed distance effects of seedling growth but not survivorship.