Seed Ecology of Selected Amazon Basin Successional Species

Abstract

Two adjacent forest sites-a mixed forest on well-drained Oxisols and a caatinga forest on waterlogged Spodosols-were similar in the number of viable seeds m-2 in the seed bank: 180 for the mixedforest site, 200 for the caatinga site. Most germinated seeds were of successional pioneer tree species Seeds were entering the mixed-forest seed bank at a rate of ca 50 seeds m-2 yr-1. Agricultural and pasture sites tended to have larger seed banks (580-1,250 viable seeds m-2) composed almost entirely of grasses and forbs. The most common grass, forb, shrub, and pioneer tree species in the forest and disturbed-site seed banks (eight species in all) were tested for their ability to persist for 1 yr in open storage cans on the forest floor and for their response to a variety of germination triggers. Seeds of all species tested were still alive after 1 yr of incubation on the forest floor. In a lighted environment these species showed good germination under both moist and flooded conditions, but neither daily tempera...