アイテム詳細

要旨

Plants are subjected to extended periods of waterlogging and submersion in the floodplains of Central Amazonia. Several adaptations and growth strategies allow them to survive. In this study, germination of plants growing in floodplains with different nutrient availability, nutrient-rich Várzea and nutrient-poor Igapó, are compared. In six tree species from Várzea and six from Igapó, germination was analyzed in the Amazon Research Institute (INPA) in Manaus, Brazil. Germination rates and duration were lower in species from Várzea than from Igapó. The cotyledons opened later and had lower longevity in Várzea, where the environment provides sufficient nutrients to the establishing seedling and there is less need for nutrient supply by the mother plant. Species from Várzea produced smaller seeds and the seedlings tended to grow less than in Igapó where large seeded species predominated. Leaf production was continuous in the Várzea species, but not so in the species from Igapó where leaves had higher longevity. The differences of germination and growth in Várzea and Igapó may be responses to the different nutrient availability in the two ecosystems and thus be related to different survival strategies of the species. In Igapó there is a higher investment in high seed mass, in fast initial growth and in the production of long-lived sclerophyllous leaves, whereas in Várzea the seeds and seedlings were smaller and nutrients are supplied more by the environment. For a better understanding of the different selective pressures operating in Várzea and Igapó it would be interesting to take taxonomic relatedness into account and to make intraspecific comparisons