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Amazonian floodplains; seed germination; submergence; tree establishment; viability
Abstract:
Rapid and exactly timed seed germination is essential for the establishment
and survival of seedlings in Central Amazonian floodplains, where the
non-flooded period is short. The peak of fruiting occurs at high water, and
the seeds must tolerate extended periods of flooding and often submergence.
Germination starts immediately after the retreat of the flood, but it is not
clear if submergence is directly responsible for the inhibition of seed
germination. In the present paper, an experiment was performed with twelve
tree species from Amazonian floodplains to test whether seed germination
occurs only in non-flooded seeds. Ten pairs of each species consisting of 1
plastic cup + seed + soil, and 1 cup + seed + soil + water (5 cm) were
tested for germination. Thirty to 100 % of the non-submerged seeds
germinated after seven weeks, compared to 0 % of the submerged seeds. Four
species showed radicle growth, but no species produced a shoot as long as it
was submerged. Independent from phylogenetic constraints and from growth
strategies among the twelve chosen species, the timing of germination is
closely linked to retreating flood water, guaranteeing efficient seedling
establishment in the floodplains prior to re-submergence.
