The Amazon is the greatest river system on the planet. Twenty per cent of the world’s freshwater enters the oceans through the river basin. It’s an immense amount of water, but the flow isn’t constant. The Amazon regularly bursts its banks with the seasons and the consequences are massive. River banks that were land can be submerged below ten metres of water and in this landscape that means flooding penetrates deep into the forest. Indeed, the wetlands of the Amazon form the largest floodplain in the world. They cover 300,000km2 – an area ten times the size of Belgium.
Ferreira et al. report on how the huge differences in water levels pose a selective pressure on plants in this extremely diverse and intensely competitive ecosystem. They look at the Várzea (archive), the white-water floodplains and the Igapó, black-water floodplains with a lower pH. The pressures of adapting to life in such a changeable environment can be seen in the variety of sexual and asexual reproduction methods used by plants. Responses to the extremes of flood and drought have been under-studied. Ferreira et al. document some of the strategies used in an ecosystem that will produce new challenges in the future.
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