Given that the Amazon climate is essentially one of constant warmth, the most important climatic factor determining growth of palms is rainfall. In general, species richness is higher in higher rainfall areas and this also seems to be true for palms. The river systems of the Amazon, and their division into white, black, and clear water also have an effect on palm distributions. Typical palms of white-water river margins are for example Euterpe precatoria, Mauritia flexuosa and Oenocarpus bataua, although few species are confined to only one water type.
Another important factor regarding the growth of palms in the Amazon region is light intensity. Common palms such as Mauritia flexuosa and Oenocarpus bataua were found to occur in inundated forests where conditions of high light intensity are met. The palms were highly specialized for growth in waterlogged soils.
Few palms are restricted to a single soil type. In general, Oenocarpus bacaba is found to grow in upland forest on well-drained soil, and Euterpe precatoria and Bactris gasipaes on alluvial soils. Vesicular-Arbuscular Mycorrhizae are known to occur in several palm genera, including Bactris, Oenocarpus, and Jessenia. The influence indigenous people may have had on palm distributions throughout the history of human occupation of the Amazon region should not be overlooked.
In some palm species, pollination, dispersal and predation are only recently being investigated. Three common pollinators were recognized until 1986: beetles, bees, and flies. Wind pollination was considered rare in palms. In general, palm dispersal does not appear to involve such mutualistic interactions as pollination. Although dispersal is often animal-mediated, a whole range of animals can be involved, and these can act either as dispersers or predators.
(1) Henderson, A (1995) The Palms of the Amazon. Oxford University Press 362 p.
(2) Balick, MJ (Ed) (1988) The Palm - Tree of life: Biology, Utilization and Conservation. The New York Botanical Garden 282 p.