XVI International Botanical Congess
The undergrowth of tropical rain forest provides a microclimate characterized by a practically constant high humid and worm milieu. However, plants which achieve their complete cycle in these conditions have to develop adaptations in reaction to two main ecological constraints : 1) the low light energy attaining the ground, 2) the relatively frequent « bombing » of the undergrowth by falling branches and trunks. The palm Astrocaryum sciophilum live in such conditions, reaching when adult, a funnel like shape up to 8 m in diameter. Due to low light energy, new leaves are produced every 12 - 19 months, with a very low size increasing. Different measurements of the growth gave an estimation of 160 to 200 years before the first fructification, then 200 to 350 years of adult stage. Because a short seed dispersal (rodents) the colonization of the species is particularly slow, offering a good model in order to study the events having affected tropical forest during the last millenaries. Different isolated subpopulations show a phase of colonization in there margins, evoking a present-day recolonization of the forest from zones having probably acted as refuges.