Fruit Removal and Natural Seed Dispersal of the Brazil Nut Tree (Bertholletia excelsa) in Central Amazonia, Brazil

Abstract

Experimental approaches to study seed dispersal of the Brazil nut tree have hitherto relied on exposed seeds deposited on the forest floor. Here we use a new method to study the natural dispersal by large rodents such as agoutis; tracking experimentally manipulated and tagged fruits containing individually marked seeds. Fruit manipulation did not deter agoutis from handling fruits. We found that agoutis usually moved intact fruits away from their original location below the parent tree before either hiding them or gnawing through the pericarp to access the seeds inside. Most fruits were moved to distances of 15-30m from their original position, but some fruits could be taken as far as 60m. A large number of seeds extracted from manipulated fruits appeared to be eaten immediately. Only 27 out of 1740 experimental seeds were found buried in shallow caches, generally within 5m of the opened fruit. Fruit removal distance accounted for a disproportionate amount of total seed movement and seeds in the current study were dispersed significantly farther than in a previous experiment using exposed seeds, suggesting that classic dispersal experiments of this character may severely underestimate seed dispersal distances. We therefore conclude that the new method provides a more realistic and accurate approach to investigate natural seed dispersal of Brazil nuts and that the removal of fruits from underneath parent trees before being opened is the key to the significantly increased distances at which seeds are dispersed. © 2011 The Author(s). Journal compilation © 2011 by The Association for Tropical Biology and Conservation.