6. Regeneration & the agouti

Similar to the specific needs of the Brazil nut tree’s flower to pollinate, another key process in the tree’s life cycle is heavily dependent on another of the rainforest’s creatures.

Under natural conditions there are only a few animals with the ability to access the tree’s seeds and help disperse them throughout the forest.  Typically, the most important of these animals is the agouti (Dasyprocta punctata sp.).  The agouti, a large rodent, is unique in its ability to use it’s incredibly tough jaws to gnaw open the hard outer pod (“cocos”) encasing the seeds (Haugaasen & Haugassen, 2010).  On opening the outer pod, the agouti can then access the  individual nuts (seeds) (see video).  The agouti may eat several nuts on the spot, but it may also cache a proportion of the nuts in the forest floor, to recover in times of food scarcity (Haugaasen & Haugassen, 2010; Haugaasen, et al., 2010).  It is these cached nuts that may eventually regenerate to become a Brazil nut tree seedling in the dense forest undergrowth.

The agouti is therefore seen to be crucial to the natural regeneration of the Brazil nut tree (Haugaasen, et al., 2010).  However ascertaining how many agouti buried seeds that germinate is difficult to quantify and remains an under studied area (Haugaasen, et al., 2010).

The tree was described by Mori & Prance (1990), as being a gap-dependent specialist, meaning that to reach reproductive size the tree requires natural forest gaps which provide an abundant source of light thus promoting growth.  This may suggest that the young seedlings require some form of canopy disturbance such as a storm event to grow and survive (Myers, et al., 2000).  There is also anecdotal evidence suggesting that there is a higher abundance of Brazil nut seedlings to be found growing along collection trails.  This may be because more nuts (seeds) are accidentally dropped from the collectors bag, but also because there may be more light reaching the forest floor following the trail maintenance that the collectors carry out at least annually.

The succesful regeneration of the trees is of key importance to the long-term sustainability of the Brazil nut tree as a species.  In a healthy population there should be an equal balance between deaths and newly sprouting trees that will reach reproductive and fruiting age.   To acheive this the vitally important agents that pollinate the flowers (large bodied bees) and disperse the seeds (the agouti) should also be in a healthy condition, combined with the appropriate light conditions occurring in the forest at the “right” times and places to allow young seedlings to flourish.

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