IUCN threat status:

Vulnerable (VU)

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The Brazil Nut tree (Bertholletia excelsa) is the only species in the genus Bertholletia. It is native to South America and is among the largest trees in the Amazonian rainforest, occurring in non-flooded (terra firme) forests of the Amazon Basin and Guiana Shield. Because of the structure of the flowers, pollen is accessible only to larger bees such as Xylocopa species and female euglossines. The flowers are essentially self-sterile. The slow-developing fruit is a large, round woody capsule, 0.5 to 2.5 kg, which contains the seeds (i.e., the "brazil nuts" of commerce). Most brazil nuts in commerce are collected from wild trees, the fallen fruits being split open with an axe to reach the 10 to 25 seeds packed within like the sections of an orange. There is some risk to collectors of injury or even death from being hit on the head by falling fruit. Brazil nuts contain up to 17% protein and 65 to 70% of a monounsaturated (almost 50% oleic acid) oil. Although there is some local consumption of harvested nuts, most are exported to the United States or Europe. World production of brazil nuts in 2008 was 78,000 metric tons, with Brazil accounting for around 40% of this total.

(Vaughan and Geissler 1997; Mabberley 2008; Reis et al. 2009; Freitas-Silva and Venâncio 2011 and references therein)

Haugaasen et al. (2010) investigated the fate of Brazil Nut seeds (i.e., brazil nuts) under natural conditions. Seeds that remain trapped inside unopened fruits suffer almost 100% mortality from fungal attack and rotting (Peres et al.1997). Haugaasen et al. found that most seeds in dispersal trials were removed by scatter-hoarding rodents such as agoutis (Dasyprocta) during the first week and were generally buried intact in single-seeded caches within 10 m of seed stations. Seeds were removed significantly faster and buried at greater distances during the dry season. However, the proportion of seeds buried intact in the wet season was around twice that in the dry season (74% vs. 38%). Haugaasen et al. suggested that reduced seed availability resulting from intensive harvest by humans could potentially create a dry-season scenario in which most seeds would be lost to pre-dispersal predation, thereby adversely affecting the natural regeneration of Brazil Nut trees.

Shepard and Ramirez (2011) argue that a range of data indicate that anthropogenic (i.e., human-caused) disturbance facilitates Brazil Nut regeneration and that genetic studies showing a lack of sequence diversity and a lack of geographical structuring of within-population variability support a historical scenario of rapid and recent population expansion from a smaller ancestral distribution. According to these authors, historical linguistic analysis of indigenous terms for Brazil Nut suggests a northern/eastern Amazonian origin for Brazil Nut, with a subsequent spread of distribution or cultivation to the south and west. They argue that ecological, phytogeographic, genetic, linguistic, and archeological data reinforce the hypothesis that ancient Amazonian peoples played an important role in establishing the present-day distribution of this emblematic and economically important tree.

An excellent historical review of the Brazil Nut industry by botanist Scott Mori, an expert on the Brazil Nut family (Lecythidaceae), addresses both the natural history and economic importance of the Brazil Nut (as seen from the vantage point of 1992) and can be viewed on the New York Botanical Garden website. Silvertown (2004 and references therein) explored some of the challenges in transforming the gathering of wild brazil nuts into a sustainable harvest that could help preserve Amazonian rainforests; nevertheless, some researchers remain optimistic that developing sustainable brazil nut harvesting holds real potential as a valuable and effective rainforest conservation strategy (e.g., Wadt et al. 2008; Paiva et al. 2011).

Freitas-Silva and Venâncio (2011) discuss the challenge of controlling aflatoxins that may be produced by certain fungi infecting brazil nuts.


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© Leo Shapiro

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