Brazil-nut tree (Bertholletia excelsa)

Description

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Brazil-nut tree fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Brazil-nut tree description

A particularly distinctive species because of its towering height ^{(2) (3)}, the Brazil-nut tree is widely considered to be one of the most economically important plants of the Amazon ⁽⁴⁾. Its valuable seeds are harvested and the oil, in particular, is extracted and used in a wide variety of products. The Brazil-nut tree is also the only widely traded commodity that is still harvested from the wild, rather than plantations and is possibly the most significant non-timber forest product besides rubber ^{(3) (5)}.

The seeds of the Brazil-nut tree are long and angular, and have a hard, thin outer shell, a white kernel (the edible part of the seed), and a nutty texture ^{(3) (6)}. Between 12 and 25 seeds are enclosed inside the large, round fruits (‘pyxidia’), which are typically around 10 centimetres in diameter, and weigh up to 2.2 kilograms ^{(2) (3) (4) (7)}. The outer layer of the fruit is tough and woody, giving it a heavily armoured, bark-like appearance. The flowers of the Brazil-nut tree are zygomorphic, with six fleshy, oblong, yellow-cream or yellow petals and pale green calyx ^{(4) (6)}.

Also known as

para nut.

French

Noix Du Brésil.

Spanish

Turury.

Size

Height: up to 50 metres ⁽²⁾

Brazil-nut tree biology

The Brazil-nut tree occurs in stands (groups of trees) that usually contain between 50 and 100 individuals, with each tree capable of producing around 60 to 100 fruits each season ⁽⁸⁾. The tree will usually begin fruiting after 12 years of age, and the development of the fruit takes around 15 months, with mature fruits dropping to the ground during the rainy season ^{(6) (8)}. The fruits are indehiscent, meaning that the woody capsules do not break open and disperse the seeds when they hit the forest floor. Instead, the Brazil-nut tree relies upon agouti (rodents in the genus Dasyprocta) to gnaw through the tough outer wall of the fruit, releasing the seeds. Some of these seeds will be eaten by the agouti, whilst others will be hoarded and buried intact. Seeds that are not subsequently destroyed or eaten by the agouti or another seed predator will remain in these scattered caches and may germinate after 12 to 18 months ^{(2) (6) (7) (8)}. 

Flowering generally occurs through the dry season, with a peak in flowering between October and December ^{(4) (8)}. Pollination of the Brazil-nut tree is limited to a specific group of insects, the large-bodied bees, and some bats, because of its unusual flower structure. An arched ‘hood’ is formed by several elongated staminodes (stamens that do not produce pollen), creating a chamber that encloses the reproductive organs. Only bats and those insects which have the necessary size and strength to lift the hood are able to gain entry into the flower to obtain the nectar ^{(4) (8)}.

Brazil-nut tree range

The Brazil-nut tree is native to South America and naturally occurs throughout the Amazonian rainforest, in Brazil, Bolivia, Columbia, Ecuador, Peru, Suriname and Venezuela ^{(1) (3) (8)}.

Brazil-nut tree habitat

The Brazil-nut tree grows in non-flooding areas, commonly known as terra firma, in the lowland rainforests of the Amazon ^{(2) (5) (6) (8)}.

Brazil-nut tree status

Classified as Vulnerable (VU) on the IUCN Red List ⁽¹⁾.

Brazil-nut tree threats

The seeds of the Brazil-nut tree are some of the most economically valuable non-timber forest products produced within the Amazon region, and the Brazil-nut has long been harvested from the wild ^{(4) (8)}. However, research has indicated that juvenile trees of the Brazil-nut are missing from populations where nuts have been persistently harvested over many generations, causing concern that the current level of exploitation may not be sustainable ⁽⁵⁾.

Evidence also suggests that people involved in the harvest of Brazil-nuts are often involved in other activities which may negatively affect the biodiversity of the forest, such as slash-and-burn agriculture, timber extraction, hunting and mining ^{(5) (8)}. Deforestation in particular is thought to be having an increasingly negative effect on the Brazil-nut tree, usually as a result of clearing land for agriculture ^{(1) (5)}. 

Brazil-nut tree conservation

Conservation of the Brazil-nut is likely to rely on developing sustainable harvest of the nuts, as there has been very little success in establishing plantations outside of the Amazon ⁽¹⁾. Organisations like the Amazon Conservation Association are working with local harvesters and forest services in Peru to manage Brazil-nut concessions as ‘privately managed conservation areas’, and elsewhere, small populations of the Brazil-nut tree are present in protected areas and reserves. These managed areas aim to prevent future deforestation and create sustainable initiatives that will protect the biodiversity of the forest, and provide an income for the local people ^{(8) (9)}. 

Find out more

To find out more about sustainable Brazil-nut harvest and conservation, see:

• Amazon Conservation Association:
  http://www.amazonconservation.org/ourwork/livelihoods.html

To find out more about other conservation projects occurring throughout the Amazon region, see:

• WWF:
  http://www.wwf.org.uk/what_we_do/safeguarding_the_natural_world/forests/forest_work/amazon/

Authentication

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Glossary

Calyx

All of the sepals (floral leaves) of a flower, which form the protective outer layer of a flower bud.

Germinate

The beginning of growth, usually following a period of dormancy and in response to favourable conditions. For example, the sprouting of a seedling from a seed.

Pollination

The transfer of pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.

Slash-and-burn

The cutting and burning of forests or woodlands to create space for agriculture or livestock.

Stamens

The male reproductive organs of a flower. Each stamen is comprised of an anther (the pollen-producing organ) and a filament (stalk).

Terra firma forest

Latin for ‘dry land’; forest that is not seasonally flooded.

Zygomorphic

A type of symmetry in an irregular shaped flower, where it can only be divided into two equal halves along one axis.

References

1. IUCN Red List (August, 2010)
   http://www.iucnredlist.org/
2. Zuidema, P.A. and Boot, R.G.A. (2002) Demography of the Brazil nut tree (Bertholletia excelsa) in the Bolivian Amazon: impact of seed extraction on recruitment and population dynamics. Journal of Tropical Ecology, 18: 1-31.
3. Raintree Nurition: Tropical Plant Database (August, 2010)
   http://www.rain-tree.com/brazilnu.htm
4. Motta Maués, M. (2002) Reproductive phenology and pollination of the Brazil-nut tree (Bertholletia excelsa Humb. and Bonpl. Lecythidaceae) in Eastern Amazonia. In: Kevan, P. and Imperatriz Fonseca, V.L. (eds) Pollinating Bees - The Conservation Link Between Agriculture and Nature. Ministry of Environment, Brazil.
5. Silvertown, J. (2004) Sustainability in a nutshell. TRENDS in Ecology and Evolution. 19(6): 276-277. 
6. Agroforestry Tree Database (August, 2010)
   http://www.worldagroforestry.org/
7. Peres, C.A. and Baider, C. (1997) Seed dispersal, spatial distribution and population structure of Brazil-nut trees (Bertholletia excelsa) in south eastern Amazonia. Journal of Tropical Ecology, 13: 595-616.
8. Mori, S.A. (1992) The Brazil-nut Industry: Past, Present and Future. In: Plotkin, M. and Famolare, L. (Eds.) Sustainable Harvest and Marketing of Rain Forest Products. Island Press, Washington, D.C. and Covelo, California.
9. Amazon Conservation Association (August, 2010)
   http://www.amazonconservation.org/ourwork/livelihoods.html