Brazil nut; Bertholletia excelsa

The Brazil nut is an exception among cultivated plants: it does not grow in fields, but deep in the rainforest of South America – wild, high up in the tops of ancient trees. It can only grow and spread in symbiosis with a multitude of other necessary species – the nut is the result of an ecological network. This complex symbiosis cannot be replicated in any field.

A tree for generations

The Brazil nut tree is one of the most impressive plants in the Amazon region. It can grow over 50 meters high and live up to 500 years. Its mighty crown towers above the canopy of the tropical lowland rainforests – they are true giants of the rainforest. The nuts grow in coconut-sized, capsule-covered fruits, which are as hard as wood and weigh up to two kilos. Each of these capsules contains around 10 to 25 triangular seeds – what we know as Brazil nuts. They are traditionally harvested by picking up the fallen fruit in the forest – often at great risk, as a falling fruit can be fatal.

Unique interplay of different species

The large, pale yellow flowers of the Brazil nut tree only open once. The blossom opens in the morning and already begins to fall in the afternoon. Although it is a hermaphrodite, the blossom must be pollinated – a major effort for bees, which have to pollinate during this narrow time frame. However, not all bees can pollinate the Brazil nut tree, with only the very large bee species, in particular the orchid bee, being up to the job. The flowers of the Brazil nut tree are closed with a kind of lid, which only large bees are able to open. In order to fertilise all the Brazil nut blossoms and thus make the extensive Brazil nut harvest possible, large numbers of of these solitary bees are necessary. Sustaining this important symbiotic relationship requires an intact rainforest ecosystem.

The relationship between these bees and orchid flowers is unique. The males of the orchid bees need certain orchid flower species to find a mate. This is because they can only attract females to mate with the help of certain orchid scents. So the orchid bee can only reproduce with enough of the right orchid flowers.

Aguti are needed to spread the Brazil nut in the rainforest. Aguti are rodents that weigh three to six kilos. They take the large, heavy Brazil nuts that fall from the tree, open them and carry the nut kernels to their hiding places. If the nuts are not eaten by the agutis or other animals, they remain in the ground and later grow into new Brazil nut trees over decades.

Interestingly, it is still not clear how the Brazil nut was able to spread over large areas – the small range of the agutis only allows for local spread of the trees.

Humans pose a threat to the ecological network

Today, humans pose a threat to the survival of the symbiotic community of the Brazil nut tree. One reason for this is overharvesting. Because we humans collect almost all the Brazil nuts, there are hardly any nuts left for Aguti. In regions where harvesting has been going on for decades, the lack of new trees can already be observed – in these regions, the Brazil nut forests could die from old age. To make matters worse, people who collect the nuts often hunt agutis during the harvest season.

Illegal deforestation, infrastructure projects and the expansion of livestock farming and soybean cultivation are also threatening the habitats of the Brazil nut.

Rich in selenium

Brazil nuts are a real powerhouse. They are particularly well-known for their high selenium content – an essential trace element that is important for immune defense, thyroid function and cell protection. Just one nut can cover the daily required dose. In addition to selenium, Brazil nuts contain high-quality fats, protein, magnesium and vitamin E. They are eaten raw, roasted or in nut mixes and are also used in muesli, oils and vegetable spreads. They have a mild, nutty flavor with a buttery note – a real treat from the rainforest.

Between preservation and exploitation

As valuable as the Brazil nut is, its harvesting also brings challenges for the collectors. The collection work is hard, physically demanding and often poorly paid. Many collectors – known as ‘castanheiros’ – live in remote areas and have limited access to medical care or safe working conditions. The long transport routes through the jungle, uncertain market prices and middlemen make the trade less lucrative for many harvest workers. From these collectors, mainly from Brazil, Bolivia and Peru, the nuts then reach the global market and are savoured around the world.

Sources

Oro Verde: The Brazil nut. Link.
Protecting the rainforest: The Brazil nut tree – an ecosystem in the smallest of spaces – a detailed example. Link.
IVA: Brazil nut – recommended with restrictions. Link.