Survival in a nutshell.

• Author: Ortiz, Enrique G.
• Position: Brazil nut trees

The Brazil nut trees in southeastern Peru not only preserve large tracts of the tropical Amazon but also support intricately interrelated biological and economic systems

Until I saw a Brazil nut tree for the first time, I had no idea of the surprise awaiting mean and that it would change my relationship with the forest forever. In 1990 I was in the Parque National del Manu in southeastern Peru, looking for a theme for my doctoral thesis. John Terborgh, the world-famous tropical researcher, suggested I visit an area in the park's core, near the Cocha Cashu Biological Station, where there were, he said ironically, a few "arbolitos." Upon my arrival, I found myself among the largest trees I had ever seen in all my years of research in the tropics. These were immense trees, more than 150 feet tall - the equivalent of a fifteen-stow building - and more than 15 feet in diameter; the oldest of them may have been several hundred years old. My only thoughts at that moment were of awe and respect for these trees, which might have witnessed the great pre-Columbian cultures of the Amazon. I would spend the next five years in the forests of Madre de Dios in Peru studying the Brazil nut tree and all the organisms - plant, animal, and human - that depend on it for survival.

From its biology, to its commercialization, to its social importance, every aspect of the Brazil nut stow is significant. Known in Peru as castana, in Bolivia as almendra, and in Brazil as the castanha do Para, this nut is one of the few foods eaten the world over that comes strictly from natural forests and not plantations. Most importantly, though the Brazil nut's collection and harvest directly supports the conservation of huge tracts of the tropical Amazon.

When I began my research, virtually nothing had been written about the biology of Bertholletia excelsa the Brazil nut species. It seemed incredible that no one had ventured to explore the biology of a tree that produces nuts harvested exclusively from natural forest areas; provides valuable income for thousands of families in the Amazon; generates millions of export dollars for Peru, Brazil, and Bolivia; and plays an important role in conserving the forests of the Amazon.

Resembling a giant umbrella, this impressive tree grows almost completely straight up, with a crown that bears leaves only at the highest point. Hanging from its immense crown (about 120 feet in diameter) are the tree's fruits. Few people realize that the Brazil nuts we enjoy eating come from inside a fruit that looks like a coconut. This fruit is often called the Brazil nut coconut. Technically speaking, even though it is commonly called a nut, what we are actually eating is the seed.

The main suppliers of Brazil nuts to the world market are Brazil, Bolivia, and Peru, where the trees are found densely distributed in certain areas. Although the trees also grow in Colombia and Venezuela, they are less prevalent and thinly distributed, and may have reached these northern reaches by way of indigenous travelers or foreign missionaries.

These high-density areas are called manchales, or stands. Within the manchal the tree crowns stand virtually elbow to elbow in a thick canopy. Studies have suggested that this peculiar density (in some cases, more than fifteen trees per hectare) may have been a deliberate planting practice by pre-Columbian Indians. However, despite archaeological evidence and firsthand accounts of Brazilian indigenous groups that support this hypothesis, other manchales exist in areas never inhabited by indigenous groups.

In order for one tree to survive, it needs a great deal of sunlight. However, because of the high density of the stands, the only way that the proper amount of light can reach the growing tree is by natural disturbance - strong winds, hurricane, or fire. It is generally accepted that the trees' distribution in the manchal is the result of unrelated ecological and cultural circumstances. Also, although the trees are found in different soil types, they are located exclusively in high-ground forest areas and are never found in flooded zones.

The story of the nut begins with the appearance of the first flowers in early October. Yellow and slightly smaller than a ping pong ball, the flowers have a somewhat peculiar shape. They are almost round, with a structure similar to the hood covering the stamens (the male organ...