• Water Production Connections

Postcard from the Field: Brazil Nuts and Rainforest Biodiversity

By Cassie Sevigny

A tropical forest scene, with a tall thick tree trunk surrounded by lush diverse foliage
Photo credit: Cassie Sevigny

The Connections between Water and Rural Production project (CAP) investigates whether and which farmers adapt their production systems when they experience water variability, what adaptations they make, and whether these adaptations reduce income losses when droughts occur. Improved understanding of these feedbacks will inform efforts by government agencies and civil society to help farmers respond to water scarcity. I accompanied economist Katrina Mullan to Brazil while working on my Masters in Economics. The Executive Committee for Cacau Crop Planning (CEPLAC) manages a forest preserve next to Grauna hotel, the CAP team headquarters, and granted us permission to tour the forest in July 2019. The hotel manager, Alfredo Rodrigues, was our guide.


Veins of ants crawled in thin lines over the leaf litter. Unlike my home in Montana, leaves fall and collect on the floor year round here. Palms of all heights and varieties grew around us. Woody, twisty vines draped and dangled from these trees. The larger ones, perhaps a few centimeters in diameter, were sturdy enough to hold the weight of a person.


We saw a pile of large round pods at the base of a tree, seeds extracted through a carved hole. Brazil nuts! I learned that Brazil nuts are one of the taller tree species in the Amazon. Their limbs extend only from the top of the trunk, and tower above the canopy. While the trees can grow in plantations, most Brazil nuts are harvested from trees growing naturally in the forest. This is because the Brazil nut relies mainly on large bodied orchid bees to pollinate its flowers. Alfredo, our forest guide, explained that the bees use other plants as a pollination stepladder to reach the Brazil nut flowers. Without trees of diverse heights leading a path to the Brazil nut flowers, the bees will stick to flowers they don’t have to fly so high to reach. The male bees also need access to wild orchids to perfume themselves to attract mates. This means the Brazil nut pollinator requires intact rainforest to reproduce and to pollinate Brazil nuts.

A pile of hollowed-out brazil nut pods on the forest floor
A pile of hollowed-out brazil nut pods on the forest floor. Photo: Cassie Sevigny

After Brazil nuts form, the pods fall to the ground and the nuts are spread by agoutis, a local rodent. Like squirrels, they bite into the pod’s shell to get to the nuts and bury them. Many of these remain underground and grow into new trees. It fascinated me to learn of an unfamiliar animal that behaves just like one I am familiar with, since squirrels are common across the United States.


The Brazil nut’s need for biodiversity to reproduce creates an interesting case for forest preservation. If Brazil nut sales are profitable enough, maintaining forests on their property will earn farmers more money than cutting the forest to grow something else. But the incentive of high profits can also lead to illegal collection from wild Brazil nut trees in protected areas, evidenced by the pile of empty pods in the preserve. While on our tour, Alfredo pointed out the large neat holes carved in the pods and that they were clustered in a pile instead of scattered around. The agouti doesn’t leave such neat messes behind, but humans can. These opposing effects are an important reminder that it may be difficult to predict the overall impact of a change in economic incentives. Collection and analysis of empirical data are necessary to understand what will encourage forest conservation in different contexts.


Sources:

1. https://www.britannica.com/topic/mutualism-1673060

2. http://brazilnuttree.co.uk/bees.html