If you fly over the agricultural zones of West Africa, you do not see bare fields.

You see trees. Standing in the fields. Spread across the landscape in a pattern that looks, at first, like scattered woodland. But the pattern is not random. Every tree you see was chosen — by a farmer, by that farmer's parents, by generations before them — because it earned its place.

This is the West African parkland system. And it is one of the most sophisticated agroforestry traditions in the world.

The Farm That Was Also a Forest

The parkland system works on a principle that the trees and the crops are not competing. They are cooperating.

The shea tree — Vitellaria paradoxa — is the anchor of the Sahel parkland. Its fruit produces shea butter, a food and trade commodity. Its deep roots bring water and minerals up from below the...