An essential component of any regenerative landscape will be the Nitrogen-fixing perennial plants within the community of fruits, nuts and herbs and other plants. During this post, we will look at why Nitrogen is important for plants, How Nitrogen can be biologically sourced and we'll profile some of our favorite Nitrogen-fixing trees, shrubs and herbs
By the way, I did several years of ethnographic fieldwork among hunter-gatherers in the Kalahari. When I first arrived, I expected to find them occasionally hunting giraffe. I had seen the film made in the far western Kalahari by John Marshall, a film called “The Hunters” – which showed a giraffe hunt. So I was puzzled to see plenty of giraffe in the area but no evidence of them being hunted by the Kua San. I asked about this. I was told that a giraffe that “offered itself” would not be refused, but that this was extremely rare, and that giraffe were not generally targeted. If I wanted the whole story, I was told, I should go and see a certain woman.
So I did.
I found her in a campsite deeper into the remote area, very near the Central Kalahari Game Reserve. She was tending to her grandchildren and eagerly agreed to answer my questions about giraffe. Apparently she was the local expert; obsessively interested in anything to do with giraffe since childhood. She had assembled a massive number of observations, both on her own, and from accounts of hunters, and other people, and handed down through many generations. I found this out in later interviews.
Her answer to my initial query was masterful in its simplicity and accuracy. Hunting giraffe is unwise, she said “because they were the midwives of the Acacia trees.” God had made the giraffe, she told me, just tall enough to eat the leaves and harvest the pods of the tree, because they would then deposit the offspring of the tree far from the parent plant. This ensured that Acacia continued to “spread life” into the sands. She had often noticed the young of the tree sprouting from giraffe dung heaps.
I noted all this down and essentially forgot about it until many years later when I learned that these Acacias are, in fact, woody legumes: through a symbiotic bacterial colony in their roots, they fix nitrogen. In the sandy Kalahari, these trees and other legumes were essential species that permitted grasses and herbs to flourish.
Giraffe and Acacia were also symbiotes, both equally critical in keeping the savanna green.
another great article, thanks. When I teach this aspect (N-fixation) I try & keep it clear that it's not the plants that fix N but the microbes living symbiotically with them. In theory there's no such thing as a N-fixing plant. It may seem pedantic, but just giving credit where it's due.... and illustrating the functionality of symbiosis.
https://www.sciencedirect.com/science/article/abs/pii/S1164556317305502
By the way, I did several years of ethnographic fieldwork among hunter-gatherers in the Kalahari. When I first arrived, I expected to find them occasionally hunting giraffe. I had seen the film made in the far western Kalahari by John Marshall, a film called “The Hunters” – which showed a giraffe hunt. So I was puzzled to see plenty of giraffe in the area but no evidence of them being hunted by the Kua San. I asked about this. I was told that a giraffe that “offered itself” would not be refused, but that this was extremely rare, and that giraffe were not generally targeted. If I wanted the whole story, I was told, I should go and see a certain woman.
So I did.
I found her in a campsite deeper into the remote area, very near the Central Kalahari Game Reserve. She was tending to her grandchildren and eagerly agreed to answer my questions about giraffe. Apparently she was the local expert; obsessively interested in anything to do with giraffe since childhood. She had assembled a massive number of observations, both on her own, and from accounts of hunters, and other people, and handed down through many generations. I found this out in later interviews.
Her answer to my initial query was masterful in its simplicity and accuracy. Hunting giraffe is unwise, she said “because they were the midwives of the Acacia trees.” God had made the giraffe, she told me, just tall enough to eat the leaves and harvest the pods of the tree, because they would then deposit the offspring of the tree far from the parent plant. This ensured that Acacia continued to “spread life” into the sands. She had often noticed the young of the tree sprouting from giraffe dung heaps.
I noted all this down and essentially forgot about it until many years later when I learned that these Acacias are, in fact, woody legumes: through a symbiotic bacterial colony in their roots, they fix nitrogen. In the sandy Kalahari, these trees and other legumes were essential species that permitted grasses and herbs to flourish.
Giraffe and Acacia were also symbiotes, both equally critical in keeping the savanna green.
She knew.
That's wonderful , thanks for sharing. I'm curious whether the Giraffe browse on the Acacia young saplings that emerge from the dung?
Giraffe do not usually browse that low to the ground, and also apparently prefer trees with seed pods on them.
another great article, thanks. When I teach this aspect (N-fixation) I try & keep it clear that it's not the plants that fix N but the microbes living symbiotically with them. In theory there's no such thing as a N-fixing plant. It may seem pedantic, but just giving credit where it's due.... and illustrating the functionality of symbiosis.