Teaching kids Holistic Decision Making

By Sarah Savory:

I use this example to teach children Holistic Decision Making and Ecological Literacy – it was never a case of there being too many kudu but a case of human management resulting in an imbalance of predator and prey which was causing too many kudu to behave unnaturally – without enough pack hunting predators to keep the kudu herds bunched together and constantly on the move, they began to spread out and stay too long which resulted in the knock-on consequence of over browsing of the trees and the devastating longer term consequence of humans blaming the damage on too many kudu and either culling or translocating them. The exact same thing happened with elephants – we took the humans out of National Parks but that was an apex predator keeping hundreds of thousands of elephants behaving naturally. As soon as people were removed, the elephants stopped moving naturally and the ecosystem damage began to get worse.

All of these reductionist human management decisions results in ecosystem imbalance – there is a vital symbiotic relationship between grass plants, and the correct balance of herbivores and pack hunting predators.

So, overgrazing causes desertification of grasslands but so does over resting.

When we rest land in non-brittle (humid) environments it will recover, but resting land in brittle (arid) climates leads to desertification. This is because the micro-organisms that break down plant material are activated by moisture, so in humid areas, micro-organisms are constantly breaking down vegetation, but in brittle environments during the long, dry seasons, something else is needed to provide the moisture that activates micro-organisms to begin breaking down old vegetation. These brittle environments are the world’s grasslands and make up about two-thirds of the planet’s land mass. They rely on a symbiotic relationship between plants, herding animals and predators to survive.

Imagine all the different shapes and sizes of hooves and feet of the herding animals here in Africa, and how different they are. They have each been perfectly designed by nature to impact soil: from impala’s sharp little hooves, ideal for breaking up the soil surface and trampling down small plants, with their delicate mouths designed to nibble softer grasses…through every size and shape of feet, hooves, mouths and dung, until you get to elephants who eat courser grasses as their big, flat feet trample vegetation to help cover and protect the soil, while aerating and fertilising it. While this is all going on, many trillions of microorganisms are being activated by moisture in the animals’ guts, dung and urine to begin breaking down plant material.

Timing is vital: when herds stay too long, plants get over-grazed. If herds don’t bunch together or don’t stay long enough, the soil doesn’t get mulched. The timing is perfected by predators, whose job is to keep herds bunched together and moving, always flowing with the unpredictable variables going on around them, ensuring the health and survival of all.

Neil Lindsay
In the 1980s, the mysterious death of thousands of Kudus led to one of the biggest scientific breakthroughs in understanding plant communication.
Kudus are nearly pure browsers, eating the leaves of various trees. But during this time of extreme drought, they relied heavily on the leaves of the widely spread and resilient Acacia tree.
To prevent overbrowsing, Acacias have evolved physical defenses like thorns and symbiotic relationships with stinging ants. But Acacias also have chemical defenses, and when under pressure from overfeeding browsers, can produce high doses of tannin in their foliage.
The tannin makes their leaves bitter and unpalatable. It also interferes with protein and digestive enzymes, by binding to consumed plant proteins, making them more difficult to digest. In the case of the Kudus, the negative influence on fermentation in the rumen caused the animals to starve, even though they had ingested sufficient food.
It was also discovered that the trees communicate with each other, releasing an airborne chemical warning system (ethylene) that can travel as far as 45 meters. Within a few minutes, the neighbouring trees also step up their leaf tannin production to repel browsers.
In certain areas, the Kudus had become too much for the carrying capacity of the land. A tipping point was reached and the Acacia trees, stressed from over-browsing impacted on antelope populations, essentially killing them off.
This is why it is essential for us to conserve entire ecosystems on a large scale. We simply have no idea what we may destroy if we don’t.
Stay safe and keep the conservation flag flying.

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