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Sunday, January 15, 2017
As those of you who are frequent readers of my blog probably know, my hobby is engineering with biological systems. In everything I do, I do my best to be holistic. Each organism in an ecosystem has a job and the whole works as a whole when all of the necessary pieces are where they are supposed to be and doing the job they evolved to do. The problem with the modern world is that our ecosystems are so degraded that the animals are often absent completely or at the least rarely seen in natural systems. As such, it is so easy to forget that they are an integral part and are often seen as pests or otherwise harmful. But nothing could be farther from the truth. Animals are an integral part of the nutrient cycling function of a healthy ecosystem. The tricky part, though is to manage the animals. It's important to choose the right animals (or encourage the right ones to come to you) and help them have the right impact.
There is no place this axiom is more true than in a brittle ecosystem. The inconsistency of moisture in an area that has distinct rainy and non-rainy seasons means that the organic matter (typically perennial bunching grasses) cannot break down into its component nutrients when exposed to open air like it does in a non-brittle environment, one with constant exposure to moisture. But the cycling of nutrients is critical for any ecosystem to function. It is how each and every organism functions within the ecosystem. For the plant, the fungus, the bacteria, and the animal each, it is their food source.
In a brittle environment, the dead grasses still need to be removed so the plants have room to grow at the beginning of the next rainy season. As any gardener knows, the best thing for all that grass is to finely chop it, compost it in a warm, moist environment, and deposit the finished compost back on the ground where it can be worked into the soil. Being a bit of a mad scientist, I propose we automate the process. Let’s make the composting unit mobile, something that moves around and continually collects the grasses. I think I will call this new invention a “cow.”
This is basically how a ruminant works. They are mobile organic matter collection and composting units. They provide the moisture needed to break the plant matter down and keep the food web going. Remember, those grade school science books downplayed the importance of poop in the nutrient cycling of an ecosystem. In reality so many more nutrients are cycled through dung than through dead bodies.
Ecosystems develop through an intricate process called “evolution.” Often, evolution picks some minor function, one often overlooked, and makes it an integral part of the whole. This is absolutely true with the animal impact on a grassland. Yes, the cow eats the grass, but they miss a lot. They dung and urinate all over everything and tend to not eat the contaminated vegetation. But all of the vegetation needs to be lowered to ground level.
Also, bare ground is pretty much the biggest problem in a brittle environment. As ground sits bare (nothing growing from it and no plant litter covering it), there is nothing to replenish the soil carbon content and it just bakes in the sun. Bare soil loses its carbon content eventually and forms a hydrophobic (water repelling) crust. This crust matures over time, becoming more and more effective at repelling what rain comes to it. As the environment further degrades, the soil crust forms a permanent crust, grows a sad layer of algae and gets protection in a state park from people who can’t tell the difference between a healthy ecosystem and a biological response to extreme environmental degradation.
In order to keep the grassland healthy, the soil crust needs to be broken regularly and the uneaten litter scattered over the surface, along with a healthy dose of dung and urine applied. But this process breaks down when the cattle spread out across the landscape, grazing peacefully. The hooves naturally break the crust, but not when they step gingerly. The weight of the animals crushes the dead clumps of grass and scatters the remnants across the bare soil, but not when they walk carefully between the grasses. The piles of dung help fertilize, but not when they are twenty or thirty feet apart.
See, the ecosystem doesn’t respond specifically as a single block. Each clump of grass responds to the pressures and stimuli it is subjected to. Grass is overgrazed a clump at a time. Grass is undergrazed a clump at a time. And the two can be right next to each other. When cows are allowed to live a leisurely, spread out life with plenty of room to wander and plenty of time to pick and choose what they eat, they do exactly that.
It is the natural system of predator and prey that brings the whole thing together. In the wild, the great herds of ungulates are subjected to the predation of pack hunting predators like lions and wolves. The herds bunch together for safety. But in bunching, they eat huge amounts of food and leave behind huge amounts of dung and urine. In the excitement of being bunched and worrying about predators, they aren’t careful about where they step and trample the bunches of grass and break up the soil crust.
See, it is only the original system that works completely to maintain the grassland ecosystem. The herds have to be big enough that they can eat or spoil the food, then move on before the grass starts growing back. They have to be bunched and excited to disturb the ground just right to get the benefits.
The problem is that those great herds are largely gone, as are their pack hunting predators. But if the land dies without them, what are we going to do?
It turns out that Allan Savory has worked out a way to mimic the impact of the animals and built a whole system around it. The system is called Holistic Management. It uses smaller paddock sizes to mimic the bunching and manage the time spent grazing. It even turns out that the excitement and trampling can be mimicked without the stress of predators. Ivan Aguirre, a rancher in Mexico, uses mesquite hulls, the parts filtered out after the milling of mesquite pods, as a treat. Mesquite pods are naturally sweet and the cows get so excited about their treat (a waste product, really), that they trample everything to get to the hulls.
Unfortunately, it is likely that the great herds are gone forever. However, with enough dedicated people and the will to make a difference, we have the tools to restore the grasslands of the world to some of the most productive ecosystems in the world.