Brittle Environments are simply areas where humidity is distributed unevenly throughout the year. See this InfoGraphic for more information on the “Climate Brittleness Scale”.
Properly managed livestock are simply livestock managed to mimic the natural herds which used to roam the Earth. Managing livestock properly is actually fairly complex, you can read more about properly managing livestock here.
Ecosystem processes (like the water and nutrient cycles, for example) function very differently in Brittle Environments than in Non-Brittle Environments. In Brittle Environments large grazing animals, bunched together in herds, are actually essential to ecosystem health.
Why are herds of herbivores so essential in these environments?
Microbes require moisture to function. Without moisture all natural nutrient cycling stops. Large herbivores are nature’s way of keeping the nutrient cycle going during the long dry periods. Animals essentially carry the humid environment in their guts. The gut of an herbivore is the only place biological decomposition can take place at these times… so animal manure and urine are the only sources of plant nutrients during the dry months.
Brittle Environments tend to develop hard crusts on the soil surface where there is bare soil. This hard “cap” on the soil prevents seeds from germinating and it prevents the little rain that does fall from entering the soil where plant can actually use it. Instead the rain runs over the surface of the soil (which is why flash floods are so common in desert environments). Properly managed livestock will quickly break up this hard crust on the soil surface which will once again allow seeds to germinate and rainfall to infiltrate the soil.
In Brittle Environments plants that die or go dormant do not fall to the ground and decompose like they do in more humid environments. If this standing plant material is not trampled onto the soil surface it will not decompose biologically which means the nutrients it holds will mostly be unavailable for future soil and plant growth. The standing plant material will also shade new growth which is trying to establish. If the standing plant material is trampled into the ground it becomes litter/mulch: preventing evaporation, feeding the soil food web, moderating temperatures, and allowing rainfall to infiltrate the soil where it can be used. This trampling can only be accomplished on the necessary scale with properly managed livestock.
The trampling of livestock also presses seeds into very tight contact with the soil. This close contact allows the seed to draw more moisture from the soil, which often means the difference between the seed growing into a new plant or just remaining dormant.
How Many Livestock Are Needed?
In Brittle Environments all grass must be trampled or grazed every year or the land will start to deteriorate. This means that livestock numbers in Brittle Environments must exactly match the productivity of the grass in those environments. (Note: Stocking rates are typically increased by 50 to 100% the first year that proper management is implemented compared to conventional stocking rates in that area). When properly managed livestock are introduced to Brittle Environments grass productivity starts increasing dramatically, so livestock numbers must also increase dramatically until the ecosystem reaches its peak productivity. This is one very good reason why the system of Planned Grazing is so useful in Brittle Environments: it makes it easy for livestock managers to have the exact right number of livestock for their lands current production.
Why Livestock Must Be The Predominant Land Use
Crops cannot grow without a functioning water and nutrient cycle. The water and nutrient cycles of Brittle Environments rely on annual application of heavy animal impact in order to function. Therefore crop areas must be rotated with pasture areas to maintain fertility, or animal impact must be regularly applied directly to the cropland. This places a severe limit on the amount of cropland that can be in production compared to the amount of land that must be dedicated to perennial pasture for livestock. Crop production is possible, but, by far, the predominant source of food and income for farmers in Brittle Environments must be livestock.
We Must Mimic Natural Herds
Brittle Environments co-evolved with large herds of animals who played an essential role in the cycling of nutrients and the soil health. In a healthy state they are grasslands. Without herds of herbivores, the land desertifies. (reference) Desertifying land is not a place that you will find much food for human consumption. Desertifying land also represents a loss of biodiversity and a loss of habitat for the once-abundant dry grassland plants and animals which existed in these environments along with the large grazing animals. Desertification is a loss for the environment, a loss of potential happy animal lives, and a loss for humans.
Brittle Environments Are Incredibly Important For The Health Of The Earth
Brittle environments cover more than half of the Earth’s land surface. In other words: more than half of the land on earth requires herds of large animals (in high densities) to produce any significant amounts of food. If your food comes from a Brittle Environment it cannot be produced sustainably unless properly managed livestock are a part of the production.
We Cannot Use Technology To Replace The Role Of Livestock In Brittle Environments
There are machines which can mimic the hoof action of livestock, breaking up the surface cap on soil, trampling vegetation, and pressing seeds into the ground. There are not yet any machines which can graze, digest, and poop. But they could be invented.
The problem is not a lack of technology, the problem is that technology is not as efficient at performing ecosystem functions as animals are. Animals graze, digest, poop, and trample, but they also produce food, income, habitat for birds and bugs, and food for predators. No machine can do all of that.
But the main reason that machines cannot replace the role of livestock in Brittle Environments is that animal impact (or machine impact, in this case) is require on every single acre of every single Brittle Environment on Earth at least once every year! What a logistical nightmare that would be! Not to mention the gigantic energy needs of these machines and the huge costs of running them. Its just not practical. No way. Livestock are cheap, and they actually generate income over time. They reproduce themselves, for free. They can be easily managed by poor and illiterate people (who often are the occupants of very Brittle Environments). They are available right now in every country on earth.
There is no way that technology can replace the essential role of livestock in Brittle Environments any time in the foreseeable future.