A background to this problem
Grazing is an activity that has been part of the environment long before humans came into the picture. Many of the grazers today; horses, cows, buffaloes, bisons, have ancestors who were also grazers. They survived in the grasslands that were extensive in the Miocene epoch in Earth’s history. It is a way of life, it is part of the food chain.
Around the time ancient humans discovered that plants could be grown, they also discovered that some animals can be tamed. These animals, once tamed, can also be used to grow future generations that help them achieve a large number of activities. Grazers were used for agriculture, transport and meat. These humans were smart about two things; one, they didn’t have too many people in a community and two, they knew how to manage grazers effectively.
Everything was going well until the boom of two things; population and capitalism. As population increased, opportunistic people noted that meat is not only a necessity, it can be made into a commodity. There were a lot more people to feed, so more grazers were raised for milk and meat. This would not have been a problem if humans encroached on these pastures and grasslands as well. As this encroachment increased, the area for grazers decreased.
This lead to a problem that we now face; overgrazing. Overgrazing is not just having too many animals in one piece of land. It is the inability to rotate these grazers once they have grazed a land so as to allow grasses to grow back. This is where most people who raise grazers fail to do.
Overgrazing- an ecological killer
Due to this inability to rotate grazers around the patch, a lot of problems arise. These grazers are all-or-nothing kind of animals. If they like a plant/grass, they eat it completely, roots and everything. So that land that they are grazing in is completely removed of all vegetation. The free land is now available for colonization and is perfect for invasive species to attack. These new species, while fast growing, are not something the animals like. So, they don’t touch them. They continue to gorge on the plants they do like and soon, from a grassland landscape, we have a weed landscape.
With no vegetation cover (and if weeds don’t colonize), soil binding decreases leading to soil erosion. The grazers also trample along these soils and compress them. This decreases infiltration rate, and increases run-off.
What’s more, once the land is completely trampled and devoid of all vegetation, the subsequent changes caused by soil erosion and trampling make it very, very difficult for grasses to grow again.
Basically, overgrazing forms a positive feedback loop–
Increased grazing —> decreased vegetation cover —> soil loss and compaction —> decreased infiltration and increased runoff —> more difficult for plants to establish and more loss in vegetation.
If this continues indefinitely, the area can be converted into a desert.
What’s the solution?
Most grasses have an inbuilt response to being grazed. Once grazed, they restore their leave parts or the seeds that fall off during grazing produces new grasses. This entire process takes about 6-8 weeks. The grazed area should be given this time to regrow for a sustainable practice of grazing animals.
What’s the ideal period after which these grazers should be rotated? That depends on the species of grasses and grazers, climate of the area, and the season. For example, during peak growing season, it is advisable to rotate the grazers more frequently so as to allow quick regrowth. Certain grasses may regrow quickly, and these need to be identified to formulate a rotation pattern. Also, if the area is prone to high rainfall like the tropics, then it makes sense to rotate more often. Different permutations and combinations should be looked at and the rotation period should always be flexible.
This problem, while massive, is something we can easily solve. If the herders and farmers are given the knowledge to rotate, and if the pressure on grazer related products eases a little bit, overgrazing will cease to be a problem.