Despite naysayer claims to the contrary, grazing livestock are a necessity to manage, heal and build the landscape.
There are myriad reasons, but here are six key components of the symbiotic animal-grassland relationship.
First, grazing livestock are needed to cycle carbon and other nutrients essentially locked in above-ground vegetation and put it back on the ground in a more biologically active form to feed soil life and further vegetation growth.
Second, they are vital for terminating cover crops, using low-quality forages and crop residues, again putting them into a more bio-available form that quickly feeds soil life. Put another way, grazing livestock are an important management tool.
Third, livestock are also vital to produce a profit from enterprises that would otherwise be an expense. Cover crops are an example. They have many benefits that pay the crop farmer in the long run but cannot produce a profit in their own right without grazing livestock and good management to harvest them at correct levels that leave soil covered at the same time they produce beef or other meat products. As any fool should be able to understand, without profit for the operator there can be no one to manage the land.
Fourth, they are the only affordable option to manage large acreage. Mowing is too expensive and total rest has proven a miserable failure.
Fifth, different grazing and browsing species eat and provide control of different plant types. This is a case for us to use more than one type of livestock. The fossil record on all continents tells us the variety of species was extremely rich, but the complexity of that discussion must wait for another time. However, it is clear that cattle, sheep and goats provide better usage of a wide variety of plant species than does a single one of these species.
Sixth -- and a point not yet proven but suspected true -- some producers believe the microflora in the gut of ruminants and hind-gut fermenters are either some of the same species, or are certainly symbiotic with the myriad species of soil life. These folks talk about "inoculating the soil" with livestock presence. Again, the circumstantial evidence tells us when grazing is applied correctly, the relationship between gut life and soil life is true and good.
A bit of history and paleontology also shows us the Creator used a wide variety of grazing and browsing animals to manage the environment, including extremely large herds of ruminants. Holistic management consultant Allan Savory was one of the first, perhaps the first, to note publicly that grazing animals and grasslands evolved together. If we consider the growing evidence that soil is built by modern livestock herds managed with the a facsimile of the chaotic pulsing effect the giant herds would have had, we can see the sense in these claims. (See June 2017 issue of Beef Producer.)
Many people are led to believe the bison in North America is the ultimate example of this principle. Although their herding behavior appears typical of large-herd herbivory of the pattern we still see in remnant behavior in wildebeest in Africa and caribou in northern Canada and other uninhabited tundra, bison were not the original North American grassland symbiots. In fact, the fossil record tells us that outside of Africa, human encroachment coincided with massive extinction of the so-called megafauna -- those animals large enough to provide ample food supply for skilled hunters. Depending on whose data you care to use, North America lost about 70% of its megafauna, Europe and Asia lost about 60% of its megafauna, and Australia lost more than 90% of its megafauna.
Two very good books on the topic of the wide variety of animals that once grazed in symbiosis with plains, savannahs and forests are Jim Howell's For the Love of Land and Tim Flannery's The Future Eaters. They describe in the early years of recorded human settlement huge herds of wildebeest, zebra and Thomson's gazelle in the Serengeti region of Africa, springbok in South Africa, caribou in the arctic tundra, saiga antelope in southern Russian and Kazahkstan, to name a few. For the record, settlers and travelers in the Great Basin of the US noted pronghorn in herds so large they could not count, but estimated at possibly 2 million head -- similar to springbok herds in southern Africa.
The American bison, although the fossil record says they came from Eurasia many thousands of years ago, grazed in herds so large they were said by travelers to have taken several days for a herd to pass by and leave almost no forage standing in their back-path. This is the same large-herd behavior we're discussing in other environments. It seems to have been common before disruption by large-scale hunting and habitat fragmentation by settlement.
Moreover, we've primarily discussed ruminants, which tended to be in large herds over perhaps long periods of the year. There are also descriptions of hind-gut fermenters, rhinoceros in Africa in particular, gathering into fairly extensive herds of at least thousands of animals at some times of the year.
Past is future
The salient point here is that large numbers of grazing animals tended to eat and trample forage plants on a massive scale, leaving so little behind they could not pass that way again before the plants fully recovered. This is the apparatus that appears to have built soils all over the world on the prairies and probably elsewhere. In turn it is the method modern humans can use to rebuild the prairies and make a profit at the same time.