Native vegetation evolved with grazing animals similar to domestic cattle and sheep; grazing by large ungulates is the “natural” condition for these lands. Plants and grazing animals co-existed in a symbiotic relationship, each benefiting the other.
Richard Teague, Texas A&M AgriLife Research rangeland ecology and management scientist, says grasslands are adapted to and need periodic disturbance of either grazing or fire. “If you don’t defoliate them at all, grasses grow tall and shade themselves, and don’t capture as much sunlight.
What drives an ecosystem is the energy captured by plants, which in turn feeds soil microbes, which feed the plants with the minerals they pick up. It’s a mutualistic, self-supporting system,” he says.
Plants allowed to grow tall cover the soil and keep it from getting too hot – but don’t capture as much energy. “If plants are grazed periodically, however, they grow up again and are photosynthesizing again,” says Teague. “The way animals grazed in large herds (staying together as protection against predators), like the mob grazing some livestock producers use, works best for the plants.”
“If a herd grazes in one spot for even half a day, their excrement discourages them from eating where they just pooped, so they keep moving. They graze an area quickly and move on,” he explains. Feces add fertility to the soil, and recovery period – before the animals return again to that spot – allows the plants to regrow. Then the herds come back and graze it again. Good grazing management uses those principles, mimicking natural movement of large herds.
Overgrazing and undergrazing
Fred Provenza, professor emeritus with the department of wildland resources at Utah State University, has been observing and researching grazing for 50 years, studying animal behavior around the world.
“Many well-meaning people think livestock grazing is harmful and destructive for rangelands. What distorted our thinking and got us off on the wrong foot about arid parts of our country was that our ancestors came from Europe and the East, where there was ample rainfall,” Provenza says. “When people came to the arid West, they didn’t understand that you have to be more careful on these landscapes. With too many animals grazing year-round, stockmen overgrazed arid ranges.”
These regions don’t have the moisture to withstand season-long grazing or to rebound as quickly after grazing. Grazing native rangelands just once during growing season and giving plants ample time to recover (and sometimes grazing again in late fall and winter when plants are dormant) is best – like the migrating bison and other grazers did.
Livestock can enhance biodiversity of rangeland, as Provenza and Michel Meuret discuss in their book The Art and Science of Shepherding: Tapping the Wisdom of French Shepherds. Grass that is never grazed is never as healthy or productive. Livestock grazing can enhance habitat for other herbivores, just as bison grazing improved the food source for elk and antelope.
“Rank overgrown pastures without grazing are stagnant. The CPR program was a perfect example – ground that wasn’t grazed or cropped. It needed grazing as part of the cycle,” Provenza says. Elk preserves/refuges where livestock were removed to protect/provide habitat for elk were another example; elk didn’t want to stay in those areas where grass grew up rank and over-mature.
They went into grazing lands instead to eat tender, nutritious regrowth after cattle gazed. The same thing occurs in areas where people removed cattle to protect sage grouse. Grouse prefer grazed areas, as shown by studies of sage grouse in central Utah.
Good range science is built on the premise of a symbiotic relationship between grass and grazer. “Biologists I worked with at Utah State determined spring grazing by livestock can lead to better winter range for mule deer by putting pressure on some of the grasses and forbs (to reduce their competitive edge) to enhance the shrubs mule deer depend on,” says Provenza.
When Teague was in Africa, wildlife biologists were studying effects of grazing on various plants, including stimulatory effects of grazing animals’ saliva on grazed plants. “Some of the work done in Colorado 30 years ago also showed the effects of saliva and how plants respond positively,” he says.
When a big herd of bison, cattle or other grazers go over the landscape and graze it down, then leave it and don’t come back until plants regrow, this cycle stimulates more growth. “Saliva on the grazed plant, and the urine and feces left behind as fertilizer, aids the plant. The saliva is just one more factor that stimulates growth,” Provenza says.
“When a plant is grazed, root growth halts temporarily and exudates are released into the soil. About 30 percent of the carbon that plants fix goes into the soil and serves as an energy source for bacteria and other soil microbes, stimulating life in the soil.
Bacteria are breaking down soil, decomposing it into minerals that can be utilized by plants. This is part of the symbiosis that takes place below ground and very important for the health of the plant, health of the life in the soil that in turn feeds the plants – that feed animals that feed humans,” he explains.
“If you graze poorly, you diminish those functions and degrade the resource,” says Teague. “Good grazing allows you to use the plants to feed the animals, give them recovery time and then graze them again. This is done with mob grazing, also called adaptive multipaddock grazing.
“With many paddocks, the animals can be moved around – grazing each paddock for a short period so they don’t overgraze the plants, then providing adequate recovery time. But you must be flexible in timing because not every season is the same. As growth rates change, you must adapt the period of grazing and recovery.”
Stockmen have learned a lot in the past several decades about grass management via cattle, with methods that provide high animal impact and adequate recovery time. Soil health in regions that were plowed, farmed and depleted of soil nutrients can be restored much faster simply by using livestock and intensive grazing to add manure and organic matter to the soil profile.
“We’ve also learned how to handle livestock better, with people like Bud Williams teaching low-stress stockmanship and placing animals on the landscape,” says Provenza. “When you put these ideas together, you are where the French shepherds and herders were – able to manage the landscape with livestock and gain optimum potential from both the livestock and the land,” he says.
In their book, Meuret and Provenza make the case people using shepherding to rejuvenate rangelands are ecological doctors, creating healthy soil, plants, wildlife, livestock and people.
“Some people are becoming ecological doctors – thinking about the landscape and the health of soil, plants, wild and domestic animals and people. It’s all about health – human health included.”
PHOTO: Mob grazing, also called adaptive multipaddock grazing, gives plants optimum conditions for stimulation by grazing, fertilizer and litter trampling, and ample recovery time before returning to the same piece of pasture. Photo provided by Tim Hoven.
Heather Smith Thomas is a freelance writer based in Salmon, Idaho. Email Heather Smith Thomas.