RESTORING THE RANGE CHAPTER 12 GRASSLANDS The key to recovering the world’s grasslands may be a surprising one

Grasslands refers to a biome that is predominantly grasses, due to low rainfall, grazing animals and/or fire.

Desertification is the process that transforms once-fertile land into desert. Desertification is normally a gradual and imperceptible process. These days, it’s occurring more rapidly: 10 feet per year in West Texas alone.

Most experts agree the biggest culprit is overgrazing: when too many animals feed on a given patch of land.

Desertification is a global problem: 70 percent of the planet’s rangeland (where animals graze) is threatened.

Since the 1980s, the U.S. government has paid ranchers to quit ranching so grasslands can have a chance to recover.

But critics say these types of conservation reserve programs decimate local prairie economies.

Horse Creek Ranch in South Dakota is trying a different solution: graze more cattle, not less.

Grasslands provide important ecosystem services: nutrient cycling, soil formation, surface water protection, and habitat for wildlife.

Grasslands also provide human goods and services: grazing for cattle, farmland for cereal crops, grassland plants as potential fuel.

In addition to overgrazing, grasslands are also threatened by climate change and human land-use decisions.

As temperatures rise, scientists expect that shifting rainfall patterns will help push many current grasslands into desert.

Rising global populations will force us to convert more land into cities and suburbs for living, and into croplands for food.

Ironically, grazing is usually good for grasslands. Grazing animals return nutrients to the soil that plants can easily absorb.

When grass is overgrazed, the blade can’t regenerate and the plant dies. When too many plants die at once, soil has nothing to hold it in place.

When too many grazing animals stomp their hooves on the soil, it becomes compacted, making it harder for water to penetrate and seedlings to grow.

Plant loss and compaction increase the rate of soil erosion: a process in which soil is swept away by wind and rain faster than it can be replenished.

Soil formation is a slow process: It takes one year to form just one millimeter of soil.)

When too many grazing animals are in one area, the constant compaction of the soil by their hooves and the overgrazing of the grass roots will lead to _________________. A. denitrification B. erosion C. evolution D. desertification Question

Soil is classified by distinct layers, called horizons. Identify the horizon containing topsoil that includes decaying organic matter. A. O Horizon B. A Horizon C. B Horizon D. R Horizon Question

In the 1930s, overgrazing on the Great Plains led to the Great Dust Bowl. It took nearly three decades for the prairies to recover.

Now, soil erosion is approaching Dust Bowl rates. The problem is worst in New Mexico and western Texas.

Grassland degradation has cost 12 percent of global grain production. The food supply of more than one billion people is threatened.

Horse Creek Ranch is using biomimicry to change their approach to grazing. They are now grazing livestock the same way wild herbivores grazed.

Herders used to practice what is now known as rotational grazing: grazing their stock in tight herds, moving them across swaths of land.

This meant that grasses were eaten down severely over a short period, but then left for a long time to recover.

Ranchers began to partition livestock in the 19th century, leading to undergrazing. Animals would pick only tastiest grasses, leaving weeds to grow.

At Horse Creek Ranch, planned grazing helps keep plant biomass within an ideal range, where plants capture maximum sunlight and grow quickly.

Ranch owner Jim Howell says land productivity is maximized: “You’re raising twice as many animals in the same amount of space. It’s like getting a second ranch for free.”

Not all ranchers agree that planned grazing is the right approach, but most agree that sustainable grazing is essential to protecting global grasslands.