Grazing Animals Could Help Repair Human-Altered Grasslands

Grazing animals could help counteract the human-made overdose of fertilizer that threatens to alter the biodiversity of the world’s native prairies, according to a five-year study published this month.

The comparative study conducted six continents suggests that grazing animals such as the pronghorn (pictured) and other large herbivores can effectively crop the excess growth of fast-growing grasses that would normally out-compete native plants in an over-fertilized world.

The study, which was carried out at 40 different sites, was published this month in Nature. More than 50 scientists who belong to the Nutrient Network, an organization that studies grasslands worldwide, co-authored the study.

The UN Food and Agricultural Organization estimates grasslands cover between one-fifth and two-fifths of the planet’s land area and are home to more than one-tenth of humankind, Nutrient Network says.

Grasslands, like other plant communities, are suffering from too much fertilizer introduced through the disposal of manure from livestock, dosed crops and burning of fossil fuels.

At the same time, grasslands are being converted to pastures for domestic animals with native grazers such as elk and antelope losing ground to cattle and sheep, Nutrient Network says.

The group of scientists, lead by the study’s lead author Elizabeth Borer, set out to test the ecological theory that grazers can counteract the effects of over-fertilizing in most cases. In each group, one plot was fenced to keep grazing animals out and one was treated with a set dose of fertilizers, but not fenced. Another plot was both fenced and fertilized and another was left alone.

Patagonia among companies leading the effort to restore grasslands and find ways to sustainably manage vegetation.

Patagonia launched a program in 2013 to restore 15 million acres of grassland in its namesake region, and bring a new line of sustainable merino wool products to consumers, through a partnership with the Nature Conservancy and Argentine rancher network Ovis XXI

Last year, the Chicago Department of Aviation (CDA) hired a herd of goats to provide sustainable vegetation management at O’Hare International Airport. The CDA planned to begin the pilot grazing program once sufficient foliage for the goats is available at the airport.

Photo: USFWS