Journey across grasslands


The journey examining the life and challenges of grasslands around the globe took less than one hour.

“I love to talk about grasslands,” said Ingrid “Indy” Burke, director of the Haub School of Environment and Natural Resources at the University of Wyoming, speaking at the Buffalo Bill Center of the West Draper Museum’s Lunchtime Expedition on June 4.

“... the very lovely science about grasslands,” she added.

Grasslands cover 9 million square kilometers (3.4 million square miles) worldwide and 3 million square kilometers (1.1 million square miles) in North America. Of that, about 600,000 square kilometers (231,661 square miles) are in the northern mixed grass prairie, which covers parts of Wyoming, Montana, the Dakotas and Nebraska, Burke said.

Grasslands receive nine to 40 inches of precipitation of mostly rain annually, Burke said.

A photo on the screen shows a grassy plain. One could easily suppose it is grasslands around Laramie, but it is Mongolia.

Laramie’s grasslands are similar to those found around the globe, Burke said.

Snow in northern grasslands protect the ground from freezing. “Snow is a great insulation for organisms,” Burke said.

Light rains in summer aid plant growth. Grass is drought and grazing resistent. “They capitalize on small precipitation events,” Burke said.

Western wheatgrass is a cool season grass and an example of warm season grass is blue grama, good cattle forage, Burke said.

Cactus is an important player in biodiversiy, possibly because its sharp spines discourage herbivores from feeding on the plants around it, she said.

Ponderosa, limber and juniper are pines found on grasslands.

Animals best suited to grasslands are the species that can weather dry summers and cold winters. Prairie dogs can evade predators by taking sanctuary underground. Fox and coyotes take advantage of the wide open spaces to spot their prey, Burke said.

Rattlesnakes, horny toads, burrowing owls and mourning doves are grassland inhabitants. Mountain plover thrives in heavily grazed areas. Blue herons, killdeer and turtles can be found at prairie potholes or ponds, Burke said.

Grasslands in the United States are fairly well adapted to livestock grazing. Native plants do reasonably well under moderate grazing by livestock. It’s important to understand that livestock grazing causes the least impact compared with other disturbances, such as plowing, because the land evolved with herbivores like bison, Burke said.

An entire ecosystem exists underfoot too.

“If you look at the ground, you’re looking at an upside down forest,” Burke said.

More organisms exist below the ground than above it. Healthy soil is chock-full of organic matter and organisms, such as fungi, nematodes, arthropoda, roots and carbon. Soil stores carbon. It takes hundreds, perhaps thousands of years to replace soil carbon, Burke said.

There is twice as much carbon in the soil worldwide as there is in the atmosphere. Keeping carbon in the soil keeps an important greenhouse gas, carbon dioxide, out of the air. Soil carbon exists as part of organic matter that provides nutrients and holds water for plant growth. “More simply, it’s the basis of soil fertility,” Burke said.

Endangered ecosystem

Most grasslands around the world have already been converted to crops. Grasslands are probably the most endangered type of ecosystem on earth. At this time, places in China and Uruguay that have not already been transformed into cropland are being converted rapidly, Burke said.

Grasslands are resistent to fire, but not invasive species like thistle and Japanese brome, similar to cheatgrass, Burke said.

Launched in 1985, the Conservation Reserve Program (CPR) pays farmers about $40 per acre not to grow crops in an effort to prevent erosion, increase water storage in soil and preserve wildlife. Farmers enrolled in the program can plant grass or trees, Burke said.

Global warming models predict more precipitation, but warmer temperatures for grasslands. Without the presence of snow to insulate soil it is unclear what the impact will be, Burke said.

Preserving grasslands is crucial.

“To maintain biological diversity and soil carbon, not to mention a way of life associated with rangelands,” Burke said.