INTRODUCTION

The Great Plains region includes parts of the Canadian provinces Alberta, Saskatchewan and Manitoba and parts (or all) of 10 US states: Montana, Wyoming, North Dakota, South Dakota, Nebraska, Colorado, Kansas, New Mexico, Oklahoma, and Texas. The location of the ecosystems of the Great Plains are strongly linked to the gradients of temperature and the geological histories of the parts.

This presentation focuses on a specific area of the Great Plains: The Prairie Pothole Region.

The Great Plains

GEOGRAPHIC LOCATION

PRAIRIE POTHOLE REGION (PPR)

The Northern part of the Great Plains is an area of mid-grass and tall-grass prairies that contains thousands of potholes (shallow wetlands). These potholes were made during the Wisconsin Glaciation time, which ended approximately 10,000 years ago. The ice sheets of the retreating glaciers left behind depressions formed by the uneven deposition of glacial sediments and melting ice blocks. These depressions filled with water, forming the seasonal wetlands known as potholes.

Some parts of the Canadian provinces-- Alberta, Saskatchewan and Manitoba-- as well as parts of US states-- Montana, North Dakota, South Dakota, Minnesota and Iowa-- are part of this region.

BIOTIC FACTORSMost of these potholes, however, have been drained and converted to agricultural lands. The remaining natural potholes are important habitats for migratory waterfowl and other wildlife. The Prairie Pothole Region is one of North America's most important areas for populations of mallard, gadwall, blue-winged teal, northern shoveler, northern pintail, redhead, and canvasback ducks.

These ducks are not the only examples of wildlife found in the PPR. The wildlife in and near the natural potholes is very divers. There are many insects, spiders, reptiles, amphibians, mammals, fish etc. in this ecosystem as well. The grasslands surrounding the potholes have large-sized grazers and other predominantly herbivorous ungulates (long legged hoof animals). Predators, such as wolves, coyotes, foxes and birds of prey also inhabit the Prairie Pothole Region.

MacrophytesAlthough many of the Prairie Potholes have been converted to agricultural lands, the natural potholes that are left have very dynamic and continually changing plant communities. As a result of fluctuating water levels, wetland plants need to adapt to the wet/dry cycle. The 4 wetland stages are the following: dry marsh, regenerating marsh, degenerating marsh, and lake marsh.

Many plants are annual species germinating on exposed mudflats during the dry periods. When the water returns, the emergent macrophytes survive and expand.

Macrophytes are aquatic plants that grow near water and are either emergent, submergent or floating.

The grasslandsBefore the farmers arrived, the Great Plains were the most extensive grasslands in the world, with about 100,000 acres of prairie pothole wetlands. Today, only a small fraction of the grasslands remain and only 50 percent of the prairie pothole wetlands still exist. The remaining wetlands are surrounded by grasslands-they are not wild anymore- and by agricultural lands.

The wild grassland of the prairie pothole region was a mix of short and tall grasses. It consisted of open areas of an endless sea of grass.

Prairie Pothole GrassesMost of the wild grasses are perennials with a deep root system. Buffalo grass is a very hardy grass; it is a perennial short grass and very resistant to heat and cold. It sends out thin roots that can reach 5 feet below the surface, forming a dense sod. It is one of the most important grasses of the prairie and it provides food for livestock, deer, buffalo, pronghorns, jackrabbits and prairie dogs.Big Bluestem grass, sometimes called Turkey feet or Beard grass, grows very tall, 3 to 10 feet. And it belongs to the tall grasses. It grows in dense stands and keeps other grasses from growing. This grass has very deep roots, which prevents erosion. It also was an important food for the wild buffalo. (Blueplanet, 2010)The grasslands can withstand low rainfall and scorching sunshine because many grasses grow in a particular way. When the stems are damaged, they can seal off their broken veins to prevent leakage of sap. The only condition that grasses require is good light.(Attenborough,1984 )

A-BIOTIC FACTORSThe most important a-biotic factors that have formed this ecosystem are the following:

THE CLIMATEThe climate determines many aspects of life in the PPR. The winters are usually harsh and cold. The summers are hot and dry and because of a lack of trees and forests, wind is an important factor. This area lies in the rain shadow of the Rocky Mountains, thus periods of drought are common and heightens the importance of water in this region. Plants surviving in grasslands must use the spring rains to grow and they must be able to tolerate dry summer conditions and drought. Grasses have very deep root systems that reach far down to get water, they also lose less water through their leaves than other plant types.

GEOLOGYThe potholes are the results of depressions made by the remains of the glacier moraines. ”The deposition of glacial till was unevenly distributed throughout the PPR. Large moraines accumulated along the terminal ends of glaciers and formed ridges of low, rolling hills in a northwest to southeast orientation, such as the Missouri Coteau.” (NPWRC,2006 ) The ridges at the edges of the potholes are very stony: They consist largely of limestone, dolomite, quartzite, granite, and gneiss.

•WATER There are few natural surface water drainage systems in the region; pothole wetlands are not connected by surface streams. They receive most of their water from spring snowmelt. The potholes serve as natural sponges that hold excess water, which reduces the risk of downstream flooding. They provide water and forage for wildlife and livestock. Most of the grasslands in between the potholes do not receive enough rainfall for trees and shrubs. Only grasses can withstand the relative lack of water. The Prairie Pothole Region receives its water primarily from the atmosphere. Some of the potholes, however, because of their position in the landscape, function as groundwater discharge sites and receive the bulk of their water supply from the groundwater table. Their principal water loss is through evaporation. As a result, the salinity of that water can, in some cases, exceed that of seawater. In most areas the evaporation of water exceeds precipitation, a typical condition for grasslands. (NPWRC, 2006)

•CHEMISTRYThe salinity of some potholes can become so high that it becomes toxic for plants. The most saline parts of the PPR have the fewest plant species.The soil of the grasslands is very rich in nutrients and is, when turned into farmland, highly productive. The fertile soil is the result of the large amount of biomass (plant tissue) that has been building up year after year. It contains a large proportion of clay which retains water better than sandy soils.

Grassland soil profile

IMPACT OF HUMAN ACTIVITY ON PPRMost of the wild grasslands in the PPR have been converted to farmland. The nutrient rich soil and the water providing potholes were excellent for agricultural and grazing purposes. In the past poor farming techniques and a long period of drought have led to the Dust Bowl Period. Large sandstorms of loose surface soil turned the rich farmland into desert like areas.Although new farming techniques have improved the protection against such a severe erosion, the extensive use of water, the continuing threat of loss of water quality as a result of turbidity (cloudiness) , overgrazing, the use of herbicides, salinization and the loss of plant and animal diversity are still endangering this ecosystem.

What can we do to protect this area?

Click on movie

FUTURE SOLUTION

One of the major disadvantages that cultured crops have compared with their wildgrass relatives is the root system. Crops such as wheat , corn and soy are annual plants with a relatively shallow and small root system. These crops require irrigation, use of plowing (to grow the next year’s crop) and they do not prevent erosion.Perennial grains or grasses, however, have a root system that is much larger and reachesdeeper. Their long roots hold on to soil, water and fertilizer, which means less water use,less erosion and less pollution.

Perennial solution• As humans started cultivating wild plants about 10,000 years ago, they unwittingly chose annuals. All the

grains that we grow today to feed billions of people, such as wheat, rice and corn, come from annual plants. Annual plants sprout from seeds and they die every year. The advantage of using annuals was that they (the farmers) were able to improve them rapidly by selective breeding, which eventually resulted in a high yield of produce. Perennials did not have such a benefit.(Kunzig, 2011)

• However, perennials do have the benefit of the large and deep root systems and the fact that the soil does not need to be plowed for the next year’s growth.

• The price we pay for high yields is that our top soil layers are being depleted by the shallow root systems of annual grains. Therefore farmers rely on high amounts of fertilizers. However, most of the fertilizer washes away with the surface water and ends up in the potholes, increasing the turbidity and lowering the water quality. It fertilizes the growth of algae and these algae expel the macrophytes from the pothole area. The shallow root system of our grains and extensive use of groundwater for irrigation also promotes soil erosion.(Kunzig, 2011)

• Scientists are now trying to breed perennial grains and they are crossing modern grains with their perennial relatives. Perennial grains would help with the problems of erosion, poor water quality and depletion of the groundwater. They would also keep the ground covered, thus reducing erosion and the need for pesticides. They would even capture water and nutrients 10 to 12 feet below the surface.(Kunzig, 2011)

• Although the yield of the hybrid perennial grains is still too low for becoming competitive with the annual grains, more research and testing could revolutionize agriculture and preserve the Prairie Pothole Ecosystem.

REFERENCESAttenborough, D. (1984) The Living Planet Boston, MA; Little Brown

Hewitt, P.G and others. (2007) Conceptual Integrated Science. San Francisco, CA; Pearson Education, Inc

Kunzig, R. (2011). Perennial Solution. National Geographic, April 2011 Edition, page 30

Slide 1, picture. Retrieved from: http://usa.usembassy.de/etexts/outgeogr/map10.htm

Slide 2 picture and information. Retrieved from:http://www.npwrc.usgs.gov/resource/wetlands/pothole/prairie.htm

Slide 3 duck pictures. Retrieved from:http://www.wildlifenorthamerica.com/thumbnails/Bird/0.html

Slide 4 Macrophytes picture and information. Retrieved from:

http://www.biology-online.org/articles/macrophytes.html

Slide 5 picture and information grasslands. Retrieved from: http://www.agpix.com/view_caption.php?image_id=61435&photog=1

Slide 6 pictures and information. Retrieved from: http://www.blueplanetbiomes.org

Slide 7 picture potholes. Retrieved from:

http://www.fws.gov/bentonlake/benton%20lake%20wetland %20management%20district2.htm

Slide 8 picture soil profile. Retrieved from: http://marlimillerphoto.com/chemical.html

Slide 9 pictures and information Dust Bowl. Retrieved from:http://www.weru.ksu.edu/symposium/dean_slides/slide5.htm

Slide 10 picture Wetland protection. Retrieved from: http://www.iowaaudubon.org/IBA/sitedetail.asp?siteID=283

Slide 10 movie. Retrieved from: http://www.youtube.com/watch? v=VBb0ZdmfYQc&feature=player_embedded

Slide 11 picture perennial versus annual plant. Retrieved from:http://ngm.nationalgeographic.com/2011/04/big-idea/perennial-grains- text

Slide 14 picture pothole. Retrieved from:http://www.sawtoons.blogspot.com/

Slide show by Nienke Adamse4/22/2011