Prairies of the Great Plains

Dr. Mark McGinleyHonors College and Department of

Biological SciencesTexas Tech University

Grasslands

• Communities dominated by grasses

– Plants in Family Poaceae

• Two main types of grasslands

– Tropical Savannah Grasslands

• South America, Africa, Australia, Asia

– Temperate Grasslands

• North America, South America, Europe, Asia

Distribution of Grasslands

Prairies

• “Prairie” is the term used to describe temperate grasslands found in North America

Origin of the term “prairie”

• The French got there before the English, and they had a word for it: prairie, their name for a meadow. But what they encountered, in what is now Indiana, Illinois, Iowa, and points north and west, was more than your everyday meadow. It was a seemingly endless sea of grass as high as a person's head, teeming with flowers and bugs and other critters. And not a tree in sight.

• There was nothing like this in England, and no English word for it. Besides, the French, who were the first Europeans in that part of the country, had already taken to calling it prairie, so prairie it became. In English, it is attested as early as 1773 in the journal of a traveler on the Illinois River: "The lands are much the same as before described, only the Prairies (Meadows) extend further from the river."

• By the early 1800s, as more and more travelers and settlers ventured into prairie land, the parenthetical definition was no longer needed. Prairie became a descriptive term for the distinctive flora and fauna of these lands

• From Houghton Mifflin Word Origins

Distribution of Prairie in North America

Precipitation Map of USA

Three Main Prairie Types

• Prairies can be divided into three main types from the east to the west

• Tall Grass Prairie

• Mixed Grass Prairie

• Short Grass Prairie

• Prairie types change from east to west as the climate becomes drier.

Prairie Climates

• Prairies are found in temperate climates

– Warm summers, cool to cold winters

• Most prairie regions receive more precipitation in the summer than they do in the winter

• Lower precipitation in the western prairie regions than in the eastern prairie regions

Origin of Prairies

• The upwelling of the Rocky Mountains created a rain shadow in the middle of the continent so conditions became too dry for forests.

• Most prairie soil was deposited during the last glacial advance that began about 110,000 years ago. The glaciers expanding southward scraped the landscape, picking up geologic material and leveling the terrain.

• As the glaciers retreated about 10,000 years ago, it deposited this material. Wind deposits also form an important parent material for prairie soils.

• Wikipedia

Vegetation During Last Glacial Maximum

Glacial Deposition

Grasses

• Grasses are members of the monocot family Poaceae

• http://www.botany.wisc.edu/courses/botany_400/Lecture/0pdf/30bPoaceaeBW.pdf

Poaceae

• 4th largest family - 620 genera, 10,000 species

• most important family (ethnobotanically)

important grain crops are all grasses

Grasses are thought to have originated in South America, but have spread across the world

- • first diversified about 70 mya in late Cretaceous in the understories of tropical forests

Vegetative Characteristics of Grasses

• jointed, hollow,

circular stems

• leaves 2-ranked or

spiralled

• blade, sheath, and

ligule

• intercalary meristem above nodes

Adaptive Vegetative Features

• intercalary meristem

- allow plants to respond to grazing & fire

• silica in stems

- protects leaves from predators

• C4 photosynthesis

- allows for more efficient photosynthesis in warm and arid climates

Reproductive Characteristics of Grasses

• Distinctive flower morphology

• Wind pollinated

Tall Grass Prairie

• Northern Tall Grasslands– Dominant grass species

• big bluestem (Andropogongerardii)

• switchgrass (Panicumvirgatum)

• Indian grass (Sorghastrumnutans)

• Only 5% remains undisturbed– Agriculture– 75% rated as heavily

altered

Tall Grass Prairie• Central Tall Grasslands

– Most mesic of the tall grass prairie ecoregions• Dominant grass species

– big bluestem (Andropogon gerardii)

– switchgrass (Panicumvirgatum)

– Indian grass (Sorghastrumnutans)

– Converted to the “corn belt”• Very little remains

Tall Grass Prairie• Flint Hills Tall Grasslands

– Shallow soil – Dominant grass species

• big bluestem (Andropogongerardii)

• switchgrass (Panicumvirgatum)

• Indian grass (Sorghastrumnutans)

– Not as much has been plowed because of shallow soil depth.

– Lots has been grazed

Tall Grass Prairie DominantsBig Bluestem (Andropogon gerardii)

Tall Grass Prairie DominantsSwitchgrass (Panicum virgatum)

Tall Grass Prairie DominantsIndian grass (Sorghastrum nutans)

Mixed Grass Prairie• Northern Mixed

Grasslands– Dominant grass species

• grama (Boutelouagracilis)

• little bluestem (Schizachriumscoparium)

• needle-and-thread grass (Stipa comata)

• Western wheatgrass (Agropyron smithii),

Mixed Grass Prairies• Central and Southern

Mixed Grasslands– Dominant grass species

• little bluestem (Schyzachriumscoparium)

• western wheatgrass(Agropyron smithii)

• grama grasses (Boutelouacartipendala)

– Only 5% remains intact

Mixed Grass Prairie DominantsLittle Bluestem (Schizachyrium scoparium)

Mixed Grass Prairie DominantsWestern wheatgrass (Agropyron smithii or

Pascopyrum smithyii)

Mixed Grass Prairie Dominantswestern wheatgrass (Agropyron smithii or

Pascopyrum smithyii)

Mixed Grass Prairie DominantsBlue Grama (Bouteloua gracilis)

Mixed Grass Prairie DominantsNeedle-and-thread grass (Stipa comata)

Short Grass Prairie

• Northern Short Grasslands

– Dominant grass species

• grama (Bouteloua spp.)

• needlegrass (Stipa spp.)

• wheatgrass (Agropyronspp.)

– Only 2% remains intact

• 85% grazed or cropland

Short Grass Prairie• Western Short

Grasslands

– Dominant grass species

• grama (Boutelouagracilis)

• buffalo grass (Buchloedactyloides)

Short Grass Prairie DominantsBuffalograss (Buchloe dactyloides)

Other Prairie Plants

Prairie Plant Root Systems

Prairie Fires

Prairie Animals- Large Grazers

American BisonBison bison

ElkCervus elaphus

Prairie Animals- Small Grazers

Prairie VoleMicrotus ochrogaster

grasshoppers

Prairie Animals- Mammalian Predators

Prairie WolfCanis lupus

CoyoteCanis latrans

Prairie AnimalsBlack Tailed Prairie DogCynomys ludovicianus

Prairie Animals

Prairie Animals Today