Images © by James L. Reveal, Norton-Brown Herbarium, University of Maryland, unless otherwise credited.

BSCI 124 Lecture Notes

Department of Plant Biology, University of Maryland

LECTURE 35 - BIOMES, Part 5
Grasslands

Mid-grass prairie near Ottawa, Kansas

XII. Grasslands

A. Location: Major grasslands are widely scattered, covering nearly a quarter of the landed surface: North America ("prairie") Russia ("steppes"), South Africa ("veld"), Argentina ("pampas"). Several grasslands in North America.
B. General features:
- 1. Dominant plants are members of the grass family (Poaceae), several genera and species common but usually with one or two dominate.
  2. Most grasses are rhizomatous (possessing rhizomes) and are wind pollinated.
  3. Moderate temperature but notable extremes: -20° F to 110° F common, and even colder temperatures in the north.
  4. Variable precipitation: 6-40 in (15-100 cm).
  5. Soils generally fertile, deep and rich; variable
  6. Growing season of 120-200 days.
  7. Generally flat to rolling topography cut by stream drainages where there is a riparian or river-bank habitat.
  8. Scattered rain and lightening common in summer months ("convection storms") with more general rains and snows in winter months.
  9. Fire a major factor in maintaining biome.
  10. Summary:
  - a. Introdution.
    b. Origin.
    c. Environment.
    d. Environment.
    e. Biota.
    f. Population structure.
    g. Biological productivity.
Transistion to mid-grass prairie near Lamar, Colorado

C. The Great Plains:
- 1. Location: Alberta, Saskatchewan and Manitoba in southern Canada southward to northern Mexico from eastern Chihuahua to Tamaulipas.
  2. Features: Divided into three associations
  
  Example of tall grass (left) and short grass (right) habit
  - a. Short-grass Prairie: western element, largest.
    - i. Short grasses (less than 20 in or 50 cm tall); "sod grasses".
      ii. Buffalo grass (Buchloe dactyloides) and blue grama (Bouteloua gracilis) are the dominate species.
      iii. About 10 in precipitation annually.
    b. Mid-grass Prairie: central unit.
    - i. Grasses to 4 ft (1.5 m) tall, mixture of sod and "bunch" grasses.
      ii. Short: buffalo grass, blue grama and hairy grama (Bouteloua hirsuta); tall: little bluestem (Andropogon scoparius) and needle-and-thread grass (Stipa comata); big bluestem (Andropogon gerardii) in moist areas.
      iii. 14-25 in (35-65 cm) precipitation annually.
    c. Tall-grass Prairie: eastern unit
    - i. Tall grasses (3-4 ft or 1-1.5 m tall); "bunch grasses" - see left.
      ii. Species of bluestem (Andropogon), one finds representatives of cordgrass (Spartina), panic grass (Panicum), Indian grass (Sorghastrum) and wild-rye (Elymus). See this site for other kinds of plants
      iii. 24-40 in (65-100 cm) precipitation annually.
  3. Animals: Dominated by grazing animals (deer, antelope, buffalo - once common but now rarely native to the range) and song birds that sing on the wing. A common animal is the prairie dog. The black-footed ferret is a rare species.
  4. History:
  - a. Northern third extensive glaciated.
    b. Grassland pushed well to the south (where the Chihuahuan Desert is today) during last ice age, moved northward during Late Pleistocene and Early Holocene.
    c. Grazed by migratory animals; these eventually hunted by humans.
    d. Numerous Indian tribes occupied the grasslands (e.g., the Pawnee and the Lakota)
  5. Exploitation:
  - a. Majority of tall- and mid-grass prairie now farmland.
    b. Short-grass prairie grazed, some areas now overgrazed.
Palouse Prairie near Camas, Idaho

D. Palouse Prairie:
- 1. Location: Eastern Washington and portions of adjacent Idaho and Oregon. Scattered elsewhere as in parts of northern Utah; some define the unit so as to include the northern Great Plains
  2. Features: Short grasses, diverse, lots of wild flowers; mixed with shrubs.
  3. Vegetation: Grasses: bluebunch wheatgrass (Agropyron spicatum) with Idaho fescue (Festuca idahoensis) and Sandburg's bluegrass (Poa sandbergii). Shrub: sagebrush (Artemisia tridentata).
  4. Animals: Deer and antelope today; buffalo, camels, horses and mammoth along with an array of predators such as great cats and wolves into early Holocene.
  5. History: Always small but now invaded by desert species.
  6. Exploitation: Dry-land farming and grazing.
Light fog on coastal grasslands near Butano State Park, California

E. California Grasslands:
- 1. Location: Two areas.
  - a. Central Valley.
    b. Coastal California.
  2. Features:
  - a. Central Valley: dry, dense grasses and scattered hardwoods on margins.
    b. Coastal: moist, fog-influenced, meadow-like with shrubs.
  Dry inner coastal grasslands near Alcalde, California
  
  3. Vegetation:
  - a. Central Valley: Grasses: purple needlegrass (Stipa pulchra) (the dominant), rye-grass (Elymus), bluegrass (Poa), muhly (Muhlenbergia) and three-awn (Aristida). Trees: Poplar (Populus), ash (Fraxinus) and walnut (Juglans hindsii).
    b. Coastal: Grasses: Idaho fescue, California oatgrass (Danthonia californica), Pacific reed-grass (Calamagrostis nutkaensis) and velvetgrass (Holcus lanatus). Shrubs: Numerous representatives.
  4. Animals: Deer, antelope, elk (see Tule elk in morning beach fog at right) and buffalo were common, only deer still common. Numerous birds including many species of waterfowl.
  5. History: Long-term areas with little or no impact from recent glaciation.
  6. Exploitation: Central Valley grassland almost totally converted into farm land. Coastal grasslands being invaded by expanding urbanization. Grazing and exotic weeds major problems in some areas.