Essay on Grassland Biomes (653 Words)

Grasslands typically occur in the interiors of contine­nts and include the tall grass prairies, short grass prairies, or Great Plains and arid grassland of North America as well as the steppes of Eurasia (Southern Russia, Siberia and Asia), the veldt of Africa and the pampas of South America (Argentina). The grassland com­munities are open land communities with limited moisture condi­tions, irregular rainfall, sharp seasonal and diurnal variations and very high radiation.

Since tall trees or other thick vegetations are excluded from these communities there is a free movement of air. These winds carry the particles of sand or dust. These open habitats provide natural pasture for grazing animals (herbivore) which are excluded from predation by predators which hide in thick vegeta­tion and prey upon them.

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In grasslands, the stratification is reduced essentially to a single story, but within that level, species diversity may be as high as in a deciduous forest-especially for the tall grass prairies. Only along the streams are trees to be found, but the “gallery forests” within a few meters of stream bank are characteristics of grasslands.

The grasses comprising of the grasslands can be divided into two basic groups, the tall grasses more than lm high, which are found in moist por­tions of the grassland, and the short grasses less than 1 m high, which are found in the drier regions.

For example, prior to its con­version to agriculture and urban development, the tall grass prairie toward east of North America was dominated by species of blue- stern (Andropogon) forming dense covers four to six feet tall. West­ward, Buffalo grass (Buchloe dactyloides) and other grasses but a few centimeters high dominated the landscape. Flowering herbs in­cluding many kinds of composites are common, but much less important than grasses.

Since the precipitation —evaporation ratio is below 1 in the grassland, leaching is considerably less. The soils of the grasslands are rich, fertile prairie soils (black-earths) and chernozems. Organic matter (humus) accumulates in the upper portion of the soil, ren­dering it dark ; this upper portion remains neutral to slightly alka­line because of the continued replenishment of cations like calcium and potassium ‘through the upward movement associated with eva­poration.

Typical animals of grasslands tend to be quite small, with the exception of a few very large cursorial herbivore animals such as the bison and pronghorn in North America, the wild horse, ass, and saiga antelope of Eurasia and zebra and antelops of Southern Africa.

The large herbivores are nowhere near as diverse as they are in savanna areas. Likewise, carnivores are relatively small such as coyotes, weasels, badgers, foxes, ferrets, owls and rattle snakes, Rodents such as prairie dogs, rabbits, and ground squirrels are common.

Most herbivores characteristically aggregate into herds or polonies; this aggregation provides some protection against preda­tors. The characteristic birds of grasslands are prairie chickens larks, and rodent hawks. Further, salutatorian motion is widespread, not only in mammals such as rabbits and kangaroo rats, but also in insects, such as grasshoppers and crickets.

This probably has to do with increasing rate at which animal can move through or over the tall grasses, as well as making it harder for a predator to catch the animal. Visibility in the grasslands is exceeding well and the premium placed on efficiency including preda­tors is very high.

The common insects of steppes are termites, locusts (Locusta figratoria, Schistocerca gregaria and Melanoplus sp.), bees, burrow wasps, mutilid wasps, bumble bees and blister bees. The steppes also harbour an undisturbed reptilian fauna. Lizards and shakes are met with in large numbers and possess, remarkable diver­sify. Most of them are fossorial, insectivorous and carnivorous.