How do we characterize a grassland?
Grasslands are characterized as lands dominated by grasses rather than large shrubs or trees. In the Miocene and Pliocene Epochs, which spanned a period of about 25 million years, mountains rose in western North America and created a continental climate favorable to grasslands. Ancient forests declined and grasslands became widespread. Following the Pleistocene Ice Ages, grasslands expanded in range as hotter and drier climates prevailed worldwide. There are two main divisions of grasslands: (1) tropical grasslands, called savannas, and (2) temperate grasslands.
Weather?
Temperatures in this biome vary greatly between summer and winter. The summers are hot and the winters are cold - much colder than Santa Barbara! With cold winters, it’s surprising how hot the grassland summers can get! Sometimes the temperature is more than 100°F (37.8°C). Rain in the temperate grasslands usually occurs in the late spring and early summer. The yearly average is about 20 - 35 inches (55 - 95 cm), but much of this falls as snow in the winter. Fire is not foreign in temperate grasslands. They are often set by lightning or human activity. Fire regularly swept the plains in earlier times, and to some extent still does today.
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Location?
Major grasslands in North America are the Great Plains of the Midwest, The Palouse Prairie of eastern Washington State, and other grasslands in the southwest. Not all grasslands are located in the mid-west, but most are located there.
In Eurasia temperate grasslands are known as steppes and they are found between the Ukraine and Russia. In South America they are called pampas, and are located in Argentina and Uruguay. In South Africa temperate grasslands are known as veldts. Savannas are comprised mostly of grasses and a few scattered trees. They cover half the surface of Africa, large areas of Australia, South America, and India. |
Inhabitants?
All grasslands share a lack of shelter from predators, and an abundance of grass for food; therefore, grassland animal populations are similar throughout the world. The dominant vertebrates in grasslands are herbivorous or plant-eating grazers called ungulates. Ungulates are mammals with hoofs, like horses and deer. Their long legs help them run fast to escape grassland predators. Some animals that inhabit temperate grasslands in North America are bison, antelope, birds, gophers, prairie dogs, coyotes, and insects. On the steppes you’ll find similar animals to the Great Plains including lynx, antelopes, falcons, and fox.
Grasses dominate temperate grasslands. Trees and large shrubs are rarely found in grassland areas. There are many species of grasses that live in this biome, including, purple needlegrass, wild oats, foxtail, ryegrass, and buffalo grass. Many animals munch on these grasses, but they survive because the growth point on the grasses is very close to the ground. Also, with underground stems and buds, grasses are not easily destroyed by fire. Wildflowers also grow well in temperate grasslands. Popular flowers that you might find growing on grasslands are asters, blazing stars, goldenrods, sunflowers, clovers, and wild indigos. |
Soil?
The fires prevent trees from growing and they also return nutrients to the soil. Because the soil below the surface doesn’t heat up much during a typical grassland fire, the mat-like roots of the grasses survive and send up shoots the following spring. Because grasslands have amazingly rich soil, many areas that were once natural grasslands have been taken over for farming. We don't see forests popping up in grasslands because the soil can get dry. The composition of the soil is mostly sand, but there is about 10% of clay. The soil composed of clay is deeper because it is remnants of dead plants; this provides nutrients for the new plants and shrubs.