Prairies are temperate grassland biomes consisting of longer grasses with an absence of trees or shrubs. A range of different grasses coexist in temperate grasslands alongside seasonal flowering plants. The dominant seasonal characteristics of prairie grasslands are hot summers and cold winters, with moderate amounts of rainfall. Temperatures for prairie grasslands can range from more than 100 degrees Fahrenheit in summer to minus 40 degrees Fahrenheit in winter, and rainfall is more common in late spring and early summer. Prairie grasslands receive an average of 20 to 35 inches of rainfall annually. Heights of grasses in these biomes will vary, dependent upon the amounts of rainfall; wetter regions will have taller grasses. Droughts and fires are frequent occurrences in grassland biomes and are the reason for the lack of trees and shrubs.
The seasonal characteristics of steppes are similar to prairie grasslands, but they receive less annual rainfall, averaging around 10 to 20 inches of rainfall annually. As a consequence of the lower rainfall, grasses are shorter. Examples of steppes can be found in the former Soviet Union and parts of North America.
Savannas are examples of tropical grassland biomes. Savannas can be found in Africa, Australia and South America. They are characterized by concentrated rainfall through six to eight months of the year, followed by drought conditions. Amounts of rainfall can vary from 20 to 50 inches annually, and the following months of drought conditions result in frequent fires. The rainy season heralds a period of intense growth for the grasses and plants of the savanna. Few trees grow in savannas due to poor soil conditions and the annual droughts.
One of the common characteristics of both temperate and tropical grassland biomes is the frequency of drought and fire. The reason grasses are prevalent is that they are deep-rooted and re-establish quickly after drought or fire.
