How did the Climate Develop?
Millions of years ago, the grasslands began developing after the mountainous areas brought upon climate change. Take North America's Rocky Mountains as an example. This mountain chain acted as a large barrier which prevented moisture from moving farther into the continent from the Pacific Ocean. This resulted in a drier climate as you moved towards the center of the piece of land. A similar process occurred in other parts of the world such as in central Asia and South America. This new drier climate caused trees and other vegetation requiring larger quantities of water to die. These plants were replaced by grasses, which are more adapted to drier areas. After this period, which occurred approximately twenty-five million years ago, biomes such as the grasslands became more ordinary as drier climates and diverse regions became more common. The two main types of grasslands include tropical grasslands, or savannas and temperate grasslands. Savannas are located all around the world, inhabiting much of Africa, Australia, and South America.
Savannas
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Savannas are found in hot, dry areas. The average annual rainfall for this particular type of grassland ranges from about twenty to fifty inches. They have a designated period of time in which it rains, appropriately known as the rainy season. This period of time ranges from about six to eight months out of the year. In the time that follows, rain is scarce. This leads to wildfires which help to maintain the savanna. Near the beginning of October, a series of harsh thunderstorms and strong, drying winds signify the beginning of the dry season. The peak of the dry season typically occurs in January, when wildfires are frequent. These fires, however, do not destroy the wildlife. Many of the organisms that come into harm's way by the fire are the ones that have shorter life spans, which tend to be insects. Birds flock to the areas that are affected by these fires, for they are able to feed off of the victims of the fires. Plants have also evolved to cope with this climate by retaining moisture after the fire or burying their roots deep in the soil and awaiting the rainy season which will help to replenish the plant with nutrition. In March, the brutal thunderstorms come again, bringing with them the rainy season. These rains bring new birth, for grasses thrive at this time. This leads to a boost in the birth population in herding animals, which without the grasses would die.
Temperate Grasslands
Temperate grasslands have temperatures that fluctuate more in the summers and winters than in the savanna. They are known for having grasses for their dominant vegetation. The amount of rain the temperate grasslands receive determines the height of the grasses that grow there. Like the savannas, temperate grasslands have seasons which bring periods of drought and rain. The effects of these seasons do not bring as much of a dramatic effect as in the savannas, though. Rain tends to fall in the late spring and into the early summer months. The average annual rainfall for the temperate grasslands is between twenty to thirty-five inches. Temperatures in the summer rise above one hundred degrees Fahrenheit. Winter temperatures can fall to forty degrees below zero. In the winter, temperate grasslands also receive snow, which is nonexistent in the savannas.