Savanna and Rainforest Grasslands

A biome is a sizeable and stable terrestrial ecosystem featured by a self-sustaining community of land-based plants and animals and their abiotic environment (Christopherson, 2006). Each biome is usually named for its dominant vegetation since it is the most visible and easily identified feature of the biotic landscape (Trewartha, Robinson & Hammond, 1967). As Christopherson (2006) suggested, the vegetations' growth, form, and distribution illustrate their own existence in relation to the Earth's energy patterns, atmospheric composition, temperature, winds, air masses, water quality and quantity, seasons, soils, regional climates, geomorphic processes, and ecosystem dynamics. This is why biomes are terrestrial and particularly climate-dependent.

There are many different types of biome and there is also a good variety of ways to their classification. In general, biomes can be grouped into four major categories according to the nature of vegetation: forest, grassland, desert, and tundra (Arbogast, 2007). The forest biomes, representing a third of the Earth's land, are dictated primarily by trees. These biomes span a great climatic range from wet equatorial to cold subarctic (Strahler, 1975), such as tropical rainforest, tropical deciduous forest and scrub, Mediterranean woodland and shrub forest, mid-latitude coniferous forest, and boreal forest (Christopherson, 2006). The grassland biomes are usually semi-arid areas of land dominated by grass as the main form of vegetation with little or no trees, such as tropical savannah and mid-latitude grassland (WorldBiomes.com, 2009). The desert biomes are associated with aridity and extremely low precipitations (WorldBiomes.com, 2009). As a result, they have thinly dispersed plants and a high percentage of ground exposed to direct insolation and weathering (Strahler, 1975). Hot and dry desert, semi-arid desert, and cold desert are examples of desert biomes (Christopherson, 2006).

Savannas are wide open expanses of grasslands with occasional trees. They tend to occur inside large landmasses and are therefore likely to be drier and have greater extremes of temperature. Rainforests have high precipitation and are close to the equator so are always warm and humid and have dense forest. The tropics do not contain the largest plants, or even necessarily the most unusual plants, but they do contain a greater number of different kinds of plants than all the other areas of the world put together. Among this great diversity are plants that have medicinal potential that could benefit many people.

Basing on presence of liquid water, tropical rainforests are subject to regular precipitation all or nearly all year, and they may have many rivers and streams running through the ground beneath their canopy. Rainy season and long periods of drought are typical of savannas. The amount of rain in a savanna can be as high as 150 cm a year, but most of it falls heavily during