Tropical and Subtropical Grasslands
The grassland, known as savanna, is located climates in which rainfall mostly occurs during one time of the year, followed by a long drought period that is punctuated by fires that prevent trees from growing. Humans can also have this effect by overuse and underplanting of trees, as shown in a study conducted by the University of California.
The great prairies of the Americas are temperate grasslands, but they are also found in Europe and South America. They have less rainfall than the forested regions that typically surround the grassland, and that, in conjunction with the fires that sweep through the grassland in times of drought, and the grazing of animals, keep them grassy. Many regions of temperate grassland throughout the world have been converted to prime farm land, and the pollution of over fertilization has had an impact on them.
Flooded grasslands are typified, of course, by water. The most familiar example if the Florida Everglades, but the grassland can also be found in Africa and South America. Flooded grasslands are very vulnerable to water pollution, and the runoff from over fertilization of farmlands can cause algae blooms that kill native flora and fauna. In a sweeping and encouraging project, the restoration of the Everglades is being attempted.
Montane grassland is a derived habitat, the grassland that has come about at the disturbance of human activity. It is extensive in Africa, where it is caused by overgrazing. It can support little wildlife because of this, and the characteristically short grasses would soon give way to reforesting if the livestock were removed.
The coldest places in the world are mostly covered with tundra, the grassland which is noted for the low temperatures year round, and low precipitation. The permafrost layer found only inches below the surface prevents the growth of trees. The tundra does not heal quickly because of the short growing seasons, so traces of human disturbance can be found for a very long time. The Canadian Geotechnical Journal has conducted a study showing the damage even a walking trail can leave on this biome.
Desert, or Xeric Grassland
Xeric, or desert, grasslands are kept grassy not by the frequent fires of their damper cousins, but by lack of rainfall, which prevents the development of deep root systems needed to support trees. The grasses in a xeric biome are more noted for their capacity to store water than to spread quickly, as grasses elsewhere must to dominate. Because of this, there is more diversity of plants in a xeric grassland than in a prairie. According to a study conducted by M Halassy between the two main types of grassland, the temperate grassland, and the xeric grassland, they account for about 85% of the world’s plants that reproduce not by seed, but by cloning themselves through production of runners.