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Biomes are terrestrial areas that form sets of ecosystems classified according to their geographical distribution, the vegetation that inhabits them, and their climatic conditions. An example of a biome is that of grasslands.
General characteristics of grasslands
Distribution. Grasslands are distributed on all continents, predominantly in the Americas and Africa.
Vegetation. In general, grasslands are made up of deciduous vegetation (that is, it loses its leaves during times of drought), organized into extensive areas of grass that may or may not be accompanied by shrubs and isolated trees, which periodically experience natural fires. The soils of some types of grasslands have a high organic content, are porous, and do not compact easily, which favors root growth and nutrient cycling, which in turn makes them highly fertile.
Weather conditions. The grasslands present a period of rains followed by droughts. In grasslands such as those located in Africa, the climate is hot and dry, while in those located in North America , summers are very hot and winters are very cold.
grassland types
There are three main types of grasslands: temperate or grasslands, tropical or savannas, and steppe.
- Temperate grasslands or prairies. Grasslands are located in North America, South America, Asia, Africa, and Australia. Its climate is characterized by a marked cold season and seasonal rains. Average annual precipitation is 250 to 750 mm and the temperature ranges from -40°C to 38°C. The predominant plant species are tall grasses that flower in spring or at the beginning of summer and are accompanied by broad-leaved herbs; there are no trees in the prairies. An example of this biome is the one found in the Pampean region of Argentina, where the characteristic animal species are herons, deer and a variety of small rodents.
- Tropical grasslands or savannahs. The savannahs are located in Africa, South America and Australia. The climate is characterized by seasonal rainfall, but reduced compared to other tropical areas, which causes a pronounced water deficit that prevents the development of forests. The average annual precipitation is 600 to 1500 mm and the temperature ranges between 20°C and 30°C. The predominant plant species are grasses accompanied by scattered trees. An example of a savannah is the African, where the characteristic animal species are lions, hyenas, elephants and zebras.
- Steppe grasslands.The most representative steppes are located in North America and Eurasia. The climate is characterized by a cold season and water deficit during the dry season. Average annual precipitation is 200 to 500 mm and the temperature ranges from -12°C to 37°C. The predominant plant species are short grasses that are grouped in sets similar to scrub, which means that a portion of the soil has no plant cover; in the steppe grasslands there are scattered shrubs and low-growing trees. If the drought intensifies in a steppe, it can acquire semi-desert characteristics; if the precipitations increase, it acquires features of a prairie. An example of a steppe is the vast plains of North America, where the characteristic animal species are bison, gazelles, coyotes, and deer.
Environmental problems of grasslands
Pastures have historically been used for intensive livestock and agriculture. This is due to the abundance of grasses, their palatability (or flavor) and the fertile soil conditions. Consequently, this biome is heavily intervened and transformed by human activities. Among the transformations are the loss of fertility and the depletion of the soil by monocultures, the contamination produced by the use of agrochemicals, the advance of desertification and the change in the composition of species.
Sources
Curtis, H., Barnes, N.S., Schnek, A., Massarini, A. Biology . 7th edition. Editorial Médica Panamericana., Buenos Aires, 2013.
Biggs, A., Hagins, W.C., Holliday, W.G., Kapicka, C.L., Lundgren, L., Haley, A., Rogers, W.D., Sewer, M.B., Zike, D. Biology . Glencoe/McGraw-Hill., Mexico, 2011
