Savannah - natural area with a predominance of herbaceous vegetation on the red laterite soil.This zonal natural complex (PC) is distributed between the rainforests and semi-deserts.More than 40% of Africa occupy vast expanses of savannah.The soils are reddish formed under tall vegetation with a predominance of grasses, rare specimens of trees and thickets of shrubs.
tropical forest steppe
Savannah, except Africa, are common in Australia, and the Indian subcontinent.This type PCs are Campos and Llanos on the mainland of South America.Often compared with the savanna forest-steppe temperate zone of Eurasia.There are some similarities, but there are more differences.The main features that characterize the savannah:
- soil with low humus content;
- xeromorphic herbaceous vegetation;
- trees and shrubs with umbellate crown;
- rich and diverse fauna (in contrast to the steppes, it has been preserved).
Campos - the Brazilian savanna plateau - formed different types of plant communities.Cerrados characterized by the presence of low-growing trees and shrubs.Limpos forms tall steppe.Llanos on both sides of the Orinoco River in South America, are covered with thick grass and separate groups of trees (palms).
African savanna.Soil and climate
area of tropical forest in the hot continent occupies about 40% of the territory.In the Northern Hemisphere
savanna reach semi-desert at latitude 16-18 °, closely matched to Lake Chad and the sands of the Sahara.The boundary of the spread of PCs in the south zone is Tropic of Capricorn.Savannah plains occupy space and rise to a considerable height within the East African highlands.
predominant types Climate - sub-equatorial and tropical.A clearly visible throughout the year two seasons - wet and dry.During the rainy season is reduced when moving from the equator to the tropics from 7-9 up to 3-4 months.In January, when it is wet season in the Northern Hemisphere, the Southern drought begins.Total moisture reaches 800-1200 mm / year.Coefficient of moisture - less than 1 (not enough precipitation).Some areas suffer from meager revenue water (0,5-0,3 Kuvl below).
What is the soil in the savanna is formed in such a climate?In the rainy season the nutrients are washed extensively with water in the lower horizons.When it's dry season, there is a reverse phenomenon - the rise soil solutions.
type of vegetation and climate
receiving moisture, tropical forest steppe in Africa alive.Yellow-brown shades dry stalks are replaced by the emerald green.The leaves grow on the trees and bushes that dropped the leaves during a drought, the grass is rapidly stretched, sometimes reaching 3 meters in height.Soil and flora and fauna of the savannah of Africa is influenced by climate.The temperature conditions and moisture depends on the geographical location of the site.
Closer to the border rainforest during the rainy season lasts about 9 months.There is formed tall-grass savanna;groups of trees and shrubs more numerous.There mimosa and palm trees that form the valleys of gallery forests.The most interesting species of flora savanna - baobab.Tree trunk often reaches 45 meters in girth.
As the distance from the equator and closer to the tropics during the rainy season is reduced, develop typical savanna.Border with semi-desert territory gets moisture 3 months a year.The vegetation, which is formed under dry conditions, refers to the type of desert savanna.At 50 ° C, it differs little from the desert.North African nations called these natural areas "Sahel", the residents of South Africa - "the bush".
What kind of soil is dominated by savanna
Soil tropical forest - a red-brown color, which gives it an iron compound.For this type characterized by a low humus content - between 1.5 and 3%.The middle part of the profile contains the clay at the bottom noticeable illuvial-calcareous soil horizon.The above mentioned features are characteristic of East Africa, the northern part of the Australian continent and selected regions of South America.What
soil formed in the savanna depends on the type of moisture.If sufficiently long period of dry humus accumulates as a result of gradual decomposition of vegetation.More fertile soil in dry savannas of Africa and the steppes of South America.With regular moisture on the surface of the earth formed grain structure or shell (hard crust).
soil types within a single natural zone drops different amounts of rainfall vary in duration dry periods.Features relief and climatic conditions imprinted on the savanna vegetation type.Soils formed in the interaction of all elements of the natural complex.For example, the plant remains in the humid forests do not have time to decompose, nutrients are washed heavy rainfall.
Compared with the red and yellow ferrallitic forest soils of the equatorial belt in savannas accumulate more humus.Thanks to the dry period there is a slow decomposition of plant residues and humus.The intermediate type - red ferralitic substrates changeable rainforest.By cereal savannas are mainly located lateritic and reddish-brown soils.Under this type of dry natural area formed by black soil.As we approach the desert regions, they are replaced by a reddish-brown soils.Bright brownish or brick red color of the soil becomes due concentrations of iron ions.
Fauna savannah
surprisingly rich and diverse fauna of the tropical forest.There are representatives of all groups of the animal world.Spiders, scorpions, snakes, elephants, hippos, rhinos, wild boars found in the savannah food, shelter from the heat of the day or rain.Everywhere towering earthen structures termite cones, enlivening a flat surface savanna.Soils inhabit spiders and small rodents in the grass constantly hear noises - scurry about snakes and other reptiles.Large predators - lions, tigers - cleverly hidden in the tall grass to attack the victim unexpectedly.
Ostriches are cautious: tall and long neck allows a massive bird to notice the danger and hide his head.Most of the inhabitants of the savanna escape from predators in flight.Travel long distances hoofed herbivorous animals: zebras, gazelles, antelopes, buffaloes.Giraffes eat around exquisitely delicate leaves on the tallest trees, and on the lake in a thicket of grass turning over clumsy hippos.
Agriculture in the area of savannas and woodlands
Large areas of tropical forest in Australia and South America are occupied for grazing and cultivation of cotton, corn, peanuts.In Indian agriculture, Africa also used savannas and woodlands.Soils are red-brown color when wet and fertile proper treatment.Low culture of agriculture and the absence of reclamation led to the development of erosion processes.Sahelian zone of Africa is a territory of modern desertification caused by a combination of natural and anthropogenic factors.
Problems of soil conservation savanna
Nature Africa changed under the influence of man: forests are cut down, swings open savanna.Vegetation and animals are experiencing the negative impact of anthropogenic factors.Reduce the number of predators and prey, is threatened primate populations.Violation of the vegetation in the savanna or plowing deforestation leads to a rapid degradation of the soil.Livni blur the upper fertile layer is exposed dense mass of clay and iron compounds.She cemented under the influence of high air temperatures.These phenomena occur in areas of intensive agriculture and grazing.Red-brown soils of the savannah in need of protection and restoration over large areas in the developing countries of Africa and Latin America.
