Savannah soils: 3 predominant types and what is characteristic of them, vegetation

The composition of the soil of such a zone as the savannah is not particularly fertile. The prevailing climate in this area does not contribute to the formation of a thick layer of humus. In savannahs, low-growing grasses and xerophytic plants grow, adapted to a long dry period. This natural area is located near the equator. The savannas do not experience sub-zero temperatures, but due to the lack of rainfall, the land here is infertile.

Features of savanna soils

Planet Earth is divided into 10 natural zones. One of them is savannah. This zone is located in the subequatorial belt a few degrees north and south of the equator, in South America (Brazil), northern Australia, eastern Africa, and southern India.The soil composition of the savannas depends on the climate, the prevailing vegetation, the duration of the dry winter and rainy summer periods.

The closer to the equator, the richer the soil in iron oxides and the poorer in humus. In the immediate vicinity of the equatorial forests, in the light forest zone, it rains for about 8 months. Lush herbaceous vegetation and abundant rainfall all contribute to the formation of acidic, humus-poor red ferrallitic soils.

The farther from the equator, the longer the dry period. In the savannah zone, where the rainy season lasts about 6 months, the soil is red-brown. Prickly bushes and various types of cereals and sedge grasses grow in this area. During the dry season, vegetation has time to decompose and turn into a thin layer of humus on the surface of clay rocks.

As the dry period lengthens, in conditions of moderate humidity, more fertile black tropical soil is formed.Near deserts and semi-deserts, the soil is unproductive, with a thin layer of humus. In an area where it rains for only 2 months, the vegetation is sparse, consisting mainly of grasses and trees adapted to the long dry season.

Which soils are the most common

On the territory of the savannas, the soil is not particularly fertile. The climatic features of this area do not contribute to the accumulation of a thick layer of humus.

Red-brown

Brick-colored soils are characteristic of the savannah zone, which is located at a small distance from the equator. In the location of such soil, there are incessant rains for 6 months in a row, and the rest of the time there is hot dry weather.

In the rainy season, this area has an abundance of vegetation. True, the soil is often eroded, water carries away nutrients from the surface. In the dry season, fallen leaves, withered grasses decompose and the soil is enriched with humus.

In the heat, the top layer of soil becomes reddish-brown due to intense heating. This is the result of thermal dehydration of iron oxides. Up to 1.5-2% of humus with a width of 20-25 cm is formed in the soil. The reaction of the soil varies from slightly acidic to slightly alkaline. According to the granulometric composition, the red-brown soil of the savannas is sandy, clayey and loamy.

Brown tropical subarids

This type of soil is formed under the influence of the prevailing climate in this area. In this zone of the savannas, there are heavy rains for 3 months in a row, and the rest of the year - drought and heat. The surface is covered with grasses and sparse shrubs.

During the rainy season, a lush grass cover appears in this area. During the dry season it is very hot here, fires often occur, therefore, the root system of plants, and not the upper tier, is mainly involved in soil processes.Brown tropical soils form under short-grass savannahs. The humus horizon does not exceed 30 cm and is 2%. The reaction of such soil is generally slightly acidic or neutral.

Black tropical

This type of soil is formed under the influence of a dry climate with moderate humidity. On the territory of the formation of these soils, 25 degrees of heat all year round, and the dry period lasts about 8 months. Herbs and low-growing shrubs grow here, as well as baobabs, acacias. During a dry season, withered vegetation forms a layer of humus on the surface of clayey, volcanic rocks.

The main features of black tropical soils: lumpy structure, humus content of about 4%, high content of calcium and magnesium, alkaline and neutral reaction. In the dry period, the soil dries up and cracks, and in the wet, on the contrary, it swells. The dark color was formed due to the relationship of organics with clay.Black tropical soils have nothing to do with fertile black soil.

Vegetation

Savannahs are reminiscent of woodlands or grassy steppes. Vegetation depends on the prevailing climate in a particular area. In the rainy season, the savannahs are covered with thick grass, the leaves on the trees and shrubs are filled with juice. During the dry season, the vegetation dries up and withers. Xerophytes (cacti, aloe, acacia, spurge, baobab) are common in this area, that is, plants that can tolerate prolonged drought.

Where the surface is covered with red-brown soil and it rains for 6 months, and then it is hot for 6 months, hard-leaved grasses and sedge grasses, thorny bushes and stunted trees grow. Savannah is rich in succulent plants (cacti, aloe). In this zone you can find elephant grass, spurge, baobabs, acacias, oil palm, tamarix.Trees are often overgrown with epiphytes, and their branches are braided with vines. Local residents use the territory of the savannas as pastures. With well-established artificial irrigation, tea, citrus fruits, peanuts, corn, and cotton are grown in this zone.

Red-brown soils are replaced by brown tropical subarid ones. Low grasses, grassy herbaceous vegetation (aristida, andropogon), thorny bushes, and acacias predominate here. Herbs grow in tufts. Local residents irrigate these lands and use them for growing peanuts, rice, corn, and millet.

Short trees, thorny shrubs and grasses, as well as acacias, baobab and plant species such as bearded vulture, drin, grow in the zone of black tropical soils. Under irrigation conditions, cotton, rice, sugar cane, cereals, corn are grown here.