Variable-moist forests are characteristic of areas that alternate between seasonal rains and dry weather. They are distinguished by unique climatic characteristics, beautiful landscapes, diverse flora and fauna. During the wet season, these zones are similar to equatorial forests. The soils of variable-moist forests also have unique characteristics.
Description and features
Such forests are predominantly found in a subequatorial climate, which is characterized by drought and precipitation patterns. This type of forest is located in small areas, but affects many regions - Africa, South and North America, Asia.
The main distinguishing feature of the soil of this type of forest is its bright red color. It is associated with the weathering of useful elements. The formation of humus requires vegetation, which saturates the soil with organic matter. But heavy precipitation leads to the penetration of nutrients deeper and reduces the humus content in the upper horizon.
With the arrival of dry weather, the final stage of the formation of red soils begins. The fact is that the beneficial substances that remain on the surface erode. As a result, iron oxides remain, which affect the color of the soil.
Such soils are typical for zones with sharply variable climates. A striking example is the tropics and subtropics. There, the duration of precipitation and dry days is 6 months each. The color of the soil depends on the climate and plants of the region. It can be red-brown or red-yellow. The first group of lands is called red soils, and the second - yellow soils.
Both types of soil are found in subtropical and tropical forests and steppes. They are characterized by a lumpy-grainy structure. The main difference is the organic content. Red soils are considered the most weathered. However, they have more humus than yellow soils, and therefore are considered more fertile.
Climate and geography
Summer temperature in areas of such forests is +27 degrees. In winter it rarely drops below +21 degrees. The rainy season begins after the hottest month.
Variable rain forests are mainly localized in the subequatorial climate. It is characterized by drought and precipitation regimes. This type of forest occupies many regions:
- Africa - Cameroon, southern Sudan, Congo, northern Angola;
- North America;
- South America - in particular large areas of Brazil;
- Indochina;
- Sri Lanka;
- India.
Such forests are typical for temperate and subtropical climate zones. This primarily concerns the monsoon climate on the eastern side of Eurasia. Variably humid forests are found in China, Korea, and Russia. In the Russian Federation they are localized in the Khabarovsk Territory, Primorye, and Sakhalin.
What soils predominate in variable-humid forests?
The soils in all areas of variable-moist forests differ significantly from other types. They are characterized by a red tint and strong weathering of minerals. In such areas, a lot of precipitation falls in a short period of time. Constant warmth creates conditions for active growth of greenery.
Due to these features, soils are called ferallitic. The iron oxides present in the structure give the soil a red, dark brown and yellowish tint.
Vegetation and fertility
For the soil to be fertile, it must contain a large supply of humus. If its content is up to 4%, the soil is considered infertile. Red soils contain almost no humus. Its content is approximately 3%. Only the most resistant substances remain in the composition - quartz and kaolinite.
Due to the composition of the soil, the flora in variable-humid forests is considered very monotonous, since only specific plants have adapted to weather conditions. Thus, in savannas where red soils are found, trees can rarely be seen. Herbaceous vegetation predominates here. At the same time, trees are sometimes found - most often baobabs.
The vegetation of such forests is mainly represented by coniferous, deciduous and evergreen tree species. There are also vines and ferns here. It is worth considering that during the wet period the trees have rich green foliage. During dry climates it crumbles.
The only exceptions are evergreens. These include palm trees, ficus trees, and bamboo. This category also includes cypress trees, various types of magnolias, and camphor wood. Fir and spruce trees are found quite often in these areas. Among deciduous trees, it is worth highlighting linden, oak, maple, walnut, and ash.
Application
Despite the low fertility of red soils, the humus in their composition is excellent. It is approximately 20 centimeters. Thanks to this, it is possible to use the land in agriculture. They allow you to grow citrus fruits and individual vegetables - in particular, beets.
Yellow soil types are considered less fertile. This is due to the high clay content and weak humus. However, such lands are also permissible for agricultural cultivation. They are used for tea and grape plantations.
Variably humid forests have a number of features. Such zones are distinguished by unique soil that can be used in agriculture. At the same time, the soil is considered not very fertile and requires careful attention to the implementation of agrotechnical measures.
