Equatorial forests occupy a vast area of Central Africa, South America and Southeast Asia. Let's consider the characteristics of the soils of humid equatorial forests, common types - red-yellow and red soils, their origin, structure, morphological features and characteristics. What vegetation usually grows in equatorial forests.
Features of soils of equatorial forests
Rain forests are common in the equatorial belt, which is north of the equator to 25°N latitude and south to 30°S latitude.This area has stable climatic conditions - all year round the temperature is on average above 25 ° C and high humidity - it rains almost constantly, with more than 2500 ml of precipitation falling per year.
Under them, 2 types of soils are formed - red-yellow and red. Their characteristic feature is red-orange and dark red color, due to the presence of iron and aluminum oxide. Due to the leaching water regime, mineral elements are not retained in the upper layer of soil; they are washed down.
Equatorial soils are not very fertile, because, despite the accumulation of foliage and other organic matter, nutrients do not accumulate in the soil, but are constantly consumed by the plants themselves. Their humus content is low. The rapid decay of plant and animal residues caused by bacteria prevents the accumulation of a layer of humus. In areas where the soil is quite young, especially if it is of volcanic origin, fertility is higher.
Common types
In the territory of equatorial forests there are 2 types of soils - red-yellow and red. They have a lot in common, but there are also differences.
Red-yellow
Soils of this type are characteristic of the warmest and wettest areas of the equatorial belt. The percentage of humus in the upper horizon is 4-5. In the lower ones, its concentration cannot be more than 1%. Humus is formed from fulvate compounds, which give it a yellowish color.
The profile of such soil consists of forest litter, a humus horizon 12-17 cm thick, then there is a reddish-brown horizon, under which there is a red or brick-colored soil-forming rock. All layers have an acidic reaction. The intensity of absorption is insignificant.The predominant compounds absorbed are hydrogen and aluminum, the concentration of silica is relatively low. Red-yellow soils are well suited for trees of equatorial species, which have high productivity here.
Reds
They are formed in the equatorial zone, with a large volume of precipitation alternating with a 3-4 month dry season, during which the soil dries out. The soil acquires a red color due to the thermal effect on iron, which is abundantly contained in the soil layer. The top layer is 30-40 cm thick, the humus content is 4%, its composition is dominated by fulvic substances.
Red soils are formed under the influence of laterization processes. This is a process by which iron compounds are diluted with soil solutions. Under hydromorphic conditions, the lower horizons are dense and have a thick layer. When dry, they harden if they come to the surface. In this form, red soils are not suitable for use in agriculture, although they are used as a building material.
Vegetation
The humidity and warmth of the equatorial climate ensure constant vigorous growth of all kinds of vegetation; due to the density of plants, humid forests still remain impenetrable and poorly explored.
Equatorial forests are considered complex ecosystems that contain hundreds of different species of plants, insects, and animals. 2-3 hundred plant species can grow on one hectare.
It is home to many endemic species found nowhere else. The trees grow densely, in several tiers, and there are few bushes and herbaceous vegetation.
The soil red-yellow and red cover of the equatorial forest is not highly productive due to its generally low fertile capacity. The result of plowing the lands showed that it is difficult to obtain large yields from them. In most cases, decent yields are observed only in the first years after development; then it is necessary to either clear fresh territory or use complex agrotechnical measures.
The soils of equatorial forests are formed under the influence of a year-round humid and warm climate, contain a lot of iron, and are not sufficiently saturated with nutrients in the fertile layer. Their economic value is small.
