7 junio, 2024

Rainforest: what it is, flora, fauna, characteristics, climate

what is the rain forest?

The rain forest It is a plant formation dominated by the tree biotype with a complex structure that develops in the intertropical zone. It is characterized by having several layers of vegetation and is one of the biomes with the greatest biological diversity on the planet.

There are basically four types of tropical forests, which are the warm rain forest, the montane forest, the semi-deciduous forest and the deciduous forest. These jungles extend in the intertropical strip (between the Tropics of Cancer and Capricorn) in America, Africa, Asia and Oceania.

The flora of the tropical forest is made up of broadleaf angiosperms with little representation of gymnosperms. Among the most abundant families are legumes, bignoniaceae, nightshade, rubiaceae and palms.

In the understory (lower part) there is a great diversity of ferns, with some arborescent species reaching up to 5 meters in height. In the jungles of tropical America, epiphytic orchids, bromeliads and aroids abound.

The fauna is equally diverse with abundant insects, amphibians, fish, reptiles, birds, and mammals. There is a predominance of small mammals, but among the larger ones the jungle gorilla, the African jungle elephant, the leopard and the chimpanzee stand out.

Rainforest Features

Tropical forests are the most biologically diverse terrestrial ecosystems. They make up a biome that manifests itself in the form of large masses of vegetation located in the intertropical strip.

plant structure

The tropical forest presents a complex plant structure with 4 to 5 layers of vegetation and variable degrees of epiphytism (plants that grow on other plants) and climbing (plants that climb on other plants). In the case of the sub-humid tropical forest, the structure is simpler with only two or three layers.

leaves and light

The diverse adaptations of the plants in the tropical forest are conditioned by the light, the depth of the soil or the high relative humidity.

Solar radiation enters the forest in a vertical gradient that will influence the size and structure of the leaves. In the canopy the sunlight is very intense and the leaves tend to be small.

In the intermediate strata, the leaves have a wider and thinner blade and tend to be larger in the understory plants. In this way, it is possible to take advantage of the low light radiation that manages to penetrate into the forest.

Tabular or lateral roots

In many tropical forests the soil is shallow and large trees cannot develop deep roots. This limits their bearing capacity, so they develop extensive lateral roots similar to the buttresses of medieval churches.

very high relative humidity

In tropical rain forests, with high temperatures and high rainfall, the relative humidity is very high. Plants transpire (release water vapor) through stomata found on the leaves.

When the relative humidity in the environment is very high, as it happens in many tropical forests, the transpiration process is difficult. For this reason, some plant species have developed an active mechanism to release water in liquid form.

This process is known as guttation and is carried out through pores called hydatodes located on the margins of the leaf.

Nutrient cycling in the soil

In general, the soil of tropical forests is not very fertile and in some cases it is shallow soil.

In tropical forests, nutrients are accumulated in the plant biomass and in the litter that is located on the soil surface. The nutrient cycle in the ecosystem is associated with decomposing organisms as well as the mycorrhizal network.

biogeography

Most of the territories where tropical forests develop have a common biogeographical history. The entire area corresponding to South America, Africa, Madagascar, India and Australia formed part of the ancient Gondwana continent 200 million years ago.

This continent separated from the Jurassic and Cretaceous to the present day and much of the flora and fauna of these tropical forests have relationships mainly at the family level.

Role in planetary balance

carbon sinks

Tropical forests are the most productive terrestrial ecosystems on the planet and their capacity to accumulate biomass makes them an important carbon sink. Therefore, each tree in the forest is incorporating atmospheric CO2 and fixing carbon as plant tissues.

This contributes to regulating atmospheric CO2 and reducing global warming, which today is one of the greatest environmental threats.

oxygen production

Tropical forests are not lungs (they do not consume oxygen or release CO2), they fulfill the opposite function. The jungles consume CO2 and release O2 into the environment, but they also consume oxygen when breathing.

These ecosystems are one of the main sources of O2, surpassed by marine phytoplankton.

Water cycle

Tropical forests are huge masses of plants that transpire, taking water from the ground, filtering it and expelling it into the environment as steam. On the other hand, the forest works as a great protector of the soil, slows down water runoff and facilitates infiltration.

Location

Tropical rainforests are located between the Tropic of Cancer (23º 26′ 14″ north latitude) and that of Capricorn (23º 26′ 12.9″ south latitude).

America

In America there are 57% of the tropical forests, from the south of Mexico to the north of Argentina. The largest mass of tropical forest is the forest of the Amazon basin.

The Amazon jungle extends for the most part through Brazilian territory and the rest is distributed between Bolivia, Peru, Ecuador, Colombia and Venezuela. Another large extension of tropical forests corresponds to the forests of the Guiana Shield (Venezuela, Brazil, Guyana, Suriname and French Guyana).

Africa

In Africa tropical forests develop south of the Sahara desert to the savannahs and shrublands bordering the Kalahari desert. The largest extensions are found in the tropical forests of the Congo and Madagascar.

The almost total extension of tropical forest in this continent is located in west-central Africa. This covers Cameroon, Gabon, the Central African Republic and the Republic of the Congo.

Asia

They are located in the Indo-Malaya region in Southeast Asia, highlighting the equatorial jungle of Borneo. These forests are currently threatened by deforestation for timber and oil palm cultivation (elaeis guinensis).

Oceania

Lowland tropical rain forests and montane rainforests are found in Papua New Guinea, New Caledonia, and northeastern Australia. The Queensland rainforests contain most of the remnants of the ancient rainforests of Gondwana.

Types of Rainforests

Warm tropical rain forest

The term «rainforest» has been used to refer exclusively to the warm rain forest (such as the jungles of the Amazon, the Congo and the Selva Lacandona in Chiapas). These plant formations develop in the intertropical zone on flat or slightly undulating terrain at low altitude.

The tropical rain forests present relatively high temperatures (27 ºC average or more) with low oscillations throughout the year.

Rainfall is high, in some cases over 6,000 mm per year and without a clearly defined dry season. Given the high temperatures and precipitation, the relative humidity is also high, being higher than 70-80%.

These are the tropical forests with the greatest structural complexity, they can have up to 5 layers and numerous epiphytes and climbers. The undergrowth is not very developed due to the scant light that manages to reach the ground.

Montane tropical rain forest or cloud forest

It is a tropical rain forest where the temperature is moderated by the altitude above sea level. In these cases, the average annual temperature is lower and there is no well-defined dry period due to the occurrence of orographic rain.

Orographic rain is formed when moisture-laden air masses collide with mountains and rise. As these masses rise, the temperature drops, clouds form, and water condenses and precipitates.

This type of jungle is very exuberant, with high relative humidity and 3 to 4 layers of vegetation and is also known as cloud forest.

The undergrowth is made up of herbs and shrubs and is highly developed on the slopes most exposed to sunlight. In flat areas where the upper canopy is more closed and not much light from the side enters, the understory is more open.

semi-deciduous rainforest

They are tropical forests in a biseasonal climate with 3 to 4 layers of vegetation and a dense understory. They may have a sufficient supply of water at the water table (groundwater).

In this ecosystem, some plant species maintain foliage because they can obtain water from the water table thanks to a deep root system.

Another group of trees shed all their foliage in the dry season and thus reduce water loss. Therefore, in the dry season between 40 and 50% of the trees lose their foliage and in the rainy season they replace it.

deciduous rainforest

They are dry tropical forests with a marked bi-seasonal climate and relatively low rainfall (900 to 1,500 mm per year). They can occur in areas with higher rainfall, but with limitations of water retention, due to the slope of the land or soil permeability.

In this type of forest, 80% or more of the species lose all their foliage in the dry season. The structure is relatively simple, with 2-3 layers, an open upper canopy, dense understory, and less climbing and epiphytism.

Rainforest Flora

One family that characterizes the popular image of the tropics is the Palmae or Arecaceae, and it is possible to find palm species in almost all tropical forests. Other families are common among the tropical forests of America, Africa, Asia and Oceania such as legumes, gutiferous, moraceae and myrtaceae.

A characteristic element of tropical forests around the world, especially cloudy ones, are tree ferns. These giant ferns are part of the understory of the jungles and belong to the Cyatheaceae family.

american rain forest

In the American tropical forests there are abundant species of legumes, meliáceas, moráceas, malváceas and rubiáceas.

Among the legumes, there are species of the genera albizia, lonchocarpus, Anadenanthera, among others. In the meliáceas the American cedar (cedrela spp.) and mahogany (Swietenia macrophylla) which are fine wood trees.

Species of the genus are of great importance in the Moraceae family. Ficus and in the malváceas the ceiba (kapok pentandra). Rubiaceae are an outstanding element of the understory with herbs and shrubs.

In the Amazon there are lecithydaceous species called coco de mono (Lecythis ollaria) and plug or cannonball (couroupita guianensis).

Cocoa (Theobroma cacao) is native to the Amazon basin, as well as the pineapple (

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