What Is A Rainforest, And Where Are They Found?

By Oishimaya Sen Nag on April 25 2017 in Environment

Example of a tropical rainforest environ in Thailand.
Example of a tropical rainforest environ in Thailand.

What are Rainforests?

Rainforests are dense forests occurring in regions with a high annual rainfall (usually higher than 1,800 millimeters annually) and a relatively warm or very warm climate. These forests are of vital ecological and environmental significance, as they are often seen housing a wealth of plant and animal life, regulating global climates, and providing a plethora of benefits to mankind the world over.

Tropical Rainforests

The tropical and subtropical rainforests, popularly regarded as the “lungs of the world” due to their oxygen-generating capacities, are found near the Equator and humid subtropics. These forests are characterized by relatively high humidity throughout the year, with very little seasonal variation. Average daily temperatures vary between 30° Celsius during the daytime and 20° Celsius at night. The tropical rainforests are also known as tropical or subtropical moist broad-leaf forests. This definition is used to differentiate them from the tropical or subtropical dry broad-leaf forests of tropical and subtropical regions with drier climates and more distinctive seasonal variations. The tropical and subtropical rainforests occur in Southeast Asia, Sub-Saharan Africa, South America (such as the Amazon), Central America, and the Pacific Islands.

Temperate Rainforests

Coniferous or broad-leaved forests that occupy areas with high rainfall in the mid-latitudes are known as the temperate rainforests. Three key features distinguish them from the other classes of temperate forests. Namely, these are high levels of rainfall, proximity to the oceans, and short distances from coastal mountains. Though the first factor is absolutely essential for a forest to be defined as a rainforest, the latter two factors aid in attracting rainfall to these higher latitude forests. Temperate rainforests are found in western North America, the western Balkans, the western Caucasus, the northwestern parts of Europe, parts of Asia and Oceania, the southern parts of Africa, and mid-latitude portions of South America.

Layers of a Rainforest, & Their Flora and Fauna

The top layer of the rainforest is known as the emergent layer, denoting the trees, some reaching nearly 70 meters in height that are seen towering above the canopy. These tall trees serve as the habitat for a large variety of birds and agile mammals such as monkeys. The canopy layer lies below the emergent layer, and is comprised by a dense growth of trees up to 40 meters tall that spread out their branches in all directions. These branches form a continuous canopy of trees throughout the rainforest. The largest diversity of rainforest species are found in this canopy layer. This layer of the world’s rainforests account for nearly 40% of all plant species found on Earth. A wide diversity of avian species, insects, tree frogs, and reptiles, as well as leopards, jaguars, and other large mammals in search of prey, can be spotted in the canopy layer. The canopy layer encloses the understory layer within its dark confines. This layer is made up of leafy bushes and small trees, and supports a moderate diversity of animal life, including reptiles, amphibians, and certain mammalian species. The forest floor is the lowest layer of the rainforest, and one which receives only about 2% exposure to direct sunlight. Contrary to the commonly perceived notions, the forest floor is usually devoid of plant life, and is primarily covered by dead and decaying organic matter from higher layers, and a few specially adapted plants that can grow in low-light conditions. Snakes, lizards, and anteaters are among the animal species found in this bottom rainforest layer.

The Importance of Rainforests

Rainforests are vital to maintaining global climate systems. The trees of these forests collectively act as a global carbon dioxide sink, clearing the air above them of this major greenhouse gas, thus cooling down the atmosphere. Rainforests also regulate water cycles and trigger rainfall. The absence of these forests would induce droughts and desertification. The extensive root systems of these forests' trees soak up water from heavy rainfall, decreasing the risk of flooding. They also host 50% to 90% of the world’s species. Besides these environmental and ecological advantages, rainforests also act as a source of livelihood for people settled along their fringes around the world. Forest products like rubber, cocoa, coffee, fruits, tannins, and gums are obtained from these forests. Rainforests are also known as the “world’s largest pharmacies”, since a large number of drugs are derived from the plants of these forests. Over 120 prescription medicines are linked to rainforest-based plants, and scientists have also discovered over 3,000 plants in these forests with potential to cure diseases, prospectively including certain cancers, AIDS and other major modern illnesses.

Threats to Rainforest Habitats

As per the current rates of rainforest destruction, it is estimated that between 1 and 2 acres of rainforest are being cleared every second. Clearance of land for livestock grazing and cultivation are regarded as the two major factors leading to the loss of these ecologically vital forests. 137 species of flora and fauna are lost due to this habitat destruction. Up to the present day and age, about 136 million hectares of rainforests have been lost to animal agriculture, and 26 million hectares have been cleared for palm oil production alone. This destruction could only spell disaster for much of the life on Earth, including that of mankind. We are losing out on valuable potential medicines, food and other forest produce due to irresponsible exploitation of rainforests. Climates worldwide are being affected as a result, and the incidence of natural calamities like flooding have increased. Hence, there is an urgent need to protect the last remaining rainforests of the world to ensure the survival of life on our planet, including our own.

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