Layers and Types of Rainforest

Rainforests are forests characterized by high rainfall. Rainforest, also spelled rain forest, luxuriant forest, generally composed of tall, broad-leaved trees and usually found in wet tropical uplands and lowlands around the Equator. Rainforest is believed to be the oldest living ecosystems on Earth which gets maximum amount of rainfall.

Most of the rainforests in this world are located around the middle of earth near the equator like South and Central America, Africa, Asia and Australia. A tropical woodland with an annual rainfall of at least 100 inches (254 centimeters) and marked by lofty broad-leaved evergreen trees forming a continuous canopy .

Different Layers of Rainforest

A rainforest is divided into following 4 layers. Each layer has characteristic flora and fauna adapted for life in the particular surroundings.

1. The Emergent layer

The emergent layer is made up of the tallest trees, standing as high as 200 feet, towering above the canopy layer that features large mushroom shaped crowns. This layer is naturally inhabited by butterflies, bats and large birds of prey. Trees in the emergent layer enjoy the greatest possible quantity of sunshine, only they have to bear strong winds, extremely high temperatures, and low humidity. Eagles, bats, monkey and butterflies are main animals found here.

2. The Canopy layer

The canopy layer is the thickest layer of the rainforest consisting of the tops of most trees. The trees have smooth, oval leaves that form a dense maze, covering the other two layers as a wide roof. The canopy layer harbors most birds and animals that are able to navigate to the emergent layer to seek the bright light. The branches of trees in the canopy layer are typically wrapped with other plant species and joined with vines.

3. The Understory layer:

It forms the middle layer of the rainforest located between the canopy and the ground. It’s home to snakes, big cats, and lizards. This layer only receives 2 to 15 percent of the sun’s rays that hit the canopy. It’s a very dark section of the rainforest. This layer is considerably open and teems with leafy herbaceous plants and young trees that are able to survive on minimum light. Most popular houseplants originate from this layer.

4. The Forest Floor

The forest floor completes the layers of a rainforest. This layer gets well below 2% of sunlight. Many animals that live in the forest layer survive by consuming dead animal and plant matter.

 

Types of Rainforests

1. Tropical rainforests are warm and wet, characterized by mean monthly temperatures of more than 18⁰C (64^OF) around the year and average annual rainfall of about 400 inches.  These are located in the monsoon trough, between the Tropic of Cancer and Tropic of Capricorn. They have thousands of broad-based leaves aged between 50-100 years old. Diverse variety of plants and animals occupy tropical plants. Decomposition occurs at a very fast rate in tropical rainforests. These are also known as ‘Earth’s lungs’ because they contribute oxygen to the atmosphere. Fifty seven percent of all tropical rainforests are found in Latin America. One third of the world's tropical rainforests are in Brazil. Other tropical rainforests are located in Southeast Asia and the Pacific Islands (25% of the world's tropical rainforests) and West Africa (18%). 

2.     Temperate rainforests are cool and wet, characterized by mean annual rainfall of 50-140 inches and average daily mean temperature of around 50-80 degrees. These are located in the temperate regions. They have evergreen trees aged between 500-1000 years old. The temperate rainforests possess seasonal climate, hence less diversity of flora and fauna. Trees generally have needle-like leaves. In temperate rainforest, decomposition occurs at comparatively slow rate. Temperate rainforest are commonly found in North America, East Asia, Europe, South America, Australia and New Zealand. These kinds of forests are characterized by broadleaf and coniferous forests that thrive in the temperate zones, which receive a lot of rainfall.

 Coniferous forests are chiefly composed of cone-bearing trees. Temperate forest areas receive an average temperature of 40 to 55 degrees Fahrenheit. The main temperate rainforest areas in the world include the British aisle of Europe, the Pacific North West of the United States and some areas in Australia and New Zealand.The largest temperate rainforests are found on the Pacific coast of North America. They stretch from Oregon to Alaska for 1,200 miles. Smaller temperate rainforests can be found on the southeast coast of Chile in South America. There are a few other coastal strips with temperate rainforests, including small areas in the United Kingdom, Norway, Japan, New Zealand, and southern Australia. 

3.     Montane forests are also known as cloud forests.A montane forest is another special forest type. It is found only in mountainous areas, beginning between 1000 m and 1200 m above sea level (asl) to the tree line between 3350 m and 3700 m above sea level This forest is very moist and cold!
The structure of a montane forest is very different from that of lowland forest. There are very few tall trees. A montane forest also has lots of epiphytes like orchids and ferns growing on the trees. The ground is covered with green moss, making it look like it is carpeted. Many rare and beautiful orchids are found in such areas.This types of montane forests are found mainly in Papua New Guinea and the Solomon Islands.The more prominent ones are in Mt. Popomanaseu area of Guadalcanal Province , highland of  the Solomon Islands and also in Papua New Guinea and Iran Jaya the Central Cordillera.

4.     Lowland Rainforests:

The lowland forest is one of the most complexes, dense and species-rich forests. The term rainforest is used to describe forest where there is little or no seasonal water shortage and where the climate is continuously warm and humid (humidity can reach 100% at night). Within this environment there are more than 2,000 species of tree and plant forms, as well as a diverse range of animal and insect species. Some are endangered, some are endemic, while there are others that have yet to be discovered and studied.

This rainforest has great value for wildlife conservation and scientific research; And  it is the type of forest that's under enormous threat because of its value for commercial timber extraction. The tree canopy of a lowland forest has three layers. The upper layer towers at between 30 to 40 m, with occasional giants of 60 m, while the second layer is between 23 to 30 m. The lower level is made up of saplings of a number of species. The ground vegetation is often sparse and comprises mainly small trees and herbs.

5.     Flooded rainforests are the ones that flood for short or long periods of time due to heavy rains. Seasonal flooding is characteristic of many tropical rivers, although few compare to the so-called igapo  which is swamp forest and varzea which is flooded forest) of the Amazon River Basin, where large tracts of rainforest are inundated to depths of 40 feet during seasonal flooding.Trees and fish adapt to survive in this environment – trees form strange shapes and freshwater fish enter into these flooded forests.

6.     Mangrove forests are found on river banks and coasts. Mangrove forests occur along estuaries and deltas on tropical coasts. Mangroves are trees that live along tropical coastlines, rooted in salty sediments, often underwater. Like sea grasses, mangroves are flowering plants, but unlike seagrasses, most of the plant lives above water.These consist of wetland plants which filter the water that flows through them. These trees reach a height of 24 meters and possess stilt-like roots to prevent decomposition in water. They can survive in salty environment with periods of drought in the dry season.

 ***Photo courtesy goes to Google