EVERGREEN RAINFOREST BIOME

Geographical Background

This biome extends upto 10 degree latitude on both sides of the equator. It covers the area of Amazon low land of south America, Congo basin of equatorial Africa and South Eastern Asian Islands extending from Sumatra to New Guinea.

This area experiences high temperature throught the year with range as little as 2 degree celsius. However, the daily range of temperature is much higher than the annual range of temperature.

This area gets heavy rainfall ranging between 150cm-250cm. It is distributed throughout the year. Rainfall occurs in the afternoon almost on daily basis. This also happens because of huge amount of water vapor reaching in the atmosphere due to high temperature. Hence, this area is considered to be an equable
climate as both temperature and rainfall are high for whole of the year.

Natural Vegetation  

The combination of heat and moisture make this biome as perfect environment for a great variety of plants and animal species. The variety of plant species can be understood from the fact that one square kilometer may contain as many as about thousand of different types of plant species. Most of the trees have buttressed trunks, shallow roots and large dark evergreen leaves. The evergreen rainforest are arranged in three levels-

(a) The canopy or upper level where trees lies between about 20 metres to 50 metres. Most of them are hard wood trees like ebony,  Mahogany, rose wood, sandalwood, cinchona, etc.

(b) The second level of intermediary level where trees lies between about 10 meters to 20 meters. The most important plant of this group is palm trees. Apart
from palm trees, epiphytic and parasitic plants are also found in this layer

(c) The third or lower level lies from surface level to about 10 meters of heights. Under this category variety of plants are found namely orchids, ferns, mosses, herbs, bananas, pineapples etc. Because of tall and broad leaved dense plants, sunlight could not reach at the lowest level/surface. Because of poor photo-synthesis process at this level, number of plant species are very low.

Animal Life

Like vegetation, evergreen rainforest is inhabited by numerous birds, mammals, insets etc. Some important animals of this biome are Jaguar, lemur, orangutan, elephant, etc. Macaw parrot, sloth and toucan are some of the important birds of this area. Most of the birds are colorful.

The water bodies of the equatorial areas are also rich in animal life with alligators, tactless, fishes, frogs, Hippopotamus etc. Because of the impenetrability and high vegetation growth in the lower part, most
of the insects, birds and animals resides on the branches of the trees. Generally, they do not come down to the ground.

The productivity of the tropical rainforest biome is the highest of all biome types of the world. It may be pointed out that the rainforest biome represents only 13 percent of the total geographical area of the world
but this biome accounts for the 40 percent of the total productivity of the world.

Human Response

Human being has also started to damage this biologically rich ecosystem through various developmental activities. These activities are
construction of large dams and reservoirs, roads and high ways, extraction of timber clearance for pasture or crops, encroachment and clearance by landless peasants etc.

Ecologists argue that if clearance continues at recent rates, all of the world’s undisturbed rainforest is likely to have disappeared or to be damaged by 2020. This would lead to an irrepairable loss of biological
assets.

Rainforests contain about 40% of all known species of plants and animals. Clearance of rain forest causes the loss of valuable natural resources including hard wood trees and tree products such as quinine rubber vegetable gums etc. This loss is just not ecological but also has very significant environmental consequences.

The evergreen forest provides various environmental services by helping to regulate global weather patterns, soil erosion, river flooding in the tropics etc. Evidences show that tropical deforestation have lead to the green house effect and global warming by removing an important carbon sink.