Forests Described
A forest is an area with a high density of trees. There are many definitions of a forest, based on various criteria.
These plant communities cover approximately 9.4% of the Earth's surface (or 30% of total land area) and function as
habitats for organisms, hydrologic flow modulators, and soil conservers, constituting one of the most important
aspects of the Earth's biosphere. A woodland is ecologically distinct from a forest. It is less densely treed.
The latitudes 10 degrees north and south of the Equator are mostly covered in tropical rainforest and the latitudes
between 53N and 67N with boreal forest.
Rainforests are forests characterized by high rainfall, with definitions setting minimum normal annual rainfall
between 1750-2000 mm (68-78 inches). From 40 to 75% of all species on Earth are indigenous to the rainforests.
It has been estimated that many millions of species of plants, insects and microorganisms are still undiscovered.
Tropical rainforests have been called the "jewels of the Earth", and the "world's largest pharmacy", because of
the large number of natural medicines discovered there. Rainforests also supply 28% of the worlds oxygen,
processing it through photosynthesis from carbon dioxide. The undergrowth in a rainforest is restricted in many
areas by the lack of sunlight at ground level. This makes it possible to walk through the forest. If the leaf
canopy is destroyed or thinned, the ground beneath is soon colonized by a dense, tangled growth of vines, shrubs
and small trees called a jungle. There are two types of rainforest, tropical rainforest and temperate rainforest.
Below is an example of some of the types of animals you could find in a jungle. Try and spot all 20 of them.
Below is a typical food chain for the types of animals you could find in a jungle. From the predators on top all the way down to the producers on the bottom.
|
The above food chain image is copyright © 1999. Elizabeth Anne Viau and her licensors. All rights reserved. This material may be used by individuals for instructional purposes but not sold. Please inform the author if you use it at eviau@earthlink.net