Greenspeak

By Rebecca Evered, Curriculum & Content Director, Greenspeak International

Rainforests are forests with high rainfall, with a minimum of between 1750–2000 mm (68-78 inches) per year. They are home to between 40 to 75% of all species on Earth, and a large number of natural medicines have been found there. It has been estimated that many millions of species of rainforest plants, insects, and microorganisms are still undiscovered. Rainforests also supply 28% of the world’s oxygen through the photosynthesis of the plants, making them a very important ecosystem.

There are two types of rainforest, tropical rainforest and temperate rainforest. Tropical rainforests are located around the equator, while temperate rainforests are in the temperate zones of the world. The majority of the world’s rainforests are in South America, Asia and the Pacific, and famous ones include the Amazon in South America, and the Daintree in Australia. Are valuable as they provide timber as well as animal products such as meat and skins. Rainforests also have value as tourist destinations and for the ecosystem services provided (like producing oxygen). Many foods originally came from tropical forests, as do plant based medicines.

Tropical rainforests are usually divided into four main layers, each with different plants and animals adapted to them. They are the emergent, canopy, understory and forest floor layers. The emergent layer contains a few very tall trees (45-60m) that rise above the main canopy layer. Animals that inhabit this layer are birds (like eagles), Bats, monkeys and insects (butterflies). The canopy contains most of the tall trees (30-45m) and forms a continuous umbrella of leaves, which shade the lower layers. This layer has the highest biodiversity of the forest, and animals include many species of insects. The understory is between the canopy and the forest floor, and receives only 5% of the sunlight falling on the rainforest. It is home to a wide variety of animals such as birds, snakes (boa constrictors), insects and some mammals like jaguars. The forest floor is the lowest layer, receiving only 2% of the total sunlight. It usually is fairly clear of vegetation, with only plants adapted to low light levels growing there such as ferns, mosses and fungi.

Unfortunately rainforests are being destroyed at an alarming rate, mostly through human activities such as logging and development. This is called deforestation. Because of this, large numbers of rainforest species are being driven to extinction, with scientists estimating that as many as 50 000 a year are disappearing.

References

1. Butler, R. A. (2005) A Place Out of Time: Tropical Rainforests and the Perils They Face. Published online: rainforests.mongabay.com Retrieved on 8-6-2009

2. Hadiet, Amanda, Final Paper: The Medicinal Value of the Rainforest May, 15 2003

3. The Independent, Entire rainforests set to disappear in next decade, http://www.independent.co.uk/environment/entire-rainforests-set-to-disappear-in-next-decade-585840.html Retrieved on 2-7-2009

4. IrScience,CostaRica,http://jrscience.wcp.muohio.edu/fieldcourses03/PapersCostaRicaArticles/FinalPaper.TheMedicinalVa.html Retrieved on 2-7-2009

5. Myers, N. (1985). Killer Inhabitants of the Rainforests, The primary source. W. W. Norton and Co., New York, pp. 189-193.

6. New York Times, Talks Seek to Prevent Huge Loss of Species, http://www.nytimes.com/1992/03/03/news/talks-seek-to-prevent-huge-loss-of-species.html Retrieved on 2-7-2009

7. Rainforests at Animal Center http://www.animalcorner.co.uk/rainforests/rainforests.html Retrieved on 2-7-2009

8. Richards, P. W. (1996). The tropical rain forest. 2nd ed. Cambridge University Press

9. Whitmore, T. C. (1998) An introduction to tropical rain forests. 2nd ed. Oxford University Press. 10. Variables and math http://www.rainforests.net/variables.htm. Retrieved on 1-4-2009.

10. Image from http://www.cairnsunlimited.com/images/i/lush_rainforest.jpg