The popular image of a rainforest is a tangled mass of vegetation teeming with wildlife. From a [P 007 / river bank] or a road where sunlight can reach the ground, vigorous plant growth does occur on the ground and this helps lend credibility to the myth that all rainforest is like this.
In reality, rainforests are rather different. At ground level there is little vegetation. Here, the rainforest is shaded and quiet. A great deal of the wildlife lives far above the ground in the [G 05 / canopies] of the enormous trees.
A rainforest can be simply defined as forest that experiences a great deal of rainfall. The combination of constant high temperatures and heavy rainfall throughout the year, enables both plants and animals to flourish. Rainforests harbor an astonishing [V 000 / diversity of wildlife] in significant numbers; around half of all the world's species are found in tropical forests.
Sunlight is the primary source of energy for all plants. In the tropics, a great deal of solar radiation reaches the earth, giving plants the means to make their own food through [G 22 / photosynthesis]. The abundant vegetation ensures a good food supply for [G 19 / herbivores], which in turn are food for [G 06 / carnivores].
INHABITANTS OF THE TROPICAL RAINFOREST:
The Amazon rainforest is particularly rich in wildlife - half of all the plant and animal species of the world are found in the rainforests. The [L2 302 / diversity of wildlife] makes the rainforests fascinating places to study. With so many different plants and animals, competition for food is intense.
As each species evolved, it had to find a particular place (niche) in the complex rainforest [G 10 / ecosystem] where it could find enough food to survive and find protection from predators. For this reason, many plants and animals have adapted to very specialized lifestyles, growing only in one particular place or depending on one particular food.
The rainforest may look like a huge overgrown garden, but it actually grows in a very organized way. [L2 303 / I002 / Rainforest plants grow in several different layers] depending on their height at maturity. Different animals are found in different strata - each layer providing a [G 16 / habitat] that meets the particular needs of certain animals. Most [P 001 / levels below the canopy are cloaked in darkness] since the huge branches of the large trees block out much of the sunlight.
RAINFOREST PLANTS:
The vast majority of plants found in tropical rainforests are [L2 304 / trees] and climbing plants which have woody stems (lianas).
Tree species can grow from only three to about 160 feet high. Most rainforest trees are evergreen (meaning they do not shed their leaves seasonally). Their leaves are generally a dark green color, leathery and thick. Some of the large trees have [P 024 / buttresses] (triangular growths) which extend out from the trunk. These help to keep the tree stable in the shallow soil.
Lianas shelter much of the rainforest animal life and produce a great deal of their food. In the tropical climate, they grow very rapidly up towards the light - so fast that their trunks are not able to carry the weight of their leaves. Therefore, lianas cling to trees for support, climbing up the tree trunks to the top branches of the tallest trees. Like steel cables, they wind up and around, linking the boughs of their hosts.
Non-woody plants of the jungle include [L2 305 / epiphytes] (plants which grow on other plants), and ferns and grasses which grow on the forest floor.
RAINFOREST ANIMALS:
There is such a huge variety of Amazonian rainforest animals that many have not even been named and classified by zoologists. A wide range of different kinds of animals can be found in just a few acres of rainforest. However, within this small area, it is possible that some animals may never meet since many have [L2 308 / adapted to life at a particular altitude]. The red uakari monkey, for example, may never touch the ground in its entire lifetime by feeding entirely on the fruit, insects and leaves of the trees.
From the [P 017 / jaguar], which is the largest Amazonian animal to the smallest insects, practically every kind of animal can be found in Amazonia. Butterflies range from the large and brightly colored, to the small and well camouflaged. [L2 306 / One fifth of all bird species] come from Amazonia and these are represented in all shapes and sizes from the tiny hummingbirds to the large [P 011 / macaws] and [I 006 / toucans]. [L2 307 / Insects] make up the largest proportion of Amazonian animals.
Pollination is one of the most important processes in any [G 10 / ecosystem] and for a plant to be fertilized, pollen from a plant of the same species must reach its flower's [G 34 / pistil]. Bees and [P 023 / butterflies] are the two most important pollinators. However, some birds and small mammals (like bats) also play a large role in tropical regions.
Flowers often have [I 011 / vivid colors] to appeal to the keen sight and color sense of birds and a stronger construction to accommodate them. Bird-pollinated flowers will also yield more nectar and they may even provide a twig perch near the blossom. In turn, some birds have adapted their beaks and tongues to reach the nectar from deep inside the longest flowers. For example, the sword-billed hummingbird has a bill that is nearly the length of its body.
HOW THE RAINFOREST FUNCTIONS:
The rainforest is like a highly complex garden which has been allowed to grow for millions of years, becoming increasingly rich in new species. Thousands of plants and millions of animals live together in [L2 309 / an association called an ecology] - an [G 09 / ecology] so rich and complex as that of a rainforest seems very stable. Left alone, it is. However, because there is so much interdependency in the food web, once one link is broken, other links will also be broken.
[L2 310 / The rainforest ecology is fragile], and can be seriously damaged if a key element (for example, a particular tree) is removed. Each animal helps a plant to survive and in return, plants provide food for animals. [L2 311 / Pollination and seed dispersal] are two of the most important functions performed by animals in the rainforest.
A rainforest [G 10 / ecosystem] provides everything it needs for its plants to grow, [N 001 / recycling] everything so it can be used again. [L2 312 / This recycling process] is helped by the tropical climate and the large numbers of small insects and microorganisms in the soil which break down dead organic material. Rainforest plants derive most of their nutrients from rainwater and a few from the soil.
