On my first visit to the rainforest I was amazed by the lushness of the vegetation, the giant trees, and the hanging vines. There were so many more types of plants than in the forests near my home in California. I had never seen so many shades of green.
Since then I have made many more trips to the rainforest—more than I can count. I have also traveled to a lot of non-rainforest places: deserts in Africa, coral reefs in the South Pacific, boreal forests in Alaska, and many others. While each of these places has its own unique plants and animals, there is one constant: the unpredictability of nature. When you spend a day out in the forest or on the ocean you never know exactly what you are going to see. Maybe you’ll find an unusual insect under a leaf, see a whale breach, or hear a new bird song. Whatever it is, nature always holds the promise of something new and unexpected.
I’ve had many surprises in my travels to the rainforest. One of the scariest took place in the rainforests of Gabon, a small coastal country in Central Africa. Gabon is famous for its wildlife, including lowland gorillas. On a hike in the forest with some rangers and a photographer we unexpectedly encountered a group of gorillas, which was led by a giant male silverback. As soon as we saw them we stopped, but it was too late—the silverback had already decided to let us know who ruled the forest. He charged, beating his chest and grunting while galloping full speed at me. The ground shook with his weight—a full grown silverback can easily weigh 350 pounds, most of which is muscle. On my knees—the recommended position if a gorilla charges—all I could do was to try to avoid conflict by averting my eyes from him and staring at the ground where the leaves bounced with his every stride. My heart raced as he barreled closer and closer. Then suddenly he stopped. His tense body relaxed, his breathing slowed, and he turned away, seeming to lose interest. The forest was again still and we crept slowly away. What had started out as a hike through the forest, turned into one of the most exhilarating moments of my life.
What is a rainforest?
Tropical rainforests are forests with tall trees, warm climates, and lots of rain. In some rainforests it rains more than one inch nearly every day of the year!
Where are rainforests located?
Rainforests are found in Africa, Asia, Australia, and Central and South America. The largest rainforest in the world is the Amazon rainforest in South America.
Rainforests are found in the tropics, the region between the Tropic of Cancer and the Tropic of Capricorn, just above and below the Equator. In this tropic zone the sun is very strong and shines about the same amount of time every day all year long, keeping the climate warm and relatively stable.
Many countries have tropical forests. The countries with the largest areas of tropical forest are (in order):
• Brazil
• Democratic Republic of Congo
• Indonesia
• Peru
• Colombia
Other countries that have large areas of rainforest include Bolivia, Cameroon, Central African Republic, Ecuador, Gabon, Guyana, India, Laos, Malaysia, Mexico, Myanmar, Papua New Guinea, Republic of Congo, Suriname, and Venezuela.
In addition to tropical rainforests, there are few areas in the world with temperate rainforest. These densely forested regions are usually near a coastline and though they are not tropical, they are considered “rainforests” because of the large amount of annual rainfall they receive. The largest temperate rainforest in the world occurs long the coast of northern California to Alaska. However, the rest of this book will focus on tropical rainforests.
What makes a rainforest?
Each rainforest is unique, but there are certain features common to all tropical rainforests.
• Location: rainforests lie in the tropics.
• Rainfall: rainforests receive at least 80 inches (200 cm) of rain per year.
• Canopy: rainforests have a canopy, which is the layer of branches and leaves formed by closely spaced rainforest trees. Most of the plants and animals in the rainforest live in the canopy. The canopy may be 100 feet (30 m) above the ground.
• Biodiversity: rainforests have a high level of biological diversity or “biodiversity”. Biodiversity is the name for all living things—like plants, animals, and fungi—found in an ecosystem. Scientists believe that about half of the plants and animals found on Earth’s land surface live in rainforests.
• Symbiotic relationships between species: species in the rainforest often work together. In a symbiotic relationship, two different species benefit by helping each other—you can think of it as a partnership. For example, some plants produce small housing structures and sugar for ants. In return the ants protect the plants from other insects that want to feed on the plant’s leaves.
What is the canopy?
In the rainforest most plant and animal life is not found on the forest floor, but in the leafy world known as the canopy. The canopy, which may be over 100 feet (30 m) above the ground, is made up of the overlapping branches and leaves of rainforest trees. Scientists estimate that 60-90 percent of life in the rainforest is found in the trees, making this the richest habitat for plant and animal life. Many well-known animals such as monkeys, frogs, lizards, birds, snakes, sloths, and small cats are found in the canopy.
The conditions of the canopy are very different from the conditions of the forest floor. During the day, the canopy is drier and hotter than other parts of the forest, and the plants and animals that live there are specially adapted for life in the trees. For example, because the amount of leaves in the canopy can make it difficult to see more than a few feet, many canopy animals rely on loud calls or lyrical songs for communication. Gaps between trees mean that some canopy animals fly, glide, or jump to move about in the treetops.
Scientists have long been interested in studying the canopy, but the height of trees made research difficult until recently. Today there are special facilities with rope bridges, ladders, and towers to help scientists discover the secrets of the canopy.
The canopy is just one of several vertical layers in the rainforest. Take a look at the diagram on the left to see the other layers (the overstory, understory, shrub layer, and forest floor).
The rainforest floor
The rainforest floor is often dark and humid due to constant shade from the canopy’s leaves. Despite its shade, the rainforest floor is an important part of the forest ecosystem.
The forest floor is where decomposition takes place. Decomposition is the process by which fungi and microorganisms break down dead plants and animals and recycle essential materials and nutrients.
Also, many of the largest rainforest animals are found on the forest floor. Some of these are elephants (in Asia), the tapir (Southeast Asia and Central and South America), tigers (Asia), and the jaguar (Central and South America).
Rainforest rivers
Due to the tremendous amount of rainfall they receive, tropical rainforests have some of the largest rivers in the world, like the Amazon, Mekong, Orinoco, and Congo. These mega-rivers are fed by countless smaller tributaries, streams, and creeks. For example, the Amazon alone has some 1,100 tributaries, 17 of which are over 1,000 miles (1,600 kilometers) long!