This week is Rainforest Awareness Week. If you love rainforests as much as we here at Critter Squad do, then you are definitely going to want to give this article a read!
What is a Rainforest?
Rainforests are different from other forests by their high level of rainfall and humidity. In a given year, a rainforest may receive an average of 8 to 14 feet of precipitation. Many use the terms “jungle” and “rainforest” synonymously and while many rainforests can indeed described as jungles, they are not exactly the same. A jungle by definition is land covered in particularly dense vegetation, typically trees, and usually confined to the tropics. While tropical rainforests can be found in equatorial regions of South America, Central Africa, Southeast Asia, Hawaii, and Northern Australia, there are also temperate rainforests. Temperate rainforests can be composed of coniferous and/or broadleaf trees and are frequently found along the coasts the Pacific Northwest, the British Isles, the Balkans, East Asia, and New Zealand. Despite the abundance of plant life, rainforest soil is surprisingly poor in nutrients. The high moisture levels promotes rapid bacterial growth which in turn prevents the accumulation of organic matter on the forest floor. As a result, most of the trees have fairly shallow roots and receive their nutrients from decomposing animals and leaves rather than the soil itself.
Layers of the Rainforest
Rainforests can be divided up into several distinct layers, each with its own types of specially-adapted plant and animal life. The uppermost layer is known as the emergent layer. This layer contains the tallest rainforest trees, with some reaching heights of 200 feet or more, and receives the most sunlight. Lifeforms at this height need to be able to withstand hotter temperatures and stronger winds than at lower levels. Commonly found species include pollinators like butterflies and bats as well as birds of prey and primates.
The majority of a rainforest’s trees are not found within the emergent layer, but the canopy. These trees are usually between 100 and 150 feet tall and form a continuous roof of foliage over the rest of the forest. More food is found in this layer than in other parts of the forest, so the bulk of the rainforest’s biodiversity is concentrated here. It is believed that a quarter of the world’s insect species are found in the canopy, as well as numerous species of birds. Many of the plants are epiphytic, meaning they grow on the surface of trees and obtain their nutrients form the surrounding environment rather than putting out a root system.
Below the canopy is the understory. Very little sunlight reaches this layer, and as a result plants have broader leaves adapted to absorb as much light as possible in shade-heavy environments. They also rarely exceed 12 feet in height. The understory is home to many charismatic rainforest animals, such as big cats and large constrictor snakes.
The bottommost layer of the rainforest is the forest floor. Only two percent of the available sunlight reaches this far below the canopy, meaning there is less flora than in other levels. This lack of light coupled with the high humidity means that organic matter decays very quickly and sports large numbers of decomposers, such as fungi, scavenging insects, and microorganisms. Most rainforests have a poor fossil record for this reason. Rainforests generally do not contain many large mammals but those few that call the first home can be found here, including giant anteaters, gorillas, and forest-adapted ungulates.
Why the Rainforest is Important
Rainforests are one of the most important ecosystems on the planet. They may only cover a mere 6% of Earth’s surface, but they contain over two-thirds of all known species. Many of the plant species contain medicinal properties and over a quarter of Western pharmaceuticals contain ingredients found in only in rainforests. Many commonly cultivated food plants originated in rainforests, including yams, coffee, avocados, chocolate, sugarcane, and a great many fruits like bananas and mangos. Rainforests also serve to help regulate the planet’s climate by absorbing atmospheric carbon dioxide. Humans can benefit from the rainforest in many ways. Numerous tribal cultures have called the rainforest home for generations. In addition to serving as a source of raw materials, rainforests are a huge attraction for ecotourists and can help to stimulate local economies. New species are being described on a daily basis, so rainforests can serve as a frontier for scientific discovery.
Threats to the Rainforest
Rainforests throughout the globe are under threat. The vast store of natural resources provides a tempting target for human exploitation. Vast stands of trees are cut down and burned to fuel logging industries and make room for agricultural development. Wildlife is poached to meet the demand for exotic pets, bushmeat, and luxury items. Mining companies dig up the land and promote soil erosion in their quest for precious minerals and fossil fuels. This deprives native animal species of their habitat and threatens many of them with extinction as entire food webs collapse. Potential medical breakthroughs could be destroyed before their healing potential is fully understood. Rainforests have a huge impact on the global climate as as they decrease in area, carbon dioxide levels and temperatures may rise. If we do not act now, the beauty and majesty of the rainforests may be lost forever.
For info on medicinal plants found in the rainforest, check out our Botany Center!
For info on how you can help conserve the rainforest, check out our Endangered Species Center!
For info on unique rainforest mammals, check out our Mammal Center!