Rainforest Features

Tropical rainforests are aptly named. Moisture is constantly evaporating from the tree canopies, resulting in a high level of humidity and thick mists which blanket the trees in the evening and early morning. Much of the annual rainfall is the result of evaporation falling back to the Earth as recycled precipitation. Temperatures range between 68 degrees Fahrenheit (20 Celsius) at night to 93 degrees Fahrenheit (34 Celsius) during the day.

The tropical rainforest ecosystem is almost completely dependent on the existence of the massive trees that inhabit it. The soil on the forest floor acquires nutrients from fallen leaves, carrion, and the droppings of animals. These nutrients are quickly absorbed back into the plantlife, which provide food, water, and dwellings for the diverse animal population. Rainforest trees maximize nutrient and water absorbtion with their shallow roots, which quite often grow above ground. Without these root systems, the topsoil washes away into mudslides due to the high volume of rain.

[Photo of Rainforest Epiphyte]

Tropical rainforest trees also harbor a vast array of plant species. Lianas are woody vine-like plants which originate from roots on the forest floor, but grow up and around the trunks and branches of trees like webs. These climbing plants are extremely varied in shape and sometimes reach incredible lengths; the largest lianas can grow as long as 3,000 feet (914 meters) and achieve the same thickness as the trees surrounding them. Epiphytes, another type of rainforest plant, begin life as foliage and roots on the trees themselves. Over time they spread and wrap themselves around their host, living off of the organic matter and water that collects upon them. Due to a lack of soil-based root system, epiphytes use unique methods of storing water and nutrients. Orchids, a common epiphyte, extract moisture and nutrients from the plants surrounding it and even the air itself; these are stored in their wide stems and waxy leaves. Bromeliads, a second type of epiphyte, have their leaves arranged in a tight rosette which holds water and organic matter like a tank. These reservoirs sometimes hold up to 8 gallons (30 liters) of water and are also utilized by a number of animal species including frogs and snakes. Stranglers, a third type of epiphyte, begin life similarly to other epiphytes, but grow roots down into the forest floor. Stranglers sprout a canopy of their own which competes with the host tree and eventually results in the tree's death, leaving the strangler itself standing as a hollow mass of roots and foliage.

Rainforest Strata

The rainforest environment can be very different depending on where you are within it. This is largely due to the filtration of sunlight as it moves down through the thick canopy and into the darker area below. The various layers of the rainforest ecosystem are known as "strata".

At the ground level, sunlight is very faint due to the thick foliage far above. Because of the low amount of light energy, ground covering is relatively scarce; instead, the soil is moist and covered in animal and vegetable decay. In areas where trees have fallen or near the bank of a river, saplings, vines, and smaller plants are plentiful and lush, making these areas difficult to pass through. Although the tree canopy towers far above the ground, the trunks themselves are much smaller than one might imagine; generally, most are no more than 3 feet around. To stabilize their weight, rainforest trees often develop additional growths such as "stilt" roots near the base of the trunk. The roots underground are shallow to maximize nutrient absorption; ants, termites, spiders, toads, and other smaller creatures flourish in this compost-rich area. Worms, termites, and fungi accelerate the breakdown of organic matter, quickly releasing the nutrients back to the local plantlife. Predators such as the jaguar move stealthily through the trees, hoping to catch passing prey.

Scientists use the terms sub-canopy or understory to refer to the area between the rainforest floor and the leafy foliage many dozens of feet above. In the understory there are few branches; sunlight here is still scarce. Plants which grow here possess large leaves to capture as much light energy as possible. The moisture in the air is thick and rarely falls below 95% humidity. Various species of insects, reptiles, and bats are found in this area of permanent twilight; one may also see the occasional hummingbird. As with the jaguar, the ocelot may find its way into the lower branches of rainforest trees, ready to pounce on the back of an unsuspecting tapir or deer.

[Aerial Photo of Rainforest Canopy]

At the top of the trees is a thick ceiling of patch-worked greenery called the canopy. This busy place contains 90% of all living things found in the rainforest. The lower canopy is about 70 feet (20 meters) above the forest floor and home to many tree-dwelling mammals such as sloths and howler monkeys. Light is dim due to the thickness of branches, vines, foliage, and animals, but this area just below the tops of the trees is a haven from predators on the ground and also in the sky above. In the upper canopy, sunlight and rainfall are plentiful, resulting in lush vegetation and brisk growth rates. This portion of the stratum is 100 feet (30 meters) above the ground, and a dangerous place for tree-dwelling creatures unlucky enough to cross paths with birds of prey. Insects are everywhere in the canopy: Dr. Terry Erwin of the Smithsonian Institution once estimated that rainforests may contain up to 30 million species of insects.

Crowning the sea of treetops is the emergent layer, consisting of the branches and foliage of the largest trees. These massive plants possess trunks more than 7 feet (2 meters) across and are 115 to 230 feet (35 to 35 meters) above ground level. Emergent layer tree-tops are home to many species of birds, including the colorful toucan and macaw.

Biodiversity

Vast numbers of plant and animal species are found in the world's rainforests. One-fifth of the world's birds are found in Amazonia. Panama alone has more species of plants in its forests than the entirety of Europe. A report by the U. S. National Academy of Sciences claimed that a typical four square-mile patch of rainforest contains up to 1,500 species of flowering plants, 750 species of trees, 400 species of birds, and 150 species of butterflies. Sometimes many of these species are endemic to that specific area and exist nowhere else in the world.

The tropical rainforest ecosystem is a unique environment. Many of the plant and animal species found there have developed adaptations specifically suited for the rainforest. Tree-dwelling animals use prehensile tails, claws, and adhesive pads to travel from perch to perch. Orchids use two separate root systems - one for physical support, and one free-hanging root wrapped in a white, absorbant tissue designed for extracting water and nutrients. Rainforest biodiversity has resulted in some plants and animals developing a dependence on another species. The anteater, for example, lacks teeth and feeds solely on the plentiful ants and termites found both on the ground level and in the trees. Brazilnut trees apparently require pollination by euglossine bees, which in turn depend on on the chemicals of a specific orchid for its mating rituals. The ant species Pseudomyrmex ferruginea lives specifically in Acacia cornigera, also known as the ant acacia tree. These ants are completely dependent on the nectar and juices found in the leaves and leaf stalks of this tree species and will consume nothing else. These are but a few examples of the complex web of interdependence between plants and animals in the rainforest environment; this challenging puzzle makes for an exciting topic of study for scientists and researchers around the world.

Indigenous Peoples

Over the past several thousand years, humans have also developed unique methods of living in harmony with the rainforest environment. The native forest people still practice many of the traditions of their ancestors, although this is becoming increasingly difficult in today's world.

It is impossible to know how long humans have lived in the rainforests areas of Central and South America. Some scientists have theorized that humans migrated into the Americas from Asia using a land bridge between modern-day Alaska and Siberia some ten thousand years ago. The oldest remains of human settlements in Latin America date back around 7,000 years. When Europeans first visited the Central and South American regions half a millenia ago, an estimated 6 to 9 million native peoples flourished in Amazonia.

Tribal rainforest peoples have physically adapted to their unique - and sometimes harsh - environment. Their metabolic rate is lower than the average human's. They also tend to be physically shorter, require less water, and sweat less. The overall health of adults is generally good: chronic diseases, obesity, hypertension, and other issues which plague industrialized nations are virtually unheard of. However, rainforest natives do not recover well when ill: their life expectancy is half that of people from the outside world.

The cultures of the indigenous rainforest peoples are varied and highly developed. Some Brazilian natives, for example, live in a single, massive structure called a maloca. Here, a tribal community shares food and resources equally; the building offers protection as well as storage for supplies. Native tribes possess an enormous understanding of their habitat; everything from their food to medicine to even birth control comes from plants in the rainforest.

Amazonian native tribes use materials from the rainforest to assist in everyday life. To more effectively kill animal prey, darts and arrows are tipped with poison derived from toxic tree frogs and lianas. When thirsty, hunters can find water contained within low-hanging yuhi vines; other plants provide fiber for ropes and twine. Many modern medical remedies are a direct result of the native peoples' vast knowledge of the properties of local plant life.

Rather than clearing large areas for agricultural use, some indigenous tribes have modeled their farming methods after the rainforest strata. The Lacandon Maya in southeast Mexico cultivate layers of crops in small two to three acre plots called milpas. Fast-growing papaya and banana trees are planted first to provide shade to maize, sugarcane, and rice. These in turn protect vine and root-based plants such as the sweet potato and yam. Crops are planted in no particular order and are spread throughout the plot to reduce the spread of disease. To the untrained eye, this area may look disorganized and wild, but to the Lacandon farmer, it may contain up to eighty crops and will ultimately yield more food and supplies than the "industrialized" immigrants in their area. After three to seven years, weeds inevitably take over the milpas, and a new one is formed. Meanwhile, the Lacandon plant rubber trees and other useful vegetation in the old plot as it lays fallow.

While the western world owes a great debt to the indigenous rainforest peoples, the history of its interaction with them has not necessarily been a pleasant one. Large and rather advanced civilizations such as the Incans and Mayans were annihilated by European invaders. The discovery of gold in South America prompted the enslavement of local peoples to work as forced labor in mines. In the late 1800's, more land was taken from the rainforest inhabitants as rubber plantations were organized. By 1900, the original native population of the Brazilian Amazon had been reduced to one million; since this time, 87 distinct tribal cultures have been exterminated. Today, less than 200,000 rainforest natives continue to exist. Every year is a struggle as industrial projects, immigration, and forced relocation threaten to destroy these ancient cultures.

However, in today's fast-paced modern world, several native tribes in Central and South America are working to preserve their ways of life. The Kuna people in Panama, for example, acquired rights to their own land and pass laws to protect their local economy and natural environment. The Ayoreo tribe in Columbia produced a film to introduce foreigners to their culture and explain the problems they are facing. Other native groups in Brazil have formed unions to protect their interests; the Xingu tribes even organize demonstrations and protests to force the Brazilian government to recognize their troubles with land rights and other issues.

Rainforest Products

The tropical rainforest has given us many important products that today we take for granted. The most obvious examples are everyday items one may find in the supermarket: bananas, coffee, cocoa, and vanilla. But many other exports have had just as much, if not more, of an impact on the industrialized world.

Modern industry owes an enormous debt to the tropical rainforest ecosystem. Rubber, derived from the rubber tree Hevea brasiliensis, is used in virtually every facet of our society. The silky fibers from the seed pods of the ceiba tree, called kapok, are waterproof and used in waterjackets and insulation. While studying liquid balsam from the copaiba tree in 1979, Dr. Melvin Calvin found that chemical composition of the tree's sap is almost identical to diesel fuel; removing the water from the sap resulted in a powerful oil. Oils and resins from rainforest plants form the base of many cosmetics and solvents used today.

Modern medicine would be quite different without the amazing properties of some rainforest plants. Quinine, an alkaloid found in the bark of cinchona trees discovered in the Andes in South America, is used to treat malaria. Curare, an extract from several species of rainforest lianas, is used by doctors as a muscle relaxant and in several medical drugs. Other rainforest alkaloids have been found to reduce blood pressure and even to treat diseases such as leukemia, Hodgkin's disease, and cancer.

Species of wild plants from rainforests have been used to assist modern agriculture as well. Several Amazonian cocoa plants have proved to be resistant to several diseases; these are now being grown throughout the world, reducing loss and boosting profits for cocoa harvesters. Wild tomatoes and latex trees from Peru have both been introduced to foreign farms and plantations, improving product quality and increased production. Wild peanuts from Amazonia have been cross-bred with domesticated strains, resulting in a plant resistant to leafspot; the International Crops Research Institute estimated this improvement to be worth $500 million dollars a year to the peanut industry.

Deforestation

Unfortunately, the complex ecosystem that has given us these important products is in danger. The mechanized modern world has traded the rainforests' long-term benefits for immediate, short-term profits. Much of this is due to the massive global population and its consumer demands. Tropical rainforests are disappearing at a rate of approximately 24,000 to 30,000 square miles (62,000 to 80,000 square kilometers) a year: approximately the size of the state of West Virginia. Almost half of the world's virgin rainforests have been depleted or destroyed, leaving only 3.5 million square miles. Most of this damage has been done over the past half century.

The main reason why rainforests are being cut down is timber. The massive trees contain valuable wood for both fine art and manufacturing. While only 20 percent of the world's industrial wood products come from rainforests, more than half of that benefits the richest countries around the globe, such as the United States, Great Britain, and Japan. The incentive for logging companies is great: in 2005, a square meter of Peruvian Mahogany sold for between $1580 to $1620 in the United States [Source].

Many acres of trees are also removed for agriculture. Ironically, the soil is acidic and generally low in nutrients; after three to four years, a farm can no longer produce adequate crops, and thus more trees are felled to expand. In addition, without the natural mix of various plant species, large plots of the same crop are quite often subject to plant-bourne diseases or insect infestation. Once the original land is allowed to lay fallow for many years, some trees and plants do return, but nothing like the ecosystem that once existed there.

Sadly, enormous portions of Central and South America's rainforest have been clear-cut for cattle ranching. By 1984, one-third of Costa Rica had been converted to pastures. One report claimed that one-fourth of all forests in Central America had been cleared for the purposes of beef production. 200,000,000 pounds (more than 90,000,000 kilograms) of beef are imported from the Central and South American rainforest areas every year. This is big business for ranchers in Central and South America, but those who benefit from this business are in the minority. In Guatemala, for example, 2.2% of the population owns 70% of the land. And since the wealthy land owners generally will acquire the best land, the poorest in the country are forced to use the poorest land to raise crops for food. Meanwhile, cash crops such as bananas, coffee, and beef are exported to other countries.

Modern industry takes a toll on the rainforest ecosystem as well. Construction projects such as dams, roads, and power stations results in the elimination of thousands of acres of rainforest. Mining and oil drilling result in more destruction. Construction projects sometimes remove entire portions of land reserved for native rainforest peoples, or force them to relocate completely.

The cost of modern industry is high. Pesticides from modern farms, animal wastes from cattle, and petroleum spills routinely pollute both the land and water. Flooded reservoirs for hydroelectric dams deteriorate the surrounding forest areas, resulting in toxic gases and acidic water conditions. Rainforests also act as natural "buffer zones" for the tropical rainy season; without them, these storms are much more severe. Wet season precipitation quickly finds its way to waterways, flooding rivers and reducing water quality, fish population, and the forests surrounding the river. Mudslides cause damage and death: in Guatemala alone, more than half a thousand people fell victim to mudslides during the 2005 hurricane season [Source]. Insects descend to the ground and breed unchecked in flooded areas, bringing more death and disease.

One often reads that the deforestation of tropical rainforest areas may result in global carbon dioxide increases due to the reduction of oxygen-releasing plantlife. Journalist and author Catherine Caufield, however, suggests that this may not be entirely accurate: rainforests are so efficient at nutrient and mineral recycling that much of the plants' oxygen output is invested in the swift decomposition of organic matter. But the popular "slash and burn" forest clearing technique both destroys necessary organisms in the soil and adds to the global carbon gas output. Increased carbon gases in the air behave similarly to closed car windows during a sunny winter day: over time, the trapped air inside heats and becomes much warmer than the outside. In the past century alone, the amount of carbon dioxide in the Earth's atmosphere increased 15%. Some scientists have predicted that if the present trend continues, carbon dioxide levels could double in another half century, resulting in major temperature changes around the globe. These changes could affect sea levels, ocean currents, and much more.

Alternatives to Products Relating to Deforestation

Given the benefits of the tropical rainforest, its continued existence seems to be more beneficial than destroying it for short-term gain. To deal with the popular "slash and burn" farming method, some researchers have been experimenting with shifting cultivation. Similar to that of the Lacandon Maya peoples, this practice involves the rotation of plots of land, rather than the rotation of crops. Due to the relatively poor Amazonian rainforest soil and the availability of land, this method seems the most feasible: a variety of crops are grown for several years, and then the land is allowed to return to its natural state before it is once again used for agricultural purposes. Farmers who use "modern" methods to grow crops find that increasing the use of fertilizers year after year becomes a losing battle; since many who work the land are poor, these fertilizers are often uneconomical. Instead of true shifting cultiation, immigrants to rainforest areas use destructive methods of clearing the forest for agriculture, which results in about half of the deforestation that occurs today. Responsible and sustainable agriculture may lessen this blow.

Cattle ranching exacts a terrible toll on deforested land. Ranchers repeatedly torch the soil to keep poisonous weeds at bay; the damage done by this process is permanent. 2.5 acres (1 hectare) of Latin American ranchland produces 150 pounds (68 kg) of meat. A Lacandon milpas, using the same amount of land, can produce more than ten metric tons of grains and vegetables per year. Given the disparity of wealth between the poor farmers and the wealthy cattle ranchers, the latter seems to be a more sensible solution.

It is doubtful that the industrial nations' demand for timber will decrease. However, it is possible to change the way trees are extracted from rainforests. Instead of clear-cutting entire areas for wood, a combination of selective logging and the use of human and animal labor could not only reduce the damage done to forests, but also offer four times as many jobs to the local population. Once the necessary wood has been extracted, fast-growing tree species such as Albizia falcata and Eucalyptus deglupta can be planted to replentish what was taken. After twenty to thirty years, these species can then be used for everything from pressboard to veneer.

We can also reduce the demand for rainforest timber by turning to more sustainable alternatives. As an example, the hardy hemp plant Cannabis sativa can be grown virtually anywhere - up to three crops a year - and can replace timber both as a better paper and pressboard wood product. This versatile plant's oil and fibers can also be used as a base for textiles, plastics, paint, health products, and fuel.

You Can Help!

One of your greatest assets is knowledge. Be aware that the manufacturing of many products commonly found in the supermarket results in damage to the rainforest habitat. Make the decision to support products that benefit the rainforest and those who live in it. "Fair trade" goods, for example, are products derived from manufacturers who maintain respectful and humane workplace conditions, as well as environmentally-sustainable industry practices. Avoid the purchase of products made from valuable rainforest woods such as mahogany and teak: this only puts money in the hands of those who would eliminate rainforest areas for monetary gain. Purchase grain-fed beef from local farmers - know where your food comes from and who it benefits.

The indigenous peoples of the world's tropical rainforests know how to peacefully co-exist with their environment. You can also put these values into good use no matter where you live. Instead of throwing away garbage into the trash, see if that garbage is re-useable (water bottles, plastic containers) and can replace other disposable items (sandwich baggies, juice boxes). Ask about recycling programs in your community. Research composting, and return the nutrients of organic wastes back to the Earth where it belongs. Make a conscious effort to purchase bulk items rather than products with a large degree of packaging (such as individually-wrapped lunch snacks).

Remember that knowledge empowers. Educate co-workers and classmates; let them know what you have learned and how they, too, can make a difference. Organizations such as CrunchTime have developed school fundraisers which benefit the environment; talk to your teachers to see if these fundraisers can be used to raise money for your school. Does your class or workplace recycle paper? It may be as simple as separating paper from other trash and placing it into the cardboard dumpster outside. Set an example for others and dare to care!