Species-Rich, Soil-PoorThe soil of most tropical rain forests contains few nutrients. The rich biodiversity in the canopy and quick decomposition from fungi and bacteria prevent the accumulation of nutrient-rich humus. Nutrients are confined to the rain forest’s thin layer of topsoil. For this reason, most of the towering trees in tropical rain forests have very shallow, widespread root systems called “buttress roots.”Slow RainRain forests are so densely packed with vegetation that a drop of rain falling from the forest’s emergent layer can take 10 minutes to reach the forest floor.Jungles and Rain ForestsJungles and rain forests are very, very similar. The main difference is that rain forests have thick canopies and taller trees. Jungles have more light and denser vegetation in the understory.Drip TipsMany plants in the humid rain forest canopy are pointed, so that rain can run off the tips of the leaves. These “drip tips” keep the leaves dry and free of mold.Rain forests are Earth’s oldest living ecosystems, with some surviving in their present form for at least 70 million years. They are incredibly diverse and complex, home to more than half of the world’s plant and animal species—even though they cover just 6% of Earth’s surface. This makes rain forests astoundingly dense with flora and fauna; a 10-square-kilometer (4-square-mile) patch can contain as many as 1,500 flowering plants, 750 species of trees, 400 species of birds and 150 species of butterflies.Rain forests thrive on every continent except Antarctica. The largest rain forests on Earth surround the Amazon River in South America and the Congo River in Africa. The tropical islands of Southeast Asia and parts of Australia support dense rain forest habitats. Even the cool evergreen forests of North America’s Pacific Northwest and Northern Europe are a type of rain forest.Rain forests’ rich biodiversity is incredibly important to our well-being and the well-being of our planet. Rain forests help regulate our climate and provide us with everyday products.Unsustainable industrial and agricultural development, however, has severely degraded the health of the world’s rain forests. Citizens, governments, intergovernmental organizations, and conservation groups are working together to protect these invaluable but fragile ecosystems.Rain Forest StructureMost rain forests are structured in four layers: emergent, canopy, understory, and forest floor. Each layer has unique characteristics based on differing levels of water, sunlight, and air circulation. While each layer is distinct, they exist in an interdependent system: processes and species in one layer influence those in another.Emergent LayerThe top layer of the rain forest is the emergent layer. Here, trees as tall as 60 meters (200 feet) dominate the skyline. Foliage is often sparse on tree trunks, but spreads wide as the trees reach the sunny upper layer, where they photosynthesize the sun’s rays. Small, waxy leaves help trees in the emergent layer retain water during long droughts or dry seasons. Lightweight seeds are carried away from the parent plant by strong winds.In the Amazon rain forest, the towering trees of the emergent layer include the Brazil nut tree and the kapok tree. The Brazil nut tree, a vulnerable species, can live up to 1,000 years in undisturbed rain forest habitats. Unlike many rain forest species, both the Brazil nut tree and the kapok tree are deciduous—they shed their leaves during the dry season.Animals often maneuver through the emergent layer’s unstable topmost branches by flying or gliding. Animals that can’t fly or glide are usually quite small—they need to be light enough to be supported by a tree’s slender uppermost layers.The animals living in the emergent layer of the Amazon rain forest include birds, bats, gliders, and butterflies. Large raptors, such as white-tailed hawks and harpy eagles, are its top predators.In rain forests on the island of New Guinea, pygmy gliders populate the emergent layer. Pygmy gliders are small rodents that get their name from the way flaps of skin between their legs allow them to glide from branch to branch.Bats are the most diverse mammal species in most tropical rain forests, and they regularly fly throughout the emergent, canopy, and understory layers. One of the world’s largest species of bat, the Madagascan flying fox (found on the African island of Madagascar), for instance, is an important pollinator that mainly feeds on juice from fruit, but will chew flowers for their nectar.Canopy LayerBeneath the emergent layer is the canopy, a deep layer of vegetation roughly 6 meters (20 feet) thick. The canopy’s dense network of leaves and branches forms a roof over the two remaining layers.The canopy blocks winds, rainfall, and sunlight, creating a humid, still, and dark environment below. Trees have adapted to this damp environment by producing glossy leaves with pointed tips that repel water.While trees in the emergent layer rely on wind to scatter their seeds, many canopy plants, lacking wind, encase their seeds in fruit. Sweet fruit entices animals, which eat the fruit and deposit seeds on the forest floor as droppings. Fig trees, common throughout most of the world’s tropical rain forests, may be the most familiar fruit tree in the canopy.With so much food available, more animals live in the canopy than any other layer in the rain forest. The dense vegetation dulls sound, so many—but not all—canopy dwellers are notable for their shrill or frequent vocalizing. In the Amazon rain forest, canopy fruit is snatched up in the large beaks of screeching scarlet macaws and keel-billed toucans, and picked by barking spider and howler monkeys. The silent two-toed sloth chews on the leaves, shoots, and fruit in the canopy.Thousands and thousands of insect species can also be found in the canopy, from bees to beetles, borers to butterflies. Many of these insects are the principal diet of the canopy’s reptiles, including the "flying" draco lizards of Southeast Asia.Understory LayerLocated several meters below the canopy, the understory is an even darker, stiller, and more humid environment. Plants here, such as palms and philodendrons, are much shorter and have larger leaves than plants that dominate the canopy. Understory plants’ large leaves catch the minimal sunlight reaching beyond the dense canopy.Understory plants often produce flowers that are large and easy to see, such as Heliconia, native to the Americas and the South Pacific. Others have a strong smell, such as orchids. These features attract pollinators even in the understory’s low-light conditions.The fruit and seeds of many understory shrubs in temperate rain forests are edible. The temperate rain forests of North America, for example, bloom with berries.Animals call the understory home for a variety of reasons. Many take advantage of the dimly lit environment for camouflage. The spots on a jaguar (found in the rain forests of Central and South America) may be mistaken for leaves or flecks of sunlight, for instance. The green mamba, one of the deadliest snakes in the world, blends in with foliage as it slithers up branches in the Congo rain forest. Many bats, birds, and insects prefer the open airspace the understory offers. Amphibians, such as dazzlingly colored tree frogs, thrive in the humidity because it keeps their skin moist.Central Africa’s tropical rain forest canopies and understories are home to some of the most endangered and familiar rain forest animals—such as forest elephants, pythons, antelopes, and gorillas. Gorillas, a critically endangered species of primate, are crucial for seed dispersal. Gorillas are herbivores that move throughout the dark, dense rain forest as well as more sun-dappled swamps and jungles. Their droppings disperse seeds in these sunny areas where new trees and shrubs can take root. In this way, gorillas are keystone species in many African rain forest ecosystems.Forest Floor LayerThe forest floor is the darkest of all rain forest layers, making it extremely difficult for plants to grow. Leaves that fall to the forest floor decay quickly.Decomposers, such as termites, slugs, scorpions, worms, and fungi, thrive on the forest floor. Organic matter falls from trees and plants, and these organisms break down the decaying material into nutrients. The shallow roots of rain forest trees absorb these nutrients, and dozens of predators consume the decomposers!Animals such as wild pigs, armadillos, and anteaters forage in the decomposing brush for these tasty insects, roots and tubers of the South American rain forest. Even larger predators, including leopards, skulk in the darkness to surprise their prey. Smaller rodents, such as rats and lowland pacas (a type of striped rodent indigenous to Central and South America), hide from predators beneath the shallow roots of trees that dominate the canopy and emergent layer.Rivers that run through some tropical rain forests create unusual freshwater habitats on the forest floor. The Amazon River, for instance, is home to the boto, or pink river dolphin, one of the few freshwater dolphin species in the world. The Amazon is also home to black caimans, large reptiles related to alligators, while the Congo River is home to the caimans’ crocodilian cousin, the Nile crocodile.Types of Rain ForestsTropical Rain ForestsTropical rain forests are mainly located between the latitudes of 23.5°N (the Tropic of Cancer) and 23.5°S (the Tropic of Capricorn)—the tropics. Tropical rain forests are found in Central and South America, western and central Africa, western India, Southeast Asia, the island of New Guinea, and Australia.Sunlight strikes the tropics almost straight on, producing intense solar energy that keeps temperatures high, between 21° and 30°C (70° and 85°F). High temperatures keep the air warm and wet, with an average humidity of between 77% and 88%. Such humid air produces extreme and frequent rainfall, ranging between 200-1000 centimeters (80-400 inches) per year. Tropical rain forests are so warm and moist that they produce as much as 75% of their own rain through evaporation and transpiration.Such ample sunlight and moisture are the essential building blocks for tropical rain forests’ diverse flora and fauna. Roughly half of the world’s species can be found here, with an estimated 40 to 100 or more different species of trees present in each hectare.Tropical rain forests are the most biologically diverse terrestrial ecosystems in the world. The Amazon rain forest is the world’s largest tropical rain forest. It is home to around 40,000 plant species, nearly 1,300 bird species, 3,000 types of fish, 427 species of mammals, and 2.5 million different insects. Red-bellied piranhas and pink river dolphins swim its waters. Jewel-toned parrots squawk and fly through its trees. Poison dart frogs warn off predators with their bright colors. Capuchin and spider monkeys swing and scamper through the branches of the rain forest’s estimated 400 billion trees. Millions of mushrooms and other fungi decompose dead and dying plant material, recycling nutrients to the soil and organisms in the understory. The Amazon rain forest is truly an ecological kaleidoscope, full of colorful sights and sounds.Temperate Rain ForestsTemperate rain forests are located in the mid-latitudes, where temperatures are much more mild than the tropics. Temperate rain forests are found mostly in coastal, mountainous areas. These geographic conditions help create areas of high rainfall. Temperate rain forests can be found on the coasts of the Pacific Northwest in North America, Chile, the United Kingdom, Norway, Japan, New Zealand, and southern Australia.As their name implies, temperate rain forests are much cooler than their tropical cousins, averaging between 10° and 21°C (50° and 70°F). They are also much less sunny and rainy, receiving anywhere between 150-500 centimeters (60-200 inches) of rain per year. Rainfall in these forests is produced by warm, moist air coming in from the coast and being trapped by nearby mountains.Temperate rain forests are not as biologically diverse as tropical rain forests. They are, however, home to an incredible amount of biological productivity, storing up to 500-2000 metric tons of leaves, wood, and other organic matter per hectare (202-809 metric tons per acre). Cooler temperatures and a more stable climate slow down decomposition, allowing more material to accumulate. The old-growth forests of the Pacific Northwest, for example, produce three times the biomass (living or once-living material) of tropical rain forests.This productivity allows many plant species to grow for incredibly long periods of time. Temperate rain forest trees such as the coast redwood in the U.S. state of California and the alerce in Chile are among the oldest and largest tree species in the world.The animals of the temperate rain forest are mostly made up of large mammals and small birds, insects, and reptiles. These species vary widely between rain forests in different world regions. Bobcats, mountain lions, and black bears are major predators in the rain forests of the Pacific Northwest. In Australia, ground dwellers such as wallabies, bandicoots, and potoroos (small marsupials that are among Australia’s most endangered animals) feast on the foods provided by the forest floor. Chile’s rain forests are home to a number of unique birds such as the Magellanic woodpecker and the Juan Fernández firecrown, a hummingbird species that has a crown of color-changing feathers.People and the Rain ForestRain forests have been home to thriving, complex communities for thousands of years. For instance, unique rain forest ecosystems have influenced the diet of cultures from Africa to the Pacific Northwest.MbutiThe Mbuti, a community indigenous to the Ituri rain forest in Central Africa, have traditionally been hunter-gatherers. Their diet consists of plants and animals from every layer of the rain forest.From the forest floor, the Mbuti hunt fish and crabs from the Ituri River (a tributary of the Congo), as well as gather berries from low-lying shrubs. The giant forest hog, a species of wild boar, is also frequently targeted by Mbuti hunters, although this species is hunted for sale more often than food. From the understory, the Mbuti may gather honey from bee hives, or hunt monkeys. From the canopy and emergent layers, Mbuti hunters may set nets or traps for birds.Although they are a historically nomadic society, agriculture has become a way of life for many Mbuti communities today as they trade and barter with neighboring agricultural groups such as the Bantu for crops such as manioc, nuts, rice, and plantains.ChimbuThe Chimbu people live in the highland rain forest on the island of New Guinea. The Chimbu practice subsistence agriculture through shifting cultivation. This means they have gardens on arable land that has been cleared of vegetation. A portion of the plot may be left fallow for months or years. The plots are never abandoned and are passed on within the family.Crops harvested in Chimbu garden plots include sweet potatoes, bananas, and beans. The Chimbu also maintain livestock, particularly pigs. In addition to their own diet, pigs are valuable economic commodities for trade and sale.TlingitThe temperate rain forest of the northwest coast of North America is the home of the Tlingit. The Tlingit enjoy a diverse diet, relying on both marine and freshwater species, as well as game from inland forests.Due to bountiful Pacific inlets, rivers, and streams, the traditional Tlingit diet consists of a wide variety of aquatic life: crab, shrimp, clams, oysters, seals, and fish such as herring, halibut, and, crucially, salmon. Kelps and other seaweeds can be harvested and eaten in soups or dried. One familiar Tlingit saying is “When the tide is out, our table is set.”In more inland areas, historic Tlingit hunters may have targeted deer, elk, rabbit, and mountain goats. Plants gathered or harvested include berries, nuts, and wild celery.YanomamiThe Yanomami are a people and culture native to the northern Amazon rain forest, spanning the border between Venezuela and Brazil. Like the Chimbu, the Yanomami practice both hunting and shifting-cultivation agriculture.Game hunted by the Yanomami include deer, tapirs (an animal similar to a pig), monkeys, birds, and armadillos. The Yanomami have hunting dogs to help them search the understory and forest floor for game.The Yanomami practice slash-and-burn agriculture to clear the land of vegetation prior to farming. Crops grown include cassava, banana, and corn. In addition to food crops, the Yanomami also cultivate cotton, which is used for hammocks, nets, and clothing.Benefits of Rain ForestsEcological Well-BeingRain forests are critically important to the well-being of our planet. Tropical rain forests encompass approximately 1.2 billion hectares (3 billion acres) of vegetation and are sometimes described as the Earth’s thermostat.Rain forests produce about 20% of our oxygen and store a huge amount of carbon dioxide, drastically reducing the impact of greenhouse gas emissions. Massive amounts of solar radiation are absorbed, helping regulate temperatures around the globe. Taken together, these processes help to stabilize Earth’s climate.Rain forests also help maintain the world’s water cycle. More than 50% of precipitation striking a rain forest is returned to the atmosphere by evapotranspiration, helping regulate healthy rainfall around the planet. Rain forests also store a considerable percentage of the world’s freshwater, with the Amazon Basin alone storing one-fifth.Human Well-BeingRain forests provide us with many products that we use every day. Tropical woods such as teak, balsa, rosewood, and mahogany are used in flooring, doors, windows, boatbuilding, and cabinetry. Fibers such as raffia, bamboo, kapok, and rattan are used to make furniture, baskets, insulation, and cord. Cinnamon, vanilla, nutmeg, and ginger are just a few spices of the rain forest. The ecosystem supports fruits including bananas, papayas, mangos, cocoa and coffee beans.Rain forests also provide us with many medicinal products. According to the U.S. National Cancer Institute, 70% of plants useful in the treatment of cancer are found only in rain forests. Rain forest plants are also used in the creation of muscle relaxants, steroids, and insecticides. They are used to treat asthma, arthritis, malaria, heart disease, and pneumonia. The importance of rain forest species in public health is even more incredible considering that less than one percent of rain forest species have been analyzed for their medicinal value.Even rain forest fungi can contribute to humanity’s well-being. A mushroom discovered in the tropical rain forest of Ecuador, for example, is capable of consuming polyurethane—a hard, durable type of plastic used in everything from garden hoses to carpets to shoes. The fungi can even consume the plastic in an oxygen-free environment, leading many environmentalists and businesses to invest in research to investigate if the fungi can help reduce waste in urban landfills.Threats to Rain ForestsRain forests are disappearing at an alarmingly fast pace, largely due to human development over the past few centuries. Once covering 14% of land on Earth, rain forests now make up only 6%. Since 1947, the total area of tropical rain forests has probably been reduced by more than half, to about 6.2 to 7.8 million square kilometers (3 million square miles).Many biologists expect rain forests will lose 5-10% of their species each decade. Rampant deforestation could cause many important rain forest habitats to disappear completely within the next hundred years.Such rapid habitat loss is due to the fact that 40 hectares (100 acres) of rain forest are cleared every minute for agricultural and industrial development. In the Pacific Northwest’s rain forests, logging companies cut down trees for timber while paper industries use the wood for pulp. In the Amazon rain forest, large-scale agricultural industries, such as cattle ranching, clear huge tracts of forests for arable land. In the Congo rain forest, roads and other infrastructure development have reduced habitat and cut off migration corridors for many rain forest species. Throughout both the Amazon and Congo, mining and logging operations clear-cut to build roads and dig mines. Some rain forests are threatened by massive hydroelectric power projects, where dams flood acres of land. Development is encroaching on rain forest habitats from all sides.Economic inequalities fuel this rapid deforestation. Many rain forests are located in developing countries with economies based on natural resources. Wealthy nations drive demand for products, and economic development increases energy use. These demands encourage local governments to develop rain forest acreage at a fraction of its value. Impoverished people who live on or near these lands are also motivated to improve their lives by converting forests into subsistence farmland.Rain Forest ConservationMany individuals, communities, governments, intergovernmental organizations, and conservation groups are taking innovative approaches to protect threatened rain forest habitats.Many countries are supporting businesses and initiatives that promote the sustainable use of their rain forests. Costa Rica is a global pioneer in this field, investing in ecotourism projects that financially contribute to local economies and the forests they depend on. The country also signed an agreement with an American pharmaceutical company, Merck, which sets aside a portion of the proceeds from rain forest-derived pharmaceutical compounds to fund conservation projects.Intergovernmental groups address rain forest conservation at a global scale. The United Nations’ REDD (Reducing Emissions from Deforestation and forest Degradation) Program, for example, offers financial incentives for reducing carbon emissions created by deforestation to 58 member countries. The Democratic Republic of the Congo used REDD funds to create an online National Forest Monitoring System that tracks and maps data on logging concessions, deforestation in protected areas, and national forestry sector measures. REDD funds were also used to investigate best practices in solving land disputes in Cambodia, which lacks proper forest zoning and boundary enforcement.Nonprofit organizations are tackling rain forest conservation through a variety of different approaches. The Rainforest Trust, for example, supports local conservation groups around the world in purchasing and managing critically important habitats. In Ecuador, the Rainforest Trust worked with the Fundación Jocotoco to acquire 495 more hectares (1,222 more acres) for the Río Canandé Reserve, considered to have one of the highest concentrations of endemic and threatened species in the world. Partnering with Burung Indonesia, the Trust created a 8,900-hectare (22,000-acre) reserve on Sangihe Island to protect the highest concentration of threatened bird species in Asia.The Rainforest Alliance is a nonprofit organization that helps businesses and consumers know that their products conserve rather than degrade rain forests. Products that bear the Rainforest Alliance seal contain ingredients from farms or forests that follow strict guidelines designed to support the sustainable development of rain forests and local communities. The Alliance also allows tourism businesses use of their seal after they complete an education program on efficiency and sustainability. In turn, this seal allows tourists to make ecologically smart vacation plans.
Term Part of Speech Definition Encyclopedic Entry abandoned Adjective
to soak up.
to gather or collect.
to adjust to new surroundings or a new situation.
agricultural development Noun
modern farming methods that include mechanical, chemical, engineering and technological methods. Also called industrial agriculture.
the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).
Encyclopedic Entry: agriculture air circulation Noun
natural or artificial movement of air in a closed environment. Also called ventilation.
plenty or more than enough.
to study in detail.
having to do with water.
land used for, or capable of, producing crops or raising livestock.
inflammation of a joint often resulting in pain and stiffness.
to evaluate or determine the amount of.
disease that makes it difficult to breathe.
to shock and amaze.
layers of gases surrounding a planet or other celestial body.
Encyclopedic Entry: atmosphere aversion Noun
strong dislike or repulsion.
a dip or depression in the surface of the land or ocean floor.
Encyclopedic Entry: basin beak Noun
hard, protruding jaws of a bird.
all the different kinds of living organisms within a given area.
Encyclopedic Entry: biodiversity biologist Noun
scientist who studies living organisms.
living organisms, and the energy contained within them.
natural or artificial line separating two pieces of land.
Encyclopedic Entry: border boundary Noun
line separating geographical areas.
Encyclopedic Entry: boundary bountiful Adjective
dense growth of bushes, shrubs, and small trees.
sale of goods and services, or a place where such sales take place.
tactic that organisms use to disguise their appearance, usually to blend in with their surroundings.
Encyclopedic Entry: camouflage cancer Noun
growth of abnormal cells in the body.
one of the top layers of a forest, formed by the thick leaves of very tall trees.
carbon emission Noun
carbon compound (such as carbon dioxide) released into the atmosphere, often through human activity such as the burning of fossil fuels such as coal or gas.
cows and oxen.
member of a country, state, or town who shares responsibilities for the area and benefits from being a member.
all weather conditions for a given location over a period of time.
Encyclopedic Entry: climate coast Noun
edge of land along the sea or other large body of water.
Encyclopedic Entry: coast complex Adjective
measure of the amount of a substance or grouping in a specific place.
concession Noun space or privilege secured within a larger space for a specific business or service. conservation Noun
management of a natural resource to prevent exploitation, destruction, or neglect.
Encyclopedic Entry: conservation consume Verb
to use up.
person who uses a good or service.
one of the seven main land masses on Earth.
Encyclopedic Entry: continent convert Verb
to change from one thing to another.
critically endangered Noun
level of conservation between "endangered" and "extinct in the wild."
crocodilian adjective, noun
order of reptiles that includes crocodiles, alligators, caimans, and gharials.
Encyclopedic Entry: crop crucial Adjective
learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.
structure built across a river or other waterway to control the flow of water.
to rot or decompose.
type of plant that sheds its leaves once a year.
organism that breaks down dead organic material.
destruction or removal of forests and their undergrowth.
to lower the quality of something.
having parts or molecules that are packed closely together.
construction or preparation of land for housing, industry, or agriculture.
foods eaten by a specific group of people or other organisms.
Encyclopedic Entry: diet dispersal Noun
spread of something to a new area.
debate or argument.
unique or identifiable.
varied or having many different types.
to overpower or control.
droppings Plural Noun
dung of certain animals, usually in pellet form.
period of greatly reduced precipitation.
Encyclopedic Entry: drought dry season Noun
time of year with little precipitation.
strong and long-lasting.
having to do with money.
community and interactions of living and nonliving things in an area.
Encyclopedic Entry: ecosystem ecotourism Noun
act and industry of traveling for pleasure with concern for minimal environmental impact.
able to be eaten and digested.
ability to accomplish a task.
emergent layer Noun
uppermost layer of a forest, where sunlight is plentiful and trees tower on thin trunks.
to enclose or completely confine.
to inspire or support a person or idea.
to trespass or enter upon the property or rights of another.
to put at risk.
native to a specific geographic space.
to compel or force a course of action.
to lure, or lead on with hope and desire.
conditions that surround and influence an organism or community.
process by which liquid water becomes water vapor.
Encyclopedic Entry: evaporation evapotranspiration Noun
loss of water from the Earth's soil by evaporation into the atmosphere and transpiration by plants.
tree that does not lose its leaves.
unusual or extraordinary.
area used for agriculture.
animals associated with an area or time period.
having to do with money.
plants associated with an area or time period.
leaves of a plant, or the leaves and branches of a tree or shrub.
food crop Noun
plants grown and harvested for human consumption.
to search for food or other needs.
ecosystem filled with trees and underbrush.
forest floor Noun
ground-level layer of a forest.
management, cultivation, and harvesting of trees and other vegetation in forests.
portion or section.
delicate or easily broken.
having to do with a habitat or ecosystem of a lake, river, or spring.
to give money to a program or project.
fungi Plural Noun
(singular: fungus) organisms that survive by decomposing and absorbing nutrients in organic material such as soil or dead organisms.
wild animals hunted for food.
system or order of a nation, state, or other political unit.
greenhouse gas Noun
gas in the atmosphere, such as carbon dioxide, methane, water vapor, and ozone, that absorbs solar heat reflected by the surface of the Earth, warming the atmosphere.
environment where an organism lives throughout the year or for shorter periods of time.
Encyclopedic Entry: habitat harvest Noun
the gathering and collection of crops, including both plants and animals.
organism that eats mainly plants and other producers.
Encyclopedic Entry: herbivore historic Adjective
significant or important to history.
containing a large amount of water vapor.
person who gets food by using a combination of hunting, fishing, and foraging.
hydroelectric power Noun
the rate of producing, transferring, or using hydroelectric energy, often measured in kW or mW.
offer or encouragement to complete a task.
to add or become larger.
having to do with factories or mechanical production.
structures and facilities necessary for the functioning of a society, such as roads.
first step or move in a plan.
small indentation in a shoreline.
new, advanced, or original.
chemical substance used to kill insects.
material used to keep an object warm.
two or more individuals or communities that rely on each other for survival.
having to do with the national governments of more than one state.
to contribute time or money.
to study or examine in order to learn a series of facts.
tropical ecosystem filled with trees and underbrush.
complex, constantly changing pattern of shapes and colors.
keystone species Noun
organism that has a major influence on the way its ecosystem works.
Encyclopedic Entry: keystone species landfill Noun
site where garbage is layered with dirt and other absorbing material to prevent contamination of the surrounding land or water.
distance north or south of the Equator, measured in degrees.
Encyclopedic Entry: latitude livestock noun, plural noun
animals raised for sale and profit.
industry engaged in cutting down trees and moving the wood to sawmills.
profitable or money-making.
organ in an animal that is necessary for breathing.
long-tailed parrot native to the Americas.
infectious disease caused by a parasite carried by mosquitoes.
animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.
a skillful movement.
having to do with the ocean.
mammal that carries its young in a pouch on the mother's body.
very large or heavy.
having to do with curative therapy (medicine).
migration corridor Noun
area connecting wildlife habitats disturbed and interrupted by human activity. Also called a green corridor.
process of extracting ore from the Earth.
screen used to display an electronic device's video output.
political unit made of people who share a common territory.
Encyclopedic Entry: nation natural resource Noun
a material that humans take from the natural environment to survive, to satisfy their needs, or to trade with others.
sweet plant material that attracts pollinators.
having to do with a way of life lacking permanent settlement.
nonprofit organization Noun
business that uses surplus funds to pursue its goals, not to make money.
substance an organism needs for energy, growth, and life.
Encyclopedic Entry: nutrient oil Noun
fossil fuel formed from the remains of marine plants and animals. Also known as petroleum or crude oil.
old-growth forest Noun
collection of trees and shrubs that has not been harvested for timber or other uses in about 200 years, although definitions vary. Also called a primeval forest, primal forest, or ancient woodland.
composed of living or once-living material.
living or once-living thing.
drug or having to do with drugs and medications.
plant with large, flat leaves native to the Americas.
process by which plants turn water, sunlight, and carbon dioxide into water, oxygen, and simple sugars.
person who is among the first to do something.
chemical material that can be easily shaped when heated to a high temperature.
infection where lungs fill with fluid.
animal, object, or force such as wind that transfers pollen from one plant to another, allowing seeds to develop.
type of plastic used as a foam (for packing), fiber (for clothing), hard lining (for coatings), or flexible material (similar to rubber).
all forms in which water falls to Earth from the atmosphere.
Encyclopedic Entry: precipitation predator Noun
animal that hunts other animals for food.
animal that is hunted and eaten by other animals.
type of mammal, including humans, apes, and monkeys.
leading or dominant.
before or ahead of.
to encourage or help.
public health Noun
services that protect the health of an area, particularly sanitation, immunization, and environmental safety.
moist wood fibers from which paper is made.
amount of precipitation that falls in a specific area during a specific time.
rain forest Noun
area of tall, mostly evergreen trees and a high amount of rainfall.
Encyclopedic Entry: rain forest rampant Adjective
unrestrained or widespread.
practice of raising livestock for human use, such as food or clothing.
Encyclopedic Entry: ranching rapid Adjective
bird of prey, or carnivorous bird.
to lower or lessen.
to determine and administer a set of rules for an activity.
to resist or push back.
scientific observations and investigation into a subject, usually following the scientific method: observation, hypothesis, prediction, experimentation, analysis, and conclusion.
order of mammals often characterized by long teeth for gnawing and nibbling.
to quickly and playfully run from one place to another.
to make a rough, high-pitched cry.
formal or official stamp, emblem, or other mark.
marine algae. Seaweed can be composed of brown, green, or red algae, as well as "blue-green algae," which is actually bacteria.
section or a part of something.
part of a plant from which a new plant grows.
shifting cultivation Noun
type of agriculture where a field or plot is cleared, cropped, and harvested until its fertility is exhausted. Also called slash-and-burn, milpa and swidden.
having to do with a high-pitched, piercing sound.
type of plant, smaller than a tree but having woody branches.
to move in a secretive or stealthy manner.
method of agriculture where trees and shrubs are cleared and burned to create cropland.
to slide along a surface, from side to side.
top layer of the Earth's surface where plants can grow.
solar energy Noun
radiation from the sun.
Encyclopedic Entry: solar energy solar radiation Noun
light and heat from the sun.
scattered and few in number.
to anchor or make strong and reliable.
type of organic compound that is often important to the functioning of an organism.
subsistence agriculture Noun
type of agriculture in which farmers grow crops or raise livestock for personal consumption, not sale.
sustainable development Noun
human construction, growth, and consumption that can be maintained with minimal damage to the natural environment.
land permanently saturated with water and sometimes covered with it.
Encyclopedic Entry: swamp temperate rain forest Noun
wooded areas in cool, mild climate zones that receive high amounts of rainfall.
degree of hotness or coldness measured by a thermometer with a numerical scale.
Encyclopedic Entry: temperature terrestrial Adjective
having to do with the Earth or dry land.
cloth or other woven fabric.
device used to establish and maintain a temperature.
threatened species Noun
organism that may soon become endangered.
to develop and be successful.
rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun.
Encyclopedic Entry: tide timber Noun
wood in an unfinished form, either trees or logs.
top predator Noun
species at the top of the food chain, with no predators of its own. Also called an alpha predator or apex predator.
large-billed bird native to South America.
area of land.
buying, selling, or exchanging of goods and services.
historic or established by custom.
evaporation of water from plants.
stream that feeds, or flows, into a larger stream.
Encyclopedic Entry: tributary tropical Adjective
existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.
tropical rain forest Noun
grouping of tall evergreen trees, usually close to the Equator, which receives more than 203 centimeters (80 inches) of rain a year.
tropics Plural Noun
region generally located between the Tropic of Cancer (23 1/2 degrees north of the Equator) and the Tropic of Capricorn (23 1/2 degrees south of the Equator).
Encyclopedic Entry: tropics tuber Noun
thick part of an underground stem of a plant, such as a potato.
ecosystem between the canopy and floor of a forest.
one of a kind.
having to do with city life.
all the plant life of a specific place.
almost or nearly.
to say, sing, or otherwise make a vocal noise.
vulnerable species Noun
level of conservation between "near threatened" and "endangered." Vulnerable is the lowest of the "threatened" categories.
material that has been used and thrown away.
water cycle Noun
movement of water between atmosphere, land, and ocean.
Encyclopedic Entry: water cycle wind Noun
movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.
system of sectioning areas within cities, towns, and villages for specific land-use purposes through local laws.