• An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life. Ecosystems contain biotic or living, parts, as well as abiotic factors, or nonliving parts. Biotic factors include plants, animals, and other organisms. Abiotic factors include rocks, temperature, and humidity.

    Every factor in an ecosystem depends on every other factor, either directly or indirectly. A change in the temperature of an ecosystem will often affect what plants will grow there, for instance. Animals that depend on plants for food and shelter will have to adapt to the changes, move to another ecosystem, or perish.

    Ecosystems can be very large or very small. Tide pools, the ponds left by the ocean as the tide goes out, are complete, tiny ecosystems. Tide pools contain seaweed, a kind of algae, which uses photosynthesis to create food. Herbivores such as abalone eat the seaweed. Carnivores such as sea stars eat other animals in the tide pool, such as clams or mussels. Tide pools depend on the changing level of ocean water. Some organisms, such as seaweed, thrive in an aquatic environment, when the tide is in and the pool is full. Other organisms, such as hermit crabs, cannot live underwater and depend on the shallow pools left by low tides. In this way, the biotic parts of the ecosystem depend on abiotic factors.

    The whole surface of Earth is a series of connected ecosystems. Ecosystems are often connected in a larger biome. Biomes are large sections of land, sea, or atmosphere. Forests, ponds, reefs, and tundra are all types of biomes, for example. They're organized very generally, based on the types of plants and animals that live in them. Within each forest, each pond, each reef, or each section of tundra, you'll find many different ecosystems.

    The biome of the Sahara Desert, for instance, includes a wide variety of ecosystems. The arid climate and hot weather characterize the biome. Within the Sahara are oasis ecosystems, which have date palm trees, freshwater, and animals such as crocodiles. The Sahara also has dune ecosystems, with the changing landscape determined by the wind. Organisms in these ecosystems, such as snakes or scorpions, must be able to survive in sand dunes for long periods of time. The Sahara even includes a marine environment, where the Atlantic Ocean creates cool fogs on the Northwest African coast. Shrubs and animals that feed on small trees, such as goats, live in this Sahara ecosystem.

    Even similar-sounding biomes could have completely different ecosystems. The biome of the Sahara Desert, for instance, is very different from the biome of the Gobi Desert in Mongolia and China. The Gobi is a cold desert, with frequent snowfall and freezing temperatures. Unlike the Sahara, the Gobi has ecosystems based not in sand, but kilometers of bare rock. Some grasses are able to grow in the cold, dry climate. As a result, these Gobi ecosystems have grazing animals such as gazelles and even takhi, an endangered species of wild horse.

    Even the cold desert ecosystems of the Gobi are distinct from the freezing desert ecosystems of Antarctica. Antarcticas thick ice sheet covers a continent made almost entirely of dry, bare rock. Only a few mosses grow in this desert ecosystem, supporting only a few birds, such as skuas.

    Threats to Ecosystems

    For thousands of years, people have interacted with ecosystems. Many cultures developed around nearby ecosystems. Many Native American tribes of North Americas Great Plains developed a complex lifestyle based on the native plants and animals of plains ecosystems, for instance. Bison, a large grazing animal native to the Great Plains, became the most important biotic factor in many Plains Indians cultures, such as the Lakota or Kiowa. Bison are sometimes mistakenly called buffalo. These tribes used buffalo hides for shelter and clothing, buffalo meat for food, and buffalo horn for tools. The tallgrass prairie of the Great Plains supported bison herds, which tribes followed throughout the year.

    As human populations have grown, however, people have overtaken many ecosystems. The tallgrass prairie of the Great Plains, for instance, became farmland. As the ecosystem shrunk, fewer bison could survive. Today, a few herds survive in protected ecosystems such as Yellowstone National Park.

    In the tropical rain forest ecosystems surrounding the Amazon River in South America, a similar situation is taking place. The Amazon rain forest includes hundreds of ecosystems, including canopies, understories, and forest floors. These ecosystems support vast food webs.

    Canopies are ecosystems at the top of the rainforest, where tall, thin trees such as figs grow in search of sunlight. Canopy ecosystems also include other plants, called epiphytes, which grow directly on branches. Understory ecosystems exist under the canopy. They are darker and more humid than canopies. Animals such as monkeys live in understory ecosystems, eating fruits from trees as well as smaller animals like beetles. Forest floor ecosystems support a wide variety of flowers, which are fed on by insects like butterflies. Butterflies, in turn, provide food for animals such as spiders in forest floor ecosystems.

    Human activity threatens all these rain forest ecosystems in the Amazon. Thousands of acres of land are cleared for farmland, housing, and industry. Countries of the Amazon rain forest, such as Brazil, Venezuela, and Ecuador, are underdeveloped. Cutting down trees to make room for crops such as soy and corn benefits many poor farmers. These resources give them a reliable source of income and food. Children may be able to attend school, and families are able to afford better health care.

    However, the destruction of rain forest ecosystems has its costs. Many modern medicines have been developed from rain forest plants. Curare, a muscle relaxant, and quinine, used to treat malaria, are just two of these medicines. Many scientists worry that destroying the rain forest ecosystem may prevent more medicines from being developed.

    The rain forest ecosystems also make poor farmland. Unlike the rich soils of the Great Plains, where people destroyed the tallgrass prairie ecosystem, Amazon rain forest soil is thin and has few nutrients. Only a few seasons of crops may grow before all the nutrients are absorbed. The farmer or agribusiness must move on to the next patch of land, leaving an empty ecosystem behind.

    Rebounding Ecosystems

    Ecosystems can recover from destruction, however. The delicate coral reef ecosystems in the South Pacific are at risk due to rising ocean temperatures and decreased salinity. Corals bleach, or lose their bright colors, in water that is too warm. They die in water that isnt salty enough. Without the reef structure, the ecosystem collapses. Organisms such as algae, plants such as seagrass, and animals such as fish, snakes, and shrimp disappear.

    Most coral reef ecosystems will bounce back from collapse. As ocean temperature cools and retains more salt, the brightly colored corals return. Slowly, they build reefs. Algae, plants, and animals also return.

    Individual people, cultures, and governments are working to preserve ecosystems that are important to them. The government of Ecuador, for instance, recognizes ecosystem rights in the countrys constitution. The so-called Rights of Nature says Nature or Pachamama [Earth], where life is reproduced and exists, has the right to exist, persist, maintain and regenerate its vital cycles, structure, functions and its processes in evolution. Every person, people, community or nationality, will be able to demand the recognitions of rights for nature before the public bodies. Ecuador is home not only to rain forest ecosystems, but also river ecosystems and the remarkable ecosystems on the Galapagos Islands.

    Tall grasses and Bison bison—must be the tallgrass prairie ecosystem.

    Bactrian and Dromedary
    Different desert ecosystems support different species of camels. The dromedary camel is tall and fast, with long legs. It is native to the hot, dry deserts of North Africa and the Arabian Peninsula. The Bactrian camel has a thicker coat, is shorter, and has more body fat than the dromedary. The Bactrian camel is native to the cold desert steppes of Central Asia.

    It is easy to tell the two types of camels apart: Dromedaries have one hump, Bactrians have two.

    Coral Triangle
    The most diverse ecosystem in the world is the huge Coral Triangle in Southeast Asia. The Coral Triangle stretches from the Philippines in the north to the Solomon Islands in the east to the islands of Indonesia and Papua in the west.

    Human Ecosystem
    "Human ecosystem" is the term scientists use to study the way people interact with their ecosystems. The study of human ecosystems considers geography, ecology, technology, economics, politics, and history. The study of urban ecosystems focuses on cities and suburbs.

    The destruction of entire ecosystems by human beings has been called ecocide, or murder of the environment.

  • Term Part of Speech Definition Encyclopedic Entry
    abiotic Adjective

    lacking or absent of life.

    adapt Verb

    to adjust to new surroundings or a new situation.

    agribusiness Noun

    the strategy of applying profit-making practices to the operation of farms and ranches.

    algae Plural Noun

    (singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

    animal Noun

    organisms that have a well-defined shape and limited growth, can move voluntarily, acquire food and digest it internally, and can respond rapidly to stimuli.

    aquatic Adjective

    having to do with water.

    arid Adjective


    biome Noun

    area of the planet which can be classified according to the plant and animal life in it.

    Encyclopedic Entry: biome
    biotic factor Noun

    effect or impact of an organism on its environment.

    bison Noun

    large mammal native to North America. Also called American buffalo.

    butterfly Noun

    type of flying insect with large, colorful wings.

    canopy Noun

    one of the top layers of a forest, formed by the thick leaves of very tall trees.

    carnivore Noun

    organism that eats meat.

    Encyclopedic Entry: carnivore
    characterize Verb

    to describe the characteristics of something.

    climate Noun

    all weather conditions for a given location over a period of time.

    Encyclopedic Entry: climate
    complex Adjective


    constitution Noun

    system of ideas and general laws that guide a nation, state, or other organization.

    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    coral reef Noun

    rocky ocean features made up of millions of coral skeletons.

    corn noun, adjective

    tall cereal plant with large seeds (kernels) cultivated for food and industry. Also called maize.

    crocodile Noun

    reptile native to parts of Africa, Asia, and the Americas.

    crop Noun

    agricultural produce.

    Encyclopedic Entry: crop
    culture Noun

    learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.

    curare Noun

    resin obtained from South American trees, often dried and used as an ingredient in muscle relaxants.

    date palm Noun

    type of fruit tree.

    delicate Adjective

    fragile or easily damaged.

    desert Noun

    area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

    Encyclopedic Entry: desert
    destruction Noun


    determine Verb

    to decide.

    distinct Adjective

    unique or identifiable.

    dune Noun

    a mound or ridge of loose sand that has been deposited by wind.

    Encyclopedic Entry: dune
    ecocide Noun

    total destruction of an ecosystem.

    ecology Noun

    branch of biology that studies the relationship between living organisms and their environment.

    Encyclopedic Entry: ecology
    economics Noun

    study of monetary systems, or the creation, buying, and selling of goods and services.

    ecosystem Noun

    community and interactions of living and nonliving things in an area.

    Encyclopedic Entry: ecosystem
    endangered species Noun

    organism threatened with extinction.

    Encyclopedic Entry: endangered species
    epiphyte Noun

    plant that grows on the branches or trunk of another plant or object.

    evolution Noun

    change in heritable traits of a population over time.

    farmland Noun

    area used for agriculture.

    fig Noun

    fruit and tree native to Asia.

    flower Noun

    blossom or reproductive organs of a plant.

    fog Noun

    clouds at ground level.

    Encyclopedic Entry: fog
    food Noun

    material, usually of plant or animal origin, that living organisms use to obtain nutrients.

    Encyclopedic Entry: food
    food web Noun

    all related food chains in an ecosystem. Also called a food cycle.

    Encyclopedic Entry: food web
    forest Noun

    ecosystem filled with trees and underbrush.

    frequent Adjective


    freshwater Noun

    water that is not salty.

    Galapagos Islands Noun

    archipelago in the Pacific Ocean, off the coast of Ecuador.

    gazelle Noun

    small antelope native to Africa and Asia.

    geographic Adjective

    having to do with places and the relationships between people and their environments.

    geography Noun

    study of places and the relationships between people and their environments.

    Encyclopedic Entry: geography
    goat Noun

    hoofed mammal domesticated for its milk, coat, and flesh.

    government Noun

    system or order of a nation, state, or other political unit.

    grass Noun

    type of plant with narrow leaves.

    grazing animal Noun

    animal that feeds on grasses, trees, and shrubs.

    Great Plains Noun

    grassland region of North America, between the Rocky Mountains and the Mississippi River.

    health care Noun

    system for addressing the physical health of a population.

    herbivore Noun

    organism that eats mainly plants and other producers.

    Encyclopedic Entry: herbivore
    herd Noun

    group of animals.

    hermit crab Noun

    type of marine animal (crustacean) that uses found materials, such as other creatures' shells, as its shell.

    hide Noun

    leather skin of an animal.

    history Noun

    study of the past.

    human ecosystem Noun

    environment constructed or adapted to by people and culture.

    humidity Noun

    amount of water vapor in the air.

    Encyclopedic Entry: humidity
    ice sheet Noun

    thick layer of glacial ice that covers a large area of land.

    Encyclopedic Entry: ice sheet
    income Noun

    wages, salary, or amount of money earned.

    industry Noun

    activity that produces goods and services.

    insect Noun

    type of animal that breathes air and has a body divided into three segments, with six legs and usually wings.

    Kiowa Noun

    people and culture native to the Great Plains of North America.

    Lakota Noun

    people and culture of seven Sioux tribes native to the Great Plains.

    landscape Noun

    the geographic features of a region.

    Encyclopedic Entry: landscape
    maintain Verb

    to continue, keep up, or support.

    malaria Noun

    infectious disease caused by a parasite carried by mosquitoes.

    marine Adjective

    having to do with the ocean.

    medicine Noun

    substance used for treating illness or disease.

    monkey Noun

    mammal considered to be highly intelligent, with four limbs and, usually, a tail.

    moss Noun

    tiny plant usually found in moist, shady areas.

    mussel Noun

    aquatic animal with two shells that can open and close for food or defense.

    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    oasis Noun

    area made fertile by a source of fresh water in an otherwise arid region.

    Encyclopedic Entry: oasis
    ocean Noun

    large body of salt water that covers most of the Earth.

    Encyclopedic Entry: ocean
    organism Noun

    living or once-living thing.

    Pachamama Noun

    goddess of the Earth recognized by many cultures of the Andes Mountains.

    perish Verb

    to die or be destroyed.

    persist Verb

    to endure or continue.

    photosynthesis Noun

    process by which plants turn water, sunlight, and carbon dioxide into water, oxygen, and simple sugars.

    plain Noun

    flat, smooth area at a low elevation.

    Encyclopedic Entry: plain
    plant Noun

    organism that produces its own food through photosynthesis and whose cells have walls.

    politics Noun

    art and science of public policy.

    pond Noun

    small body of water surrounded by land.

    preserve Verb

    to maintain and keep safe from damage.

    public Adjective

    available to an entire community, not limited to paying members.

    quinine Noun

    drug used to treat malaria.

    rain forest Noun

    area of tall, mostly evergreen trees and a high amount of rainfall.

    Encyclopedic Entry: Rain forest
    reef Noun

    a ridge of rocks, coral, or sand rising from the ocean floor all the way to or near the ocean's surface.

    Encyclopedic Entry: reef
    reliable Adjective

    dependable or consistent.

    remarkable Adjective

    unusual and dramatic.

    resource Noun

    available supply of materials, goods, or services. Resources can be natural or human.

    river Noun

    large stream of flowing fresh water.

    Encyclopedic Entry: river
    rock Noun

    natural substance composed of solid mineral matter.

    Sahara Desert Noun

    world's largest desert, in north Africa.

    salinity Noun


    sand Noun

    small, loose grains of disintegrated rocks.

    scorpion Noun

    animal related to a spider with a poisonous sting in its tail.

    seagrass Noun

    type of plant that grows in the ocean.

    sea star Noun

    marine animal (echinoderm) with many arms radiating from its body. Also called a starfish.

    seaweed Noun

    marine algae. Seaweed can be composed of brown, green, or red algae, as well as "blue-green algae," which is actually bacteria.

    shelter Noun

    structure that protects people or other organisms from weather and other dangers.

    shrimp Noun

    animal that lives near the bottom of oceans and lakes.

    shrub Noun

    type of plant, smaller than a tree but having woody branches.

    skua Noun

    bird related to the seagull.

    snake Noun

    reptile with scales and no limbs.

    snowfall Noun

    amount of snow at a specific place over a specific period of time.

    soil Noun

    top layer of the Earth's surface where plants can grow.

    soy Noun

    beans, or fruit, of the soybean plant, native to Asia.

    spider Noun

    eight-legged animal (arachnid) that usually spins webs to catch food.

    survive Verb

    to live.

    takhi Noun

    endangered species of wild horse native to Central Asia. Also called Przewalski's horse.

    tallgrass prairie Noun

    plain where grasses grow up to 2 meters (6 feet) tall.

    technology Noun

    the science of using tools and complex machines to make human life easier or more profitable.

    temperature Noun

    degree of hotness or coldness measured by a thermometer with a numerical scale.

    Encyclopedic Entry: temperature
    tide Noun

    rise and fall of the ocean's waters, caused by the gravitational pull of the moon and sun.

    Encyclopedic Entry: tide
    tide pool Noun

    small pond created by an ebb tide and submerged by a high tide.

    tropical Adjective

    existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

    tundra Noun

    cold, treeless region in Arctic and Antarctic climates.

    underdeveloped country Noun

    country that has fallen behind on goals of industrialization, infrastructure, and income.

    understory Noun

    ecosystem between the canopy and floor of a forest.

    urban ecosystem Noun

    environment of cities, towns, and suburbs.

    vast Adjective

    huge and spread out.

    vital Adjective

    necessary or very important.

    weather Noun

    state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness.

    Encyclopedic Entry: weather
    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.