• vegetation region
    These trees are unusual for a desert vegetation region.

    Photograph by Seetha Karunaratne, MyShot

    Is It Hot in Here?
    Deserts take up approximately one-third of the Earth's land surface!

    Garden Variety
    Vegetation zones, also called hardiness zones, are smaller, more-detailed vegetation regions. Vegetation zones divide land according to temperature and precipitation. Most gardeners look at a map of vegetation zones before planting any flowers, trees, or vegetables.

    The United States, for example, is usually divided into 10 vegetation zones. Zone 1 is the coldest zone and supports plants like aspen. Zone 10 is the warmest zone. Gardeners here might plant ferns or palms.

    Regional Culture
    People have adapted to live in the natural environment of every vegetation region except the ice sheet. Many of the Yanomamo people continue to live in the Amazon rain forest of Brazil and Venezuela. Plains Indian tribes, such as the Lakota, are native to the Midwest grassland of North America. The Chukchi culture of Russia's far east developed on the tundra. The San culture has thrived in the Kalahari Desert of southern Africa for thousands of years.

    Scientists divide the Earth’s land into what are called vegetation regions. These areas have distinct types of plants, soil, and weather patterns. Vegetation regions can be divided into five major types: forest, grassland, tundra, desert, and ice sheet. Climate, soil, the ability of soil to hold water, and the slope, or angle, of the land all determine what types of plants will grow in a particular region.

    Forest

    Forests are areas with trees grouped in a way so their leaves, or foliage, shade the ground. Forests can be found just about anywhere trees can grow, from below sea level to high in the mountains. From tropical rain forests near the Equator to boreal forests in cold climates close to the Arctic Circle, different types of forests can be found all over the world.

    One way to classify different types of forests is by the type of trees a forest has. Deciduous forests have trees with green leaves that change color in the fall and drop altogether in the winter. Trees that are common in deciduous forests are oak and maple. The northeastern United States is covered in deciduous forest, and tourists flock to the area every autumn to experience the orange, yellow, and red leaves blanketing the region.

    Evergreen forests have trees with leaves that stay green all year long. One of the places evergreen forests can be found is on the opposite side of the North American continent—in the Pacific Northwest, which includes the Canadian province of British Columbia and the U.S. states of Washington and Oregon. The Pacific Northwest is full of evergreen trees like fir.

    Sometimes forests are classified by the type of leaves on their trees. Trees in broad-leaved forests have wide, flat leaves. Tropical rain forests are a type of broad-leaved forest. Tropical rain forests, such as Brazil’s Amazon Basin rain forest, are found near the Equator. They contain more than half of the world’s biodiversity, or variety of plant and animal species.

    Coniferous forests have trees with cones and needles instead of leaves. Coniferous forests have the tallest (coast redwood), largest (giant sequoia), and oldest (bristlecone pine) trees in the world.

    Many forests are mixed, meaning they have both broadleaf and coniferous trees. The eucalyptus forests of Australia are mixed forests, for instance. The evergreen eucalyptus trees are mixed with deciduous trees like beech.

    Grassland

    Grasslands are, as their name suggests, flat and open areas where grasses are the dominant type of vegetation. Grasslands can be found on every continent except Antarctica.

    Climate plays a role in the type of grassland you get. In cool, mild climates, like northwest Europe, grasslands are dominated by tough vegetation, such as oats, that thrives all year. Some of these grasses are so tough and hardy that they are considered weeds.

    In warmer climates, seasonal vegetation survives better. Temperate grasslands exist where there are seasonal variations in temperature over the course of the year: hot summers and cold winters. Different grasses thrive in different temperatures here. Temperate grasslands exist from the prairies of North America to the veld, or rural grassland, of South Africa.

    Tropical grasslands are called savannas. They do well in weather that is warm year-round and usually pretty dry. The most famous savannas are in Africa. Serengeti National Park, in Tanzania, has three distinct types of savanna grassland: long grass, intermediate grass, and short grass. This part of the Serengeti is known as the Serengeti Plains, and it supports wildlife from aardvarks to zebras.

    Grasslands are important for milk and dairy production; dairy cows are happiest, and most productive, in areas in which they can munch on grass all day.

    Tundra

    Tundra is an area where tree growth is difficult because of cold temperatures and short seasons. Vegetation in tundra is limited to a few shrubs, grasses, and mosses. Scientists estimate roughly 1,700 different species live in the tundra, which isn’t much compared to forests and grasslands. The ground is often too cold for plants to set down roots, and without plants, few animal species can survive.

    There are two types of tundra: alpine tundra and arctic tundra. Alpine tundra is separated from a forest vegetation region by the tree line, the area beyond which conditions are too harsh or cold for tree growth. The weather in alpine tundras is cold, snowy, and windy. Most of the Tibetan Plateau, the so-called “roof of the world” located in Tibet, China, and India, is alpine tundra. Animals like mountain goats live in this vegetation region.

    Arctic tundra occurs in the far-northern hemisphere of the Earth. It has a bare landscape and is frozen for much of the year. Here, the tundra can include permafrost, or soil that is permanently frozen. Russia and Canada have huge areas of arctic tundra. During the summer, the permafrost thaws just a bit, allowing some plants to grow in the wet, marshy ground. You won’t find many mammals in the arctic tundra, but thousands of insects and birds show up every year and enjoy the marshes before they freeze. Among the few mammals that actually thrive in the arctic tundra are caribou and polar bears.

    Desert

    Deserts have almost no precipitation, or rainfall. In fact, deserts are specifically defined as areas with an average annual precipitation of less than 10 inches per year. Deserts usually have really high daytime temperatures, low nighttime temperatures, and very low humidity.

    Desert soil is often sandy, rocky, or gravely. Plant life is highly specialized to adapt to these coarse, dry conditions, with long roots, small leaves, stems that store water, and prickly spines that discourage animals from touching or eating them. Cactuses, which are native to deserts in North and South America, are an example of this kind of plant. Despite the barren look of hot deserts, they are full of animal life. Most desert animals, such as lizards or snakes, are nocturnal, meaning they are active at night. Nocturnal animals take advantage of the cooler nighttime temperatures of the hot desert.

    Not all deserts are hot and sandy, however. The largest desert in the world is the Antarctic Desert, which takes up most of the continent of Antarctica. In the Antarctic Desert, ice sheets cover barren rock. Few animals can live in the Antarctic Desert. Those that do are often microscopic, such as lice.

    Ice Sheet

    The interesting thing about the ice sheet “vegetation region” is that there really isn’t any vegetation there at all! An ice sheet is a large stretch of glacier ice that covers the land all around it for more than 50,000 square kilometers (20,000 square miles). Currently, the only ice sheets are in Antarctica and Greenland. Don’t confuse the ice sheets, called polar ice caps, with other ice shelves or glaciers; an ice sheet is much, much bigger.

    Ice sheets are important research sites for scientists. The Antarctic ice sheet is a record of Earth’s atmospheric changes. By looking at layers in the ice, scientists can keep track of different levels of pollution or volcanic gases in the atmosphere. The 1883 eruption of the Indonesian island volcano of Krakatoa can be located and dated by the distinct air bubbles in the Antarctic ice sheet, for instance.

    Scientists are also studying ice sheets to measure the rate of melting ice. Parts of the Greenland ice sheet were once thought to be permanent, but they are now melting at a fast pace.

  • Term Part of Speech Definition Encyclopedic Entry
    alpine tundra Noun

    flat, treeless vegetation region separated from a forest by the tree line.

    Antarctic Desert Noun

    dry, barren rocks covered by an ice sheet that makes up most of the continent of Antarctica.

    Arctic Circle Noun

    paralell of latitude that runs 66.5 degrees north of the Equator.

    arctic tundra Noun

    flat, treeless vegetation region near the Arctic Circle.

    aspen Noun

    variety of poplar tree.

    atmospheric changes Noun

    alterations in the layer of air surrounding the Earth, such as an increase of pollution or humidity.

    autumn Noun

    season between summer and winter. Also called fall.

    beech Noun

    tree native to Asia, Europe, and North America.

    biodiversity Noun

    all the different kinds of living organisms within a given area.

    Encyclopedic Entry: biodiversity
    bird Noun

    egg-laying animal with feathers, wings, and a beak.

    blanket Verb

    to cover entirely.

    boreal forest Noun

    land covered by evergreen trees in cool, northern latitudes. Also called taiga.

    bristlecone pine Noun

    oldest living tree species on Earth. Also called hickory pine.

    broadleaf forest Noun

    land covered by trees with wide, flat leaves.

    caribou Noun

    large deer native to North America.

    Chukchi Noun

    people and culture native to Siberia.

    classify Verb

    to identify or arrange by specific type or characteristic.

    climate Noun

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

    Encyclopedic Entry: climate
    coast redwood Noun

    tallest tree species on Earth.

    cone Noun

    hard, spiral structure that is the fruit of some trees.

    coniferous forest Noun

    land covered by trees with thin needles instead of flat leaves.

    continent Noun

    one of the seven main land masses on Earth.

    Encyclopedic Entry: continent
    cow Noun

    large, domesticated mammal used for milk and meat.

    dairy production Noun

    art, science, and industry of cultivating milk and milk products, such as cheese.

    deciduous Adjective

    type of plant that sheds its leaves once a year.

    desert Noun

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

    Encyclopedic Entry: desert
    distinct Adjective

    unique or identifiable.

    dominant Adjective

    main or most important.

    Equator Noun

    imaginary line around the Earth, another planet, or star running east-west, 0 degrees latitude.

    Encyclopedic Entry: equator
    eucalyptus Noun

    tree native to Oceania.

    evergreen Noun

    tree that does not lose its leaves.

    fern Noun

    flowerless plant.

    fir Noun

    variety of pine tree.

    flower Noun

    blossom or reproductive organs of a plant.

    foliage Noun

    leaves of a plant, or the leaves and branches of a tree or shrub.

    forest Noun

    ecosystem filled with trees and underbrush.

    giant sequoia Noun

    largest species of tree on Earth.

    glacier Noun

    mass of ice that moves slowly over land.

    Encyclopedic Entry: glacier
    grass Noun

    type of plant with narrow leaves.

    grassland Noun

    ecosystem with large, flat areas of grasses.

    hardy Adjective

    strong or able to withstand severe weather.

    hemisphere Noun

    half of a sphere, or ball-shaped object.

    Encyclopedic Entry: hemisphere
    hike Verb

    to walk a long distance.

    ice sheet Noun

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

    Encyclopedic Entry: ice sheet
    ice shelf Noun

    mass of ice that floats on the ocean but remains attached to the coast.

    insect Noun

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

    island Noun

    body of land surrounded by water.

    Encyclopedic Entry: island
    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
    leaf Noun

    organ growing from the stem of a plant.

    lice Noun

    insects that prey on animal blood. Singular: louse.

    mammal Noun

    animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.

    maple Noun

    type of tree.

    marsh Noun

    wetland area usually covered by a shallow layer of seawater or freshwater.

    Encyclopedic Entry: marsh
    microscopic Adjective

    very small.

    Midwest Noun

    area of the United States consisting of the following states: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.

    milk Noun

    white liquid produced by female mammals to feed their young.

    moss Noun

    tiny plant usually found in moist, shady areas.

    mountain Noun

    landmass that forms as tectonic plates interact with each other.

    mountain goat Noun

    variety of wild or domesticated mammal.

    munch Verb

    to eat by chewing vigorously.

    needle Noun

    long, thin, pointed leaf.

    oak Noun

    tree native to the Northern Hemisphere.

    oats Noun

    type of edible grass.

    Pacific Northwest Noun

    the area made of the U.S. states of Oregon and Washington, and the Canadian province of British Columbia.

    palm Noun

    type of tree with a tall trunk, no branches, and a leafy crown.

    permafrost Noun

    permanently frozen layer of the Earth's surface.

    Encyclopedic Entry: permafrost
    Plains Indian Noun

    one of many people and cultures native to the Great Plains in North America.

    plant Noun

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

    polar bear Noun

    large mammal native to the Arctic.

    pollution Noun

    introduction of harmful materials into the environment.

    Encyclopedic Entry: pollution
    province Noun

    division of a country larger than a town or county.

    Encyclopedic Entry: province
    rain forest Noun

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

    research Noun

    scientific observations and investigation into a subject, usually following the scientific method: observation, hypothesis, prediction, experimentation, analysis, and conclusion.

    root Noun

    part of a plant that secures it in the soil, obtains water and nutrients, and often stores food made by leaves.

    San Noun

    people and culture native to southern Africa. Also called Bushmen.

    sapling Noun

    young tree.

    savanna Noun

    type of tropical grassland with scattered trees.

    sea level Noun

    base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.

    Encyclopedic Entry: sea level
    seasonal vegetation Noun

    plants that grow, bloom, or flower during a specific time of year.

    Serengeti plains Noun

    grassland of the Serengeti ecosystem of Kenya and Tanzania.

    shrub Noun

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

    slope Noun

    slant, either upward or downward, from a straight or flat path.

    soil Noun

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

    temperate grassland Noun

    flat, grassy area where there are seasonal differences in temperature and precipitation.

    thrive Verb

    to develop and be successful.

    Tibetan Plateau Noun

    flat, elevated landform located in Tibet, China, and India. Also known as the "rooftop of the world."

    tree Noun

    type of large plant with a thick trunk and branches.

    tree line Noun

    elevation point above which trees can no longer grow.

    tundra Noun

    cold, treeless region in Arctic and Antarctic climates.

    vegetable Noun

    plant that is grown or harvested for food.

    vegetation region Noun

    area with distinct plant types, determined by climate, soil, drainage, and elevation. There are five major vegetation regions: forest, grassland, tundra, desert, and ice sheet.

    vegetation zone Noun

    altitude, soil, and precipitation region in which a plant best survives.

    veldt Noun

    rural grasslands of southern Africa.

    volcanic gas Noun

    gas such as water vapor or carbon dioxide that is released into the atmosphere by a volcano.

    volcano Noun

    an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

    Encyclopedic Entry: volcano
    weather pattern Noun

    repeating or predictable changes in the Earth's atmosphere, such as winds, precipitation, and temperatures.

    weed Noun

    unwanted plant.

    Yanomamo Noun

    people and culture native to the Amazon Basin.

    zebra Noun

    mammal, related to a horse, native to Africa.

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