Grassland

How Grasslands Develop

Kinds of Grasslands

Climate

Geography of Grasslands

Plant Life

Animal Life

Human Life

The Food Web

Spotlight on Grasslands

For More Information

A grassland is a biome in which the dominant plants are grasses rather than trees or tall shrubs. Often described as “seas of grass,” grasslands cover about one fourth of Earth’s surface. They are usually found in the interiors of every continent except Antarctica.

Although grasslands vary in climate and the type of plant and animal life they support, most have several things in common. They are covered with grasses, which may be of different heights and varieties. They are usually windy and dry for part of the year. They occur primarily on flat land or gently rolling hills, but a few are found on mountains where the environment is suitable. Grasslands are considered transition zones between deserts, which receive little rain, and forests, which get a lot of rain.

How Grasslands Develop

Grasslands develop as a result of changes in climate, changes in plant communities, and fires.

Climatic change

Grasslands first appeared millions of years ago after mountains formed and caused climates to change. In North America, for example, the Rocky Mountains blocked moist air traveling across the continent from the Pacific Ocean, making the middle part of the continent drier. This caused trees to die and be replaced by grasses, which could adapt to the drier climate. The same process happened on other continents, allowing grasslands to form in places such as central Asia and South America. Grasslands throughout the world were fairly well established about 5 million years ago, covering more than 40 percent of Earth’s surface.

Succession

Grasslands also develop through a process called succession, a slow sequence of changes in a plant community. In dry areas, the growth of mosses and lichens (LY-kens) may be followed by the growth of leafy,

nonwoody plants. Gradually, the grasses, which are hardier plants, begin to take over and become the major form of plant life in the area.

In ponds or other areas of still or slow-moving water, submerged plants like pondweed, grow beneath the water. Dead stems and leaves from these plants make the water thick, shallow, and slow moving. This dead matter forms a thick layer of organic material in which plants that must be anchored in soil, such as reeds and grasses, begin to grow. As this process continues, the pond fills with decaying plants until the water is gone and a grassland has developed.

Fires

Fires help form and sustain grasslands. Most naturally occurring fires are started by lightning. Lightning strikes the ground, igniting dried grass. All vegetation (trees, shrubs, flowers) and grass are completely burned. The grass regrows because it has adapted to this dry environment and has a very deep root system and, often, underground stems. Fire helps to eliminate competition from trees, shrubs, and flowers for nutrients, water, and growing space, making it easier for grass to grow.

People may start fires that help establish grasslands. As far back as the Stone Age, hunters burned forests so that grasses would grow and attract the wild animals they relied on for food. Later, shepherds and herders burned brush and trees to encourage the growth of grasses for grazing.

Kinds of Grasslands

Grasslands may be classified as tropical, temperate, and upland grassland.

Tropical grassland

Tropical grasslands, called savannas when they have scattered trees, are found in regions around the equator. Savannas are hot all year and have long dry seasons followed by very wet seasons. Savanna grasses vary across continents, depending on average rainfall. Thorn trees, for example, are found in North African savannas and can range from 13 to 50 feet (4 to 15 meters) in height. More trees grow in savannas than in any other type of grassland.

In Africa, Australia, South America, and India, savannas are transition zones between the rain forests and the deserts of the higher latitudes (distances north or south of the equator). In South America, the Llanos (YAH-nos) covers parts of northwestern Venezuela and northeastern Colombia, while larger and more wooded grasslands lie across southeastern Venezuela and southern Guyana. Brazilian grasslands include the Cerrado, a highland region, and the Pantanal, a wet savanna within the Cerrado. The Pantanal is the world’s largest area of continental wetlands.

Almost half of Africa, about 5,000,000 square miles (13,000,000 square kilometers), is covered with savanna, making it the world’s largest tropical grassland. A well-known savanna in Tanzania is the Serengeti (sur-in-GEHT-ee) Plain. Savannas are also found in Australia and on India’s Deccan Plateau.

Temperate grassland

Temperate grasslands are those with moderate climates located farther from the equator. They have fewer trees than tropical grasslands and the grass is shorter.

Most savannas are tropical, but some occur in places with temperate climates, where they form borders between other grasslands and deciduous (trees that lose their leaves at the end of the growing season) forests. For example, oak savannas, 20 percent of which are tree covered, are found in midwestern states of the United States, such as Illinois, Indiana, Missouri, Kentucky, and Wisconsin. The major temperate grasslands include prairies, steppes, pampas, and velds.

Prairie

The vast sweeping grasslands in North America are generally called prairies. The many different types of prairie grasses grow in a variety of textures and colors, which range from green to gold. These grasses vary in height but typically are 5 feet (1.5 meters) tall.

Three prairie regions are located east of the Rocky Mountains. The shortgrass prairie begins in the foothills of the Rockies and stretches east,

where it merges with the mid-grass region of the Great Plains. The tallgrass prairie is easternmost, ending in Illinois.

Other prairie regions include the desert grassland of the southwestern United States, the intermountain grassland in the northwestern United States, and the central valley grassland in California. Within these prairie regions are subprairies—gravel prairies, hill prairies, sand prairies, and dry sand prairies. Gravel prairies grow on gravelly soil, while hill prairies are found in clearings on forested slopes. Sand prairies are characterized by sandy soils, and dry sand prairies are found on the crests of sand dunes.

Steppe

Steppe is the Russian word for “grassy plain.” A steppe is similar to a prairie, except that the grasses are shorter. Steppes are found primarily in southeastern Europe and Asia. One of the world’s largest grasslands, the Eurasian steppe, stretches thousands of miles from Europe to China. Siberia is also home to steppes.

In general, there are two kinds of steppe: the meadow steppes of the North and the dry steppes of the South.

Pampas

The pampas, which is Spanish for “plains,” are temperate grasslands in South America. The land is flat and rolling and supports about twenty species of grasses that are tall and reedlike with silvery plumelike flowers. Many pampas grasses grow in tussocks (small clumps).

Veld

In South Africa a temperate grassland is called a veld (FELT) or veldt, the Dutch word for “field.” Velds are found at different elevations— high, middle, and low. They are home to a large variety of vegetation. The highveld, for example, is dominated by red grasses that may be sweet or sour. The sweet grasses provide a good source of food for animals.

Upland grassland

A few grasslands exist at high altitudes where it is too cold for trees to grow and only the hardiest of grasses survive. Upland grasslands include alpine meadows and alpine savannas. Alpine meadows are mountainous grasslands and occur in mountain ranges throughout the world. Alpine savannas occur in the tropics (the part of Earth’s surface between the Tropic of Capricorn and the Tropic of Cancer, two lines of latitude above and below the equator). One example of alpine meadows is the Puna of the Andes Mountains of southeastern Peru and western Bolivia. Native and introduced grasses grow at elevations ranging from about 9,000 to 11,000 feet (2,800 to 3,850 meters). Forage grasses, on which grazing animals feed, grow at lower elevations.

Climate

Climate, especially rainfall and wind conditions, is the most important factor in grassland survival. Grasslands located deep in the interiors of continents in the Northern Hemisphere face extreme weather from tornadoes, droughts

(dry periods), blizzards, and dust storms. Temperate grasslands in the Southern Hemisphere, such as the pampas in Argentina, are closer to the moderating effect of the oceans, which makes their climates less extreme.

Temperature

Since tropical grasslands are near the equator, their climate is warm all year. The winter is dry and the summer brings a short, but very wet, rainy season. The average summer temperature on a tropical savanna is above 80°F (26.6°C). Winter averages about 65°F (18°C).

Temperatures in temperate grasslands vary according to how far north or south of the equator they are located and how far inland from the oceans. In general, summers are hot and winters are cold. On the North American prairies, summer temperatures often reach 100°F (37.7°C). Prairies in Canada, which are farther from the equator, can be quite cold in winter, with the temperature often sinking to 14°F (-10°C).

Precipitation

Precipitation (rain, snow, or sleet) is a key factor in determining the nature of a grassland, especially its soil and the type of plant life growing there. Grasslands typically receive 10 to 30 inches (25 to 76 centimeters) of rain every year; however, periods of drought are common. If rainfall decreases significantly over many years, grassland will become a desert. Likewise, an increase in rainfall over a long period of time encourages the growth of forests. Grasslands closer to the equator tend to have longer rainy seasons and a moister climate than grasslands farther from the equator.

Tropical savannas have what is called a monsoon climate, which means winds blow from different directions during different seasons. Winters are dry, and the dry period may last five to seven months. Summers, when the wind shifts direction, bring periods of heavy rain. Typical annual precipitation ranges from 25 to 60 inches (64 to 152 centimeters), but amounts vary depending on location. Grasslands in Australia, for example, receive fewer than 20 inches (50 centimeters) of

rainfall in the east and 30 inches (76 centimeters) in the west. Grasslands in South America receive as many as 60 inches (150 centimeters).

Temperate grasslands generally receive less precipitation than tropical grasslands. They average between 12 to 40 inches (31 to 102 centimeters) per year, with much of the rain falling in the late spring and early summer.

Dry periods in both types of grasslands are important to their survival. For example, dry conditions promote fires, which is nature’s way of encouraging new growth.

Wind

Without trees to block the wind, it sweeps across grasslands at a high speed. In tropical grasslands, winds bring the soaking monsoon rains. Wind also helps to dry things out again because it aids evaporation. This reduction in moisture helps keep trees from growing and taking over the grassland. Wind plays a major role in spreading fires during the dry season.

Some grassland winds are so ferocious and well known that they have been given names. The buran is a strong northeasterly wind that blows over the steppes of Russia and Siberia, bringing blizzards in winter and hot dust in summer. The pampero of Argentina is a strong, cold wind that sweeps in from the Andes Mountains across the South American pampas. The warm, dry winter wind that blows over the Rocky Mountains in North America is called the chinook.

Geography of Grasslands

The geography of grasslands involves landforms, elevation, soil, and water sources.

Landforms

The dominant feature of most grasslands is flat terrain or low, rolling hills. In African savannas, small hills called kopjes (KOPP-ees) are formed from rocks. Kopjes have their own type of vegetation and wildlife. In a land with few trees, kopjes provide shelter, shade, and protection for animals. The North American prairies often contain potholes, grass-filled depressions in the ground that fill with water after heavy rains.

Elevation

Grasslands are found at many elevations. The South African veld, for example, is divided into zones based on elevation. The lowveld is

Twister!

Grasslands often lie in the path of violent windstorms called tornadoes. In a tornado, a huge column of air spins like a top at speeds of up to 300 miles (480 kilometers) per hour. Some have been recorded as spinning up to 500 miles (800 kilometers) per hour. Tornadoes are often called funnel-clouds because of their funnel-like shape. They are also called twisters because they spin.

While tornadoes occur in many countries around the world, they are most common in the grassland areas of the United States, especially in Kansas and Oklahoma, where few trees block the wind. As many as 1,000 tornadoes strike there every year. They develop during thunderstorms that form when warm tropical air hits cooler northern air and when the humidity is high and the air near the ground is unstable. Tornadoes travel a narrow path, usually about 600 feet (200 meters) wide, at an average speed of 40 miles (64 kilometers) per hour. Inside the center of the funnel cloud is a very strong updraft (an air current that moves upward). The updraft is so powerful it can lift heavy objects, like trees, cars, and even homes, into the air. Tornadoes can leave a path of destruction up to 15 miles (24 kilometers) long, often causing millions of dollars in damage and killing many people.

found between 500 and 2,000 feet (152 and 610 meters), the middle veld between 2,000 and 4,000 feet (610 and 1,219 meters), and the highveld between 4,000 and 6,000 feet (1,219 and 1,828 meters).

Colder grasslands are found at much higher elevations. The altiplano of the central Andes Mountains in Bolivia and Peru is about 12,000 feet (3,650 meters) above sea level.

Soil

Grassland soil helps to determine what plants and animals can survive in an area.

Tropical savanna soils

Soils in savannas are called “red earth” and are mostly sandy and dusty. Their red color comes from a high iron content. The long dry periods between the rainy seasons prevents dead plant matter from decomposing (breaking down) and releasing nutrients into savanna soil. This soil is not as rich as in other grasslands. Termites and other burrowing creatures turn the soil, helping air to circulate and water to reach lower levels.

Temperate grassland soils

Temperate grassland soils are rich with humus, a dark, moist layer composed of decayed plant and animal matter and small grains of rock. Humus is rich in nutrients, such as nitrogen, that are vital to plant growth. It is spongy and able to store moisture.

The Role of Soil in the Food Web

Plants obtain some of their nutrients from the soil. These nutrients include minerals such as nitrogen and phosphorus, and acids such as carbonic and citric acids. Not all soils are the same and some contain a better balance of nutrients than others. Studies have shown that the quality of the soil in which a plant is grown can affect not only the plant itself, but also the creatures that eat the plant.

In a study at the University of Missouri, hay was grown on three plots of ground, all lacking nutrients. One plot (A) remained untreated. It produced about 1,700 pounds (3,740 kilograms) of hay per acre. Nitrogen fertilizer was added to the second plot (B), and it produced almost twice as much hay, about 3,200 pounds (7,040 kilograms) per acre. When the hay from both plots was fed to rabbits, the rabbits that ate hay from plot B did not grow as big as those fed hay from plot A. Although the nitrogen produced more plants per acre, those plants were not as nutritious for the rabbits.

A third plot (C) was given a balanced fertilizer to provide all the minerals the hay needed. This plot produced less hay than plot B, only 2,400 pounds (5,280 kilograms) per acre. However, when the rabbits ate it they grew twice as big as the rabbits that ate hay from plot B and 35 percent bigger than the rabbits that ate hay from plot A.

The three main types of temperate grassland soil are black earth, prairie soil, and chestnut soil.

Black earth In dry climates, there is not enough rain to wash the humus down into the soil, so it remains close to the top, producing “black earth.” Called chernozem in Russian, black earth is an extremely fertile soil that provides excellent nutrition for crops like wheat and soybeans. Black earth is found on the steppes of Russia and central Asia, on the pampas of South America, in Australia, and on some North American prairies.

Prairie soil In moist climates with an average rainfall of 25 to 40 inches (64 to 102 centimeters), rain pushes humus deeper into the ground, producing brown prairie soils. These very fertile soils cover parts of eastern Europe and what is known as the Corn Belt in the United States. This belt runs through parts of Ohio, Indiana, Illinois, Iowa, Minnesota, South Dakota, Nebraska, Kansas, and Missouri. Prairie soils may be wet or dry and contain varying amounts of sand or gravel.

Chestnut soil Chestnut soils are found in the driest of the temperate grasslands, on parts of the South African veld, in the Argentine pampas, and on the high plains east of the Rocky Mountains. These soils are light or dark brown depending on their humus content, which makes them more or less fertile.

Water sources

Rainy seasons in tropical grasslands create waterholes, swell rivers, and fill flood plains. Some tropical grasslands, like the Pantanal in Brazil, get so drenched they are under water for part of the year.

Ponds, lakes, streams, rivers, and marshes are found throughout temperate grasslands.

Plant Life

Grasslands support a wide variety of plant life, including more than 10,000 species of grasses worldwide. Grassland plants include algae (AL-jee), fungi (FUN-ji), lichens, and green plants.

Algae, fungi, and lichens

It is generally recognized that algae, fungi, and lichens do not fit neatly into the plant or animal categories.

Algae

Most algae are one-celled organisms too small to be seen by the naked eye. They make their food through photosynthesis (foh-toh-SIHN-thuh-sihs), the process by which plants use energy from the sun to change water and carbon dioxide from the air into sugars and starches they require for growth. Blue-green algae, also called blue-green bacteria, grow close to the ground in moist areas, often in mud after a rain. These algae help transform nitrogen in the soil so it can be absorbed by plants.

Fungi

Fungi are plantlike organisms that cannot make their own food by means of photosynthesis. Instead, they grow on decaying organic matter or live as parasites (organisms that depend upon another organism for survival). Hundreds of species of fungi live in grassland soil and grow best in a damp environment. In the African savanna, for example, the termite-mound fungus grows on moist termite droppings. The fungi breaks down food matter in the droppings that the termites could not digest. This food matter is then re-eaten by the termites.

Lichens

Lichens are combinations of algae and fungi. The alga produces food for both through photosynthesis. It is believed that the fungus protects the algae from dry conditions. Lichens found in grasslands grow close to the ground in moist environments.

Green plants

Most green plants need several basic things to grow: light, air, water, warmth, and nutrients. In a grassland, more than half of all plant tissue—roots, stems, and rhizomes—lies underground. It is here that the plants absorb their nutrients, water, and oxygen. Savanna elephant grasses, for example, have roots that reach 10 feet (3 meters) deep.

Tough as Grass

Grass may not be as hard as nails, but it can be just as tough. It can survive drought, subzero temperatures, high winds, fires, mowing, and being trampled upon. Grass is able to grow again even after being severely damaged. Growing points on its stems and buds close to the ground can start new growth.

A tall, rough grass called slough (SLOO) grass grows along the edges of prairies close to water sources. Slough grass reaches about 9 feet (2.7 meters) in height. Nicknamed “ripgut,” its stiff, razor-like leaves can cut a person’s hands or an animal’s mouth. While slough grass is not preferred for eating, its tough qualities make it useful for roof thatching.

Common green plants

Grasses, sedges, and forbs are the most common green plants found on grasslands. A few scattered trees and shrubs also grow.

Grasses have round, hollow stems and long narrow leaves called blades. The blades grow from the base of the plant so that, when the grass is cut off at the top, it continues to grow. More than half of the grass tissue is underground, which helps the plants survive harsh weather. Some grasses, such as needle-and-thread grass, have adapted to prefer cooler rather than warmer climates.

Grasses are categorized primarily according to their height. The tallest grasses grow in tropical areas where rainfall is greater. Bamboo, one of the tallest and strongest grasses in the world, can be 180 feet (60 meters) tall. Bamboo grows quickly, sometimes at the rate of 3 feet (0.9 meter) a day. It is found throughout the tropics. A shorter species of bamboo grows in the southern United States.

Mixed-height grasses with flowering stems grow in temperate regions. On the North American prairies the grasses are categorized as shortgrass, mixed-grass, and tallgrass. Shortgrasses, which include grama grass and buffalo grass, grow to about 18 inches (45 centimeters) in height. Little bluestem, needlegrass, and foxtail barley, three mixed-grasses, grow to 3 feet (90 centimeters) tall. Tallgrasses, ranging from 3.3 to 10 feet (1 to 3 meters), include big bluestem, slough (SLOO) grass, cordgrass, and Indian grass.

Shorter grasses that grow in arid lowlands like the dry, southern Serengeti Plain, need less rainfall to survive. These include Rhodes grass and red oat grass. Most are less than 8 inches (20 centimeters) high.

Sedges are perennial, flowering herbs that closely resemble grasses. Found all over the world, they range in size from 0.4 inch to 16 feet (1 centimeter to 5 meters). They have solid, usually triangular, stems and grasslike green leaves arranged in three rows. Sedges prefer a damper environment than grasses and are often found on the edges of marshes, ponds, or other watery locations. The remote sedge, carnation sedge, and yellow nut sedge are common species.

Forbs are flowering, broad-leaved plants without the woody stems of trees and shrubs. Wildflowers are prairie forbs and include blazing stars, sunflowers, purple coneflowers, bee balms, and shooting stars. Other North American forbs include gentian, milkweed, and fleabane. Forbs growing on the Russian steppes include anemones, red tulips, irises, and peonies.

Some temperate grasslands in drier regions support shrubs such as the mesquite and creosote bush. Along the wet edges of these grasslands, cottonwood, ash, and box elder can take root.

Baobabs and acacia trees thrive in the tropical savannas. Found in Africa and the Australian outback, the baobab has roots that go deep into the ground in search of water. It stores water in its thick trunk, which acts like a reservoir supplying water during the dry season. The African acacia produces as many as 20,000 seeds every year, ensuring that some will survive dry weather and grazing animals. As added protection for its survival, the acacia, known as a wattle in Australia, has long spines (like thorns) that are actually modified leaves. These spines keep grazing animals away and act as protection against drought, since they offer less surface area than normal leaves for moisture to evaporate.

Growing season

The length of a grassland’s growing season varies depending on precipitation and temperature. Growing seasons in tropical grasslands start when the rains come and end when the rains end.

In temperate climates, the growing season lasts from 150 to 270 days and begins when the average temperature reaches about 50°F (10°C).

Reproduction

Green plants reproduce by several methods. One is pollination, in which the pollen from the male reproductive part of a plant, called the stamen in flowering plants, is carried by wind or insects to the female reproductive part of a plant, called a pistil in flowering plants. Pollen-gathering insects distribute pollen at different times of the day according to when a plant’s flower is open. Lilies, for example, are closed in the morning and evening, but open during midday when the weather is warmer and insects are more active.

Many species of perennial prairie grasses (those that live for two or more growing seasons) reproduce with the help of rhizomes, modified stems that spread out under the soil and form new plants. Rhizomes grow roots and produce leaves, stems, and flowers that grow upward and out of the soil.

Annual grasses (those that live only one year) produce seeds with thick outer shells. These shells protect the seeds, which are spread by the wind or by attaching themselves to passing animals.

Endangered species

As grasslands become overrun by humans and animals, plants are endangered. Forbs are especially sensitive to abuse. When land is cultivated for crops or used for grazing animals, all of the native species in that area are destroyed.

Two endangered plants on the tallgrass prairies in North America are the leafy prairie clover and the prairie white-fringed orchid. The orchid is endangered because people dig it up to transplant into their home gardens and because pesticides accidentally kill the sphinx moth, an insect that pollinates the orchid.

Animal Life

Grassland animals range from very small aphids and worms to large African elephants. Different continents are home to different species.

Microorganisms

Microorganisms are tiny animals that cannot be seen by the human eye except with the help of a microscope. Those found in grasslands are mainly protozoa and bacteria, which live in the root systems of grasses and help with decomposition. Some protozoa live in the intestines of termites and make it possible for the termite to digest the wood fibers they eat.

Invertebrates

Invertebrates are animals that do not have a backbone. The invertebrate population of grasslands consists primarily of insects, such as dung (scarab) beetles, monarch butterflies, moths, and dragonflies.

Grubs, termites, and worms are invertebrates that play a key role in soil development. They churn the soil, allowing more oxygen and water to enter it. Worms rebuild the soil by digesting organic material and depositing this rich fertilizer in the ground.

Common grassland invertebrates

Two common grassland invertebrates are termites and grasshoppers. Termites are insects that resemble ants. Most of the more than 2,000 species live in the tropics, although some are found in temperate areas. Termites live by the millions in highly social and organized communities in underground nests or in mounds having many chambers. Each termite has a role in the colony and is ranked as either royalty, nobility, soldier, or worker.

The Web of Life: Protecting House and Home

Certain species of African ants make their homes in the bullhorn acacia tree. Animals that might be a threat to the tree are driven away by the ants, which bite and sting. The presence of the ants stimulates the tree to form galls, a kind of tumor that grows on the branches. The galls have spikes that help keep hungry animals away from both the tree and the ants.

On the African savanna, termites build huge brown mounds out of soil cemented with saliva or droppings, making the mounds rock hard. Termite mounds can be more than 25 feet (7.6 meters) high, 98 feet (30 meters) wide, and may last for decades.

Grasshoppers are one of the most common grassland insects. They are plant eaters with powerful hind legs that allow them to jump and wings that allow them to fly. All grasslands around the world face periodic swarms (large populations) of grasshoppers. The species that swarm are called locusts. In 1889, one of the largest swarms ever seen formed over the Red Sea in Northeast Africa and covered an area about 2,000 miles (3,200 kilometers) long, darkening the sky for days. Locusts may eat every plant in their path, including the stalks. When they are finished, all crops, as well as plants and shrubs, are destroyed.

Food

Caterpillars and grasshoppers are among the insects that eat leafy vegetation. Grubs eat grass roots, while some insects are scavengers, feeding on what is left behind by larger animals. Two types of scavengers are the carrion beetle and the flesh fly, both of which live on the African savanna. The African scarab beetle is also a scavenger, feeding on animal droppings.

Reproduction

The first stage of an invertebrate’s life cycle is spent as an egg. When the egg hatches, the emerging creature is called a larva. The larva stage is divided into several stages between which there is a shedding of the outer skin as the larva increases in size. During the third, or the pupal stage, the insect lives in yet another protective casing, like a cocoon. In the final stage, the adult emerges.

The reproductive cycle of the sphinx moth of the African savanna follows the wet and dry seasons. Eggs are laid on vegetation during the rainy season. By the time the dry season arrives, the eggs have already hatched into caterpillars that have been feeding on leaves. After several molts (stages

where insects increase in size and shed their outer skin) they burrow into the soil, where they remain in pupal form until it rains again and they emerge as adult moths. The scarab beetle lays its eggs inside a ball of animal droppings. The young beetles feed on the droppings after they have hatched.

Amphibians

Amphibians are vertebrates, animals with a backbone. Amphibians live at least part of their lives in water. Most are found in warm, moist regions and temperate zones where temperatures are seldom extreme.

Amphibians breathe through their skin, so they usually must remain close to water. Only moist skin can absorb oxygen, and if they are dry for too long they will die. On the African savanna, amphibians like the African bullfrog estivate (remain inactive) underground during the dry season. The termite frog estivates in a termite mound.

Common grassland amphibians

The green toad is common to the steppes. Once it has become an adult, it is able to live out of water. Since the steppe climate can be extreme, the toad hibernates underground when the weather is too hot or too cold.

The small North American cricket frog lives in grasslands near ponds or streams. These frogs have brown or green skin covered with bumps. They grow to about 1.2 inches (3 centimeters) in length.

Food

Amphibians eat insects and some small animals, using their long tongues to capture prey. Although they have teeth, amphibians do not chew but swallow their food whole. As larvae, they usually eat plants. Toads, for example, eat algae and water plants during the larval stage.

Reproduction

Mating and egg laying for most amphibians takes place in water. Male sperm are deposited in the water on top of eggs laid by the female. The African running frog lays its eggs in puddles that form when the rainy season begins. As the offspring develop into larvae and young adults, they have gills, which means they must live in water. Once they mature, they breathe through lungs and live on land.

Most amphibians reach adulthood at three or four years, breeding for the first time about one year after they become adults.

Reptiles

Reptiles are cold-blooded vertebrates that depend on the environment for warmth. They do not do well in extreme temperatures, either hot or cold. Reptiles are usually more active when temperatures become warmer. Many reptiles go through a period of hibernation in cold weather because they are so sensitive to the environment. Unlike amphibians, reptiles have waterproof skin, which allows them to move away from moist areas.

Common grassland reptiles

The boomslang snake is common throughout the African savannas south of the Sahara Desert. Up to 6.5 feet (2 meters) in length, the boomslang is shy and highly poisonous. Its fangs are set in the rear of its upper jaw, and a bite causes excessive bleeding and death. The boomslang eats lizards, frogs, and sometimes birds and rodents. Other snakes include the python and the coral snake.

The agama lizard is also found on the African savannas. The male has a blue-orange body and red head. These bright colors help it to be visible to females and competing males. Each male lizard has its own territory and mates with several females. Adults are around 12 inches (30 centimeters) long.

The western box turtle is a land turtle found in the prairies of North America. Box turtles grow to about 8 inches (20 centimeters) in length and have a high, round shell. They eat both plants and animals, including berries, mushrooms, insects, and worms.

Food

Most reptiles are carnivorous (meat-eating). For example, snakes consume their prey whole—and often alive—without chewing. It can often take an hour or more to swallow a large victim. Many snakes have fangs that are curved backward so their prey cannot escape.

Reproduction

Most reptiles reproduce sexually, meaning the female egg is fertilized by the male sperm. Almost all species lay eggs. A rare few species bear live young.

Birds

Hundreds of species of birds live on the grasslands. Many species must nest on the ground and perch on the grasses because there are so few trees.

Common grassland birds

Representative of grassland birds are the ostrich, the prairie chicken, and the black hornbill.

The ostrich is the largest and fastest bird in the world, weighing around 350 pounds (159 kilograms) and standing about 8 feet (2.4 meters) tall. Although it has wings, it cannot fly, but it is able to run at speeds up to 45 miles (72 kilometers) per hour. The ostrich is found on grasslands in parts of Africa and Southwest Asia. Males mate with several females, each of which typically lays twelve very large eggs in a nest built on the ground. In this species, the male and female take turns sitting on the eggs until they hatch.

Formerly one of the most familiar grassland birds in the United States is the greater prairie chicken, a species that has become quite rare. Found on tallgrass prairies, these birds live on the ground and eat seeds. Females lay about twelve eggs that hatch in fewer than forty-two days. The chicks can fly by the time they are two weeks old. The lesser prairie chicken is more common and can be found on short-grass prairies.

Black hornbills are large birds that walk along the African savanna in search of insects. They range from 12 to 47 inches (30 to 120 centimeters) in length and have large heads, thin necks, broad wings, and long tails. Hornbills nest in the grooves of large trees. The male builds the nest around the female and seals her inside with the eggs, passing food to her through a small opening. The female breaks out of the nest after the eggs hatch.

Hitchhiking on the Grassland

The bustard is a large, heavy, longlegged grassland bird found in Europe, Asia, and Africa. When the male strolls around looking for food, a small, reddish bird called a bee-eater hitches a ride on his back. As the bustard moves, it stirs up insects that are nabbed and eaten by the bee-eater.

An Upside-Down Nest

African weaverbirds build some of the most complex and unusual nests in the world. Their globe-shaped nest is woven from savanna grasses and has its entrance hole at the bottom. With its entrance hidden, the nest is protected from predatory birds that might ordinarily swoop down into the nest to steal eggs or baby birds. The nests of many weaverbirds are hung together in trees, forming a community of “apartments” that resembles the thatched roof of a house when seen from a distance. Parent birds use the same nest every year, and young birds add their nests to their parents’ structure.

Food

Many grassland birds eat grains and seeds, which are readily available. Predatory (hunting) birds, like owls, hawks, and eagles, eat rodents and snakes, while others feed on insects. The green wood hoopoe eats butterflies or beetles. Tick birds, such as the groove-billed anis, eat ticks from the backs of large animals. Storks, vultures, and ravens are scavengers and dine on leftovers from a kill.

Reproduction

All birds reproduce by laying eggs. Usually, the males must attract the attention of the females. Therefore, most males are more brightly colored than the females, and some sing or perform dancing rituals. For example, the greater prairie chicken inflates orange air sacs near its throat when beginning its mating call.

After mating, female birds lay their eggs in nests made out of many different materials and built in a variety of places. Many species, like the lark and bobolink, nest on the ground. The parent bird, usually the female, sits on the eggs to keep them warm until they hatch.

Mammals

Mammals are warm-blooded vertebrates that are covered with at least some hair, bear live young, and produce their own milk. Hundreds of species of mammals live on grasslands around the world.

Grassland mammals

Grassland mammals include prairie dogs and saigas. Saigas are endangered with a current population of about 40,000.

One of the most common North American prairie animals is the prairie dog. These small rodents weigh 1.5 to 3 pounds (0.7 to 1.4 kilograms) and live in prairie dog “towns” consisting of a network of underground tunnels. These tunnels provide a safe place to raise young, hibernate in winter, and hide from predators such as coyotes, snakes, and eagles. The many holes that lead into the tunnels can be found scattered over a wide area. The animals feed close by these holes and dart into them when danger is detected.

Getting the Most out of Every Meal

Many grasses are impossible for most mammals to digest. Some animals, like the bison, giraffe, and pronghorn antelope, are called ruminants and can eat tough grasses. These animals have a stomach with four chambers. After the grass is chewed and swallowed, it is stored in the first chamber, called the rumen, where microbes help break it down and soften it. Later, the animal brings the food back up into its mouth and chews it some more, a process called chewing cud. This cud is reswallowed and goes through all of the chambers of the stomach where it is completely digested. The four-chambered stomach probably helps grazing animals, which are always on the lookout for predators, eat large amounts very quickly and return to shelter where they can safely digest their meal.

A male prairie dog mates with two or three females and protects the group, which lives in its own section of the town.

Saigas are a type of antelope found on the steppes of Russia and Siberia. At only 2.5 feet (0.8 meter) tall, they must jump into the air to see above the grass when watching for predators. When threatened, they run away at speeds up to 50 miles (80 kilometers) per hour.

Saigas are plant-eaters that dine on forbs and grasses. Females often give birth to twins, which helps the survival of the species. Male saigas have a high mortality rate. Each year, more than half of the males starve to death.

Food

Some mammals are herbivores (plant-eaters). Some herbivores, like the zebra, buffalo, wildebeest (WIHL-duh-beest), and antelope, are grazers. Grazers have front teeth that allow them to bite off grass close to the ground and back teeth to grind up the grass. Other herbivores, like giraffes and elephants, are browsers that nibble the leaves and bark of trees and shrubs.

Other mammals, such as coyotes, lions, and cheetahs, are carnivores (meat-eaters). Jackals and hyenas are scavengers, meaning they eat the leftover carcasses and decaying meat from dead animals.

Reproduction

Mammals give birth to live young that develop inside the mother’s body. Some mammals are helpless at birth, like the hare, while others, like the zebra, are able to walk and even run almost immediately. The mother nurses the young with her own milk until they are old enough to find their own food.

Endangered species

Many grassland animals are endangered because of overhunting, pollution, and the destruction of their habitats.

Before the end of the nineteenth century, there were as many as 400 million prairie dogs living in a single prairie dog town that stretched across North America. As grasslands were turned into farms, so many of these animals were killed that they faced extinction. Many national parks in the United States and Canada now protect prairie dogs.

Found in Africa and southern Asia, cheetahs are the fastest land animals in the world. With a small head, long legs, and a tail that helps them to keep their balance, cheetahs can run almost 60 miles (96 kilometers) per hour for short distances. Once hunted for their black-spotted fur, cheetahs are now protected. The major threat remaining for cheetahs is the loss of habitat, as more land is taken for farming and development.

Many species of kangaroos are found in Australia and on neighboring islands such as New Zealand. A number of the larger species are endangered. Some are killed for hides (skins) and some for food. Kangaroos are grazing animals, and many are shot by ranchers and farmers who want their cattle to graze without competition.

North American pronghorn antelopes are found in Mexico and the western United States. In the nineteenth century, about 40 million pronghorns lived on the prairies of North America. In the early twentieth century, much grassland was destroyed for farming, and many prong-horns were killed for food and hides. There are fewer than 10,000 pronghorns left and they live in the state of Arizona. Conservation laws have provided protected areas, but the pronghorn still faces the threat of extinction because of shrinking habitats.

A similar fate occurred with the American bison. Prior to the expansion of the United States westward, there were about 30-60 million bison. Their number was reduced to only about 1,000 in the late nineteenth century. The herds have since increased to nearly 30,000 on protected lands. The purity of the species is threatened as many bison are cross-bred with cattle for commercial purposes.

The New Look of Lawns

Using grass for lawns began in France and England in the late eighteenth century. It became popular in the United States, first as a way for people to tame wild-looking plots, and eventually as a status symbol—the green yard with no weeds.

Lawns have a high environmental cost. Gas lawnmowers pollute the air, thousands of gallons of fresh water are used up in watering, and tons of pesticides (insect poisons) are applied every year. Unfortunately, these chemicals kill wildlife and endanger the health of people and pets.

Many communities encourage the use of native trees, shrubs, flowers, and grasses to replace the typical lawn. Native plants do not require the same amount of water and fertilizer necessary to maintain lawn grasses. They also return the landscape to its original beauty and protect the environment.

Human Life

Grasslands have been home to people around the world for thousands of years. Of all the flowering plants, none is more important to human life than grasses. Grasslands dominate the agricultural regions of every continent except Antarctica.

Impact of the grassland on human life

Grasslands are essential to human life because of their role in food production and agriculture. Based on their usefulness to humans, there are six major types of grasses: grazing and forage grass, turfgrass, ornamental grass, cereal grass, sugarcane, and woody grass.

Food

More than half of the world’s population relies on grasses for food. About thirty-five species of grasses are grown for human and animal use. Many grasses are harvested for hay, to feed livestock. Grasses are also cultivated for their seeds, which are processed and eaten. These grasses include the cereal grains: wheat, oats, barley, rye, corn, millet, sorghum, and rice. Wheat and corn are grown all over the world, with large crops coming from the United States, China, and Russia. Oats and rye are the chief domestic crops from Russia and Europe. Cereal, bread, and pasta are common foods made from these grains. Some wild grass species, such as wild rice, are also harvested. Sugarcane is a type of grass, but it is not a cereal grass. Its sap is concentrated into sugar. The sprouts and shoots of bamboo, which is a woody grass, also provide food for humans.

Grassland animals, such as the American bison (commonly known as the buffalo), have been used for food since the earliest times. When the horse, another grassland animal, became domesticated (tamed), hunters could follow wild herds of bison as they migrated (moved from one area to another). Overhunting is one reason the American bison has become an endangered species.

Economic factors

Many of the world’s grasslands are used for farming and ranching and have great economic importance. Grazing and forage grasses are used for feeding cattle and other animals. Turfgrass is used to cover athletic fields, lawns, golf courses, and playgrounds. Turfgrasses include Kentucky blue grass, ryegrass, Bermuda grass, and buffalo grass. Ornamental (decorative) grasses, such as pampas grass and Chinese silvergrass, are used in parks and flower gardens. Sugarcane is used not only for sugar but also for making plastic and wallboard. Woody grasses, such as bamboo, can be used to make sturdy items including furniture and even houses. Fiber from the bark of the baobab tree is used for making rope and paper.

Grasslands are favorable sites for homes and cities because they tend to be relatively flat. Saskatoon in Saskatchewan, Canada, and Omaha, Nebraska, are both grassland cities.

Many grasslands offer mineral resources. Gold and diamonds are mined under the South African veld, while natural gas and petroleum are extracted from beneath the grasslands of Texas and Oklahoma.

Impact of human life on the grassland

At one time grasslands were the largest single biome in the world, covering more than 40 percent of Earth’s land surface. None of these native grasslands remain untouched by humans.

When the railways brought large numbers of colonists to remote regions during the nineteenth century, grasslands were rapidly taken over for farms and towns. The Trans-Siberian Railroad brought people onto the steppes of Siberia. Similarly, railways crossed North America, moving large numbers of people all across Canada and the United States.

Since that time, many grasslands have become artificial, or human-made. Some of the grasslands were created in areas once occupied by forests that had been cut down. Almost all of the grasslands in Europe are artificial and are used for grazing animals and growing grain.

Use of plants and animals

Many native grassland plants are used for herbal medicines. The purple coneflower, for example, can be used to help heal wounds, and fleabane is used to repel insects. With the popularity of herbal remedies, many of these plants are being overharvested.

As more and more grassland is used for agriculture, native plants are destroyed leaving little food for wildlife. Trees are cut down and used for lumber or as fuel for cooking.

Grassland animals have also suffered from overuse. Mass slaughter and poaching of animals have nearly destroyed every major species of mammal and reptile and several species of birds in the South African veld.

Kruger National Park in South Africa is one of several protected areas in which some of these species survive.

Quality of the environment

During the 1930s, serious misuse of grassland resulted in the great “Dust Bowl” in Oklahoma and Texas. Farmers failed to use soil conservation methods and, while plowing for crops, destroyed the grasses that held the soil in place. After a long, dry period, the crops died and sweeping winds blew the dry topsoil away. The dust drifted thousands of miles and rose as high as 30 feet (9 meters). It was so thick in the air that people became sick from inhaling it. Crops could no longer be grown in the ruined land. Many people went hungry and thousands were forced to move.

Erosion (wearing away of soil) is still a problem in grasslands. African savannas are being stripped of their natural vegetation so they can be used for agriculture. In the Sahel region of North Africa, more and more grassland is becoming desert each year.

Some farmers use irrigation techniques to overcome dry grassland conditions. However, when water is pumped from underground sources, these water supplies can be completely used up.

In certain grasslands, measures are being taken to overcome the negative impact of human interference. Irrigation ditches linking fields to nearby aboveground sources bring water to crops, and farmers plow in ways that help prevent erosion. Native vegetation is protected from cattle so that it has a chance to regrow.

Native peoples

Hunter-gatherers were living on the tropical grasslands of East Africa more than 40,000 years ago. About 10,000 years ago, these hunter-gatherers learned to cultivate the grasses and to domesticate animals, which allowed them to lead more settled lifestyles. Grasslands in some parts of the world continue to support tribes of people who live a traditional lifestyle.

Nomadic (wandering) hunters, herders, and shepherds once lived and roamed freely on temperate grasslands in North America. The Blackfoot, Teton Sioux, Cheyenne, and Comanche tribes followed the bison. Food, clothing, and shelter were all provided from the meat and skins of these animals. Some tribes, such as the Pawnee, Mandan, Hidatsa, and Arikara, were semi-nomadic and spent time planting and harvesting crops, especially corn, beans, and squash. By the nineteenth century European peoples began to move onto the world’s grasslands, forcing the native peoples out of their traditional homes. Although some Native Americans still live on reservations (areas set aside for them to live), many have moved to large cities.

Learn More About Life on the Grassland

• Clark, Ann Nolan. Secret of the Andes. New York: Viking Press, 1952
• Friggens, Paul. Gold and Grass, The Black Hills Story. Boulder, CO: Pruett Publishing, 1983
• Hurwitz, Johanna. A Llama in the Family. New York: Morrow Books, 1994
• Low, Ann Marie. Dust Bowl Diary. Lincoln, NB: University of Nebraska Press, 1984
• Norton, Lisa Dale. Hawk Flies Alone: Journey to the Heart of the Sandhills. New York: Picador Press, 1996
• Warren, Andrea. Pioneer Girl: Growing Up on the Prairie. New York: Junior Books, 1998

The Kazakh (also spelled Kazak) peoples live on the grasslands of Central Asia and parts of China. The Kazakh are nomads who raise sheep, cattle, goats, camels, and horses. Most still follow the traditional lifestyle, moving from one grassland to another when their animals need fresh pasture. Their food is primarily milk products and meat from their sheep. They live in portable, dome-shaped tents called yurts, which consist of a frame of poles covered with skins or wool felt. Many of their other needs are met with products from their animals: hides are made into clothing, horns are used for utensils, and horsehair is braided into rope.

African peoples still living on the grasslands include some tribes of Maasai found in the Great Rift Valley of southern Kenya and Tanzania. They are traditionally herders who move across the savannas with their cattle. Their cultural beliefs require them to live almost entirely off the

meat, blood, and milk provided by their livestock. Most Maasai are permitted to eat grains and vegetables when food is scarce, but warriors are not. Maasai villages, called kraals, consist of mud-dung houses for four to eight families surrounded by a large circular thornbush fence. As less and less grazing land is available for the Maasai, many are forced to give up their traditional lifestyle and make their living trying to farm.

The Food Web

The transfer of energy from organism to organism forms a series called a food chain. All the possible feeding relationships that exist in a biome make up its food web. On the grasslands, as elsewhere, the food web consists of producers, consumers, and decomposers. An analysis of the food web shows how energy is transferred within a biome.

Green plants are the primary producers in the grassland. They produce organic (matter derived from living organisms) materials from inorganic chemicals and outside sources of energy, primarily the sun.

Animals are consumers. Primary consumers eat plants and include grazing animals, such as zebras, bison, and antelopes. In the savannas, where trees are more common, tall plant-eaters, such as giraffes and elephants, browse on the leaves of trees or bushes.

Plant-eaters become food for predators, which are secondary consumers such as coyotes and lions. Tertiary consumers eat both primary and secondary consumers. They include leopards and eagles. Humans are omnivores, which means they eat both plants and animals.

Decomposers eat the decaying matter from dead plants and animals and help return nutrients to the environment. For example, small underground insects called springtails help decomposition by breaking down dead plants. This allows other organisms, like bacteria and fungi, to reach the decaying matter and decompose it further.

Spotlight on Grasslands

The Llanos

The Llanos (YAH-nos) is a tropical savanna found in Venezuela and northeastern Colombia. The Llanos is bordered by the Andes Mountains in the north and west, the Amazon and Guaviare Rivers to the south, and the lower Orinoco River to the east. At its highest elevation, the Llanos is about 1,000 feet (305 meters) above sea level, although some areas may be as a low as 200 to 300 feet (61 to 91 meters).

The Llanos Location: Venezuela and northeastern Colombia in South America Area: 220,000 square miles (570,000 square kilometers) Classification: Savanna

Typical of tropical grasslands, the Llanos is flooded for part of the year and dry for the rest. During the dry season, which lasts from December through April, fires often sweep the land. When the rains begin in May, lakes, lagoons, and marshes form. The area stays wet until November, when the dry cycle begins again. Annual precipitation ranges from 30 to 98 inches (76 to 160 centimeters). The annual average temperature is approximately 80°F (27°C).

Barbed Wire and the End of the Old West

Before the end of the nineteenth century, the American West was an open range where ranchers could graze cattle freely and cowboys could drive large herds to market. As farmers began to settle in the area they needed to protect their crops and land from wandering cattle. Cattle often trampled wooden fences in an effort to get to food or water so a stronger barrier was necessary.

In 1874, Joseph F. Glidden invented a machine to manufacture barbed wire. Barbed wire was made out of two strands of wire twisted together from which sharp barbs protruded. The barbs caused pain and kept cattle from damaging the fence.

As the open range was cut up by fences, “range wars” developed between farmers and ranchers. By 1888, the farmers had won, and cattle ranchers were forced to keep their cattle on their own property. They began to use railway cattle cars rather than long cattle drives over open land to transport them to market.

Swamp grasses, sedges, and carpet grasses grow throughout the region, which is also home to the Llanos palm, the scrub oak, cassias, and the araguaney tree.

During the wet season, the great anaconda inhabits the areas around the rivers. The anaconda is the largest snake in the Americas, measuring 30 feet (9 meters) long. A type of constrictor, the anaconda wraps itself around its prey and squeezes it. The Orinoco crocodile, one of the most threatened reptiles in the world, lives along the edge of the river.

Many species of birds live on the Llanos, including herons, storks, and ibises. The scarlet ibis, a large wading bird, has long legs and a long, slender, downward-curving bill used for searching in the mud for food. The jacana is a water bird whose long toes enable it to walk on the large floating leaves of water plants.

The capybara is the world’s largest rodent, weighing about 100 pounds (45 kilograms). It eats grasses and aquatic herbs, which it finds both on land and in the water. The capybara is a favorite meal for both the anaconda and the Orinoco crocodile. The only wild animals with hooves that live on the Llanos are the white-tailed deer and the red brocket, a small deer with short, unbranched antlers.

The Llanos is home to the giant anteater and giant armadillo. A toothless animal that eats insects, but is especially fond of ants and termites, the giant anteater is 6 to 8 feet (1.8 to 2.4 meters) in length and weighs about 65 to 140 pounds (29 to 64 kilograms). The giant armadillo can weigh up to 100 pounds (45 kilograms) and is protected by a type of armor that covers its body from head to tail. In some species, the armor is in segments and is flexible. Unlike certain members of the armadillo family, the giant armadillo cannot roll into a ball to protect itself from predators. Instead, the giant armadillo quickly digs itself into the ground using the long claws on its front legs. Very shy and almost blind, it depends on its senses of smell and hearing. With its large claws, it rips apart insect nests in search of food but also eats roots and worms.

Serengeti National Park

The name Serengeti is from a Maasai word meaning “endless plains.” Serengeti National Park and Wildlife Refuge is located in north central Tanzania on a high plateau between the Ngorongoro highlands and the Kenya/Tanzania border. Stretching between Lake Victoria and Lake Eyasi, the park is best known for the millions of wild animals that live there.

Serengeti National Park

Location: North central Tanzania in Africa

Area: 5,700 square miles (14,763 square kilometers) Classification: Savanna

The park contains a vast open grassland in the southern region, a large acacia savanna in the center, and wooded grasslands in the north. Within the Serengeti are kopjes (rocky hills) with their own unique biomes. Rivers, lakes, and swamps are scattered throughout the park, providing habitats for a variety of reptiles and birds.

Located in the tropics, the Serengeti is dry and warm. Yearly temperatures range from 59° to 77°F (15° to 25°C), and the coolest weather is from June to October. The major rainy season lasts from March to May, but shorter periods of rain occur in October and November. About 47 inches (120 centimeters) of rain fall near Lake Victoria and about 20 inches (51 centimeters) on the plains.

Elevations in the park range from 3,000 to 6,000 feet (920 to 1,850 meters).

Not many amphibians or reptiles inhabit grasslands. However, in 1992, a new species of tree frog was discovered in the Serengeti’s rocky hills during the rainy season. This species is named Hyperolius orkarkarri.

More than 500 species of birds have been seen in the park. Common birds include starlings, ring-necked doves, and the barbet, a brightly colored bird with a large, strong bill with bristles at its base.

About thirty-five species of herbivores, such as wildebeests, zebras, giraffes, gazelles, topi, and konga, live here. Elephants began moving onto the Serengeti in the 1960s when human populations in the surrounding area increased, forcing them from their former homes. Carnivores include lions, cheetahs, hyenas, and leopards.

Land animals in the Serengeti migrate annually. The migration follows the pattern of the seasons and is led by the millions of wildebeests in the park. During the wet season, which lasts from December to May, herds graze on the southeastern plains. As the season progresses, they move west into woodland savanna and then north into the grasslands as their food and water supplies become scarce. When the dry season ends in November, the herds return to the rain-drenched southeastern plains, and the cycle begins again.

The Maasai were the first people to inhabit the Serengeti, arriving with their herds at the end of the nineteenth century. In the early twentieth century, Europeans and Americans arrived and began the wholesale killing of wild animals. The lion population was almost wiped out, but game reserves were established in the 1920s, and the entire area was made into a park in 1951. Although the Serengeti is one of the largest wildlife sanctuaries in the world, poachers (people who hunt or fish illegally) still pose a major threat. Elephants are killed for their ivory tusks and the black rhinoceros, which is almost extinct, is killed for its horn.

Wind Cave National Park

Wind Cave National Park is located in South Dakota and borders the ponderosa pine forests of the Black Hills. It is home to a mixed-grass prairie that contains both tall grasses from the eastern prairies and short grasses from the high plains near the Rocky

Wind Cave National Park

Location: South Dakota

Area: 28,292 acres (11,449 hectares) Classification: Mixed-grass prairie

Mountains. The park was established in 1903 to preserve its grasslands and its many limestone caverns.

The climate in the park is typical of a temperate grassland—warm in summer and cold in winter. The air that comes off the Rocky Mountains makes the park somewhat warmer and drier than the surrounding areas. In winter, temperatures range between 22° and 50°F (-5° and 10°C). Summer temperatures average 85°F (20°C). Some moisture comes from snow, which can accumulate as much as 30 inches (76 centimeters) in the winter.

Most of the vegetation in the prairie consists of grasses. When rainfall is more plentiful, the tall grasses dominate because they grow best in a moist environment. When there is less rain, the short grasses take over. Native tallgrass species include spikebent, redtop, big bluestem, and prairie sandreed. Native mixed-height grasses include slender wheatgrass, little bluestem, and Junegrass. Red three-awn, buffalo grass, and stink-grass are native short grasses. Other native vegetation includes forbs, such as small soapweed (a yucca plant), prairie clover, and Indian hemp dogbane.

Common amphibians that make this park their home include the blotched tiger salamander, the plains spadefoot toad, the upland chorus frog, and the Great Plains frog, which is easily identified by its many bumps. Reptiles found along the streams include the common snapping turtle, the wandering garter snake, and the prairie rattlesnake.

Hundreds of species of birds visit or make the park a permanent home. Permanent residents range from common finches to hawks, golden eagles, and prairie falcons.

Mammals frequently seen in the park are coyotes, prairie dogs, chipmunks, and elks. Bison, elk, and pronghorns were reintroduced to the park in 1913. There are sightings of coyote, mountain lions, and whitetail deer, but black bears, grizzly bears, and grey wolves are no longer found.

Manas National Park

Manas National Park, located in the foothills of the Himalaya Mountains in India, is part forest and part grassland. It is home to a great variety of vegetation and wildlife. To the north is the country of Bhutan, to the south is North Kamrup, and forest preserves are to its east and west. The park includes part of Manas Reserve Forest and all of North Kamrup Reserve Forest. The Manas River runs through it. Manas was declared a wildlife sanctuary in 1928 and upgraded to a

Manas National Park

Location: Western Assam State in eastern India

Area: 125,000 acres (50,000 hectares) Classification: Savanna

National Park in 1990. In 1992, it was recognized as a World Heritage Site in Danger because of heavy poaching and political unrest.

Much of the park is low-lying and flat, ranging in altitude from 100 to 361 feet (61 to 110 meters) above sea level. Summer is warm, lasting from April through June with a maximum temperature of 99°F (37°C). October through March is the chilly season with temperatures falling no lower than 51°F (11°C). The monsoon season lasts from May to September and is fairly warm. Annual rainfall, most of which falls during this season, is 131 inches (333 centimeters).

Many species of grasses and a variety of trees and shrubs are found in the park. In the northern forest region, evergreen and deciduous trees (trees that lose their leaves) grow. Tall, dense grasses used to manufacture paper are an important resource at these lower altitudes.

A few amphibian species and about 30 species of reptiles can be found in the park sanctuary. Reptiles include the vine snake, flying snake, Assam trinket snake, monitor lizard, and roofed turtle.

Hundreds of species of birds live in the park, including the great pied hornbill, the pied harrier, and the spot-billed pelican.

Elephants, hog deer, and tigers are among the more than fifty species of mammals in the sanctuary. The pigmy hog and the rare golden langur, a long-tailed monkey with bushy eyebrows and a chin tuft, rely on the park for their survival.

Eurasian steppes

One of the world’s largest temperate grasslands is the Eurasian steppe, which extends about 5,000 square miles (8,000 square kilometers) across Hungary, Ukraine, Central Asia, and Manchuria. The steppes are bisected (divided) by the Altai Mountains into the western steppe and the eastern steppe. The western steppe stretches from the mouth of the Danube River along the north shore of the Black Sea and across the lower Volga River. The eastern steppe continues to the Greater Khingan Mountain Range. The entire terrain is criss-crossed by rivers and streams.

Eurasian Steppes

Location: Hungary, Ukraine, Central Asia, Manchuria

Area: 5,000 square miles (8,000 square kilometers) Classification: Steppe

In the summer, temperatures average 73°F (23°C) June through August. The winter is cold and the area is covered with as much as 4 inches (10 centimeters) of snow. Average winter temperatures from November to March are below freezing; temperatures average 29°F (-2°C). Annual rainfall for the steppes averages between 10 and 20 inches (25 and 51 centimeters).

The steppes contain some of the most fertile land in the world. Primarily made up of black earth (chernozem), steppe soil is excellent for crops. Most of Russia’s grain, for example, is produced on the steppes.

Native steppe vegetation consists primarily of turf grasses, such as bluegrass, bunchgrass, feather grass, and fescue, as well as mosses and lichens. In the north where there is more moisture, wild tulips, irises, daisies, and sages grow. Fewer flowers grow in the drier southern region.

Common reptiles found on the Eurasian steppe include steppe vipers and whip snakes. Birds include larks, bustards, and kestrels. An unusual bird that comes to the steppes to mate is the demoiselle crane, famous for its mating dance. About 3 feet (0.9 meter) in height, this blue-gray bird is characterized by tufts of feathers on the sides of its head. Birds of prey include hawks, falcons, and eagles.

Burrowing animals, like marmots, steppe lemmings, and mole rats, do well on the open steppes. The spotted suslik, a ground squirrel, lives in underground colonies. Other mammals that live on the steppes include skunks, foxes, wolves, antelopes, muskrats, raccoons, beavers, and silver foxes. Saigas, at one time on the verge of extinction, have recovered and are now found almost everywhere throughout the regions.

For thousands of years people have lived on the steppes, beginning with hunter-gatherers in prehistoric times. Eventually the lifestyle changed to farming and, about 2000 BC, when the horse was domesticated, people began herding animals and moving from pasture to pasture. Conflict between tribes was common until the sixteenth century when the Russians conquered and colonized the area. A few small groups of nomads still make their home on the steppes.

Parts of the steppes are being preserved as national parks and wildlife refuges. For example, the Askaniya-Nova in the Ukraine works to protect endangered species. More than forty different mammals, including the onager (wild ass) and Przewalski’s horse, have been introduced to the park.

Konza Prairie Preserve

The Konza Prairie Preserve in Kansas is a tallgrass prairie, a rich environment that plays host to over 100 ecological research projects at any given time. In addition to grasslands, the Konza area contains streams and a deciduous forest. Wide expanses of tallgrass are broken up by natural depressions in the ground, such as prairie potholes. After the rain, these areas fill up and provide watering holes for animals.

Konza Prairie Preserve

Location: Riley and Geary Counties in Kansas

Area: 8,616 acres (3,487 hectares) Classification: Tallgrass prairie

The Konza climate is temperate, with warm, moist summers and cool, dry winters. Summer temperatures range from 80° to 100°F (27° to 38°C), while winter temperatures can be as low as 10°F (-12°C). Annual average rainfall is 32 inches (81 centimeters).

The most common grass on the Konza is big bluestem. Other grasses include Indian grass, switchgrass, and little bluestem. Forbs such as asters and sunflowers are abundant, while sedges are less common. Many prairie plants once used by Native Americans for food and medicine still grow in the Konza, including wild nodding onion, wild plum, prairie turnip, and prairie parsley.

Of the many different insect species found on the Konza, June beetles, dung beetles, lappet moths, butterflies, and grasshoppers are perhaps the most common.

Few amphibians live on this prairie since there are no natural ponds. Depressions that fill with water and artificial ponds originally built to provide water for livestock do provide homes for some species of frogs, toads, and salamanders. The bullfrog is the most common.

Reptiles roaming the Konza include the western box turtle and the collared lizard. The most common reptile is the Great Plains skink, a type of lizard that can detach its tail when attacked and leave it wriggling on the ground to confuse the predator. A new tail grows in quickly.

The open prairie is home to birds that nest on the ground, such as meadowlarks and mourning doves. Cowbirds have an unusual adaptation to life on the open prairie: they lay their eggs in the nests of other birds, who raise the cowbird babies with their own.

Mammals living in the preserve include a large bison herd and small groups of deer. Many rodents live here, with deer mice being the most plentiful. Voles and shrews, some of the smallest mammals in the world, also make the preserve their home.

The Konza Preserve is as a conservation partnership. Most of it is owned by The Nature Conservancy (an organization that establishes private nature sanctuaries in order to preserve plants, animals, and natural communities) and serves as an outdoor research laboratory run by the Division of Biology at Kansas State University. The area was chosen by the National Science Foundation as a long-term ecological research site.

For More Information

BOOKS

Allaby, Michael. Biomes of the Earth: Grasslands. New York: Chelsea House, 2006.

Grzimek, Bernhard. Grizmek’s Animal Encyclopedia, 2nd edition. Volume 7. Reptiles, edited by Michael Hutchins, James B. Murphy, and Neil Schlager. Farmington Hills, MI: Gale Group, 2003.

Hancock, Paul L., and Brian J. Skinner, eds. The Oxford Companion to the Earth. New York: Oxford University Press, 2000.

Humphreys, L.R. The Evolving Science of Grassland Improvement. Cambridge, UK: Cambridge University Press, 2007.

Luhr, James F., ed. Earth. New York: Dorling Kindersley in association with The Smithsonian Institute, 2003.

Moul, Francis. The National Grasslands: A Guide to America’s Undiscovered Treasures. Lincoln: University of Nebraska Press, 2006.

PERIODICALS

Cunningham, A. “Going Native: Diverse Grassland Plants Edge Out Crops as Biofuel.” Science News. 170. 24 December 9, 2006: 372.

De Silva, José María Cardoso, and John M. Bates. “Biogeographic Patterns and Conservation in the South American Cerrado: A tropical Savanna Hotspot.” BioScience 52.3 March 2002: p225.

Donaldson, Mac. “Corridors for Migration.” Endangered Species Bulletin. 28. 3 May-June 2003: 26.

Flicker, John. “Audubon view: Grassland Protection.” Audubon. 107. 3 May-June 2005: 6.

Hoekman, Steven T, I.J. Ball and Thomas F. Fondell. “Grassland Birds Orient Nests Relative to Nearby Vegetation.” Wilson Bulletin. 114. 4 December 2002: 450.

Kloor, Keith. “Fire (in the Sky): in Less than an Hour, Flames had Reduced Nearly 8,000 Acres of Grasslands to Smoldering Stubble and Ash.” Audubon. 105. 3 September 2003: 74.

Springer, Craig. “Leading-edge Science for Imperiled, Bonytail.” Endangered Species Bulletin. 27. 2 March-June 2002: 27.

ORGANIZATIONS

Environmental Protection Agency, 401 M Street, SW, Washington, DC 20460, Phone: 202-260-2090; Internet: http://www.epa.gov (accessed August 17, 2007).

Friends of the Earth, 1717 Massachusetts Ave. NW, 300, Washington, DC 20036-2002, Phone: 877-843-8687; Fax: 202-783-0444; Internet: http://www.foe.org.

Greenpeace USA, 702 H Street NW, Washington, DC 20001, Phone: 202-462-1177; Internet: http://www.greenpeace.org.

Nature Conservancy, Worldwide Office, 4245 North Fairfax Drive, Arlington, VA 22203-1606, Phone: 800-628-6860; Internet: http://www.nature.org.

Sierra Club, 85 2^nd Street, 2^nd Fl., San Francisco, CA 94105, Phone: 415-977-5500; Fax: 415-977-5799, Internet: http://www.sierraclub.org.

World Meteorological Organization, 7bis, avenue de la Paix Case postale No. 23000, CH-1211 Geneva 2, Switzerland, Phone: 41(0) 22 7308111; Fax: 41(0) 22 7308181, Internet: http://www.wmo.ch.

World Wildlife Fund, 1250 24th Street NW, Washington, DC 20090-7180, Phone: 202-293-4800; Internet: http://www.wwf.org.

WEB SITES

Blue Planet Biomes: http:http://www.blueplanetbiomes.org (accessed September 14, 2007).

Envirolink: http://www.envirolink.org (accessed September 14, 2007). “The Grassland Biome.” University of California Museum of Paleontology. http://www.ucmp.berkeley.edu/exhibits/biomes/grasslands.php (accessed September 14, 2007).

National Geographic Magazine: http://www.nationalgeographic.com (accessed September 14, 2007).

National Park Service: http://www.nps.gov (accessed September 14, 2007).

“Wind Cave National Park.” The National Park Service. http://www.nps.gov/wica/ (accessed September 14, 2007).

Grassland

Grasslands are environments in which grasses and grasslike plants dominate the vegetation. Grasslands once covered up to 25 to 40 percent of the earth's land surface, but many of these grasslands have been plowed for crop production. Prior to the European settlement of North America, the largest grasslands in the United States stretched across the Great Plains from the Rocky Mountains and deserts of the southwestern states to the Mississippi River. Other extensive grasslands are, or were, found in Europe, South America, Asia, and Africa.

Grasslands can be categorized as temperate or tropical. Temperate grasslands have cold winters and warm to hot summers and often have deep, fertile soils. In North America, other names for temperate grasslands include prairies and steppes. Tallgrass prairies in the Midwestern United States receive the most rainfall (75 to 90 centimeters [29.5 to 35 inches]) and are the most productive grasslands with grasses growing to 3 meters (almost 10 feet) in height. Historically, these were most abundant in Iowa, Illinois, Minnesota, and Kansas.

The driest grasslands (25 to 35 centimeters [9.8 to 13.7 inches] of rainfall) are termed shortgrass prairie, or steppe, with grasses seldom taller than 25 centimeters. These grasslands are found in Texas, Colorado, Wyoming, and New Mexico. Temperate grasslands are also called steppes in most of Europe and Asia, veld in Africa, and the pampas in South America.

Tropical grasslands are warm throughout the year but have pronounced wet and dry seasons with annual rainfall amounts of 50 to 130 centimeters (19.6 to 51 inches). Most tropical grasslands have a greater density of woody shrubs and trees than temperate grasslands. Other names for tropical grasslands include velds in Africa, and the compos and llanos in South America.

Grass-dominated ecosystems that contain a significant number of widely spaced trees are termed savannas . Trees may cover 5 to 30 percent of savanna landscapes, but grasses form a continuous ground cover. Africa, Australia, and South America have extensive savannas.

Fire, drought, and herds of large grazing animals are common features in most grasslands, and most plant and animal life is well adapted to these forces. Fires are most common in grasslands with high levels of plant productivity. Fires are important for keeping trees from encroaching into grasslands—many tree species are killed by fire because their active growing parts are aboveground. Grassland plants survive and even thrive after fire because their buds are below the ground and protected from lethal temperatures. Typically, grassland animals are not harmed by fire. Those animals living below the ground are well protected, and most grassland birds and mammals are mobile enough to avoid direct contact with fire.

Years of extreme drought are more common in grassland than in forested areas, and such droughts may kill even mature trees. But grasses and other grassland plants have extensive root systems that help them survive drought periods. The most conspicuous animals in grasslands are large grazers such as bison and antelope in North America and zebras, gazelles, and wildebeest in Africa. Grasshoppers also can be important consumers of plants, but nematodes (roundworms) and root-feeding invertebrates below the ground are actually the most significant consumers of plant biomass in many grasslands.

see also Biome; Tundra

Alan K. Knapp

Bibliography

Archibold, O. W. Ecology of World Vegetation. New York: Chapman and Hall, 1995.

Cole, Monica M. The Savannas: Biogeography and Geobotany. New York: Academic Press, 1986.

Lauenroth, W. K., I. C. Burke, and M. P. Gutmann. "The Structure and Function of Ecosystems in the Central North American Grassland Region." Great Plains Research 9 (1999): 223–259.

grassland Ground covered by vegetation that is dominated by grasses. Grassland constitutes a major world vegetation type and occurs where there is sufficient moisture for grass growth, but where the environmental conditions, both climatic and anthropogenic, prevent tree growth. Its occurrence therefore correlates with a rainfall intensity between that of desert and that of forest, and the range of grassland is extended by grazing and/or fire to form a plagioclimax in many areas that were previously forested. The extensive mid-latitude grassland is known as steppe or prairie, whereas the corresponding tropical vegetation is called savannah.

grassland Ground covered by vegetation that is dominated by grasses. Grassland constitutes a major world vegetation type and occurs where there is sufficient moisture for grass growth, but where the environmental conditions, both climatic and anthropogenic, prevent tree growth. Its occurrence therefore correlates with a rainfall intensity between that of desert and that of forest, and the range of grassland is extended by grazing and/or fire to form a plagioclimax in many areas that were previously forested. The extensive mid-latitude grassland is known as steppe or prairie, whereas the corresponding tropical vegetation is called savannah.

grassland A major terrestrial biome in which the dominant plants are species of grass; the rainfall is insufficient to support extensive growth of trees, which are also suppressed by grazing animals. Tropical grassland (savanna), which covers much of Africa south of the Sahara, has widely spaced trees, such as acacias and baobabs, and supports large herds of grazing animals and their predators. Temperate grasslands, such as the steppes of Asia, the prairies of North America, and the pampas of South America, have few trees and are largely used for agriculture.