OUR GREEN GRASSLANDS

1. OUR GREEN GRASSLANDS BY: Jose Luis [fatt] Maria Flores Yareth Marquez [yarete]

2. WHAT ARE GRASSLANDS? Grasses can survive fires because they grow from the bottom instead of the top. Their stems can grow again after being burned off. The soil of most grasslands is also too thin and dry for trees to survive. Grasslands (also called greenswards) are areas where the vegetation is dominated by grasses (Poaceae) and other herbaceous (non-woody) plants. Grasses came to dominate over other species, such as trees, because they are better able to thrive in hot, dry climates where spring and summer rain is sparse.

3. WHERE ARE GRASSLANDS FOUND? GRASSLANDS ARE FOUND IN ALL THE CONTENENTS EXCEPT ARTANTICA. In Asia and Europe grasslands are known as Steppes. Pampas are what grasslands are called in South America. Grasslands are called Savannas in Africa. In North America, we call grasslands Prairies. Many grassland animals are becoming extinct. Savannah's have two seasons, a dry season and a wet season.

4. TALL GRASSLANDS: The tallgrass prairie of the United States and Canada is divided into three ecoregions: the Central, Northern, and Flint Hills tall grasslands. The Central Tall grasslands cover southern Minnesota, most of Iowa, a small section of eastern South Dakota, and extend as a narrow finger through eastern Nebraska and northeastern Kansas. The Central Tall Grasslands are the most mesic of the grasslands of the central plains (Risser et al. 1981). It can be distinguished from other grassland associations by the dominance of tallgrass species–a feature once relatively uniform across its range–and by the highest levels of rainfall (100 cm/yr).

5. The Central Tall Grasslands is separated from the Northern Tall Grasslands by a much higher diversity of species and by the presence of more northerly species in the Northern Tall Grasslands. The Central Tall Grasslands must have been one of the most visually appealing ecoregions of North America in its original state. Before being settled and converted, it was the largest tallgrass prairie on Earth. The large number of brightly flowering herbaceous plants added greatly to the plant diversity as well as to its physical beauty. Because the Great Plains grasslands attained their current extent only in the post-glacial period, these associations are characterized by very low endemism in plants and animals. Low endemism is also characteristic of adjacent grassland ecoregions. Like other ecoregions of this section of North America, bison and elk once roamed these tallgrass prairies, where they were hunted by the prairie wolf (Canis lupus).

6. MIXED GRASSLANDS: The Northern Mixed Grasslands cross Alberta, Saskatchewan, and southern Manitoba in Canada, and run from North Dakota to northern Nebraska in the U.S., covering about 270,000 km2. Essentially an ecotone, this transitional belt separates the three tall grass prairie ecoregions to the east (Northern, Central, and Flint Hills Tall Grasslands) from the Northwestern Mixed Grasslands. In addition, the ecoregion separates the shortgrass prairie to the south from the cooler boreal forests to the north. This ecoregion is intermediate in growing season length, vegetation structure, and rainfall from the drier units to the west and the more mesic tall grass prairies to the east. It is separated from the Central and Southern Mixed Grasslands by climatic factors, the southern unit having a much warmer climate and a longer growing season. In the Canadian portion of this ecoregion, the mean annual temperature is approximately 3°C, mean summer temperature is 15.5°C, and the mean winter temperature is -10°C. This ecoregion is considered to be a transitional grassland ecoclimate with semiarid moisture conditions.

7. The Mixed Grass prairie was recognized by Clements (1920) as a mixture of the tallgrass and shortgrass prairies. The dominant grasses found here include grama(Boutelouagracilis), little bluestem (Schizachriumscoparium), needle-and-thread grass (Stipacomata), wheatgrass (Agropyronsmithii), Carexfilifolia, junegrass (Koelariacristata), and Poasecunda. Kuchler (1964) classified the dominant vegetation as wheatgrass-bluestem-needlegrass. The ecoregion provides continentally significant waterfowl production and is a major staging area. It is estimated that up to 80 percent of the wetlands, however, have been lost or degraded. The Cypress Uplands (Alberta/Saskatchewan), which are believed to have escaped the last glaciation, are located in this ecoregion. A large number of disjunct species populations of both flora and fauna are found here.

8. SHORT GRASSLANDS: The Northern short grasslands is the largest grassland ecoregion in North America, covering almost 640,000 km2. This ecoregion covers parts of southeastern Alberta and southwestern Saskatchewan, much of the area east of the Rocky Mountains, central and eastern Montana, western North and South Dakota, and northeastern Wyoming. Two environmental gradients determine species composition in mixed and shortgrass prairies: increasing temperatures from north to south and increasing rainfall from west to east. With increasing latitude, the shortgrass prairies take on an aspect more similar to mixed-grass such as in this ecoregion, where many cool-season species predominate.

9. The Northern short grasslands are surprisingly rich in mammals for an ecoregion so far north. Much of the bird fauna is composed of species typically associated with the prairie potholes: ferruginous hawk (Buteoregalis) and Swainson's hawk (Buteoswainsoni), golden eagle (Aquila chrysaetos), sharp-tailed grouse (Tympahuchusphasianellus) and sage grouse (Centrocercusurophasianus), mountain plover (Charadriusmontanus) and clay-colored sparrow (Spizellapallida). Black-tailed and white-tailed deer (Odocoileushemionus and O. virginianus), bobcat (Lynx rufus) and cougar (Felisconcolor) are typical large mammals. Short-horned lizard (Phrynosomadouglassi) and western rattlesnake (Crotalusviridis) occur here as well.

10. ANIMALS ADAPTATIONS: The animals that live in grasslands have adapted to dry, windy conditions. There are grazing animals (that eat the grass), burrowing animals, and their predators; insects are abundant. A moderate of level species diversity exists on a grassland. Some animals, such as bison, have broad, flat-topped teeth and digestive systems especially adapted to feed on grasses. Many prairie animals have front legs and paws that allow them to burrow into the ground, where they are protected from predators. Many prairie animals are adapted for nocturnal life; that is, they are active at night, which helps conceal their presence from predators. The color of many prairie animals blends in with the plant life, which also helps them hide from predators.

11. GRASSLANDS ANIMALS: Grasslands are full of life, with many animals that rely upon the abundant resources of grasslands to provide them with food, shelter and a place to reproduce. Deer, for example, are frequently found grazing on grasses and they are one of the few mammals that has the ability to digest grass leaves. There are also many small mammals that specialize in eating grass seeds, especially mice and voles (voles resemble mice but do not have a long tail tail). Rabbits are also common in grasslands and this abundance of rabbits, mice and voles makes grasslands ideal hunting grounds for birds of prey, also known as 'raptors', that patrol these habitats for signs and sounds of small mammals. The best-known example of a herbivorous grassland insect is the Monarch Butterfly (Danausplexippus), which feeds on plant leaves as a larva and plant nectar as an adult, particularly that of milkweeds (Asclepsias sp.). Grasslands and meadows are very important Monarch habitats because these feeding grounds help them build up energy for their long journey south to Mexico, which is their primary winter home.

12. ZEBRAS: Zebras are equids - members of the horse family (Equidae) and are medium sized, odd-toed ungulates. Zebras are native to southern and central Africa. Although zebras are very adaptable animals as far as their habitats are concerned, most zebras live in grasslands and savannas. The Grevy's zebra (Equusgrevyi) prefers to live in sub desert and arid grasslands. Zebras have excellent hearing and eyesight and are capable of running at speeds of up to 40 miles per hour. Zebras bodies are well adapted to their surroundings. Zebras have long, thin legs for ease of movement and quick, efficient escapes from predators.

13. ELEPHANTS: There are elephants that live in Africa and elephants that live in Asia. African elephants are bigger than Asian elephants and have larger ears. Asian elephants have smaller ears because they live in forests, and big ears would get torn in the branches. In Africa there are elephants that live on the savannah, or grasslands, and elephants that live in the tropical forests. Some elephants have tusks, which are big front teeth. The tusks help the elephant pick up food and help the animal protect itself. The bottom teeth are inside the elephant's mouth and are used to chew food. Elephants eat large amounts of leaves, grass, fruit and bark. They drink lots of water each day.

14. CHEETAH: Cheetahs live on the grasslands of eastern and southern Africa. These big cats have yellow fur with dark spots. Their faces have a dark line from each eye to the corners of their mouths. We think this helps them see across the grasslands in the hot sunshine: the dark fur works like sunglasses to stop the glare. Cheetahs are the smallest of the big cat group. They do not roar, but make a chirping sound. Cheetahs generally live alone. Sometimes brothers from one litter may stay together when they are grown up, and then they hunt as a team and can chase bigger prey such as zebra. Female cheetahs are  always alone, except for their cubs. Usually three or four cubs, sometimes more, are born in one litter.  The mother must continue to eat so that she has milk to feed them, and so she must hide them and leave them for long periods while she hunts.

15. GRASSLANDS PLANTS: Grasses are adapted to hot, dry areas: they have long, narrow leaves that lose less water than larger leaves do and their root systems are extensive and deep so that they can acquire water even during drought conditions. Most grasses are in the family Poaceae and share the grass characteristics of narrow, linear leaves. They often have inconspicuous flowers and rhizomes or stolons (creeping roots or stems) and many have silica throughout their tissue. Silica is what sand is mainly composed of and it makes grass strong and hard to chew and digest. They are very strong growers, accumulating a large amount of biomass each growing season, and their seeds are dispersed by wind or animals. While not as linear as grasses, grassland 'forbs' still have a very upright form in order to compete for sunlight. By growing close together. this form allows grassland plants to support each other's tall, narrow structures.

16. SAVANNA: Savanna is grassland with scattered individual trees. Savannas of one sort or another cover almost half the surface of Africa and large areas of Australia, South America, and India. Climate is the most important factor in creating a savanna. Savannas are always found in warm or hot climates where the annual rainfall is from about 50.8 to 127 cm per year. If the rain were well distributed throughout the year, many such areas would become tropical forest. Savannas which result from climatic conditions are called climatic savannas. Savannas that are caused by soil conditions and that are not entirely maintained by fire are called edaphic savannas. These can occur on hills or ridges where the soil is shallow, or in valleys where clay soils become waterlogged in wet weather. A third type of savanna, known as derived savanna, is the result of people clearing forest land for cultivation. Farmers fell a tract of forest, burn the dead trees, and plant crops in the ashes for as long as the soil remains fertile.

17. STEPPE: The steppe grassland is usually found in areas of the world which are less prone to moisture. Steppe vegetation is well suited to this drier climate, and the grass is generally shorter than that which is found on prairie grasslands. Animal life on the steppe is comprised of grazing mammals such as the antelope, and a wide variety of burrowing mammals such as ground squirrels and ferrets. Steppes are virtually semi-arid deserts in the making, and are highly threatened by overgrazing.

18. PRARIES: Prairies are generally humid and are densely covered in tall grass.  There are very few trees on prairies, most of them usually found on hill slopes or more humid near springs and rivulets.  The prairie soil is rich in nutrients and is ideal for the growth of plant life, which is why prairie regions have been exploited by farmers for centuries.  Grazing animals such as oxen and bison who fed on the prairie grass were also exploited by humans, with the bison being driven to near extinction by hunters.

19. HUMAN IMPACT IN GRASSLANDS: Human had caused a lot of changes to the landscape of and the animals in grasslands since a long time ago. Large areas of grassland have been turned into farmlands for growing crops and for rearing cattle. Sometimes, fires are started by human and they spread quickly through grasses and damage the soils. Moreover, a large number of animals have been hunted for their valuable body parts. For example, elephants were shot for their tusks, lions were killed for their fur and bison were hunted for their meats. Many animals were hunted to near extinction such as the bison and buffaloes. Fortunately, the hunting of these animals had been banned. Today, only about 1% of grasslands is officially protected but governments are now more aware of this issue. In some places, national parks are set up to preserve the grasslands and grasses are replanted in some other places where grasses have been cleared for farming. This increasing awareness is certainly necessary in protecting the grassland biome.

20. REFERENCES: http://www.blueplanetbiomes.org/grasslands.htm http://www.enchantedlearning.com/biomes/grassland/grassland.shtml http://www.marietta.edu/~biol/biomes/grass.htm http://www.ucmp.berkeley.edu/exhibits/biomes/grasslands.php http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/tempgrass/tempgras.html http://library.thinkquest.org/11353/grassland.htm http://www.hamiltonnature.org/habitats/grasslands/grass_plants.htm http://www.buzzle.com/articles/grassland-biome-animals-and-plants.html http://www.hamiltonnature.org/habitats/grasslands/grass_animals.htm http://www.blueplanetbiomes.org/savanna.htm