Grasslands (teach)


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Grasslands (teach)

  1. 1. There are two kinds of grasslands—temperategrasslands and savannas.• Temperate grasslands: called prairies•Tropical grasslands: called savannasBy Moira Whitehouse PhD
  2. 2. The largest grassland is the savanna in Africa. Thereare temperate grasslands in North America, SouthAmerica, Eurasia, South Africa and northern
  3. 3. In different parts of the world, temperategrasslands are called by different names:•In Eurasia --steppes.•In South America ---pampas•In South Africa --- veldts.•In North America--- prairies.But for this lesson we shall consider them allas prairies and will notice that the plants andanimals that grow and live in each of thetemperate grasslands have much in common.
  4. 4. found the middle of North America.As the sample for our study, let’s usethe North American Prairie:Prairie:
  5. 5. • Prairie land is usually flat.grasses•The most importantplants are(would you believe?)
  6. 6. Rainfall in the prairie is typically pretty low--about 10to 30 inches of rain per year coming more likely in thespring. Lack of precipitation in late summer, fall andwinter along with occasional fires and grazing by largemammals go together to make life a bit challenging forgrasses and very difficult for trees.
  7. 7. Fires used to be common in the temperategrasslands. Before man started fighting thefire, fire regularly swept the prairie.Any shrubs ortrees that lived inopen temperategrasslands areusually destroyedby grass fires.
  8. 8. • Trees growmainly along thebanks of therivers.•Very few treesor bushes growin the temperategrasslands.
  9. 9. Of course, there are many different kinds ofgrasses that grow in the temperate prairie.
  10. 10. Prairie grasses have some special adaptations thatallows them to survive hot dry summers.•How? They have verydeep and extensive rootsystems that can reachdeep down to get water.•And in addition, they havelong, narrow leaves thatlose less water than largerleaves.
  11. 11. Even after a prairie fire, native grasses andcolorful wild flowers called forbs would comeback the next year. How can they do that?
  12. 12. Prairie grasses grow from roots just underground andare not killed when fires burns their leaves and stem.Also these grasses survive animal’s regular munching-- cutting the blades off just at the ground-- because ofthese underground stems and buds .
  13. 13. The prairie grasses’ success, like most otherplants, is dependent on moisture. Where thereis more moisture, the prairie grasses grow verytall.
  14. 14. Where there is less rain, the grasses arelikely to be short.
  15. 15. However someareas are amixture of talland shortgrasses.
  16. 16. Little blue stemCanadawild ryeCommongrasses intheprairies inNorthAmericaBig blue stem
  17. 17. barley.Very little of the originalprairie grasses survivestoday, only one to twopercent. Because prairie soilis deep and fertile much ofthe land is now used togrow grains such as:wheatcorn
  18. 18. Temperatures in the temperate grasslandsvary with the seasons. In some areas wintertemperatures can fall to well below 0 degreesFahrenheit. And in summer, temperatures canreach above 90 degrees Fahrenheit
  19. 19. In winter, thegrasses die and snowblankets the fields ofgrass.The grasses in the prairieare green in spring andturn brown in summerand fall.
  20. 20. Winter snow cover is a good thing in the prairies --it protects the plants from the cold and alsoprovides water in spring when the snow melts.
  21. 21. Grasslands don’t provide much shelter forpredators to hide, and they do provide anabundance of grass for food, so animalpopulations are similar in grasslandsthroughout the world.Mainlyherbivores.
  22. 22. Remember the prairies are large open areas withfew trees, not much shelter and lots of grass forherbivores to eat.Prairie AnimalsThe main animals in the prairies were bison andantelope--plant eating mammals with hooves. Theirlong legs helped them run fast to escape grasslandpredators.
  23. 23. There wereabout 50 millionbison roamingthe plains ofNorth Americawhen peoplefrom Europe firstcame to the newworld.By 1903, most had been killed with fewer than 2,000surviving. These were found in zoos, privately ownedor lived in the wild in Canada or western UnitedStates. Today populations have increased somewhatwith herds living mostly in US and Canadian parks.
  24. 24. Herds of beautiful pronghorn antelope also livedon the North American prairie. There wereabout 50 million before the Europeans came;now that number is down to about one million.
  25. 25. Although huge numbers of individual animalslived on the prairies, there were not manydifferent kinds of animals. Prairie animalsother than bison and pronghorns includerodents like as gophers and prairie dogs, aswell asrabbits, coyotes, birds and insects.
  26. 26. Most prairie animalsare herbivores,however there aresome carnivores andomnivores.Red foxcoyotegarter snake
  27. 27. The Savanna is a grassland with scatteredindividual trees.
  28. 28. Savannas are near the equator so their temperaturesare?Tropical grasslands (savannas) are located near theequator.Thelargestsavannasare foundin Africa.Because they are near the equator, savannas wouldhave definite seasons (spring, summer, fall andwinter)a. hot to warm b. cool to colda. true b. false
  29. 29. Here we see a Savanna scene with tallgrasses, widely scattered acacia trees and grazingzebras.
  30. 30. Climate is the most important factor in creating asavanna. Savannas are always found in warm or hotclimates where the annual rainfall is from about 20-50 inches per yearThe largest part of the tropical savannas mayreceive as much as 50 inches of rain during the sixmonths of the wet season, but as little as 4inches during the dry season.But, the rain does not fall evenly throughout theyear in the savanna. There is a very rainy and avery dry season.
  31. 31. Many grasses and trees of the savannaflourish during the sometime brief wet seasonand then go into a state of dormancy whenthe rains stop. Grasses turn brown and treeslose their leaves to reduce the loss of waterby transpiration.
  32. 32. The acacia tree, shaped like an umbrella, is a notablespecies of the Savanna biome. This interesting treeuses its long tap roots to draw water from deep belowthe surface during the savanna dry season.
  33. 33. Although the acacia tree leaves are leathery, theyare not too leathery for this Giraffe to munch on.In addition, the trees small leathery leaves reducewater loss during the dry season.
  34. 34. The Baobab tree is another remarkable tree commonlyfound in the savanna. Why do you think it has thishuge trunk? storeswater in its trunk during the wet season and uses itduring the dry season...and it can also lose its leaveswhen it’s dry to conserve moisture.
  35. 35. With lots of long grass, the savanna is a perfect placefor large grassing eating herbivores.—more than anyother biome on Earth. Here we see a few of them.elephants giraffesrhinoceros buffalo
  36. 36. impalasgazelles kuduswildebeest zebras
  37. 37. cheetahsleopards civetsAfrican lionsWith lots of herbivores we also find lots of—guess what?yes, carnivores.
  38. 38. hyenas jackalsAfrican wild dog Serval
  39. 39. Many of the animals that live in savannas relyon speed for survival, as the vast open areasprovide little means of escape from quickpredators. If the prey is too slow, it becomesdinner. If the predator is not fast enough, it(and maybe its family) goes hungry.
  40. 40. Camouflage is also very important to animals of thesavanna.Predators need to blend in with their environmentin order to sneak up on unsuspecting prey.On the other hand, prey may use camouflage as adefense mechanism to escape predators.
  41. 41. Notice on this chart, animalherds of the savanna migrateeach year to other areas insearch of food and water.
  42. 42. There we have the savanna, Earth’s other grassland--home to many exotic animals seen on TV and in zoos.