Temperate Grasslands


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Produced by Michael G, former colleague. Good outline of temperate grasslands, with some Google Earth images of the steppes.

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Temperate Grasslands

  1. 1. Grassland Biomes location, structure and functions
  2. 2. <ul><li>The 8 major biomes of </li></ul><ul><li>the world </li></ul>
  3. 3. The temperate grassland biome Prairies of North America Pampas of South America Veldt of South Africa Russian / Mongolian Steppes Australian Bush Canterbury Plains, NZ
  4. 4. Steppe terrain in Russia and Mongolia <ul><li>Undulating land dominated by grasses </li></ul><ul><li>Large trees and shrubs are mainly absent </li></ul>
  5. 5. Steppe climate What do you think the general climate is like throughout the year and why? (think about factors such as latitude) Cool temperate climate for steppe grasslands (warm temperate climate for Veldt)
  6. 6. Steppe climate <ul><li>What annual temperature range would you </li></ul><ul><li>expect and why? (think about factors such as </li></ul><ul><li>continentality) </li></ul>Mean annual temperatures ranging from –15 in winter to +20 in summer. Continental interior results in low temperatures during winter.
  7. 7. Steppe climate <ul><li>How important would you think precipitation is </li></ul><ul><li>for grassland biomes? Why? Would they be </li></ul><ul><li>high rainfall biomes? Why / why not? </li></ul>Precipitation is a dictating factor on grassland biomes and grass type – more rain generally means taller grasses. Low precipitation (not enough for trees) of around 250-500mm per year. More precipitation in western steppe than in east as there are less rain-bearing winds. 75% of all precipitation falls during the summer months.
  8. 8. Typical Steppe climate graph
  9. 9. <ul><li>What problems could this factor of low precipitation bring? </li></ul>Steppe climate Threats of drought and fire.
  10. 12. Temperate grassland soils <ul><li>Chernozem (black earth) type </li></ul><ul><li>Very d eep , dark in colour with fertile upper layers </li></ul><ul><li>Nutrient rich from decay of surface matter in winter and due to decay of deep, wide-branching roots – especially important for recycling of Ca. </li></ul><ul><li>Approx 2m-deep grass rooting system helps keep the soil structure stable and intact (tightly-knit ‘sod’) reducing soil erosion and protecting underground stems and buds from winter frost and snow . </li></ul><ul><li>Roots reach right down to the water table so there is a net upward movement of water . </li></ul><ul><li>Ideal soils for farming but prone to wind erosion if ecosystem balance is not maintained. </li></ul>
  11. 13. A Horizon 0-50cms Organic matter on top. Strong drying action by winds. Crumbly black topsoil. Matted, random root network with accumulation of mull humus and bases Ca, Ng, Na, K and some Fe, Al and Si. Grasses extract and return minerals. Many biota such as earthworms – nutrient mixing and aids drainage . B1 Horizon 50-100cms Fine vertical roots. Slight leaching of nutrients especially after spring snow melt and summer storms. Loess B2 Horizon 100-160cms Calcification occurs - nodules of CaCo 3 form. Loess C Horizon 160-200 cms weathered parent rock Lime-rich parent rock 200cms
  12. 14. Last lesson … <ul><li>Where are the major areas of grassland biomes to be found? </li></ul><ul><li>In terms of climate, what type of biome is Steppe? </li></ul><ul><li>What did we find out about the climate in the Steppe biome? </li></ul><ul><li>What type of soil is generally found in this area? </li></ul><ul><li>Are these soils infertile? Why / Why not? </li></ul>
  13. 15. Why no trees? <ul><li>Thick grass cover – prevents tree seeds from taking hold. </li></ul><ul><li>Low precipitation inhibits tree growth. </li></ul><ul><li>Fire destroys any trees that may take hold – underground stems and buds of perennial grasses not affected by fire (as opposed to trees and shrubs that have above-ground stems and buds). </li></ul><ul><li>Grazing animals quickly destroy emerging shrubs and sapling trees. </li></ul><ul><li>Grasses are hardy and quick growing. </li></ul>
  14. 16. Steppe biodiversity <ul><li>Low flora and fauna </li></ul><ul><li>diversity when compared </li></ul><ul><li>with tropical grasslands </li></ul><ul><li>such as savanah. </li></ul><ul><li>Blue gramma and buffalo grass </li></ul><ul><li>Sagebrush and speargrass es </li></ul>
  15. 17. Flora What advantages do you think these grasses have for survival in the environment that they live in? <ul><li>Narrow, spine-like leaves </li></ul><ul><li>Waxy or downy surfaces </li></ul><ul><li>Long, water-seeking roots </li></ul><ul><li>Below-ground stems and buds </li></ul><ul><li>Seeds easily dispersed by wind </li></ul><ul><li>Some grasses and their seeds release inhibitory chemicals </li></ul>
  16. 18. F auna <ul><li>Lower biodiversity than </li></ul><ul><li>tropical grasslands … </li></ul><ul><li>Small mammals </li></ul><ul><li>(mainly rodents) </li></ul><ul><li>Gophers </li></ul><ul><li>Rabbits </li></ul><ul><li>Foxes </li></ul><ul><li>Other mammals </li></ul><ul><li>Goats, antelope </li></ul><ul><li>Horse </li></ul><ul><li>Also </li></ul><ul><li>Reptiles </li></ul><ul><li>Birds </li></ul><ul><li>Many insect varieties </li></ul>
  17. 19. GPP and NPP in temperate grasslands <ul><li>Gross primary productivity is the amount of energy trapped in organic matter during a specified interval at a given trophic level. </li></ul><ul><li>Net primary productivity is the amount of energy trapped in organic matter during a specified interval at a given trophic level less that lost by the respiration of the organisms at that level. </li></ul>
  18. 20. <ul><li>Tropical rainforest – 15000 Kcal/m 2 /yr </li></ul>Comparative NPP rates in different biomes Temperate forest – 5000 Kcal/m 2 /yr Temperate grasslands – 2000 Kcal/m 2 /yr Desert – 500 Kcal/m 2 /yr
  19. 21. <ul><li>Nutrient Cycling </li></ul><ul><li>In addition to energy, ecosystems also contain cycles of nitrogen and other plant nutrients, such as phosphates and potassium. </li></ul><ul><li>The pattern of plant nutrients can be shown as a diagram. Nutrients are derived from weathered rock or in dissolved in rainfall and they may be lost from the system by leaching , in runoff or through harvesting of crops. </li></ul><ul><li>Most nutrients are recycled within the system through plant uptake , leaf fall (and other “ fallout ” from plants and animals) and decomposition . </li></ul><ul><li>Nutrients are stored in the biomass , the litter and the soil in variable quantities depending on the type of ecosystem and seasonal changes. </li></ul>
  20. 22. Mineral recycling
  21. 24. Tropical rainforest Steppe nutrient storage nutrient storage L B S B L S
  22. 25. S B L Input dissolved in rainfall Release as litter decomposes Uptake by plants Loss in runoff Fall out as tissues die Input weathered from rock Loss by leaching