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Soil and Natural Vegetation P. 149 #1-8 1. Describe the four components that make up soil. • MINERALS, which come from rock, become part of the soil when the rock is broken down into smaller particles sand, silt, or clay. Many of these minerals(eg. Calcium, phosphorous, potassium) provide nutrients to plants. • When ORGANIC MATERIALS, ie. Plants and animals, die, they are decomposed by bacteria in the soil. As bacteria breaks down these organic materials, humus is formed. Humus provides plants with nutrients and moisture and gives the soil its dark colour. • Plants need AIR around their roots. Humus helps produce air in the soil because the loose , decaying materials allow for many air pockets. Insects, worms, and small animals that tunnel through the soil also provide air spaces. • MOISTURE, ie. Water, dissolves nutrients in the soil and is taken up by plants through their roots. Moisture is necessary for plant survival and for the chemical and physical processes that weather rock and decay organic materials. 2 a. How is topsoil formed? • It is formed as dead plants, leaves, and animals are decomposed by bacteria. 2 a. How is topsoil formed? • It has taken 6000 to 10000 years to form 15-25cm of topsoil under Canada’s forests and 40 to 100cm under the prairies/grasslands. This is how long it has been since glaciers have retreated 2 c. Why does the topsoil differ in thickness in different parts of Canada? • The creation of soil is related to the influence of climate, which in turn affects the amount of vegetation in a given area. In the cold climates where there is little vegetation. Less material means thinner soil. The opposite is true in warmer climates. 3. Why is the size of rock particles important to soil structure? • Large particles like sand= drain too quickly • Small particles like clay = drain too slowly • Even mix is the best soil. 4. Explain the difference between leaching and calcification. Leaching Calcification - Calcification occurs in areas of - Leaching occurs in areas of dry soil high precipitation - The upward movement of - Leaching process is a water downward movement of water - Water moves up through - Water carries nutrients away evaporation and leaves a mineral residue on the surface 5. In your own words, explain the meaning of the term “natural vegetation”. • Natural vegetation refers to plants and trees that grow without any human interference. 6. There are two classes of trees. Which one can survive in a harsher climate? Why? • Coniferous trees can survive in colder climates than deciduous trees because: long roots extract nutrients from poor soil, Sticky sap keeps needles from freezing, waxy needles and thick bark hold moisture better, needles conduct photosynthesis on warm days past the normal growing season of deciduous 7. Name the Canadian vegetation region which: • Largest – the Boreal and Taiga • Smallest – Deciduous • Wettest – West Coast • Coldest - Tundra 8. Explain, in your own words, the term “transition zone”. • A TRANSITION ZONE is an area where the natural vegetation of one region gradually changes into the natural vegetation of another region.
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