Soil and Productivity
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Importance of Soil
• Soil: the layer of material that covers the land
– Where plants anchor and grow
– Made of weathered rock, decomposing plant and
animal matter
– Has spaces for air and water movement
– Soils differ in organic content which effects the
ability to support plant life.
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Layers of composition
• 3 major types of soil
–
–
–
–
Horizon A: Topsoil
Horizon B: Subsoil
Horizon C: Parent Rock
Horizon D: Bedrock
• Each layer has different
characteristics
depending on where it
is found.
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Grasslands
• Horizon A is deep and
supports root growth;
small particles of rock
mixed with decaying plant
and animals (Humas).
• Horizon B is the subsoil
(mix of dirt and rock).
• Horizon C is mostly large
pieces of rock.
• Horizon D is bedrock solid
rock.
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Forest
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Deserts
• Horizon A: limited plant
growth so little
decomposition, so thin
top soil or none at all.
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Disturbing soils
• Soils change over time
naturally
• Human impact:
deforestation leads to
increased erosion of
topsoil (no roots to hold
soil in place)
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Feeding the Human Population!
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Productivity of Ecosystems
• Ecosystems have different productivities,
based on light availability, soil types,
precipitation, temperature, nutrients.
• Productivity: the quantity of biomass of plants
produced each year on a given area (g/m2)
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Productivity of different ecosystems:
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Sustaining life
• Biotic: living part of the
environment. Ex: plants
and animals
• Abiotic: non-living part
of the environment. Ex:
elements, air, and
water.
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The key events - respiration and photosynthesis
• Respiration takes
carbohydrates and
oxygen, combines
them to produce
carbon dioxide,
water, and energy.
•Photosynthesis takes
carbon dioxide, water and
energy to produce
carbohydrates and oxygen.
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