Biosphere Flashcards

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1
Q

soil

A

thin surface layer of the earths crust and the foundation for plant life

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1
Q

underlying bedrock

parent matrial

A

unweathered rock type found at the bottom of the soil

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2
Q

regolith

weathered rock

A

top layer of bedrock which has begun to be broken down by the elements of the weather

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3
Q

mineral matter

A

minerals derived from breaking down of bedrock by weathering

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4
Q

oraganic matter

soil

A

material from decaying organic matter e.g. leaves, plants, roots, organisms

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5
Q

eluviation

A

prcoess of rainwater washing organic matter down through the soil

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6
Q

leaching

A

process of rainwater washing minerals down through the soil

e.g. iron

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7
Q

illuviation

A

process of depositing mineral matter lower down in the soil

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8
Q

capillary action

A

upward movement of water within a soil

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9
Q

soil profile

A

name for a vertical cross section through a soil from the usrface to the underlying bedrock

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10
Q

factors affecting soil formation

A
  • underlying rock type
  • vegetation type
  • finish this card
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11
Q

soil properties

(other than their profile)

A
  • acidity (pH)
  • grain size
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12
Q

typical soil profile

A
  • Ao - organic layer
  • A - topsoil
  • B - subsoil
  • C - regolith (weathered rock)
  • D - parent material (unweathered rock)
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13
Q

podsol

soil profile

A
  • commonly found in taiga (coniferous forest)
  • Ao - partial slow decay of vegetation due to cold climate; trees have shallow roots so dont bring materials up from weathered bedrock; pine needles decompose to form an acidic infertile MOR humus
  • A - high precipitation and snow melt mean leaching takes place and minerals are washed from the topsoil leaving it infertile and grey in colour
  • redisposition of minerals (illuviation) leaves hardpan layer which can sometimes impede drainage making topsoil wet
  • B - reddish-brown layer due to leached minerals being redeposited (illuviation)
  • C - parent material
  • few organisms in soil means very little mixing and therefore distinct layers
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14
Q

brown earth

soil profile

A
  • commonly found in temperate climate zones
  • Ao - deap leaf litter which decays in warm climate to provide a rich fertile MULL humus (moderate rainfall helps this process)
  • A - long tree roots bring up materials from weathered regolith producing fertile topsoil; precipitation > evaporation so some leaching occurs, but minerals remain in topsoil leaving it dark in colour
  • B - the subsoil is also brown in colour due to some leaching of minerals (e.g. iron and aluminium) from the topsoil
  • C - underlying rock type often sedimentary, this weathers easily releasing minerals into the soil
  • no distinct horizons due to presence of biota, well aerated soil
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15
Q

gley

soil profile

A
  • commonly found in tundra climate zones
  • Ao - partially decayed peat like MOR humus - cold climate so slow decay of shrubs and heaths
  • A - heavy rainfall/snow melt leaches minerals out of the soil, leading to a greyish infertile topsoil
  • B - gleying occurs - pore spaces filled with water so lack of oxygen, this means oxygen is taken from iron compounds turning them from a red ferric colour to a grey ferrous colour; some red flecks (mottling) where iron compounds havent been fully broken down - due to small air pockets where reoxygenation takes place when soil dries out in summer
  • C - frozen subsoil/permafrost/high water table (if flood plain) means water cannot drain away leading to waterlogging
  • few organisms due to cool anaerobic conditions so little mixing occurs therefore distinct horizons