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Soil
and Natural
Vegetation
SOIL
• SOIL: surface layer of the earth,
composed of mineral and
organic materials, air , and water
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SOIL
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• True soil consists of 4 main
parts:
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1. Minerals,
2. Bacteria and Organic Material
3. Air
4. Moisture
• If one of these parts is
missing, the material cannot
be considered soil
COMPONENTS OF SOIL
Minerals
• The minerals in soil come from rock,
known as the parent material.
• Rock is broken down by weathering
into smaller particles of sand, silt,
and clay.
• Many minerals are nutrients needed
by plants for growth. e.g. calcium,
potassium, etc.
Bacteria & Organic
Materials
• When plants &
animals die, they
are decomposed by
bacteria in the soil.
• As bacteria break
down the organic
matter, nutrients are
released.
Bacteria & Organic
Materials
• Decaying organic materials form humus
which provides nutrients and moisture for
plants
• HUMUS: Dark, upper layer of soil made up
of partially decayed plant material
• The process of decay is nature’s way of
recycling nutrients
• Humus gives the soil its dark colour
Air
• Air is found in all soils
usually in between soil
particles
• Plants need air around
their roots
• Air spaces also created
by insects / worms and
small animals that
tunnel through the soil
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Moisture (Water)
• Water dissolves nutrients in the soil and
is then taken up by plants through their
roots
• Helps weather rock and decay
organic materials
ANIMALS
• Not an essential component of true soil
but few soils exist w/o them (worms,
mice, insects, etc.)
• Helps distribute soil particles and
nutrients & provide pathways /
openings for water and air
• Add organic material to the soil after
they have died.
Soil Profile
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• O/A - TOPSOIL -this top
layer contains humus. It is
rich in organic material. It
is dark brown/black in
colour
• B-SUBSOIL- combines
minerals and organic
layers
• C- PARENT MATERIAL mineral materials from
which soil is made.
Usually bedrock or glacial
Soil Formation
Two processes contribute to soil
formation:
• LEACHING
• CALCIFICATION
Leaching
• Is a continual downward movement
of water through the soil
• As the water moves down, it
dissolves the chemical nutrients and
carries them away
• This downward movement removes
nutrients that plants need
• You can identify leached soil by its
poor, often thin, topsoil layer
• Leached soils can be developed into
excellent farmland by adding
fertilizers
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Calcification
• Occurs in dryer climates
• As water in the topsoil evaporates, water from
below is drawn up to replace it - CAPILLARY
ACTION
• As the water reaches the surface, it
evaporates leaving behind the minerals that
were dissolved in it
• The result is a thick topsoil layer, rich in
minerals
• Calcium is the main mineral deposited
• near the surface
• In very dry climates the amount of mineral
deposits can be poisonous to plants
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Vegetation
Regions
Natural
Vegetation
Natural Vegetation - refers to
those plants that grow without
any human interference
Natural Vegetation
There are seven natural vegetation regions
across Canada:
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TUNDRA
BOREAL AND TAIGA FOREST
MIXED FOREST
DECIDUOUS FOREST
GRASSLANDS
CORDILLERA VEGETATION
WEST COAST FOREST
TUNDRA
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• It is located above the tree line
• Climate is cold and dry so trees
do not grow
• It has permafrost
• Only the active layer (top metre or so of
permafrost, thaws during the short summer
• Small shrubs, mosses, and lichen grow close
to the ground
• Little humus is found in the Tundra’s
thin layer of soil
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BOREAL and TAIGA FOREST
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South of the Tundra is the Boreal and Taiga forest
It is the largest vegetation region in Canada
Coniferous (evergreens) trees grow here
The needles are acidic, so they make the soil
acidic
• The lack of humus, the high acidity and the
leaching make these soils infertile and unsuitable
for agriculture
• White and black spruce, balsam fir, and pine
grow sparsely along the northern edge of the
boreal forest
• They are harvested by pulp and paper and
lumbering companies
BOREAL and TAIGA FOREST
Coniferous trees can withstand the harsh,
northern conditions because:
• They extract nutrients from the poor soil with
their long roots
• Sticky sap acts like anti-freeze
• Waxy needles and thick bark prevent
the loss of moisture
• The needles and flexible branches
shed snow
• The needles conduct photosynthesis
on warm days
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Mixed Forest
• South of the Boreal forest in eastern Canada
• Mixed forest of coniferous and deciduous trees
• Spruce, fir, pine, cedar and hemlock, maple, beech,
ash, oak and birch
• Excellent resource for the lumbering industry
• It is a transition zone between the Boreal forest to
the north and the deciduous forest to the south
• Humus is created because of all
the leaves
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are suitable for farming
Deciduous Forest
• Only deciduous forest in Canada is found in
southwestern Ontario
• Only small remnants remain because it has
been cleared for farming and urban
developments
• These trees need at least five months of
warm weather
• Soils are similar to those of the
mixed forest but contain more
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• The most fertile soils of eastern
Canada
Grasslands
• The grasslands, or prairies, are
located in the southern part of
Manitoba, Saskatchewan,
and Alberta
• Climate is too dry for most species
of trees to survive
• Aspen, willow, and spruce grow in river valleys
• Grass is suited to this dry climate - grass dies
off on the surface, but its roots remain alive
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Grasslands
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• Short grasses, sagebrush and cactus are the
only types of vegetation which can survive
here
• The land can be used for grazing animals,
particularly cattle
• The long grass prairie is ideal for growing
grains and oil seeds
• Rich black soil is created from humus grasses die
Cordillera
Vegetation
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• Vegetation varies
• Temperatures are warmer in the valleys than
in the mountains
• Grasses and cactuses grow in the dry, hot
valleys and soils are similar to the prairie
grasslands
• Vegetation changes with altitude
• Forests of coniferous trees grow on lower
slopes
• The vegetation on the higher slopes of the
mountain ranges is similar to that of the
tundra
West Coast Forest
• Along the West Coast of Canada grow lush
forests of Douglas Fir, spruce, red cedar, and
western hemlock
• Heavy rainfall and mild climate provide
excellent growing conditions
• Trees have played a crucial role in B.C’s
forest industry
• The lush vegetation provides
a lot of plant material to
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