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Chapter 8
The Biosphere
The Biosphere
The Biosphere is the layer of the Earth
containing organisms and their habitats.
Biogeochemical Cycles

A set of processes by which an element
pass from one environment to the next
and eventually returns to its original
environment, in a never-ending loop.
Biological – respiration, digestion
 Geological – rock erosion, sedimentation
 Chemical – combustion

Carbon Cycle
Carbon is often described as the building
block of life, since it is the basic element
of proteins, lipids and carbohydrates, and
thus all living things.
 Carbon is constantly being exchanged and
recycled through different parts of the
Earth.
 The carbon cycle is the biogeochemical
cycle involving all of exchanges of carbon.

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Stages of the Carbon Cycle
Photosynthesis: plants and phytoplankton
take in carbon dioxide (CO2) from the
atmosphere and use it to make sugars.
 Ingestion: Eat to take in carbon
 Respiration: both plants and animals
release carbon dioxide back into the
atmosphere when they breathe.
 Decomposition: organisms called
‘decomposers’ break down dead organisms
and animal waste, releasing CO2 or methane
in the process.


Forest Fires: trees and plants are
composed of carbon and upon
combustion release CO2

Ocean Sediment:
Carbon dioxide from
the atmosphere
dissolves in oceans to
form calcium
carbonate. This is used
by marine organisms to
create their shells and
skeletons, which sink to
the ocean floor when
they die, and
accumulate in the
sediment, eventually
forming carbonate
rock.
Volcanic eruptions:
Carbonate rock melts on
contact with magma and is
released back up during an
eruption.
 Fossil fuels: When dead
plant and animal matter
accumulate and are buried
under sediment, they are
converted into oil, coal or
natural gas after millions
of years. The burning of
these fossil fuels by
humans releases carbon
dioxide into the
atmosphere.

Nitrogen Cycle

The nitrogen cycle is the biogeochemical
cycle involving all of exchanges of
nitrogen.
Nitrogen Cycle
Nitrogen is used by living organisms to produce a
number of complex organic molecules like amino
acids, proteins and DNA.
 The vast majority of nitrogen is found in the
atmosphere, as N2, which cannot be directly used
by plants or animals
 As a result, nitrogen is normally the most
limiting nutrient for plant growth.
 The nitrogen cycle converts atmospheric nitrogen
into two solid forms, ammonium ion (NH4+ ) and
nitrate ion (NO3- ), which can then be taken up
by plants.

Stages of the Nitrogen Cycle

Nitrogen fixation: certain bacteria in
soil or water can convert N2 into
ammonia (NH3), which is then converted
to ammonium (NH4+) by reacting with
hydrogen.
Stages of the Nitrogen Cycle

Decomposition of waste:
decomposers break down dead organisms
and animal waste, producing ammonia
which dissolves to form ammonium.
Stages of the Nitrogen Cycle

Nitrification: bacteria convert
ammonium into nitrites (NO2-), then into
nitrates (NO3-).
Stages of the Nitrogen Cycle

Nitrogen absorption (Assimilation):
plants absorb nitrates or ammonium from
soil or water and use it to create
proteins. Animals can then get their
nitrogen by eating the plants.
Stages of the Nitrogen Cycle

Denitrification: certain bacteria can
convert nitrates into atmospheric
nitrogen.
Biomes

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Terrestrial Biomes

Biome: A large naturally occurring
community of flora and fauna occupying a
major habitat.
Factors affecting Terrestrial Biomes
Latitude
 Altitude
 Temperature
 Precipitation
 Soil type
 Solar energy
 Winds
 Proximity to bodies of water

Climate- Temperature
Temperature plays a vital role because most
organisms are adapted to live within a very
narrow temperature range. Increasing or
decreasing the temperature by even a few
degrees can cause some species to die.
 The main factors which influence temperature
are:
1. Latitude: as you move away from the equator,
there is less sunlight, and therefore a lower
temperature
2. Altitude: with increases in elevation at a given
latitude, the temperature tends to decrease

Climate- Precipitation
Precipitation plays a vital role because all living
organisms require water.
 Precipitation tends to be generally lower:
◦ near 30 o N & S latitude- dry, descending air masses
produce deserts
◦ in interiors of large continents- due to great distance from
sea (ultimate source of most moisture)

Precipitation tends to be generally higher where air is
rising & cooling, releasing moisture it contains:
◦ near the equator, most significantly- produces tropical
rainforests
◦ at 60o N & S latitude, to lesser extent- produces
temperate deciduous forests, temperate rainforests,
coniferous forests
The great world deserts lie near 30 o N or S latitude
Terrestrial Biomes: Can you name
these?
Arctic Tundra
Tropical Rainforest
Boreal Forest
Desert
Desert
Tree types

Deciduous: trees that lose their leaves
seasonally (maple)

Evergreen: Do not lose leaves
 Coniferous: grow cones to carry seed, triangular in
shape, needles or flat scales (pines)
Tropical Forests
Lie on either side of equator (warm
temperatures 20-34ºC)
 High precipitation
 Contain over half of the world’s
terrestrial biodiversity
 Seasonal or evergreen forests

Boreal Forest/Taiga





Composed mostly of coniferous trees,
which do not lose leaves/needles
Forest floors covered in moss and
lichen
Acidic, nutrient poor soils
Long cold winters, long summer days
Much of Canada
Temperate Forests




Contain mix of deciduous and coniferous trees
Nutrient rich soils make an excellent habitat for
plant growth and animals
High precipitation , avg. Temp. of 8-10ºC
Montreal!
Grasslands/Shrublands
Dry, without enough rainfall to support much tree
growth, but enough for grasses and shrubs
 There are three different types:

◦ Temperate grasslands –hot summers, cold winters
◦ Savannas- hot year-round
◦ Derived grasslands- farmer’s grain or grass fields (replaced
original natural grasslands over centuries
Arctic Tundra
Surrounds the North Pole, with long, cold
winters and short summers.
 Characterized by slow plant growth and
extensive permafrost
 Grasses, bushes, moss and lichens
 Some fauna: caribou, arctic fox

Deserts
Defined as areas with less than 25cm of
annual precipitation
 Very high or very low temperatures (ex.
Antarctica)
 Rare plant life and very few animals, which
have adapted to desert life

Alpine
Biomes that are found on mountain ranges
 As altitude increases, temperature decreases,
which changes vegetation:

◦
◦
◦
◦
◦
Submontane zone (below 1300m): deciduous trees
Montane zone (1300-1800m): deciduous/coniferous trees
Subalpine zone (1800-2400m): some conifers
Alpine zone (above 2400m): few bushes and grasses
Nival zone (above 3000m): below freezing point, only some
lichen can grow here
Aquatic Biomes
Cover 75% of Earth`s surface
Fresh water (salinity <.05%) and
marine (salinity >3%)


Factors affecting Aquatic Biomes
Salinity
 Temperature
 Water depth
 Direction and strength of current
 Turbidity (water clarity)
 Solar energy
 Nutrient availability
 Presence of oxygen and carbon dioxide

Freshwater Biomes
Lakes
 Bodies of water surrounded by land.
 Flora/Fauna consists of microorganisms,
plants, plankton, fish, amphibians, reptiles
and birds
Freshwater Biomes
Rivers
 Drainage channels for surface water.
 Plants must be adapted to the current and
highly oxygenated water (mostly types of
moss and grass).

In Quebec, water quality of rivers has
been on the decline due to industrial and
agricultural activities

Contaminated with phosphorus

Laws have been passed to protect
watersheds by reducing contaminants and
water waste
Freshwater Biomes
Wetlands (14% of Canada)
 Areas permanently or
temporarily covered with
water
o
o
o
Marshes: land covered with
stagnant water, without trees.
Swamps: land covered with
water but with trees or
shrubs.
Peat Bogs: poorly drained soil
covered with moss.
Marine Biomes
Estuaries
 The broadening at the mouth of a river
that empties into the sea.
 Fresh water mixes with salt water.
 Belugas, oysters, sponges
Marine Biomes
Oceans and Seas
 Have a wide variety of living conditions,
depending on depth:
◦ At the surface – phytoplankton act as indirect
food for fish, jellyfish, crustaceans, mammals, birds.
Marine Biomes
Oceans and Seas

Ocean floor – home of the benthos, the mollusks,
crustaceans and bottom feeding fish which eat dead
organisms on the ocean floor
>200m below surface –
not enough light for
photosynthesis (no plants),
but can still find species of
fish, eels, squid and octopus
o
Marine Biomes
Coral Reefs
 Are made of organisms called corals, which
have a hard calcium carbonate based shell.
 The habitat supports huge amounts of
biodiversity, offering food and shelter to
numerous aquatic organisms.
 Threatened by global warming, pollution,
overfishing.
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