3.1 How Changes Occur Naturally in Ecosystems

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3.1 How Changes Occur Naturallyin Ecosystems

• When an organism is born, it belongs to a
  species,
• but it also is born with unique characteristics.
• Like humans with different coloured eyes and
  different heights.
• Sometimes, these unique characteristics give that
  individual an advantage within their niche. ie, a
  salmon with a slightly larger tail may be able to
  swim a little faster or a little farther in a
  river.
• Natural selection is the process where
• individuals with advantages are better able
• to reproduce and pass along their traits.
• Those with unfavourable characteristics have
• less chance to reproduce and pass along their
  traits.
• A salmon with a smaller tail may never have a
  chance
• to spawn because it cant swim to the correct
  location.

See pages 108 - 109
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How Organisms Adapt to Change

• The Galapagos Islands, off the coast of Ecuador,
  are perhaps the most famous example of natural
  selection.
• Many species on these islands are very similar to
  each other,
• and also to species on the South American
  continent.
• There are thirteen species of finch on the
  islands.
• Each is descended from a finch species from the
  mainland.
• Each species has very unique characteristics that
  allows
• them to thrive in their own niche, and not
  compete with
• other finches for resources.
• Adaptive radiation is the term for this type of
• natural selection.
• Many different species appear from one original
  species.

Galapagos finches
See page 110
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Adaptive radiation

• Darwins finches on the left.
• Ancestors of an ancient dinosaur on the right.

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How Ecosystems Change Over TimePrimary
Succession

• Ecological succession refers to the changes in
  the biotic characteristics in an area over time.
• Over time, the life in an area changes
• There are two types of ecological succession
• primary succession and secondary succession.
• Primary succession - begins with nothing but bare
  rock
• Where glaciers scrape away dirt, or a volcano
  erupts
• Wind carries spores of lichens and organisms that
  can survive and eventually, combined with the
  weathering of rock, help form soil.
• The first organisms to survive and reproduce are
  pioneer species.
• Pioneer species alter the abiotic and biotic
  environment in some way.
• Soil improves, plants are able to grow, animals
  begin to appear.
• Primary succession occurs in this way in all
  parts of the world.
• This stage can last for hundreds of years,
• until a mature community eventually forms.

See pages 111 - 113
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How Ecosystems Change Over TimeSecondary
Succession

• Mature communities are very stable, and can
  appear
• to be unchanging over long periods of time.
• These are also known as climax communities, but
  mature correctly implies that there are still
  changes occurring, albeit more slowly.
• Secondary succession - after a major disturbance
  in an area that already has soil and once had
  living organisms.
• Forest fires are the most common reason for
  secondary succession.
• The soil remains for plant growth, and contains
• seeds, micro-organisms, earthworms and insects.
• Secondary succession is much more rapid than
• primary succession.
• There is already soil, seeds and insects, so it
• only lasts decades.

See page 114
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How Natural Events Affect Ecosystems

• Many other disturbances can affect mature
  communities.
• Flooding
• Water is not contained within natural or
  artificial barriers.
• Generally occurs in locations where water levels
  can change rapidly.
• It can result in soil erosion, as well as the
  spread of pollutants and harmful bacteria
  associated with wastes.
• Climate change and global warming may be
  increasing incidents of flooding.
• A tsunami occurs when huge waves, from large
  earthquakes or volcanic eruptions, floods coastal
  areas.
• Drought
• Occurs when an area receives a lower than average
  amount of rainfall over a very long period of
  time.
• Prolonged drought can have severe effects on
  organisms.

See pages 115 - 116
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How Natural Events Affect Ecosystems(continued)

• Insect infestations
• Many insects play important roles in their
  ecosystems.
• Even insects that appear destructive, such as the
  
• mountain pine beetle, actually play a role in
  the
• renewal of the forest.
• The beetles even have a symbiotic relationship
  with a species of fungus that inhibits the trees
  ability to use resin for protection.
• However, when normal conditions are changed,
  infestations can occur.
• Trees can be stressed from overcrowding, drought
  or animal grazing, and do not resist the insects
  as effectively.
• A warmer climate, and lack of forest fires,
  allows the insects to spread much more
  effectively than in the past.
• Not only are the trees affected, but so is the
  entire forest ecosystem, as well as any human
  industries relying on the forest.

See page 117
Take the Section 3.1 Quiz
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3.2 How Humans Influence Ecosystems

• Wetlands are special ecosystems that contain
  completely waterlogged soil for long periods of
  time.
• Not only do wetlands contain high biodiversity,
  but they also filter many impurities out of the
  water that slowly flows through them.
• For this reason, they are sometimes called the
  kidneys of the Earth.
• Because they hold large amounts of water, they
  can help prevent flooding.
• Human encroachment has caused many
• BC wetlands to disappear.
• In the past 100 years
• Up to 70 of the wetlands in the lower
• Fraser Valley have been lost.
• Up to 85 of the wetlands in the South
• Okanagan have been lost.

Wetlands are vital ecological features in British
Columbia.
See pages 122 - 123
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Understanding Sustainability

• Sustainability is a word that is used often,
  and can be defined in more than one way
• The ability for an ecosystem to sustain
  ecological processes.
• These processes enable biodiversity and keep the
  ecosystem healthy.
• People using an ecosystem to meet their needs
  today without reducing the function or health of
  the ecosystem in the future.
• Sustainable practices maintain, or even improve,
  healthy ecosystems.
• Economic opportunity, biodiversity and ecosystem
  health are all possible.

Returning young coho salmon to rivers near Port
Alice can help maintain sustainability.
See page 125
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The Effects of Land and Resource Use

• Land use refers to how humans use land around
  us for urban development, agriculture, industry,
  mining and forestry.
• All of the land around us, even in cities, was
  once a part of an ecosystem.
• Resource use refers to the ways we obtain and
  use naturally occurring materials.
• Most products you use every day involve the use
  of some natural resources in their production.
• If the land and resources are not used directly,
  they are often processed and exported to other
  places for use.

The processing and export of resources like
lumber, coal and sulphur are very important to
BCs current economy.
See page 126
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Habitat Loss

• The use of land and resources have seen humans
  encroach on natural ecosystems very aggressively
  in the past 150 years.
• As a result of this expansion, habitats have been
  lost or fragmented.
• Habitat loss refers to to loss of habitats due
  to human activities.
• Habitat fragmentation is the splitting of large
  habitats into many smaller ones, resulting in
  disrupted natural activities for plants and
  animals.

Habitat loss (left) and habitat fragmentation
(right) reveal the effects of human activities on
ecosystems.
See page 126
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Habitat Loss (continued)
See page 127
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The Effects of Deforestation

• Deforestation is the clearing or logging of
  forests for human use.
• The resulting barren land is never reclaimed or
  replanted.
• The agricultural crops that are planted are often
  one species monoculture
• This reduces biodiversity, and leaves the crop
  vulnerable to pests or disease.
• Polycultures, of many plant species, are more
  economically and biologically diverse.
• Deforestation is still occurring in many tropical
  rainforests.
• Deforestation results in soil degradation.
• Soil degradation is when moving wind and water
• erode topsoil and leave bare land behind.
• Topsoil, the upper layer of soil, is where most
• of the nutrients, water and air are found
• for plant growth.

See page 128
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The Effects of Agriculture

• If fields are left exposed during non-planting
  seasons,
• water and wind erosion can occur.
• In areas like southwestern BC, the soil can
  become compacted.
• Soil particles are squeezed together and become
  compacted.
• This is due to farm animals or vehicles.
• There is no room for water or air to enter the
  soil.
• Water then runs off the soil instead of soaking
  in.
• Loss of water, increased erosion and the addition
  
• of farm fertilizers and pesticides to the
  ecosystem.
• Aeration, which involves removing small plugs of
  soil,
• loosens soils and can reduce run-off.

Farm animals, such as these cows, can compact
soils.
See page 129
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The Effects of Resource Exploitation

• Resource exploitation resource use
• Humans depend on resource exploitation for jobs,
• materials, food, shelter and energy.
• Exploitation can lead to habitat loss, soil
  degradation
• and contamination of water supplies.
• Contamination is the introduction of harmful
• chemicals or micro-organisms into the
  environment.
• Many mining and resource exploitations require
  reclamation efforts.
• Reclamation attempts to reduce environmental
  impacts of exploitation, and tries to restore the
  original (or at least functional) habitats.
• Overexploitation is the extraction of resources
  until they are gone.
• This can result in extinction, such as with the
  passenger pigeon.
• Food webs can be greatly affected over long
  periods of time
• The overexploited species could be a keystone
  species.

See pages 130 - 132
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Resource Management and Traditional Ecological
Knowledge

• In Aboriginal cultures, traditional ecological
  knowledge is passed down from generation to
  generation.
• This knowledge reveals what past condition were
  like, and also how the ecosystem and humans
  interact.
• Knowledge is found in stories, songs, cultural
  beliefs, rituals, community laws and traditional
  practices.
• Current ecological restoration and usage
  guidelines often involve this traditional
  knowledge from Aboriginal representatives.
• Traditions such as the Spring burn allow
• for ecological renewal.
• Fire suppression, enforced in BC for over
• 100 years, has led to recent issues like the
• mountain pine beetle infestation and huge
• wildfire losses.

See pages 133 - 134
Take the Section 3.2 Quiz
17
Understanding Sustainability

• Sustainability is a word that is used often,
  and can be defined in more than one way
• The ability for an ecosystem to sustain
  ecological processes.
• These processes enable biodiversity and keep the
  ecosystem healthy.
• People using an ecosystem to meet their needs
  today without reducing the function or health of
  the ecosystem in the future.
• Sustainable practices maintain, or even improve,
  healthy ecosystems.
• Economic opportunity, biodiversity and ecosystem
  health are all possible.

Who is this player?
See pages 8 - 9
Take the Section 8.1 Quiz
18
Understanding Sustainability

• Sustainability is a word that is used often,
  and can be defined in more than one way
• The ability for an ecosystem to sustain
  ecological processes.
• These processes enable biodiversity and keep the
  ecosystem healthy.
• People using an ecosystem to meet their needs
  today without reducing the function or health of
  the ecosystem in the future.
• Sustainable practices maintain, or even improve,
  healthy ecosystems.
• Economic opportunity, biodiversity and ecosystem
  health are all possible.

Who is this player?
See pages 8 - 9
Take the Section 8.1 Quiz
19
3.3 How Introduced Species Affect Ecosystems

• Native species are plants and animals that
  naturally inhabit an area.
• Because of the immigration to North America by
  many people from other continents over the past
  400 years, many new species have been introduced
  accidentally (and on purpose) here.
• These new species of plants and animals are
  called introduced species
• Aka foreign species, non-native species, exotic
  species or alien species.
• Many of these species are harmless, or sometimes
  even beneficial.
• An invasive species, such as Purple Loosestrife,
  negatively impacts native species, and often
  reduces biodiversity as a result.

The European leaf-feeding beetle (left), and the
Purple Loosestrife.
See pages 138 - 139
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The Impact of Introduced Species

• Invasive species often take advantage of their
  new habitat.
• They may have no predators, are aggressive
  competitors, and reproduce fast.
• Competition while the native species have an
  established balance, the invasive species can
  throw off this balance.
• Predation if the invasive species is a predator,
  it may
• have a huge advantage, as the native species may
  have
• no methods to survive.
• Disease and Parasitism by weakening certain
  species,
• a micro-organism invading an ecosystem can
  drastically
• alter the entire ecosystem and the niches within
  it.
• Habitat Alteration some invasive species can
  change
• the physical structure of the ecosystem by
  digging,
• burrowing, blocking sunlight or changing the
• chemistry of the ecosystem.

The sea lamprey
See pages 140 - 141
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Invasive Species in British Columbia
See page 142
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Saving an Ecosystem Under Siege

• It often takes human intervention to save
  established ecosystems.
• The Garry Oak Ecosystem Recovery Team (GOERT) is
  trying to save several areas of the Garry Oak
  ecosystem in BC.
• 95 of the original ecosystem has been lost to
  urban development, and the remaining 5 is
  threatened by invasive species.
• Garry Oak trees are a keystone species.
• Scotch broom, English ivy and other
• plant species are its biggest threats.
• GOERT has representatives from many groups.
• The BC government, First Nations,
  conservationists,
• scientists and businesses believe this work is
  critical.
• Garry Oak forests may be better suited to survive
  in
• the future than Douglas fir forests.

See page 143
Take the Section 3.3 Quiz