Changes in Ecosystems

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Changes in Ecosystems
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Ecosystem Succession

• Just one of the amazing aspects of life on Earth
  is that it spreads to all areas where the habitat
  will allow it to survive. In hostile
  environments, where the soil is infertile, and
  therefore cannot sustain life in a sustainable
  fashion, small plants and bacteria begin to
  colonise the area, which recognise the area as a
  new ecological niche without competition.

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Ecosystem Succession

• While these small organisms begin to occupy the
  area, the pioneers, the organisms that first
  colonised the area begin to die out. This
  essential process allows the dead mass to
  decompose into the ground, and essentially
  provide nutrients to plants that continue to live
  in the habitat. Now that there is more nutrients
  available in the local environment, larger
  species are able to be supported, and this
  process can have a multiplying effect over the
  longer term. This process is called succession

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Ecosystem Succession

• Succession usually occurs in areas where no other
  species offer competition in the area.
  Succession, however, can occur in changing
  climates, where less suited species give way to
  the more evolutionary adapted species of the
  area.

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Changes in Ecosystems

• Changes in Ecosystems may be due to

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Changes in Ecosystems

• Changes in Ecosystems may be due to
• Regular and predictable events (tides and
  seasons)

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Changes in Ecosystems

• Changes in Ecosystems may be due to
• Regular and predictable events (tides and
  seasons)
• Sporadic events (floods)

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Changes in Ecosystems

• Changes in Ecosystems may be due to
• Regular and predictable events (tides and
  seasons)
• Sporadic events (floods)
• One-off events (oil spill)

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Changes in Ecosystems

• Changes in Ecosystems may be due to
• Regular and predictable events (tides and
  seasons)
• Sporadic events (floods)
• One-off events (oil spill)
• Primary changes in ecosystems may be due to
  natural agents or to human intervention.

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Human Impacts on Ecosystems 1

• Changes due to human intervention are usually
  associated with economic gain and meeting the
  needs of the growing population.

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Human Impacts on Ecosystems 1

• Changes due to human intervention are usually
  associated with economic gain and meeting the
  needs of the growing population.
• They can include
• Fire prevention
• Land clearing
• Flood control measures
• Introduction of exotic species, deliberately or
  accidentally.

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Introduction of Exotic Species

• Not all exotic species become major ecological
  pests e.g. cereal and fruit crops.

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Introduction of Exotic Species

• Not all exotic species become major ecological
  pests e.g. cereal and fruit crops.
• However, when some exotics are introduced to
  local ecosystems, displacement and loss of native
  species usually occurs.

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Exotics in Australia
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Impacts of invasive exotic species

• How do natives become lost or displaced?

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Impacts of invasive exotic species

• How do natives become lost or displaced?
• When introduced species are successful predators
  of native species (feral cats and foxes)

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Impacts of invasive exotic species

• How do natives become lost or displaced?
• When introduced species are successful predators
  of native species (feral cats and foxes)
• New diseases are brought in which natives are not
  resistant to (fungal diseases)

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Impacts of invasive exotic species

• How do natives become lost or displaced?
• When introduced species are successful predators
  of native species (feral cats and foxes)
• New diseases are brought in which natives are not
  resistant to (fungal diseases)
• Exotics use the same limited resources as
  natives.

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Impacts of invasive exotic species

• How do natives become lost or displaced?
• When introduced species are successful predators
  of native species (feral cats and foxes)
• New diseases are brought in which natives are not
  resistant to (fungal diseases)
• Exotics use the same limited resources as
  natives.
• Exotics change the environment of an ecosystem.

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Exotics in Australia
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Rabbits
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Rabbits

• The introduction of rabbits began with several
  dozen brought to a property in Victoria in 1859
  for hunting. They quickly spread to New South
  Wales, Queensland and the west by the 1900s.

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Rabbits

• The introduction of rabbits began with several
  dozen brought to a property in Victoria in 1859
  for hunting. They quickly spread to New South
  Wales, Queensland and the west by the 1900s.
• They have a high reproductive rate one female
  can produce 30 kittens a year.

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Rabbits

• The introduction of rabbits began with several
  dozen brought to a property in Victoria in 1859
  for hunting. They quickly spread to New South
  Wales, Queensland and the west by the 1900s.
• They have a high reproductive rate one female
  can produce 30 kittens a year.
• In their natural environment, their numbers are
  controlled by food shortages in winter and the
  presence of predators, parasites and competitors.

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Rabbits

• Rabbits compete more efficiently than native
  species for food and have displaced many native
  species

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Rabbits

• Rabbits compete more efficiently than native
  species for food and have displaced many native
  species
• Many attempts have been made to control numbers

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Rabbits

• Rabbits compete more efficiently than native
  species for food and have displaced many native
  species
• Many attempts have been made to control numbers
• Myxoma virus (killed many rabbits however rabbits
  become resistant to the virus)

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Rabbits

• Rabbits compete more efficiently than native
  species for food and have displaced many native
  species
• Many attempts have been made to control numbers
• Myxoma virus (killed many rabbits however rabbits
  become resistant to the virus)
• Calicivirus (causes hemorrhagic disease and
  numbers have dramatically reduced)

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Cane Toads
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Cane Toads

• Originally from South and Central America, 100
  toads were brought to Queensland to control
  greyback beetles.

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Cane Toads

• Originally from South and Central America, 100
  toads were brought to Queensland to control
  greyback beetles.
• Cane toads have now spread and are estimated to
  be increasing by about 35 km per year.

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Cane Toads

• Originally from South and Central America, 100
  toads were brought to Queensland to control
  greyback beetles.
• Cane toads have now spread and are estimated to
  be increasing by about 35 km per year.
• They have few natural predators in Australia.

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Cane Toads

• Originally from South and Central America, 100
  toads were brought to Queensland to control
  greyback beetles.
• Cane toads have now spread and are estimated to
  be increasing by about 35 km per year.
• They have few natural predators in Australia.
• They secrete venom from glands and cause the
  death of many native animals

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Carp
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Carp

• Carp was brought to Australia and escaped from
  the Victorian fish farms into the Murray-Darling
  River system

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Carp

• Carp was brought to Australia and escaped from
  the Victorian fish farms into the Murray-Darling
  River system
• They feed at the bottom of water. They take up
  mouthfuls of mud, spit it out so that the
  material becomes suspended in the water, then
  swallow particles of organic matter or small
  organisms.

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Carp

• Because of this behaviour, they destroy water
  plants and change aquatic habitats. Sunlight
  cannot penetrate through, thus some plants are
  lost from the aquatic environment.

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Carp

• Because of this behaviour, they destroy water
  plants and change aquatic habitats. Sunlight
  cannot penetrate through, thus some plants are
  lost from the aquatic environment.
• Carp excretions increase the levels of dissolved
  nutrients leading to algal blooms.

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Athel Pines
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Athel Pines

• They were introduced to provide shade for
  homesteads in arid areas.

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Athel Pines

• They were introduced to provide shade for
  homesteads in arid areas.
• Theyve changed waterways by
• Up taking salty water from ground water resulting
  in salty leaf litter.
• Very few insects eat the leaves
• Very little nectar supply compared to native
  species

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Responding to exotic invaders

• Biological control or biocontrol is used to
  control or eliminate exotic pests by using
  natural enemies (predators, herbivores, parasites
  or disease causing organisms)

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The End