V.C.E. Biology Unit 2

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V.C.E. Biology Unit 2

• Area of Study 2
• Dynamic Ecosystems
• Chapter 16 Changes in ecosystems

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Key knowledge

• develop understanding of changes to ecosystems
  over time
• recognise the scope, intensity and impact of
  various natural changes
• extend awareness of impacts of human-induced
  changes on ecosystems
• identify techniques for monitoring and
  maintaining ecosystems

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Changes in ecosystems

• We can ask ourselves the following questions
  about changes in ecosystems
• 1. What was the primary cause of the change?
• Natural event or human intervention
• 2. What part of the ecosystem is initially
  changed?
• - Biotic component or abiotic component

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Frequency of change

• Changes in an ecosystem may be due to
• regular and predictable events, such as tides and
  seasons
• sporadic (irregular) events, such as floods
• one-off events, planned or unpredictable, such as
  a massive oil spill that impacts on a marine
  habitat
• Read pages 504-506 and explain the changes that
  occur in different ecosystems.
• Changes in ecosystems can be on a small or large
  scale.

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Global monitoring of ecosystems

• Satellite Terra is one of many orbiting
  satellites that gathers data about our planet and
  the ecosystems that it supports.

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Predicting effects of change

• Can be very difficult to predict as there are not
  just primary effects direct effects as a result
  of a change, but also secondary effects effects
  that are as a result of the primary effects,
  rather than the change itself.
• Global monitoring, occurring through programs
  such as the Earth Observation System, and the
  data obtained from satellites is the best way of
  attempting to predict changes that may be
  disastrous.
• Answer Quick-check questions 4-6 on page 509

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Human impacts

• Changes in ecosystems due to human impacts are
  usually associated with economic development and
  with meeting the needs of the growing human
  population. These actions may include
• flood control measures (damming rivers and
  irrigation)
• fire prevention measures (controlled burns)
• agricultural activities (land clearing and use of
  fertilisers)
• mining activities
• industrial activities
• needs of urbanised societies
• introduction of exotic flora and fauna
  (deliberate or accident)

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Human impacts 1

• Introduction of an exotic species
• An exotic species is one that is not native to
  that particular area.
• They possess problems as they are not a natural
  part of the relationships that has evolved over a
  long time.
• Many exotic species become major ecological pests
  as they have no natural predators and parasite
  species.

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Impacts of invasive exotic species

• Displacement and loss of native species can
  occur
• When introduced species are successful predators
  of native species (foxes and feral cats)
• When introduced species bring a new disease into
  a community and the native species are not immune
  to it (exotic fungus)
• When introduces species use the same resources as
  the native species, such as food or shelter,
  therefore acting as competition (redfin perch)
• When the introduced species change the
  environment of an ecosystems so that native
  plants and animals can no longer survive (swamp
  buffalo)

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Australian exotic species

• Case 1 Rabbits (p511-512)
• Case 2 Cane Toads (p512)
• Case 3 Carp (p513)
• Case 4 Athel pines (p513-514)
• Read and summarise the Case studies of the above
  exotic Australian species

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Responding to exotic invaders

• Australian Quarantine and Inspection Service
  (AQIS) is responsible for preventing the entry to
  Australia of new exotic organisms through strict
  control measures.
• Measures to reduce or eliminate populations of
  exotic pests and weeds to prevent their spread
  include
• declaring a species to be noxious (what does this
  mean?)
• physical control measures
• chemical control measures
• biological control measures

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Biological control measures

• This refers to the use of natural enemies
  (predators, herbivores, parasites or
  disease-causing organisms) to control exotic
  pests and weeds after they have invaded a new
  habitat.
• Three different types of biocontrol can be
  identified
• Classical biocontrol (natural enemies as
  mentioned above)
• Conservation biocontrol (non-introduced, from
  that area)
• Biopesticides (bacteria, fungi or worms)

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Biotechnology

• Blocking conception in rabbits called
  immunocontraception
• Single sex in offspring for carp to only
  produce male offspring
• No functional gene -gt no enzyme -gt no females!
• As existing females in the population die, each
  successive generation will have fewer and fewer
  females, until only males.

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Human impacts 2

• 1. Over-harvesting of a biological resource
• Sustainable harvesting a species at a rate that
  they can reproduce to replenish the stock that is
  being lost
• Unsustainable use of a biological resource, which
  can push populations to a vulnerable point and
  result in a crash.
• K-selected species particularly vulnerable . Why?
• Important considerations
• where, when and at what age a species breeds
• Its rate of growth
• The time required for sexual maturity
• Read and summarise the example of the Canadian
  cod (p518)

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• Sustainability and conservation
• The use of biological resources in a sustainable
  manner requires a commitment to conservation.
• The goal of conservation is to maintain living
  things in their diverse ecological settings and
  to permit the use of natural resources in a
  sustainable manner.
• Conservation may be
• Keeping an area of habitat protected
• Restrictions of industry in vulnerable areas
• Restrictions on waste disposal
• Protecting an individual species from harvesting
• Can you think of any others?
• Can you think of some examples of conservation in
  any form?

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• 2. Land degradation producing salinity
• Salinity refers to the salt content of water or
  soil at a level where the salt content damages
  the soil and degrades the water quality.
• Excess salt in the soil or water places many
  native species at risk of extinction, and also
  causes significant agricultural losses
• Two kinds of salinity exist in Australia
• Irrigation salinity
• Dryland salinity
• Irrigation salinity
• Results from excessive irrigation flooding crop
  growing areas.
• Brings excess salt to the surface soil, killing
  the roots of plants.

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• Dryland salinity
• Results from the clearing of deep rooted native
  tree species.
• Removing these trees means that more water enters
  the soil, causing the watertable to rise,
  dissolving salt in the soil and bringing it to
  the surface.

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Human impacts 3

• Involve changes in the abiotic part of the
  ecosystem.
• 1. Damming of rivers and diversion of water from
  rivers
• Also called river regulation as we are changing
  the natural flow of the rivers.
• This is done so that the flow of water is
  constant over the year.
• Read and summarise
• - The Barmah-Millewa ecosytems and the Snowy
  river (p523-524)

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• 2. Nutrient overload of waterways and waste
  disposal
• Nutrient overload
• Changing the level of nutrients in the water
• can have serious implications for the plants and
• animals that live in the waterways.
• The accumulation of dissolved mineral nutrients
• in a body of water is termed eutrophication.
• Eutrophication can result in many secondary
• effects (as shown in the table on the right),
• including blooming of cyanobacteria and
• widespread death of aquatic plants.
• Read and summarise
• Blooming cyanobacteria (p525)
• Death of the seagrasses (p526)

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• Waste disposal
• Much of the waste produces today is recycled,
  however, large volumes of non recycle waste must
  still be disposed of.
• Procedures for waste disposal include
• Disposal in landfills
• Incineration
• Disposal of effluent into waterways and into the
  sea
• These procedures all have a negative impact on
  the environment and the various surrounding
  ecosystems.
• Think about several implications for each of the
  procedures mentioned above.

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Questions

• Answer Quick-check questions 7-11 p517
• Answer Quick-check questions 12-15 p521
• Answer Quick-check questions 16-20 p527

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Natural change agents Fire

• Due to the fact that fire has been a natural
  agent for change of the Australian environment
  for millions of years, many native species of
  flora have adapted to need fire for one reason or
  another.
• Adaptations include
• Vegetative reproducers (VR) re-grow after fire
  through means of buds located under the bark or
  in underground stems.
• Obligate seeders (OS) plants do not survive the
  fire, but the seeds to. In fact, the seeds need
  the heat produced by natural fires to initiate
  germination
• E.g. Acacia, Banksia, Casurina, Hakea and some
  Eucalyptus sp.

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• Frequency of fire
• If fires are too infrequent, the plants will not
  be able
• to regenerate through VR or OS, and will
  therefore
• not produce successive generations.
• If fires are too frequent, the germinated seeds
  from
• OS plants will not have time to produce seeds of
• their own, and when the fires come through the
• plants will die.
• Absence of fire
• Read and summarise
• Fire for the parrots (p531)
• Fire for forest giants (p531)
• Human interventions (p532)

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Natural succession in ecosystems

• Changes are continually occurring within
  ecosystems without any human intervention.
• The natural replacement over time of one
  community by another community with different
  dominant species is termed natural succession.
• There are two kinds of succession
• Primary succession
• Different communities become established on land
  that has not previously been colonised, e.g. a
  lava flow
• Secondary succession
• Different communities become established in an
  area that was previously colonised, but was
  disturbed e.g. an abandoned paddock

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Restoring the balance

• There are things humans can do to reduce the
  negative impact that we, as a species are having
  on the environment.
• Personal level
• Local council level
• State government level
• Federal government level
• Choose two dot points from each sub heading above
  on p534-535 to write for each of the above four
  headings

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The global ecosystem the biosphere

• The biosphere is the life-support system of
  planet Earth and its source of energy in the
  radiant energy of the sun.
• The biosphere contains all the ecosystems of the
  planet Earth and the continued existance of
  living things depends on a functioning biosphere.

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• Ozone layer a protective blanket
• The ozone layer protects the Earth from the
  lethal effects of shortwave ultraviolet (UV)
  radiation.
• The long term use of certain chemicals,
  chloroflurocarbons (CFCs), in many aerosols and
  propellants have caused the ozone layer to thin
  and break down.
• The long term impacts include
• Global warming (and the secondary effects
  associated with GW)
• Widespread crop damage
• Increase of incidence of skin cancers
• Total Ozone Mapping Spectrometer (TOMS)
• is used to monitor the state of the ozone layer

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Questions

• Answer Quick-check questions 21-22 on page 533
• Answer Quick-check questions 23-24 on p 534
• Answer Quick-check questions 25-26 on p 538
• Answer Chapter Review questions
• 2, 3, 4, 5, 6 and 7