CHANGES IN ECOSYSTEMS

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CHANGES IN ECOSYSTEMS
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Causes of Change?

• Natural events
• Human interventions

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Which Part of the Ecosystem is Changed?

• Biotic Components
• Abiotic Components

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Frequency of Change

• Regular and predictable changes
• Irregular (sporadic) events
• One-off events planned or unpredictable
• Daily (diurnal) changes
• Yearly (annual) changes
• Less frequent changes
• Slow gradual changes

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Regular and Predictable Changes
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Irregular Events
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One-off Events

• Planned Unpredictable

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Daily (Diurnal) Changes
Changes in light intensity
Yearly (Annual) Changes
Changes in climate
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Less Frequent Changes
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Slow, Gradual Changes

• Must be observed over a long period of time
• Rises and falls in sea level
• Movement of tectonic plates

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Global Monitoring of Ecosystems

• Satellite Systems
• MODIS (Moderate-resolution Imaging
  Spectroradiometer) records properties of clouds,
  land, atmosphere, ocean produces global images
  of snow and ice cover
• MISR (Multi-angle Imaging SpectroRadiometer)
  measures variation in land surface, clouds and
  particles in the atmosphere
• MOPITT (Measurements of Pollution In The
  Troposhere) records origin, global distribution
  concentration of methane carbon monoxide
• CERES (Cloud and Earths Radiant Energy System)
  measures the energy emitted from land, ocean and
  atmosphere measures reflection of sunlight by
  different surfaces.
• ASTER (Advanced Spaceborne Thermal Emission and
  Reflection Radiometer) measures surface
  temperatures, composition and topography/elevation

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Predicting the Effects of Change

• Because ecosystems are so complex, it is
  difficult to predict short- and long-term effects
  of change
• Natural changes less likely to permanently
  disrupt an ecosystem
• Human activities more damaging

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Human Impacts on Ecosystems

• Introduction of exotic species
• Over-harvesting
• Salinity
• Dams
• Eutrophication
• Waste disposal

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Introduction of Exotic Species

• Not all exotic species are a problem
• Some are invasive spread rapidly in ecosystems
  produce damaging effects
• Invasive plant species weeds
• Invasive animal species pests

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Problems with Invasive Species

• Prey on native species who have
• no defenses against them
• May bring disease native species have no
  resistance
• Take over resources required
• by native animals
• Change the environment

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Controlling Invasive Species

• If a species is declared noxious land owners and
  the government must act to remove members of this
  species
• Physical control measures
• Chemical control measures
• Biological control measures
• Biotechnology

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Biological Control Measures

• Classical biocontrol enemies of
• the weeds/pests introduced
• Conservation biocontrol using
• naturally occurring enemies
• Biopesticides naturally occurring
• agents (e.g. bacteria, fungi, worms)
• used to kill exotic species

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Over-harvesting

• Over-harvesting unsustainable use of a
  biological resource
• E.g. catching a specific species of fish until
  their population declines so much it cant
  recover
• Prevention of over-harvesting requires knowledge
  of
• Where, when and at what age a species breeds
• Rate of growth
• Time required to reach sexual maturity

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Salinity

• Salinity a level of salt content in water or
  soil that damages soil and degrades water quality
  
• Too much salt in water and soil means native
  plant species and aquatic animal species are at
  risk of extinction
• Salinity also leads to loss of land for crops
  threatens drinking water supply

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Salinity

• There are two types of salinity
• Dryland salinity salinity resulting from
  excessive clearing of trees
• Irrigation salinity salinity resulting from
  excessive irrigation

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Dryland Salinity

• Salt is stored below the surface of soil
• Australias natural vegetation consists of
  trees/shrubs/grasses with deep roots
• When it rains, native plants stop some water
  reaching the ground also take up water into
  their roots
• This means the water depth remains constant
  salt in the soil is undisturbed

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Dryland Salinity

• When trees are cleared, more water enters the
  soil, causing water levels to rise
• Rising water levels dissolves salt in the soil
  and allows it to enter streams/rivers
• WATERTABLE upper underground surface in which
  rocks/soil are constantly submerged with water

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Irrigation Salinity

• Excess irrigation enters soil
• Watertable rises
• Causes dissolved salts to enter water
• Watertable eventually reaches roots of plants
  those that are not salt tolerant will die
• When irrigation stops, soil dries out salt is
  left at surface

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Dams
Thomson Dam

• Unregulated rivers rivers that have no dams
• Have seasonal flows
• Reduced flow in summer heavier flow in winter
• Regulated rivers rivers whose natural flow is
  disrupted by dams
• Flow of the river fairly constant

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Ecological Impact of Dams

• Natural flow of the river is disrupted
• Releasing cold water from the bottom of dams can
  lower water temperatures
• Wetlands may rely on periodic flooding
• Movements of native migrating fish stop

Eildon Dam
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Eutrophication

• Is the build up of dissolved mineral nutrients in
  water
• E.g. build up of phosphate in a lake due to run
  off of fertilisers
• Causes many other problems

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Algal Bloom
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Waste Disposal

• Waste disposal includes
• Landfill
• Incineration
• Disposal into waterways and sea (e.g. treated
  sewage)
• Lead to negative ecological impacts
• Release of toxic chemicals into atmosphere
• Bioaccumulation

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Natural Succession in Ecosystems

• Ecosystems change without human intervention
• Succession the natural replacement of one
  community by another (with different dominant
  species) over time
• Two types of succession
• Primary
• Secondary

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Primary Succession

• Different communities become established on land
  that was not previously colonised
• E.g. the colonisation of land lifted up by an
  earthquake under the sea

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Secondary Succession

• Different communities become established on land
  that was already colonised, but has been
  disturbed
• E.g. a ploughed field, drained dam

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Succession

• Pioneer species first species to become
  established in their new habitat
• Can survive harsh conditions
• Rapid reproduction
• Succession ends when a stable community is
  established there is no further change in the
  dominant species
• Stable community known as a climax community

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Restoring the Balance

• Personal
• Local Council
• State Government
• Federal Government

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The Biosphere

• Biosphere contains all the ecosystems of planet
  Earth
• Includes
• Living part (biota) all living things
• Non-living part
• Atmosphere (the air)
• Lithosphere (the soil)
• Hydrosphere (the water)

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The Ozone Layer

• Protect Earth from ultraviolet radiation
• Chemicals used by humans have contributed to the
  destruction of the ozone layer
• Many negative effects
• Damaging crops
• Harming marine life
• Causing cancer