Transcript Revision

Conservation strategies
Bio3B
Environmental strategies
Environmental strategies involve maintaining
habitats and controlling changes eg
reafforestation, biological control
Reafforestation
• How it works planting of trees/shrubs & other plants
• Examples
Planting to reclaim areas affected by salt or erosion
Replanting after mining
Restoring native bushland along roads and paddocks to provide a bush corridor
Replanting along drains and swamps to repair damage of human impact
Replanting to absorb carbon dioxide
• Benefits
Provides habitat, food & shelter for native animals
Helps repair damaged areas (eg salt affected, eroded areas)
Bush corridors allow small animals to move in safety – allows a larger area for foraging &
connects small isolated populations  increase genetic diversity
Absorbs carbon dioxide & reduces pollution
• Knowledge needed for effective use
Species originally present – so replanting is as close to the original as possible
Species that are salt tolerant
Preferred food sources/habitat for animal species you’re trying to attract
Propagation/germination techniques – eg many species need fire to germinate
Symbiotic associations (eg orchids have a mutualistic relationship with fungi, sandal wood &
Australian Christmas trees are semi parasitic on wattles, callistemons or eucalypts)
Biological control
•
How it works an organism is found that acts as a control agent – usually
predator or disease
• Examples
• Cactoblastis moth eats prickly pear
• Calicivirus/myxomatosis kills rabbits
• Lady birds & wasps eat insect pests (eg aphids, mealy worm)
• Dung beetle disposes of cattle dung so there is nowhere for blowflies to lay
eggs
• Irradiated (sterile) male fruit flies released to breed with females  no
offspring
• Benefits
• Once in place no need for further human intervention – its self regulating
• It reduces use of poisons
• Knowledge needed for effective use
The control agent must not be able to become a pest itself:
It is specific & won’t harm anything else, it won’t introduce a disease, it dies out
when the food source dies out & it won’t hybridize with native organisms
Introduced species
Examples of
introduced species
Reasons for introduction
Effects of introduction
Fox
For hunting
Predation of native species
Cat, dog
Escaped from houses, dumped
Predation of native species
Rabbits
Brought in as food source
Competition for feed, overgrazing &
burrows cause erosion
Goats, sheep, cattle,
horses, camels,
water buffalo
Escaped from farms, dumped
Competition for feed, overgrazing
causes erosion, hooves damage river
banks
Carp
Escaped, dumped
Competition for food sources,
predation, reduces native species
Cane toad
Brought in to control cane
beetle
Predation of native species
Corellas, cockatoos
Escaped, dumped
Compete for resources – especially
nesting sites
Prickly pear,
brambles, arum lilies
Escaped, dumped
Competition, reduces native species
Duckweed, water
hyacinth
Escaped, dumped
Chokes water ways
Pest Control
Pest control involves removing the pest without damaging
other species in the ecosystem
Different strategies include biological control, pesticides
Principles for selecting the type of control used include type of
pest, control agents available, sensitivity of ecosystem,
cost
Problems include pesticide residues in food species, toxic
effects on friendly species, contamination of waterways
and biological magnification, pesticide resistance, cost,
escaped biological control agents (eg cane toad)
Short answer 2004 a & b
European settlement in Australia has had a range of harmful effects on
the environment. Widespread clearing of land for agricultural
purposes has had a serious impact.
a) Name four environmentally harmful effects of widespread land
clearing.
Introduced species are another major problem that came with
European settlement. Grasses and other weeds have escaped
from farms to establish themselves in bushland.
b) Briefly explain two different ways these non-native plants can harm
natural ecosystems.
Short answer 2004 a & b
European settlement in Australia has had a range of harmful effects on the environment. Widespread
clearing of land for agricultural purposes has had a serious impact.
a) Name four environmentally harmful effects of widespread land clearing.
Increased/changed salinity
Increased soil erosion/increased runoff
Decreased soil fertility
Loss of animal habitat
Loss of biodiversity
Easy access for introduced species
Climate change
Desertification
Rising water table/waterlogging/increased flooding
Named effect on a neighbouring ecosystem
1 mark each to maximum of 4
Introduced species are another major problem that came with European settlement. Grasses and other
weeds have escaped from farms to establish themselves in bushland.
b) Briefly explain two different ways these non-native plants can harm natural ecosystems.
Out-compete native species, leading to loss of biodiversity
Native animals die when their food plants are excluded
May be a food source for introduced species
Changes to fire behaviour, so fires may be more or less frequent
May be toxic to some native species, hence decline in numbers
An example will be accepted instead of an explanation. e.g., outcompete native species
such as bridal creeper smothering native vegetation
May introduce disease and transmit to native vegetation
2 marks/line, maximum 4
Short answer 2004 c
(c) To combat introduced pests, scientists sometimes use a strategy
called biological control.
i)
Briefly explain what is meant by biological control.
ii)
List three precautions that must be taken to ensure biological
control does not get out of control itself.
Short answer 2004 c
(c) To combat introduced pests, scientists sometimes use a strategy called
biological control.
i)
Briefly explain what is meant by biological control.
Introduction of a natural enemy (predator, parasite, disease) to control pest
numbers
ii)
List three precautions that must be taken to ensure biological control does
not get out of control itself.
The control must be specific
The control must not introduce a disease
The control must not be able to become a pest itself
The control dies out when the food source dies out
The control will not hybridize with native organisms
Short answer 2004 d & e
Another problem is caused by the fertilisers used in agriculture and
gardens. In particular, phosphate fertiliser can kill native plants that
require little phosphate and it also causes toxic algal blooms in
waterways. Part of the problem is caused by the fact that roadside
drains in urban areas drain into waterways, carrying with them
anything that goes down the drains.
d) Name four actions that householders can take to help minimise
nutrient pollution of roadside drain water.
e) List four reasons why it is important to conserve our native
biodiversity.
Short answer 2004 d & e
Another problem is caused by the fertilisers used in agriculture and gardens. In particular, phosphate fertiliser
can kill native plants that require little phosphate and it also causes toxic algal blooms in waterways.
Part of the problem is caused by the fact that roadside drains in urban areas drain into waterways,
carrying with them anything that goes down the drains.
d)
Name four actions that householders can take to help minimise nutrient pollution of roadside drain
water.
Use low-phosphate/slow release/organic fertilizer
Don’t wash cars on driveways
Don’t flush food scraps down drains
Dispose of pet droppings correctly
Minimize fertilizer use/Plant natives that minimize fertilizer use/smaller gardens
Use low-phosphate detergents and household products
Don’t overwater/use a wetting agent
Don’t overfertilize
Don’t fertilize in winter
e)
List four reasons why it is important to conserve our native biodiversity.
Aesthetic value of biodiversity
Ethics – is it right to destroy biodiversity?
Custodial – we should preserve biodiversity for future generations
Utility – biodiversity may provide useful products (e.g. medicines)
Ecosystem stability – biodiversity contributes to ecosystem services
Recreation
Ecotourism
Scientific research
Education
Better ability to cope with environmental change/greater genetic diversity
Extended answer 2006 37d
Conservation of biodiversity in our ecosystems is a very high priority for
biologists and governments around the world. However, not all organisms
enjoy the same level of protection. Poison baits for rats and mice are sold in
every supermarket but the community is horrified when whales are killed.
Use named examples to illustrate the biological factors that should be
considered when deciding the level of protection that should be given to
various species.
Extended answer 2006 37d
Conservation of biodiversity in our ecosystems is a very high priority for biologists and governments around
the world. However, not all organisms enjoy the same level of protection. Poison baits for rats and mice
are sold in every supermarket but the community is horrified when whales are killed.
Use named examples to illustrate the biological factors that should be considered when deciding the level of
protection that should be given to various species.
Up to 8 marks for individual points that have been explained/described
• Aesthetics
• Ethics/culture
• Economics – cost of protection of species
• Economics – benefit/importance to human economy of species (eg harvesting or tourism)
• How common is the species?
• How widespread is the species?
• Is the species a pest or does it have known uses?
• What is the chance that the species will go extinct?
• If the species goes extinct, will it lead to the extinctions of other species/ecosystem instability?
• What kind of protection is needed?
• What is the recruitment rate/reproductive potential of the species?
• What is our knowledge about the species?
• Need to conserve genetic diversity/biodiversity
Up to 2 additional marks for very well elaborated additional points, 1 mark for each point
Examples, can be rats/whales – up to 4 marks
Named example of species needing high protection
• Reason for protecting species
• Explanation of type of protection needed
Named example of species not needing high protection
• Reason for not protecting species/giving low protection
• Explanation of type of actions permitted against species