Ecosystems at Risk

Question 1

Ecotones

Answer 1

Ecosystems rarely have distinct boundaries, instead they blend into adjacent ecosystems via a zone of transition called a ecotone.

• contain organisms common to both ecosystems, but may also have unique organisms. Therefore ecotones have greater biodiversity than surrounding ecosystems.

Question 2

Ecosphere

Answer 2

• The ecosphere is the collection of living and dead organisms (biosphere) interacting with one another and their non-living environments.
• An ecosphere is therefore the total of all world ecosystems.

Question 3

Nutrient Cycling

Answer 3

The flow of energy through food webs that allow nutrients to be recycled from non-living environments to living environments then back to non-living environments

Question 4

The Atmosphere

Answer 4

• The atmosphere is the main source of climatic factors that impact on ecosystem functioning.
• Temperature and the amount of rainfall determine the nature of all the factors within the ecosystem and the speed at which they function.

Question 5

The Biosphere

Answer 5

• The biosphere is the domain on or near the earth’s surface where solar energy produces chemical changes necessary for life.
• The biosphere is all living and dead organisms on the earth’s surface.
• The biosphere is in a narrow zone from about 200m below the surface to about 9km above sea level

Question 6

(The Biosphere) Autotrophic and Heterotrophic Organisms

Answer 6

o Autotrophic Organisms (producers)
♣ Self sufficient manufacturers of food.
♣ Mainly green plants that make organic compounds via photosynthesis.
♣ Form the base of any food web
o Heterotrophic Organisms (Consumers)
♣ Can’t make their own food.
♣ Includes herbivores, carnivores, omnivores and decomposers.

Question 7

The Hydrosphere

Answer 7

• The hydrosphere is closely linked to the atmosphere and determines the nature of the water cycles.
• Large bodies of water moderate temperatures of adjoining land masses because water heats and cools more slowly than land.

Question 8

The Lithosphere

Answer 8

• The lithosphere determines the nature of soils and provides habitats for many decomposer organisms that recycle the minerals essential to the plants forming the basis of the food web.

Question 9

Causes of Ecosystem Vulnerability (4)

Answer 9

Location, Extent, Biodiversity, Linkages

Question 10

(Cause of Vuln.) Location

Answer 10

• At a global scale, latitude, distance from the sea and altitude play decisive roles in determining climate and ultimately the nature of particular ecosystems.

The microclimatic features of a location can be significant enough to create a range of distinctive ecosystem types within relatively small areas

Organisms capable of living in such conditions are, by necessity; highly specialised.

• The greater the degree of specialisation an organism has to a particular set of environmental conditions the more vulnerable that organism is to changes in those conditions.

EXAMPLE

• Corals are highly specialised organisms that flourish in the relatively shallow nutrient deficient waters of the tropics. An increase of just a few degrees above the usual summer temperature can be devastating.

Question 11

(Cause of Vuln.) Extent

Answer 11

• The extent (size) of any ecosystem is the product of a variety of factors.

EXAMPLE

• Tropical forests for example have relatively small populations of a large number of species confined to relatively small, localised communities. The loss of even small areas of rainforest can lead to the extinction of plant and animal species.

Question 12

(Cause of Vuln.) Biodiversity (3)

Answer 12

GENETIC, SPECIES, ECOSYSTEM

Question 13

(Cause of Vuln.) (Bio1/3) Genetic Diversity

Answer 13

Genetic diversity is the variety of genetic information contained in all individual plants, animals and micro-organisms.

Question 14

(Cause of Vuln.) (Bio2/3) Species Diversity

Answer 14

Species diversity is a measure of the number of species at each trophic level of an ecosystem.

Question 15

(Cause of Vuln.) (Bio3/3) Ecosystem Diversity

Answer 15

Ecosystem diversity refers to the diversity present within ecosystems in terms of habitat differences, biotic communities and the variety of ecological processes.

Question 16

(Cause of Vuln.) Linkages

Answer 16

Interdependence, or linkages, is related to biodiversity. The greater the level of interdependence within an ecosystem the greater its ability to absorb change.

• The loss of a primary consumer from a food web is unlikely to have a major impact on secondary consumers if there is a range of alternative primary consumers on which to feed.

EXAMPLE

• For example, impacting the number of krill in an Antarctic ecosystem will directly impact the number of whales the ecosystem can support.

Question 17

Natural Stress

Answer 17

CATATROPHIC

Drought
Flood
Fire
Volcanic Eruption
Earthquake
Landslide
Change in Stream Course
Disease

GRADUAL

Climatic Change
Immigration
Adaptation/Evolution
Ecological Succession
Disease

Question 18

Human-induced Stress

Answer 18

Industrialisation
Urbanisation
Deforestation
Afforestation
Desertification
Agriculture

• The causes of environmental degradation in today’s world are:
o Massive population growth
o Developing world poverty and the crippling burden of debt
o Non sustainable consumption
o Environmentally damaging waste generation in the developed world
o Non-sustainable agricultural practices in many countries
o Environmentally damaging industrualisation
o Exploitation of natural resources especially in poor countries struggling for export earnings

Question 19

Modifications the Natural Environment (4)

Answer 19

Removal
Clearing native vegetation and disruption of
ecological processes.
Urban settlement, transport, industrial development
and extractive industries.
Replacement
Native vegetation may be removed and then
replaced with intensively managed systems:
agriculture, horticulture and plantation forestry.
Utilisation
Utilisation refers to the exploitation of native
vegetation, with some consequent degree of
modification: forestry (in a native forest), pastoralism .
and recreation in natural areas.
Pastoralism: raising grazing animals, such as cattle,
on large, open grasslands
Conservation
Conservation involves the maintenance of natural
vegetation for conservation and scientific purposes
with minimum deliberate modification of natural
processes.
National parks, nature reserves, uncommitted
governmental land and Aboriginal land are all
examples of conservation.

Question 20

The Importance of Ecosystem Management and Protection

Answer 20

The variety of life on earth is of fathomless value. It provides the basis for the preservation of people and the environment. The conservation of the environment is therefore central to the future welfare of the Earth and its inhabitants.

Question 21

Maintenance of Genetic Diversity

Answer 21

• Ecosystems with greater genetic diversity generally have higher resilience than ecosystems with lower diversity.
• Species with high genetic diversity often survive periods of stress because some of the organisms are usually not affected by the change.
• Ecologists say that of an estimated 5 - 30 million species currently inhabiting the planet, only 1.4 have been identified.

90% have been lost to evolutionary extinction which causes the loss of about 1 species per year

EXAMPLE

Tylacine (Tasmanian Tiger)
Hunting, disease due to colonisation 1930

Question 22

Utility Value

Answer 22

All living and non-living elements of the Earth’s ecosphere have existing or potential value or usefulness. This is what geographers refer to as utility value.

o Sustaining life
o Protecting the physical wellbeing of humanity
o A source for present and future medicines
o Energy source/supply

Australia’s flora and fauna make a substantial contribution to our economy.

•	There is enormous value in the variety of ecosystems on the planet that can play roles in:
o	Protecting catchments 
o	Purifying water
o	Regulating temperature 
o	Regenerating soil
o	Recycling nutrients and wastes
o	Maintaining air quality

Question 23

Intrinsic Value

Answer 23

• Ecosystems are endowed with their own intrinsic (naturally occurring) and ethical values.
• This means they have a right to exist irrespective of their utility value.
• Central to the notion of intrinsic value is a recognition that the biophysical environment provides for many of the inspirational aesthetic and spiritual needs of people.
• In an increasingly urban society, aesthetic values make an important contribution to emotional and spiritual wellbeing.

•	Aesthetic qualities are also valued for their recreational potential. For e.g
o	Photography
o	Trekking
o	Bushwalking
o	Bird watching
o	Field studies

The growth of ecotourism

• Traditional aboriginals generally have an ecocentric view.
• Intrinsic value is used to signal amenity value – the value in providing pleasure, enrichment or satisfaction.

Question 24

Heritage Value

Answer 24

aesthetic, historic, scientific or social significance

Preserving important elements of our natural heritage for the enjoyment and wellbeing of future generations is a responsibility that we must all share

Question 25

The Need to Allow Natural Change to Proceed

Answer 25

• The multiplicity of life on earth are a product of ongoing evolutionary process.
• Many ecologists and environmentalists argue that humans have an ethical responsibility, and selfish rationale, to see that this evolutionary process continues relatively unimpeded.

Question 26

Contemporary Management Approaches

Answer 26

o Preservation
o Conservation
o Utilisation
o Exploitation

Evaluation Criteria:
ecologically sustainable development (ESD).

o INTERgenerational equity – The present generation should not use resources or degrade environments to the extent that it leaves future generations in a worse position.

o INTRAgenerational equity – All people in the present generation have the right to benefit equally from the Earth’s resources.

o The Precautionary Approach – Measure that could prevent serious or irreversible environmental damage should not be postponed due to scientific uncertainty.

•	Indicators of sustainability include:
o	Conservation of scarce resources
o	Species diversity
o	Prevalence of pests
o	Ability of the ecosystem to recover from disturbance

Question 27

Contemporary management techniques (6)

Answer 27

• Techniques used to address various types of degraded ecosystems include:
o No Action – because restoration is too expensive, previous attempts have failed.
o Restoration – of an area to its original species composition by a program of introduction.
o Rehabilitation – of some ecosystem functions and some original species.
o Replacement – of a degraded ecosystem with another productive ecosystem.
o Design – when it is impractical to remove the source of stress, artificial ways must be planned to minimize impacts of stress factor.
o Legislation – policies applying to various ecosystems.

Question 28

Traditional Management Approaches

Answer 28

• Collection of food.
• Provision of shelter with respect for the Earth.
• Respect for the Earth, its fragile nature and the interdependent relationship between people and the environment.
• Self-sufficiency.
• Planting of yams back into the holes they came from for regeneration.
• Resettled bee hives to start new ones.
• Dug pits which filled with water providing breeding places for frogs.