Term 1 Geography HSC Study Notes

1.Ecosystems and their Management:
An Ecosystem is the complex of all living organisms and their non living Environment.
(a)Biophysical Interactions which lead to diverse Ecosystems and their functioning:
It involves a number of major systems-e.g.The Biosphere,Lithosphere,Hydrosphere,Atmosphere ecosystems feature asset of processes by which nutrients are retained and recycled.
Terrestial Ecosystems:
Terrestial Ecosystems are land based Ecosystems. Aquatic Ecosystems are water based Ecosystems.
The zone of transition from one ecosystem to another is called an Ecotone.
All the worlds ecosystems together are called the erosphere.
HSC Topic 1:Ecosystems at Risk.
The functioning of an ecosystem refers to the ecosystems ability to capture,Store and transfer energy,Nutrients and water.All Ecosystems depend on 2 basic processes:
-Energy Flows
-Nutrients Cycles
Energy Flows:
All life depends on energy from the sun.Energy flows through ecosystems by means of food chains and food webs.
Solar Energy:
Solar energy is absorbed by plants and converted into usable chemical energy through Photosynthesis.This energy is consumed and used by other living organisms which in term provide food and energy for other organisms.This is known as Food Chain.A complex of food chains in an ecosystem are called a food web.
Food Chain:
A food chain shows the path of energy from one living thing to another.Decomposers like bacteria,are necessary for all food chains.
Food Web:
A system of interlocking and interdependent food chains.
Trophic Levels of Organisms:
Organisms can be divided into trophic (or feeding) levels.At each trophic level in a food chain,energy is lost,only 10% of the available energy is passed on from one trophic level to the next.
Nutrient Cycles:
Nutrients such as oxygen,carbon,,nitrogen and phosphorus are constantly cycled through ecosystems.This cycling makes the nutrients available for plant growth,and through the food chain the nutrients are made available to animals.Water is also cycled through ecosystems and is important in allowing the other cycles to take place.
The Carbon Cycle:
The earth is a vast store house of carbon.Only a small amount of this is available for use in ecosystems.Most carbon is available as carbon dioxide,plants extract the carbon from the carbon dioxide.They use the carbon and give off the oxygen as a waste product.Humans can have an impact on the carbon cycle e.g. by releasing carbon from long term storage e.g.coal+oil.Large scale destruction of forest also releases large amounts of carbon dioxide into the atmosphere. As carbon dioxide is a greenhouse gas,the impacts humans can have on the enhanced greenhouse effect is also large.
Nitrogen Cycle:
The nitrogen cycle shows how nitrogen moves between plants,animals,bacteria,the atmosphere and soil.For nitrogen to be used it must change its form.In the atmosphere it is nitrogen in the soil it becomes nitrates,nitrites and ammonium.Plants and animals could not live without nitrogen.It is used by our cells to process amino acids and proteins.It is used by plants in photosynthesis to produce food and energy.Other important nutrient cycles include the:
-Oxygen Cycle
-Phosphorus Cycle
-Water Cycle
Factors Affecting the Functioning of Ecosystems:
Biotic Factors(the living organisms)
(1)Life Cycles
Life Cycles of various plants and animals have an impact on ecosystem,especially through food chains.
(2)Migration Behavior Pattern:
The migration of birds and animals influences ecosystems through food they eat,their effects on vegetation,seed dispersal etc.
(3)Population Dynamics:
Refers to the explosions and crashes in population in populations.The change in size of populations affects a whole ecosystem through food chains/webs.
Is how the distribution of species in an ecosystem changes overtime.
Abiotic Factors:
(1)Celestial Factors:
Celestial factors include the sun and moon.Influencing the amount of day and night,heat,light and gravitational effects on tides.
Influence Include:
Seasons,Rainfall,Temperature,wind patterns,currents.
(3)Chemical Influences:
Chemical influences include salt spray.Nutrients in ocean currents,acid rains.
(4)Major Events:
Such as earthquakes,tsunamis,fires,storms,volcano’s.
The Atmosphere:
The main influence on weather and climate.
weather=The condition of the atmosphere at a certain place e.g. Sydney,Today.Nutrients in ocean currents,acid rains.
The Atmosphere:
Climatic factors such as temperature and rainfall determine the nature of all factors in the ecosystem and the rate in which they function.
The Atmosphere:
Example of the effect of climate on ecosystems include:Areas are infertile because the heavy rainfall washes the nutrients out of the soil.The whole ecosystem depends on the decaying vegetation (leaf litter) on the surface.
The Atmosphere:
Movements of the atmosphere (wind) also transport pollution e.g. acid rain from one area to another causing ecosystem. Destruction.
This is closely linked to the atmosphere.The atmosphere drives the water cycle.
Polar ecosystems are actually cold deserts (i.e.They receive less then 250mm (per year).Because of the cold and very little water,Polar ecosystems function very slowly.
In tropical rain forests the large amounts of rain cause conflicting issues:
(1)Leaves decay quickly releasing their nutrients.
(2)These nutrients are quickly washed out of the ecosystem by the excess water.
Many ecosystems depend entirely on water (Hydrosphere) e.g.
-Coral Reefs
-Coastal Systems
-Lakes and Rivers
The lithosphere determines the nature of soils and provides habitats for many of the decomposer organisms that recycle the essential nutrients to the plants which form the base of the food web.
The lithosphere stores nutrients and water that can be used by plants.
All the living organisms.The biosphere (biotic features)combines with the atmosphere ,Hydrosphere and lithosphere (The abiotic features)To produce the worlds ecosystem.
It is the plants in the biosphere that capture the energy from the sun,turn it into chemical energy,and thus provides the energy to run the whole system.
The biosphere consists of 2 types of organisms.
(a)Autotrophs=”self sufficient”-the plants,they make their own food through photosynthesis.The nutrients and energy are then passed up through the food chain to the animals.
(b)Heterotrophs=Animals-consumers they have to eat something else (food) to get the energy and nutrients they need.
Vulnerability and Resilience of Ecosystems:
Causes of ecosystem Vulnerability:
-Genetic Diversity
-Species Diversity
-Ecological Diversity
This is the variety of different species (plant and animal) in an area.If an area has Biodiversity it is able to adapt to change.If one species dies out another species can take its place.
There are 3 types of biodiversity:
Genetic Diversity:
The variety in the genetics of individuals within a species this variety of genes means that some individuals are better adapted to there environment.If that environment changes then other individuals will be better adapted and pass on their genes.Those not well adapted lose out.Because of this genetic diversity a whole species will be able to adapt to ecosystem change.
Species Diversity:
The variety of different species at each trophic level in an ecosystem.Where ecosystems are diverse,then there are a range of pathways for different ecological processes.The greater the diversity of species (i.e. lots of species at a trophic level) the more robust/dynamic the whole ecosystem is.
Ecological Diversity:
Ecological (ecosystem) diversity means the variety of habitats,and communities within an ecosystem.This is called dynamic equilibrium:Whilst individual members and species may die they are replace by similar individuals and species.To an outside observer the ecosystem looks the same,but the individuals have changed i.e. dynamic equilibrium.
This means the area or range covered by an ecosystem.The smaller an ecosystem the more vulnerable it is to change.Generally the larger an ecosystem (i.e.) extent) the more resilient it is to change.The main determinant of extent is weather and climate.Ecosystems that have a small extent,i.e. limited area,are easy to destroy.
Location of the ecosystem plays a great role in the resilience of that ecosystem.
-Latitude= heat,cold
Distance from the sun= wet,dry
Altitude= temperature
All these play important roles in type of ecosystem and its resilience.Some ecosystems are in locations that may be considered extreme e.g deserts,mountains,mangroves.
In each of these ecosystems its location puts the ecosystem under alot of stress.Only plants and animals that are specially adapted to the location can survive there.
The greater the level of independence the greater the ecosystems ability to absorb change.
Ecosystems that have a low level of independence are much more vulnerable to change.
Resilience is a natural function of ecosystems to adapt to change and restore equilibrium after an episode of stress,either natural or man made.The greater the degree of biodiversity,the greater the resilience of that ecosystem.
There are three important concepts related to resilience in ecosystems:
Is the rate of recovery of an ecosystem after stress.
Is the difference between the final recovery level and the level of pre-stress state.
Is the level of change that prevents on ecosystem from recovery.
Natural Stress:
If natural stress occurs slowly,ecosystems can adapt.Sudden natural disasters can destroy ecosystems.
Examples of catastrophic rates of stress:
Examples of gradual rates of stress:
-Climatic changes
Human Induced Modification
Ecosystems are disturbed by activities that humans partake in,in order to produce food,goods and services.
Humans have been interacting with ecosystems and modifying them for as long as human life has existed.But the scale,speed and degree of change has increased.
Examples of catastrophic human-induced change:
Examples of gradual human induced change:
-Introduction of exotic species
-Loss and degraduation of wildlife habitat.
-Over hunting and overfishing
Types of Modification:
Humans have modified natural ecosystems in many ways-intentional or unintentional.
An example of an intentional modification to ecosystems would be the construction of a dam on a river.
The unintentional changes that could result might be the extinction of some species that needed shallow water to survive.
Six major way humans have changed natural ecosystems:
-Ecosystems are destroyed
-Pest populations have become stronger
-predators are eliminated
-Alien species are introduced
-Renewable resources are over harvested
-Chemical cycling and energy flows are interfered with
Human-induced change in one ecosystem usually have knock on and unpredictable effects on other inter-related ecosystems.
Importance of Ecosystem Management and Protection:
(1)Utility Value:
Refers to the usefulness of ecosystems.All living things have actual or potential usefulness.If we remove these plants and animals we may not be able to benefit from them.
(2)Maintain Genetic Diversity:
So that ecosystems (and the plants and animals we need) can adjust to environmental change.
(3)Intrinsic Value:
All things have a certain value just because they exist i.e. all plants and animals have a right to exist.We all feel ‘happier’ just for knowing that whales are there.
(4)Heritage Value:
That certain ecosystems,plants and animals exist is part of our sense of who we are.So we want to preserve these ecosystems.
(5)Allow Unhindered Natural Change:
If we dont have natural ecosystems then as the environment changes our plants and animals may not be able to evolve to cope.
4.Traditional and Contemporary Management Strategies:
There is growing recognition that people must accept responsibility for protecting and managing ecosystems,especially those at risk.
(i)Contemporary Management Approaches:
A management strategy is a plan of attack-a response to a problem and a way to achieve goals and objectives.
Four broad approaches can be identified:
‘Lock it up’ Refers to the protection of habitat in its existing form.It involves prevention of all human activities in the area being protected.
‘Use a little’Involves active resource management.It is the planned use of natural resources in an effort to minimise environmental damage.
‘Just use it’The replacement of an ecosystem with a human made environment that is capable of proving a sustainable yield.
‘Selfishly use for profit’ When an ecosystems resources are used irrespective of ecological consequences.Underpinning the main management approaches are (Five Key Attitudes) that help define the relationship people have with the environment.
(1)Radical Environmentalism:
Includes a wide range of views ranging from those who advocate the right of all species to survive to those against all development.
A view that values the beauty of nature.Support for the protection of wilderness areas.
Humans occupy a privileged position in relation to nature. We have a responsibility to protect and nurture the land for the benefit of future generations.
The view that things only have value if they contribute to the happiness and well being of people.
(5)Environmental Imperialism:
Egocentric world view that everything in nature is subordinated to the needs and wants of humans.Ecosystems are to be exploited for profit.
(ii)Evaluation Criteria:
Contemporary management approaches focus on the extent to which the strategies adopted promote ecologically sustainable development (ESD).Sustainable development is achieved by maximising peoples economic and social well-being while protecting and maintaining biophysical environment.
ESD incorporates four important concepts:
(1)INTRAgenerational equity
(2)INTERgenerational equity
(3)The Precautiionary Approach
(4)Biological Diversity
(1)INTRAgenerational equity:
All people in the present generation have the right to benefit equity from the earth’s resources.
(2)INTERgenerational equity:
The present generation should not use resources or degrade environments to the extent that it leaves future generations in a worse position.
(3)The Precautionary Approach:
Measures that could prevent serious or irreversible environmental damage should not be postponed due to scientific uncertainty.
(4)Biological Diversity:
An essential feature for the evolution and maintenance of earth’s life support systems, as well as having aesthetic cultural value.
Indicators of sustainability include:
-Conservation of scarce resources
-Species diversity
-Prevalence of pests
-Ability of ecosystems to recover from disturbance.
(ii)Minimising human impacts on ecosystems:
There are a range of strategies to minimise environmental impact.
(a)Exclusion:Ecosystems at risk are protected by excluding activities likely to have an adverse impact.
(b)Education:Provides opportunity to inform people about an ecosystem.
Techniques used to address various types of degraded ecosystems include:
No Action because restoration is too expensive,previous attempts have failed.
Techniques used to address various types of degraded ecosystems include:
No Action:
because restoration is too expensive,previous attempts have failed.
Of an area to its original species composition by a program of introduction.
Of some ecosystem functions and some original species.
Of a degraded ecosystem with another productive ecosystem.
When it is impractical to remove the source of stress,artificial ways must be planned to minimise impacts of stress factor.
Policies applying to various ecosystems.
(iii)Traditional Management:
Traditional indigenous cultures generally have a much closer affinity with the biophysical environment.
Their attitudes emphasise respect and coexistence.They believe that they have a responsibility to protect and nurture the land for the benefit of future generations.They see themselves as custodians of the land.As such the philosophy that best reflects them is that of stewardship.
The goals and objectives of their ecosystem management focus on:
(1)Collection of food.
(2)Provision of shelter with respect for the earth.
(3)Respect for the earth,its fragile nature and the interdependent relationship between people and the environment.
Manipulation of Ecosystems:
They often manipulated and managed ecosystems They built artificial dikes,dug trenches and dammed rivers and used firestick farming.Sustained burning of the bush caused a modification of australian vegetation.Aboriginals may have contributed to the extinction of some megafauna.
Long term management practises:
(1)Planting of yams back into the holes they came from for regeneration.
(2)Resettled bee hives to start new ones.
(3)Dug pits which filled with water providing breeding places for frogs.
Other strategies of management included:
-Restriction of species caught
-Closed seasons
-Designated areas for individuals and groups
-Leadership according to age,ecologically sound practices to be handed down from one generation to another
-Limits to population growth
-Sustainable methods of hunting
Traditional Societies:
Traditional societies are generally familiar with the cycles and processes of the ecosystem in which they are living.From tribe to tribe different methods of hunting,gathering,farming and food production highlights that aboriginals did recognise the unique characteristics of each environment.
The intricate knowledge of ecosystems is passed down.

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