biophysical interactions which lead to diverse ecosystems and their functioning
Ecosystems are systems through which incoming solar energy is captured and moved through a hierarchy of life forms. Ecosystems are characterized by the complex interactions between the abiotic and biological environments. It involves a number of major systems- the biosphere, the lithosphere, the hydrosphere and the atmosphere.
Ecosystems feature a set of processes by which nutrients are retained and recycled. Ecosystems are dynamic: that is ever changing due to natural or human events Ecosystems are usually classified according to their dominant feature e.g.: polar ecosystem Land boxed ecosystems are called terrestrial e.g.: forests Water boxed ecosystems are called aquatic e.g.: coral reefs The zone of transitions between ecosystems is called an ecotone All the world’s ecosystems together are called the ecosphereEcosystem functioning
- what is functioning
The functioning of an ecosystem refers to the ecosystem’s ability to capture, store and transfer energy, nutrients and water. Ecosystems depend on 2 basic processes:-
- energy flows
- nutrient cycles
These processes link the energy, chemicals and organisms of an ecosystem.
- nutrient cycles
Nutrients such as oxygen, carbon, nitrogen and phosphorus are constantly cycled through ecosystems, making them available for plant growth. Water is also cycled through ecosystems and is important in allowing other cycles to take place.
- The Carbon cycle
The earth is a vast storehouse of carbon. Only a small amount of this is available for use in ecosystems. Most carbon is available as carbon dioxide CO², plants extract the carbon from CO² and give off oxygen. Carbon cycle varies in time and space
Humans can have a huge impact on the carbon cycles:
- releasing long term stores of CO² by mining and burning of fossil fuels
- large scale destructions of forests, again releasing large amounts of CO² into the atmosphere
As CO² is a greenhouse gas, the impact of humans has been the so-called “enhanced greenhouse effect”.
- The Nitrogen cycle
- The Oxygen cycle
- The Phosphorus cycle
- The Hydrological cycle
- energy flow
All life depends on energy from the sun. Energy flows through ecosystems by means of food chains and food webs. Solar energy is absorbed by plants and made into usable chemical energy through photosynthesis. This “energy” is consumed by other living organisms which in turn provide a food and energy source for other organisms. The system is known as a food chain, or, if more complex, a food web. Organisms can be divided into trophic (or feeding) levels. At each level of a food chain, energy is lost, therefore more bulk must be consumed.
In all ecosystems the number of consumers at higher levels is smaller because of the energy loss.
How energy flows and nutrient cycles occur (i.e. how ecosystems function) is affected by how the 4 components of the biophysical environment interact.Factors Affecting The Functioning of Ecosystems
- Abiotic influences on ecosystems
Celestial influences include the sun and the moon influencing the amount of day, night, heat, light and gravitational pull on the earth.
Earth influences include seasonal changes, rainfall, temperature and wind patterns, tidal changes and ocean currents.
Chemical influences include sea spray blown inland, nutrient up welling in the oceans and the fallout from the atmosphere of sulphur dioxide and volcanic activity.
- Major events
Major events influences such as large volcanoes, tsunamis, fires and storms
- Biotic (living) influences
- Life cycles
Life cycles influence food chain relationships.
- Migration behavior patterns
Migration behavior patterns of birds and animals influence such things as vegetation patterns, seed dispersal and cross-pollination.
- Population dynamics
Population dynamics (explosions and crashes in populations) influence species interactions.
Adaptations influence the distribution of species in an ecosystem.
- Species interactions
Species interactions determines the maintenance, health and functioning of ecosystems.
- The Atmosphere
The Atmosphere is the main source of the climatic factors that impact on ecosystem functioning. Climatic factors such as temperature and the amount of rainfall determine the nature of all factors within the ecosystem and the speed at which they function. Examples of the effect of the atmosphere on ecosystems are diverse:
- The warm moist climate of the rain forest ecosystem is the main reason why they are so dynamic. These conditions accelerate the rate of plant growth, the decay of dead material and the take-up of minerals.
- Circulation patterns in the atmosphere determine spread of pollutants.
- The Hydrosphere
The Hydrosphere is closely linked to the atmosphere. It is, after all, the atmosphere that determines the nature of the water cycle in a particular area.
For example polar ecosystems are cold deserts with annual rainfalls of less than 250mm and very little available fresh water. Because of the extreme cold and the low precipitation, polar ecosystems function very slowly.
In tropical rain forests, as large amounts of rain fall at one time, they can maintain high biodiversity levels.
Large bodies of water moderate the temperatures of adjoining land masses because water heats and cools more slowly than land.
- The Lithosphere
The lithosphere determines the nature of soils and provides habitats for many of the decomposer organisms that recycle the minerals essential to the plants forming the basis of the food web.
The lithosphere stores mineral nutrients and also stores water within the soil's interstitial spaces where it is available for use by plants. It determines the nature of soils and provides habitats for many of the decomposer organisms.
Depending on how porous the soil is, the area may turn into a wetland or desert etc. In areas of non-porous clays, for example, wetlands may develop because water is trapped close to or above the surface.
Landforms also affect ecosystems. Small variations in elevation can result in marked differences in plant communities because of changes in availability of moisture. Average temperatures decrease with increasing altitude, so the climate and ecosystems of mountains often differ markedly from those of nearby valleys and plains.
- The Biosphere
The biosphere is the domain on or near the earth’s surface here the environmental conditions enable solar energy to produce the chemical changes necessary for life.
The biosphere consists of 2 types of organisms:
Autotrophic – self sufficient manufacturers of food. Use solar energy, water, carbon dioxide and nutrients from soil to produce energy and nutrients.
Heterotrophic – consumers – herbivores, carnivores and omnivores, decomposers.
Nearly all life on earth exists in a narrow zone extending from around 200m below the surface of the sae to about 9000m above sea level.
- The Technosphere
The interdependence of all parts of an ecosystem that creates their fragility. Because of human use of technology to manipulate the environment, other elements now depend upon humans for survival. Technological advances have made humanity see itself as a separate entity of the ecosystems that support it. Development of ‘technosphere’ has encouraged ‘growth is good’. In some places now, the technology must maintain the ecosystem of it falls.
vulnerability and resilience of ecosystemsCauses of ecosystem vulnerability
What is biodiversity? Life has undergone changes in response to changes in environmental conditions over time. Species have become extinct and new ones have evolved. The result of these changes through time is present variety of life forms that are found on Earth. This biological diversity, or biodiversity, represents the variety of life forms that are best suited to survive the conditions currently existing on Earth. Biodiversity includes three things:
- Genetic diversity - variations in the genetics of individuals within a species.
- Species diversity - the variety of species in different habitats.
- Ecological diversity - the variety of biological communities that interact with each other and the non-living environment.
- Genetic diversity
The variety of genetic information contained in all the individual plants, animals and micro-organisms Favors the survival of a species because it increases the chance that some members of the species will have characteristics that help their survival if the population is subject to stress. (the plant or animal has genes that over time are now suited to survival needed in this particular ecosystem)
Genetic diversity is the variety of genetic information contained in all the individual plants, animals and micro-organisms. Genetic diversity occurs within and between populations of species as well as between species. Genetic diversity favors the survival of the species, because it increases the chance of some members of the species will have characteristics that aid their survival if the population is subject to stress.
- Species diversity
A measure of the number of species at each trophic level of an ecosystem When ecosystems are diverse, there is a range of pathways for the ecological processes
Species diversity is a measure of the number of species at each trophic level of an ecosystem. The greater the species diversity the more robust the ecosystem.
- Ecological/ecosystem diversity
Ecosystem diversity is the variety of habitats, biotic communities and ecological processes, as well as the diversity present within ecosystem in terms of habitat differences and the variety of ecological processes.
The extent is the product of a variety of factors. The most important are the microclimatic variations created by the physical features of an area. Ecosystems that are restricted to relatively small areas or subject to extensive damage are particularly vulnerable. In a rainforest ecosystem a loss of small areas can result in the extinction of a plant or animals species but as savanna grasslands have large populations of small numbers of species over much larger areas.
The Extent of terrestrial ecosystems varies in accordance with many factors, the most important of which is climate. But extent is not always easy to establish; there is usually a great deal of overlapping of ecosystem boundaries. Ecosystems that are restricted to relatively small areas or have already been subject to extensive disturbance are especially vulnerable. Tropical rain forests, for example, have relatively small populations of a large number of species confined to relatively small, localized communities. The loss of even small areas of rain forest can lead to the extinction of plant and animal species. Savanna grasslands, on the other hand, have large populations of a relatively small number of species spread over much larger areas. The loss of a small area of grassland therefore need not result in the extinction of an animal of plant species.
The latitude, distance from the sea and altitude play decisive roles in determining climate and ultimately the nature of particular ecosystems. Some ecosystems are located in environments we consider extreme: deserts, the polar regions and high mountain peaks. Organisms living in these regions must be highly specialized. The greater the degree of specialization an organism has to a particular set of environmental conditions, the more vulnerable that organism is to changes in those conditions.
The location of ecosystems plays a large role in determining their nature, including their vulnerability. Climatic variations produced by latitude, altitude and distance from the sea (continentality) determine the nature of terrestrial
ecosystems. On a smaller scale, microclimatic conditions, such as slope and location of water bodies, play a role in creating diversity in terrestrial ecosystems. The greater the degree of specialization an organism has to a particular set of environmental conditions the more vulnerable the organism is to changes in those conditions. There are two species of corroboree frogs in the Australian Alps, for example. The northern species lives only in the alpine bogs and leaf litter of Namadgi National Park in NSW. The southern species lives in the sphagnum bogs near Mt Kosciusko. Both frog species are listed as threatened. If global warming occurred, the habitat for the frogs could change and their survival could be at risk. Many ecosystems contain specialist populations like this, and it is usually these species that are most vulnerable to changes because of their inability to adapt quickly to changing conditions.
Interdependence (related to species diversity) Greater the level of interdependence, greater the ecosystem’s ability to absorb change. Ecosystems that have low levels of interdependence are much more vulnerable to change (if the animals and plants in the ecosystem do not depend on each other as much, the ecosystem is more vulnerable to change)
Interdependence or linkages between species is closely related to species diversity. Ecosystems with a high degree of interdependence have a higher capacity to absorb change while ecosystems with low levels of interdependence are more vulnerable to change. For example there are few linkages up through the
food chain of the oceans around Antarctica. Krill are the dominant primary consumer organism and the main source of energy (food) for some species of whale. There are on intermediary stages in the food chain. Any reduction in the supply of krill, from large-scale commercial harvesting for example, will directly impact on the number of whales that ecosystem can support. Interdependence can take very subtle forms. For example some flowering plants can be fertilized by only one species on insect. This insect may, in turn, be dependent on some other organism for part of its life cycle. Anything that jeopardizes this third organism, therefore, will affect the reproductive success of the flowering plant.Resilience
Resilience is a natural function of ecosystems to adapt to the changes and restore equilibrium after an episode of stress or change, either natural or man made. The greater the degree of biodiversity is, the greater the resilience in that ecosystem. Grasslands generally have a high resilience to fire and regenerate quickly. This is because their roots are underground. But grasslands can be destroyed through overgrazing or ploughing up the roots of the grasses to plant crops. Long-term damage to ecosystems occurs when the size, intensity and duration of the changes prevents the recovery of the affected components of the ecosystem. Species that are successful in regenerating and adapting are less vulnerable to changes in their ecosystem. Events like bush fires or prolonged droughts are part of the natural cycle in some ecosystems and species are able to cope with theses stresses. Their resilience is inbuilt in their species through adaptations over time to these regular events. There are three important concepts related to resilience in ecosystems- elasticity, malleability and amplitude.
Elasticity is the rate of recovery of an ecosystem after stress.
Malleability in an ecosystem is the difference between the final recovery level and the level of the pre-stress period. The greater the malleability, the less the ecosystem’s resilience. The lower the malleability, the greater the ecosystem’s resilience.
Amplitude is the threshold level of change that prevents an ecosystem from recovering to its original level.Natural Stress
If natural stress occurs slowly, ecosystems can adapt. Sudden natural disasters can destroy ecosystems. Depending on the severity, ecosystems may take a long time to recover. Climatic changes that occur over millions of years, allow plants and animals that are more suited to change to survive, breed and pass on their favorable characteristics to new generations. Those unsuited to change die out. This process is called natural selection, e.g. the Wollemi pine once covered a vast area of Australia. As climate changed it gradually died out until it is now found naturally in only one valley in the Blue Mountains of Australia.
Examples of catastrophic rates of stress:
- Change in stream course.
- Cyclone, hurricane, typhoon, tornado.
- Volcanic eruption.
Examples of gradual rates of stress:
- Adaptation, evolution.
- Climatic changes.
- Ecological succession.
Ecosystems and the communities within them are constantly responding to environmental changes, either catastrophic or gradual. The gradual change in the composition and function of communities, especially plants, is called ecological succession. There are two types of ecological succession.
- Primary succession occurs when there has been a catastrophic change such as a volcanic explosion, lava flow, mud flow, or glacial retreat, where all the topsoil has been removed. The establishment of vegetation and soil on the bare rock over a period of hundreds of years.
- Secondary succession occurs in an area where the natural vegetation has been altered, disturbed, removed or destroyed. Abandoned farmland, forests affected by fire or logging and heavily polluted streams are good examples. The soil remains intact and pioneer species such as weeds and grasses prepare the way for other species, possibly larger trees and shrubs, depending on the environmental conditions and the nature of the surrounding ecosystems.
Mt St Helens eruption: an example of natural stress. The Mt St Helens eruption shows how resilient ecosystems are to natural stress. In the case of Mt St Helens, the effects on the surrounding ecosystem were devastating.
- 120m of summit vanished, leaving in its place a crater 2km wide, 4km long and 1.5km deep.
- 380km2 of land to the north of the mountain was devastated by the blast and covered by hot volcanic debris.
- large areas of coniferous forest were destroyed and countless numbers of animals were killed.
- Volcanic ash, carried by the prevailing winds, was spread 1500km to the west.
- 100 people lost their lives.
Within just a few years of the eruption scientists found that pioneering flora and fauna was staring to colonize the ash grey volcanic landscape. Plants such as lupin, Indian paintbrush, pearly everlasting, and fire weed took root amongst the coarse grey rock. Willow and elder trees had grown to the height of 1.2m. The roots of decaying leaves and stems of the vegetation provided the organic material needed to convert volcanic grit into sustaining soil.Human Induced Modification
By activities that humans partake in, in order to produce their food, goods and services, ecosystems are disturbed. There have been 3 major surges in the human population, always related to some kind of change in technology. The first was associated to the breakthrough in weapons technology. The invention of the throwing stick increased the supply of food and moved humans up the trophic level. The second was when people settled down and domesticated certain animals and plants. The standard of living increased and farming had a major impact on the land. The third surge was technologically based. Technology has been used to greatly increase food supplies and combat disease. Rapid growth placed stresses on all aspects of ecosystems. The modification of ecosystems results in the simplification of the ecosystem and eventual breakdown.
- Impacts of modification
Impacts of modification:
- Changes the energy flows, biogeochemical cycling and nutrient cycling.
- Leads to the eventual destruction of the ecosystem or parts of it without regeneration
- Can cause global environmental crises
Humans have been interacting with ecosystems and modifying them for as long as human life has existed on Earth. But the scale, speed and degree of change that is now occurring threatens the survival and integrity of many ecosystems and indeed of human life. The impacts of human-induced modifications to ecosystems in modern times have been increased in the following ways:
- The speed at which humans can change ecosystems has never been greater.
- The scale of ecosystem change humans are capable of has never been larger, extending to the global level.
- The technology to implement large-scale changes efficiently to ecosystems is accelerating.
- The Earth’s human population is continuing to grow at an alarming rate, placing even greater pressure on ecosystems.
Examples of catastrophic rates of human-induced change:
- Change to stream course.
- Loss and degradation of wildlife habitat.
- Pesticide application.
- Toxic contamination.
- Water and air pollution.
Examples of gradual rates of human induced change:
- Depletion of groundwater.
- Elimination of ‘pests’ and predators.
- Excessive tourism.
- Introduction of exotic species.
- Loss and degradation of wildlife habitat.
- Over hunting and overfishing.
- Salinisation and waterlogging of solis from irrigation.
- Soil compaction.
- Toxic contamination.
- Water and air pollution.
- Types of modification
Types of modification:
- Physical control
- Habitat control
- Biological control
- Chemical control
- Water Cycle control
Humans have modified natural ecosystems in many ways. It is possible to classify these as intentional or unintentional, but the distinction is not always clear. 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. There are six major ways humans have changed natural ecosystems.
- Ecosystems are destroyed, degraded and simplified. Agricultural land use often requires the wholesale clearing of land to grow single crops or graze animals. This monoculture system simplifies the complex interrelationships existing in natural ecosystems and is maintained through pesticides and fertilizers. Urban land creates greatly modified ecosystems.
- Pest populations have become stronger. To maintain monocultures, pesticides and herbicides need to be applied to keep crops safe from damage. Through natural selection, insects and unwanted plants can quickly develop resistance to pesticides and herbicides.
- Predators are eliminated. Any species that may be a threat to domesticated animals, either through direct competition for grass or through preying are usually eliminated. The Tasmanian tiger was exterminated because it was seen as a threat to sheep.
- Alien species are introduced. The introduction of alien species can be intentional, such as the introduction of foxes and rabbits into Australia, or unintentional, such as the release of marine organisms like the North Pacific sea star into Australian waters through ballast water. These foreign species can have a devastating impacts on natural ecosystems where they usually have no predators. They also have sever economic costs because of the cost prevention measures and loss of production.
- Potentially renewable resources are over harvested. Overgrazing of grasslands can lead to desertification, where the ecosystem becomes degraded and the vegetation and soils are depleted. These marginal ecosystems can be transformed into semi-desert or desert and suffer sever damage. Fisheries are no exception and there have been several collapses of fisheries that had been pushed beyond their resilience.
- Chemical cycling and energy flows are interfered with. A simple monoculture is an abnormal system compared with a natural ecosystem. Vast quantities of fertilizers, herbicides and pesticides are required to sustain the yields of the crops. The runoff pollutes streams, lakes and oceans and causes changes in their ecosystems. The natural chemical cycling and energy flows are disrupted.
Energy and matter is captured, transferred and lost as it flows between the various biotic and abiotic components of an ecosystem. At each stage, heat is lost or given off. On a global level, human modification of energy flows in ecosystems can change entire biomes. The enhanced greenhouse effect may lead to increased surface
temperatures and this will change climates over the long term. Some areas may experience increased rainfall while others may experience decreased rainfall. The nature of the changes is fairly unpredictable and scientists disagree as to what the impacts will be. Natural energy flows are disrupted in urban areas through the creation of large heat islands and dust domes. The heat island around urban areas causes wind circulation patterns that create a trapped dust dome of suspended pollutants above the urban areas. Winds may move this dome away and form a dust plume spreading the city’s pollution many kilometres away. Natural ecosystems have several nutrient cycles operating in them. These cycles continuously move the elements and compounds from the abiotic environment to the biotic environment and back. They are driven by solar energy and gravity and include the:
- The Carbon cycle.
- The Nitrogen cycle.
- The Oxygen cycle.
- The Phosphorus cycle.
- The Hydrological cycle.
Human-induced changes in one ecosystem usually have cascading and unpredictable effects on other inter-related ecosystems through these nutrient cycles. Human-induced modifications to nutrient cycles are numerous and vary in scale from local to global. The clearing and removal of timber from a rainforest disrupts the nutrient cycle in these low-fertility ecosystems. The apparent richness of the rainforest ecosystem is a result of the recycling of nutrients stored in the trees and leaves. The soils are typically shallow and leached because of heavy rainfall. If the timber is removed, the nutrients are not recycled and the soil is not replenished. In addition, once the protection offered by the trees and their root systems is removed, rapid erosion occurs, removing the shallow topsoil and making regeneration of the rainforest a long, slow process that may take centuries, if It is allowed to happen.Relationships between biophysical components
Ecosystems have six key features that determine the relationships between their biophysical components:
- Adaptability (the ability of an organism to adapt to changes in its environment.
- Unpredictability (could include things like genetic evolution and climatic change).
- Limits (set by abiotic and biotic factors).
Humans simplify ecosystems and attempt to control them for their own purposes. There are many complex inter-relationships between biophysical components in
natural ecosystems that are disrupted through human activities. Some of these disruptions create feedback loops that adversely affect human activities. If crocodiles were not protected in Australia, for example, their role as a keystone species would be threatened. When hunting of crocodiles was permitted, the saltwater species was on the brink of extinction. Since protection, their numbers have built up to pre-hunting levels and the estuarine ecosystems where they live are more in balance.
The Importance of Ecosystem Management and ProtectionMaintenance of Genetic/Biological Diversity
Ecosystems rich in diversity generally have greater resilience and are, as a result, able to recover more readily from naturally induced stress, such as drought and fire, and human-induced habitat degradation. Where diversity is diminished, the functioning of ecosystems (and by association the wellbeing of people) is put as risk. Biological diversity or biodiversity covers 3 areas:
- Genetic diversity.
- Species diversity.
- Difference in Ecology
- Genetic diversity
Genetic diversity is the variety of genetic material contained in all individual plants, animals and micro-organisms Ecosystems rich in genetic diversity generally have greater resilience and therefore are able to recover more readily from natural and human stresses. Where diversity is low, ecosystem functioning is often at risk. Communities of plants and/or animals with high levels of genetic diversity often survive periods of stress because some of the organisms are usually not affected by the change. The living organisms pass on their favorable genetic traits to their offspring. In this way species over time adapt to change. This is called natural selection.
Ecologists say that of an estimated 5.3 million species currently inhabiting the planet, over 1.4 have been identified. Evolutionary extinction (i.e. natural extinction) accounts for the loss of about one species/year. The actual extinction rate is now estimated at one/day. This reflects the impacts of human. Diversity high → greater resilience We kill species → ecosystem cannot withstand natural & human stress
Genetic diversity is the variability in the genetic components among individuals of a single species. If a number of individuals are limited, then the genetic diversity is limited and the species is more likely to be vulnerable to extinction.
About 80 northern hairy-nosed wombats, for example, live in one 300-hectare site in Epping Forest National Park in central QLD. There are no others in existence. Is a disaster struck this small population, the genetic diversity would be further be reduced and inbreeding could occur. The genetic pool needs to be wide so there is a greater chance of the species surviving.
- Species diversity
Species diversity describes the variety of species in different habitats. Is a species is lost through extinction, then the species diversity of the ecosystem suffers. Species diversity varies through time and over different geographical areas. For example, the Great Barrier Reef has around 2,000 fish species and around 500 coral species compared with 100 fish species and 300 coral species in the coral reefs around New Caledonia.
- Ecological diversity
The variety of biological communities that interact with each other and their non-living environment is called ecological diversity. Scientists admit that they have not found and identified many of the world’s species. Ecologists say that of the estimated 5-30 million species that currently inhabit the planet only 1.4 million have been identified. These represent only 10% of the species that have ever existed on earth. The other 90% have fallen victim to an evolutionary process of natural extinction.
- why biodiversity should be maintained
- untapped resource
Biodiversity is an untapped resource. We do not know what species may be useful to humans in the future as a source of medicine, food and other human needs.
- economic potential
There is economic potential yet to be realised.
- ecologically sustainable development
We need the variety of living resources for ecologically sustainable development.
- insurance policy against disaster
A variety of genetic material is an insurance policy against disaster.Utility Value
This is concerning the usefulness of ecosystems in monetary terms:- Recent study estimated that total value of goods and services provided by the earth’s ecosystems is US$33 trillion. There is an enormous variety of products obtained from ecosystems:- Rattan (wild vine in SE Asian forests) – cane furniture and other products. Generates $2.7 billion in exports/year. US Coastal fishing industry valued at US$3.3 billion in 1991. Rubber & tropical fruits (Amazon rainforest) – net economic value of US$7000/hectare w/o harming the forest. If the same area is cleared however, 94m³ of timber produced. In 1992, an estimate of medicines derived from natural sources, came to US$40 billion/yr worldwide. Tribes in Peru were found to use plants to treat skin disorders, tuberculosis, fevers, animal bites, infertility, kidney disorders, wounds, burns, tooth decay. Ecosystems with a high utility value include: Mangroves Forests Swamps Floodplains Natural marshes
All the living and non-living components of the earth’s ecosphere have either an existing or potential utility value or usefulness. By maintaining and protecting ecosystems we maximise humanity’s ability to adapt to change. The sheer diversity of life represents a vast store of genetic material that can be tapped as human needs change. The loss of a species- whether plant, animal, fungus, bacterium or virus- denies humanity a possible future source of food, medicine, chemicals, fibres and other materials. Australia’s flora and fauna, for example, make a substantial contribution to the national economy through forestry, the pastoral industry, fisheries, tourism, land reclamation, beekeeping, wildflower harvesting and the kangaroo trade. Ata global scale, components of the various ecosystems play a vital role in protecting catchments, purifying water, regulating temperature, regenerating soil, recycling nutrients and wastes, and maintaining the quality of air. Their protection is critical to the physical wellbeing of humanity.
Almost all of the important food crops are native to environments at risk in the developing world: for example wheat is from Afghanistan, potatoes from the highlands of Peru, and sorghum and coffee from Ethiopia and Sudan. It is to these regions, to the wild relatives of the crop plants of the traditional varieties grown by subsistence farmers, which the plant breeders have to turn to for their genetic material. This vital resource can only be maintained by preserving the environments in which the wild species grow, and by making it worthwhile for poor farmers to continue growing their traditional varieties instead of changing to modern higher-yielding strains. In the highly competitive ecosystems, such as tropical rainforests, many organisms depend on chemically based protective mechanisms for their own survival. These naturally produced chemicals constitute a major pharmacological resource. The loss of an even a small area of rainforest could therefore mean the loss of disease-conquering chemical compounds. Medical scientists have estimated that they have managed to examine only about 5,000 of the estimated 250,000 plants that have pharmacological value. The vine Tylopora is a source of drug tyocrebrine, which has been effective in treating lymphoid leukemia. In a world where almost everything is measured in terms of its monetary value it is not surprising that some economists should attempt to value ecosystems in terms of what people are prepared to pay either to consume them or preserve them. The existence value of an ecosystem is defined as the value of a community is prepared to place on an ecosystem in its natural state. Many national parks, for example, occupy areas that could otherwise be used for farming or urban development. They also contain resources, such as timber and minerals, which could be exploited. The amount that people would be willing to pay for the land plus the cost of maintaining the parks is known as its existence value. The community, through government authorities, must be prepared to accept the cost. Given that ecosystems have an economic value it follows that they also have an option value. The option value is the cost of keeping the ecosystem or species in its natural state as opposed to exploiting its resources. Another benefit to be derived from the protection of ecosystems is the avoidance of the costs of inaction. Environmental degradation diminishes the productive capacity of the land. This not only incurs an economic cost but also diverts resources from other social priorities to the repair of environmental degradation. Exploiting the utility value of ecosystems would, if taken to its extreme, destroy the environment. Utility value, in a practical context, should incorporate appropriate management techniques so as to minimise the risk of environmental degradation.Intrinsic Value
Intrinsic having value in existing alone as a natural phenomenon Ecosystems are priceless and precious. ‘Intrinsic value’ is used to signal amenity value – the value in providing pleasure, enrichment and satisfaction. Most ecosystems are inherently useful and frequently are regarded by economists as natural capital to become useful at some time in the future. Many different religions’ theologies include an intrinsic value for nature, e.g. Jainism and Buddhism see all creatures as part of a suffering world.
Ecosystems are endowed with their own intrinsic and ethical value, that is, they have the right to exist irrespective of their utility value. While few would disagree with such a sentiment, and most people would support the view that we need to protect ecosystems for the benefit of future generations, there is still no
generally agreed mechanism or strategy by which this could be achieved. Central to the notion of the intrinsic value of ecosystems 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, for example, make an important contribution to emotional and spiritual well being. By interacting with elements of ecosystems, humans are reminded that they are part of an interdependent natural world. The aesthetic qualities o ecosystems are also valued for their recreational potential. Activities such as photography, trekking, bush walking, bird watching and field studies draw heavily on the aesthetic qualities of the biophysical environment. The growth of ecotourism is closely linked to the growing appreciation of the aesthetic and ecological qualities of environments. The intrinsic value taken to its extreme would mean that no, or minimal, human uses would take place in an ecosystem. This option would assist the long-term survival of the ecosystem due to the removal of direct human-induced change to the ecosystem that would risk degradation of its features. An area set aside for its intrinsic value, however, may experience problems from adjacent land use leading to the indirect human-induced change, and problems from lack of public support due to the lack of familiarization with the site caused by lack of utilization. In a practical context, protection of an area may involve acknowledging its intrinsic value but managing it with a utility value for social, political and economic reasons, or may require extensive public education campaigns to increase public awareness and support.Heritage Value
Heritage protection of areas seen as having outstanding universal value. In Australia, the Royal National Park was dedicated as an area of outstanding heritage as early as 1879. The latter half of the 20th century saw the emergence of great concern for the heritage value of ecosystems. The UN formed an important organization – the World Conservation Union (IUCN). The IUCN is a network of governments.
The Australian heritage Commission views natural heritage, worthy of National Estate listing, to include ‘those places, being components of the natural environment of Australia or the cultural environment of Australia, that have aesthetic, historic, scientific or social significance or other special value for future generations, as well as for the present community’. In Australia, the concept of ‘natural heritage’ is wide enough to encompass both large areas of pristine wilderness and those sites more readily accessible to humans. Education has played a critical role in developing public support for heritage listing. As support has grown, additional sites (particularly those close to human settlements) have been added to the list. In some cases, listing was granted after a public controversy arising from a development proposal that would have degraded the heritage value of an ecosystem. Current Australian World Heritage Areas: Great Barrier Reef, Kakadu National Park, Ulura-Kata Tjuta National Park, Fraser Island.The Need to Allow Change to Proceed
Ecosystems are continually changing and evolving. If we don’t allow this to occur naturally then ecosystems can be damaged and the quality of human life can be affected (dropped). Overloading Australian rivers with nutrients = blue green algae blooms = lower utility value and degraded ecosystem Increase saline water tables = changing ecosystems quickly = plants can’t adapt Global warming = increase temperature of water = coral bleaching = natural change can’t proceed The loss of crucial species may have unforeseen consequences and therefore must maintain species if natural change is to occur. We must learn from the past to protect the future.
The most valuable earth based ecosystems, estimated at US$4.9 trillion, are wetlands – mangroves, forests, swamps, floodplains & natural marshes. The most important role these wetlands have is in controlling floods, storm protection and cycling both nutrients and waste.
Wetlands in Australia’s high country are at risk through the trampling of stock and the impact of the heavy tread of bush walkers. The upland wetlands act as sponges, slowly releasing water through the catchment during dry periods. The health and integrity of these ecosystems needs to be maintained.
Human alteration of water flowing through catchments has increased the rate of flow, destroyed soil resources and exacerbated floods and droughts.
In far too many locations around the world, there is evidence of disruption to nutrient cycling. Rather than allow natural change to proceed unhindered, many ecosystems are overloaded with nutrients.
Rising saline water tables, dryland salinity and spreading acid sulphate soils are all Australian examples of interfering with natural changes and preventing natural change from proceeding unhindered.
The multiplicity of life forms on earth is 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.
To ensure that this occurs it will be necessary to protect large areas of representative ecosystems. To achieve the desired objectives these areas should:
- Be large enough to protect and conserve intact ecosystems effectively and to allow evolutionary processes to continue.
- The areas must have representative biodiversity- small fragmented areas often lack biodiversity.
- Boundaries need to be environmentally based and cross-national if possible – bilateral agreements need to put the ecosystem before political considerations.
- Local people need to be integrated into the management program so the benefits are shared in their communities. The local economy should benefit, not suffer, from the protection of the ecosystem. The knowledge of the local people should be used as part of the management strategy.
- Ideally, the surrounding areas need to have a buffer zone that allows for migration patterns of animals and regeneration of species.
- The reserves need to be well managed and adequately funded. Rangers need to ensure that the animals are protected from the people outside the area and that the people are protected from the animals within the area.
In 2000, South Africa’s Kalahari Gemsbok National Park and Botswana’s Gemsbok National Park were united to form Kgalagadi Transfrontier Park. The new 3.8-million-hectare park is managed as a single ecosystem and allows free movement of animals and people around the park. This park is southern Africa’s first ‘peace park’, established as much to foster goodwill between nations as to increase the viability and size of conservation reserves.
evaluation of traditional and contemporary management strategies
Success can only be measured over a long period of time to ensure changes are not just part of normal ecosystem fluctuations.
Some objective measures include species numbers and stability of population based on reliable benchmarks. Lack of benchmarks can be overcome by undertaking an environmental audit: measuring key aspects of environment quality. This can be used to evaluate the success of management practices. Success needs to be judged in terms of sustainability.
- Components of Ecosystem Management
The Committee on Ecosystem Management of the Ecological Society of America identified eight elements for ecosystem management. They are:
- Clear operational goals.
- Sound ecological models and understanding.
- An understanding of complexity and interconnectedness.
- Recognition of the dynamic character of ecosystems.
- Acknowledgement of ignorance and uncertainty.
- Commitment to adaptability and accountability.
- Acknowledgement of humans as ecosystem components.
Concepts/Principles of Ecologically sustainable development
Most contemporary management strategies rely on the principles of ecologically sustainable development. Some of the concepts involved in ecologically sustainable development are listed below.
- Intra-generational equity/Ensuring social equity
all people have the right to benefit from the worlds resources
- Inter-generational equity
present generations shouldn’t use resources in such a way that future generations are in a worse position. We have an obligation to ensure ecosystems are healthy, diverse and productive.
- Maintaining natural capital
- Limiting use of natural resources
- The precautionary approach
where there is any doubt about using a resource, don’t do it
- Planning for qualitative development
- Biological diversity
it is essential for the evolution and maintenance of ecosystemsStrategies for Ecosystem Management
The habitat and species are totally protected from human activity of any kind.
e.g.: GBR & some wilderness areas
- Wildlife Management
There are three alternative management approaches to wildlife. They are:
- Species approach – laws aimed at protecting endangered species, such as Australia’s Endangered Species Act.
- Ecosystem approach – this is the most effective as it aims to preserve viable populations in their natural habitat.
- Wildlife management approach – this is where humans make use of the wildlife either through ecotourism as in the African game parks or through hunting as in many of the North American parks. The aims of managing wildlife are to:
- Manipulate wildlife populations and their environments for their survival and for human benefit (sustained yield).
- Preserve endangered and threatened species.
- Enforce wildlife laws.
There is limited impact on ecosystems through sustainable use of resources.
There are around 9,000 conservation reserves around the world, protecting about 6% of the land area on earth. Scientists believe a minimum of 10% of the land area of the Earth needs to be protected to conserve ecosystems, their biodiversity and integrity from human activities. Some developing countries have very little of their land protected. In recent years, some developed countries created debt-for-nature swaps with developing countries. Under this system, some of the country’s debt is written off in exchange for the establishment of protected reserves in areas of high conservation need. Successful debt-for-nature reserves have been established in countries like Costa Rica and Colombia.
- Selecting a Reserve Site
The major priority in selecting a site for a reserve is to protect fragile ecosystems under threat. Some of these take thousands of years to form and can never be recreated if lost. The following factors should be taken into account when choosing a site:
- The diversity of species present.
- The diversity of habitats available.
- The degree to which an area is influenced by human activity.
- The size, shape and proximity to other protected areas.
- The availability of corridors between reserves to encourage movement of species and greater genetic variation.
In an ideal world, management strategies would select the best combination of these factors to preserve the ecosystems at risk. In reality, however, the choice of site is often limited to what is available after other human demands have been satisfied. This compromise puts ecosystems at risk under further pressure.
- Size and Shape of Conservation Areas
Ecologists have found that the shape and size of nature reserves and the proximity to other protected areas largely determines their success. Reserves are like islands of habitat surrounded by human-modified ecosystems.
|Large reserve||Small Reserve|
|One Large reserve||Many smaller reserves|
|Small reserves, close together||Small, Distant reserves|
|Reserves in a circular pattern||Reserves in a linear pattern|
|Corridors present||No corridors|
|Round reserve||Long reserve|
- Institutional Difficulties
Some difficulties confronting institutions involved in environmental management are:
- Varying regulatory arrangements applied to different land uses in adjacent areas making it difficult to achieve conservation on a landscape scale.
- Responsibilities that are fragmented between the levels of government and various agencies.
- Differing philosophies and approaches between non-Indigenous and Indigenous environmental managers.
- Fewer resources to ensure compliance with government legislation, policy and regulation.
- Limited corporation between public and private sectors in long-term environmental management.
Ecosystems are modified by humans for sustainable use, e.g. commercial agricultural
Ecosystem resources are exploited regardless of the consequences. This results in species extinction, ecosystem destruction and reduction, and possible ecosystem collapse.
e.g.: bugwatch – yearly junior geography activity that helps measure the quality of waterways
return an area to its original condition, e.g.: Lake Canobolas Earth Sanctuary
- Rehabilitation/Rehabilitating and restoring ecosystems
Rehabilitation, probably the most obvious of management strategies, deals with ecosystems that have been damaged or degraded. Examples include ecosystems that have been:
for a long period of time.
Rehabilitation attempts to return an ecosystem to its original state. Given enough time, the natural processes of ecological succession will eventually repair the ecosystem. Given enough time, the natural processes of ecological succession will eventually repair the ecosystem. But this depends upon the degraded ecosystem being protected and managed so that the natural processes can occur and the ecosystem be sustained. All this is costly and time consuming. In many cases, the repaired ecosystem does not have the biodiversity of a natural ecosystem for hundreds of years, if ever. If species are extinct, the ecosystem will never return to the pre-disturbance state.
use artificial methods to improve an ecosystem, e.g.: Blayney & Molong wetlands
make laws to protect ecosystems, e.g.: banning motor vehicles from some areas of the coastPhilosophies of Ecosystem Management
- Radical Environmentalism
Involves the ecosystem being completely quarantined from human activity of any kind
- Environmental Imperialism
The resources are exploited without regard for possible ecological consequences
- Romantic View
Encourages resource use that is not damaging or exploitive. e.g. Ecotourism
The ecological resources are sustainably used, with no long-term damage
Natural resources are used, and the natural ecosystem is replaced by a human-modified environment that produces a sustainable yield
The values, attitudes and beliefs of a society determine the philosophies that are implemented in ecosystem management. In some ecosystems, such as the Great Barrier Reef, the management strategies implement various philosophies in different areas. Some reefs are totally preserved (radical environmentalism) and access to people is denied. These are areas of high sensitivity. Other reefs are open to ecotourism visits, but not fishing. This follows the romantic philosophy. Finally, some reefs are designated for seasonal fishing. This is an example of stewardship.
Traditional indigenous cultures generally had a much closer affinity with the biophysical environment. Their attitudes emphasize 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. This embodies the management philosophy of stewardship, and is ecologically sustainable, seeing as it was used for thousands of years(wasn't it? probably need reference)
Traditional aboriginal Australians were hunter-gatherer nomads and their ecosystem management centered on the conservation of food and material resources.
Objectives include: Collection of food Provision of shelter w/respect for the earth → Self-sufficiency
Major degradation has been caused by: large-scale farming, mining and industrial & urban land uses.Long-term management
Planting of yams back into the holes → regeneration
Other strategies of management included:
- Sacred group and individual animal totems that are not to be hunted by that group or individual; each gourp and smaller clan had responsibility for looking after specific plants, animals, and natural features that they were spiritually connected to.
- Restriction on species caught
- Closed seasons
- Taboo areas and species
- Designated hunting areas for individuals and groups
- Leadership according to age → ecologically sound practices to be handed down from one generation to another.
- Stories, ceremonies and rituals passed on environmental knowledge to smaller children
- Limits to population growth
- Sustainable methods of hunting were used and resources were not wasted
Traditional societies are generally familiar with the cycles and processes of the ecosystem in which they are living. This intricate knowledge is passed down.
Indigenous Australians did modify their environment. A good example of long-term modification was the result of firestick burning with cool fires. This practice was widespread and animals were attracted to the regrowth, thus making hunting relatively easier. The regular burning also made passage through the bush much easier. Over time, the Australian environment was drastically modified to one that suited Indigenous Australians.
Promoting strategies for sustainable development means more than learning from indigenous culture; it involves the recognition of indigenous rights (land rights). Sustainable ecosystem management in non-indigenous areas has benefited from the knowledge of Indigenous Australians. An equal partnership between indigenous and non-indigenous management systems would provide a new vision for the conservation of Australian ecosystems. In Australia, the Aboriginal Natural Resources & Environment Council provides advice to the government on land and water management issues. There are many indigenous management practices that can assist in conserving ecosystems today. Increasingly, ecologists are incorporating indigenous techniques and wisdom in their contemporary strategies.
Contemporary management strategies
- purpose of the conservation
reasons such as:
- preserving wilderness
- preserving endangered species
- providing recreation
- a combination of these
- best areas
found through research, surveys and mapping of biodiversity
- proper protection for selected areas
Laws to protect the area, its flora and fauna and to define the use of reserves
- management plan
- rehabilitation or regeneration
- maintenance procedures such as culling species or pests, using fire regimes
- ongoing assessment
How effective management strategies are as time passes.
- revised management plan
Created based on research and assessment of the results of the original plan
- regional and national management plans
integrating the management plan with regional and national manage plans to allow a coordinating large-scale approach to be achieved.
Many of the most serious environmental issues facing the planet are global and require agreement from the international community to be successful. The 2002 Earth Summit in Johannesburg showed that political and economic concerns are often placed before environmental issues. This short-sighted approach will eventually see much of the good work being done on smaller regional and local scales undone if there is significant global warming and mass extinction of species. There is some hope, however, as most countries agree that international effort is required if the human race is to survive.
- Evaluation of contemporary management strategies
There is a trend to develop strategies that focus on sustainable development and preservation of biological hot spots. The most successful strategies always integrate the local communities in protecting and conserving the ecological resources. Non-government agencies are becoming increasingly involved in acquiring conservation reserves and managing them directly. There is also increasing acknowledgement and implementation of traditional management strategies.
Proper management assumes that there is the political will to manage ecosystems for long-term sustainability. This is not always the case, even with developed countries. Increasing public awareness of the issues facing the world and human survival are powerful catalysts for change. At the current rate of ecosystem change through human modifications, many of the world’s rain forests will be destroyed within the next fifty years and there is the real possibility of global climatic change. The urgency of implementing sound ecosystem management strategies on all scales has never been greater.
The biggest problem facing the world is the conservation of ecosystems in developing countries where populations are exploding and the pressure on the land is intense. The crippling debt most developing countries have and the urge to develop their ecosystem resources represent the real threat to the integrity of global ecosystems. A moral responsibility rests on the developed countries to provide ecological aid to these nations so their resources can be protected for the future without hindering their development.
Coastal Dune Ecosystems
- What are Coastal Dunes?
Coastal dunes are large accumulations of sand located immediately behind the active beach zone. They are formed when sand is deposited onto the shore by wave action, dries out and is blown to the back of the beach this process is referred to as accretion.
- Spatial Distribution and Dimensions of Coastal Dune Ecosystem
Coastal dunes are found on all of the world’s continental landmasses, with the exception of Antarctica. They form wherever there is sand available for their construction. Beaches generally obtain their sand from rivers flowing to the sea and from the wearing away of cliffs. In some coastal areas other forms of coastal sediments dominate. In the southeast of England, for example, the primary sediment type is shingle – rounded water worn stone – eroded from the surrounding cliffs. In such circumstances dunes do not have the opportunity to develop. The source of coastal sediment is, therefore, very important in determining whether sand is available for the construction of coastal sand dunes. The other significant factor is wind. It is the single most important factor in determining the shape and extent of coastal dunes. Dunes are most likely to develop in coastal regions that experience strong onshore prevailing winds. For this reason the most extensive dune ecosystems are found in the world’s temperate and arid tropical climate zones. In the wet tropical zones, prevailing winds are generally weaker and less able to move the volume of sand required for dune construction. This does not mean, however, that coastal dunes are completely absent from the tropical world. Along parts of the Sri Lankan coast of eastern Malaysia, extensive dune systems have developed. Despite being well within the wet tropical zone, the prevailing wind in these areas tends to be strong and onshore, allowing coastal dunes to develop. The occurrence of dune systems is, therefore, dependent on:
- the local topography
- the direction and power of the prevailing winds
- the nature of the material available for dune construction
All these factors vary from place to place. As a result, dune systems develop in a wide variety of locations and their specific nature varies considerably. However, the fundamental processes of dune construction and indeed destruction remain the same world over.
Interactions with the Biophysical Environment
- The Role of the Atmosphere
The movement of sand by the wind is referred to as aeolian transport. The volume of sand transported by wind depends on the size of the sand particles, the velocity of the wind, the local topography and the nature of vegetation cover. Generally speaking, the higher the wind velocity, the higher the rate of sand movement.
The potential of the wind to transport sand is also affected by local conditions, especially the degree of protection the sand has from the prevailing wind. Where sand is covered by vegetation, aeolian transport will be minimized. The foliage of the vegetation disturbs the flow of the wind, reducing its velocity. The roots of plants also help to bind the grains of sand together. Making them more difficult to shift.
Temperature plays an important role in determining the rate at which beach sand dries and the extent and type of vegetation grows in the area. The temperature also affects the functioning of ocean currents. These currents may have the potential to move sediment long distances or to cause beaches to be eroded or built up.
Levels of precipitation are also important in determining the nature and extent of the vegetation binding the sand together. Areas with regular rainfall are more likely to have a vegetation profile. Areas with low or irregular rainfall are likely to remain unstable and support little vegetation growth.
- Hydrological Processes
Along coasts, water is a critical factor in determining the nature of coastlines. During periods of relatively calm weather, waves bring sand from offshore deposits and deposit it on beaches. This sand is then available for the wind to transport it into the dune system. In periods of severe and unstable weather, storms create large and powerful waves that strike the coast with such force that they remove sand from beaches and the fore dune area. In very severe storms the waves may attack the dune system, creating wash overs. The effect of currents is very important, particularly the process of long shore drift. The importance of long shore drift lies in its role as a transporter of sediment. Sediment, which is produced or deposited in one part of the coastal system, is transported to other locations within the system by the process of long shore drift. This allows dunes and other sediment-based landforms to develop in areas some distance from the source of coastal sediments. Queensland’s Fraser Island, a vast island made entirely of sand, demonstrates this point. Some of the sand that makes up the island and its huge dune system is derived from sandstone deposits found in the Sydney region. In times of heavy rainfall, surface runoff accumulates in a swale. Eventually the sand becomes saturated and the water table rises. With the return of warmer weather, the swale dries out and the water table retreats. By this time, however, much of the protective vegetation has drowned and the sand is now left exposed. This causes a migrating dune to form and begin moving away from the now dry lake.
- Composition of Sands
- Dune Formation
Dune formation begins when wind blows dry sand landward from the beach. Drifts accumulate around objects, such as plants and driftwood, which interrupt the wind flow. The sand drift gradually increases in size until a dune-like feature develops. Until a dune is completely stabilized by vegetation, sand may be carried away by winds.
- Types of Dunes
- Fore dunes
The coastal dune or line of dunes that is found behind the berm. They are subjected to erosion and their form and composition are constantly changing.
- Parallel/Transverse Dunes
the lines of dunes that lie behind the fore dune. They form in lines that run parallel to the beach.
- Parabolic Dunes
created by blowouts. These are dunes that take on a ‘U’ shape as they move back through the dune system.
- Dune Profile
- Long-Term Dune Stabilization
With the invasion of, and colonization by, scrub vegetation the parallel dunes become very stable. More complex, plant species such as trees and larger shrubs, make the dune extremely stable and transform it into a permanent feature of the topography.
- Dune Vegetation
Dune vegetation tends to occur in zones that are closely related to the degree of exposure to harsh coastal conditions. This zonation also has a close relationship to the stage of dune development. The oldest dunes support the most complex plant communities; while the most recently formed dunes support only the most hardy pioneering species. Dune vegetation is divided into three groups:
- Primary Species
Closest to the sea is the pioneer zone. This zone extends landward from the debris line at the top of the beach to the area occupied by the foredune. Only specialized plants can colonize areas exposed to salt spray, sand blast, strong winds and inundation by the sea. E.g. Sand Spinifex, Marram grass and pigface.
- Secondary Species
the foredune vegetation is usually composed of semipermanent heath like shrubs and small that stabilise the foredune sand mass. E.g. coastal wattle, coastal Banksia and coastal saltbush.
- Tertiary Species
in the zones beyond the coastal heath, trees tend to dominate. Here the vegetation is protected from the wind and salt spray, and soils are characterized by larger amounts of organic matter. The type of vegetation found in this zone depends on local conditions. E.g. Banksia, She-oaks and Paperbark tea trees.
These zones are not fixed. As plants grow taller and humus accumulates, exposure to sun and soil conditions change. The soil becomes richer and holds more water. This enables scrub and woodland plants to move in, changing the type of vegetation in a process know as succession. The woodland and melaleuca forests represent the end product of this plant succession. For this reason they are referred to as climax communities: communities in equilibrium with they environment.
- Coastal Dune Fauna
Nature and Rate of Change
- Naturally Induced Change to Coastal Dune Ecosystem
- Storm Damage
- Human Impacts on Dune Systems
- Reduction and Alteration of Sediment Flows
- Coastal Development
- Recreational Uses
- Sand Mining and Extraction
- Introduced Species and Weeds
- Impacts of Global Warming and Sea Level Rise
Management of Coastal Dune Ecosystems
- Traditional Approaches to the Management of Coastal Dunes
- Contemporary Approaches to the Management of Dune Ecosystems
- Dune Protection
- Dune Restoration and Stabilization
- Fire Management
- Dealing with Weeds
- Spatial Patterns and Dimensions of Intertidal Wetlands
- Spatial Characteristics of Intertidal Wetlands
- Types of Interactions
- The Dynamics of Weather and Climate
- Geomorphological and Hydrological Processes
- Biogeographical Processes
Adjustments to Natural Stress and the Nature and Rate of Change
- Tidal Movements
Human Impacts both Positive and Negative
- Human Modification of Intertidal Wetland Ecosystems
- Positive Impacts;;;
Why Protect the Intertidal Wetland Ecosystem?
- Maintaining Genetic Diversity
- Utility Value
- Intrinsic Value
- Heritage Values
- The Need to Allow Processes of Selection, Evolution and Change to Continue
Traditional and Contemporary Management Practices
- Identify Management Goals and Objectives
- Define the Management Unit and Boundaries
- Develop and Implement Management Plans
- Select and Utilize Ecosystem Management Tools and Technologies
- Clearly Identify Ecological Constrains or Limitations
- Invoke Stakeholders in Decision-Making Processes
- The Collection, Analysis and Use if Economic, Social and Ecological Information
- Be Ecologically Sustainable
- Sustainable for Whom? Sustainable for what Purpose?
- Sustainable at the Subsistence or the Commercial Level?
- Sustainable under what Conditions?
- Short-Term and Long-Term Considerations
- Precautionary Approaches
- Acknowledge the Global Dimension of Environmental Impacts
- Broad Community Involvement
- Conservation of Scarce Resources
- State of Health of Natural Ecosystems
- Education Programs
- Environmental Impact Assesment
- 1091287761_2004_Geography_Notes_Naomi.doc (boredofstudies.org)
- 1100404251_2004_Geography_Notes_Tenille.doc (boredofstudies.org)
case studies of ecosystems
The syllabus requires a case study to be done on two separate ecosystems at risk. These can be in your local area which you can visit on a field trip, or may be far away, in which case you would prepare a case study for by researching information through various sources.
the biophysical environment
• the nature and functioning of the four components: the atmosphere, hydrosphere, lithosphere and biosphere in a specific biophysical environment including:
– atmospheric processes, climatic components, climatic variation
– operation of the water cycle and the role of water in geomorphological processes
– parent material, slope processes, weathering, mass movements, erosion, transport and deposition, and the fluvial, aeolian and/or coastal
– the variety and distribution of plants and animals and soil formation
• the interactions between, and the human impacts on, the functioning of the
atmosphere, hydrosphere, lithosphere and biosphere.
• a case study investigating ONE issue in ONE of the biophysical components, to illustrate how an understanding of biophysical processes contributes to sustainable management in the environment. The investigation will include:
– identification and explanation of the key biophysical processes which relate to the issue
– scale of operation
– interactions with other components of the biophysical environment
– the sensitivity of the biophysical environment to change
– the importance of understanding key biophysical processes for effective management
• the issue should be selected from ONE of the following components:
– in the atmosphere, one issue such as greenhouse warming, acid rain, ozone depletion
- in the biosphere, one issue such as biodiversity, forestry, land clearing, fire
– in the hydrosphere, one issue such as river regulation, urban run-off, coastal sediment budgets, flood or drought
– in the lithosphere, one issue such as soil degradation, soil erosion, salinisation, soil contamination, mass movement.
Students learn to:
investigate and communicate geographically by
• asking and addressing geographical questions such as
– what are the biophysical interactions which occur between components of the biophysical environment?
– what are the effects of human impacts on the functioning of the hydrosphere?
– how is the biophysical environment changing in response to climatic variations?
use geographical skills and tools such as
• constructing and interpreting flow charts describing the key biophysical processes operating within a given area
• identifying, collecting and recording data about erosion and deposition from primary sources
• constructing a transect to describe the variety and distribution of plants in a specific area
• planning a field work activity to assess the impacts of flood or drought interpreting ternary graphs to describe elements of biodiversity or soil variation
• recognising the key features of changing weather patterns to describe atmospheric processes in a given location.
identify geographical methods applicable to, and useful in, the workplace such as
• contributing to Environmental Impact Assessments
• collecting and analysing field data
• environmental mapping
• the relevance of a geographical understanding of biophysical interactions to a particular vocation such as: planning hazard mitigation, practising environmental law, meteorological forecasting, local council maintenance of coastal areas.