Ecosystems at Risk


Summary of HSC Geography Syllabus for Topic 1
Lucy Chen
Slide Set by Lucy Chen, updated more than 1 year ago
Lucy Chen
Created by Lucy Chen over 8 years ago

Resource summary

Slide 1

    Ecosystems at Risk
    Biophysical interactions which lead to diverse ecosystems and their functioning Vulnerability and resilience of ecosystems Causes of ecosystem vulnerability Importance of ecosystem management and protection Evaluation of traditional and contemporary management strategies  Towra Point Intertidal Wetland Ecosystem  Great Barrier Reef Coral Ecosystem Snowy Mountains Alpine Ecosystem

Slide 2

    Biophysical Interactions
    Ecosystem: the dynamic complex of plant, animal and micro-organism communities and their non-living environment as a functional unit. They are systems of interdependent relationships between living organisms and their biophysical environments, where solar energy is captured and channeled through a hierarchy of life forms. Ecosystems rarely have distinct boundaries, instead they blend into adjacent ecosystems via zone of transition called an ECOTONE. Ecotones contain organisms common to both ecosystems, but also have unique organisms, leading to greater biodiversity.Ecosystem functioning is the ability of ecosystems to STORE, CAPTURE, and TRANSFER energy, nutrients and water.The productivity of an ecosystem is expressed by: The amount of biomass produced in an area - new living matter produced per square metre of land/water Energy flows - the amount of energy in kilojoules that is locked into all the organism per area per unit of time Both rates depend on the amount of ENERGY and NUTRIENTS in the environment and the EFFICIENCY that these are incorporated by producers and passed up the food chain.

Slide 3

    Energy Flows and Nutrient Cycling
    The sun's energy flows through the trophic levels of each ecosystem, but energy is lost in the form of heat at each level of the food chain. A plant will lose up to 50% of energy from photosynthesis, whereas consumers lose from 80-90% of the energy available. Only about 1/10th of the energy received is passed on.Nutrient Cycling: 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.The nutrient cycles include the: Carbon Cycle Phosphorus Cycle Nitrogen Cycle Water Cycle Oxygen Cycle
    Caption: : The Food Chain

Slide 4

    Factors Affecting the Functioning of Ecosystems
    Natural changes can take place over tens of thousands of years, allowing ecosystems to slowly adapt, but human-induced changes are typically too rapid for natural systems to adjust. While the world's climate naturally changes over time, human activities (such as the burning of fossil fuels) have significantly altered the world's climate in a very short period of time.CLIMATIC FACTORSClimatic factors such as TEMPERATURE and PRECIPITATION determine the nature and the speed of ecosystem functioning. Precipitation Important because it affects the rate of photosynthesis. Ecosystems are affected through the intensity of precipitation e.g. vigorous water cycle in tropical rainforests quickly leach and erode the land, so deforestation will result in the silting of neighbouring rivers and destruction of river ecosystems. Temperature Most plants prefer 10-35°C for photosynthesis. The warm, moist climate of rainforest ecosystems provides an environment which accelerates the rate of plant growth, decay of dead material, and the absorption of minerals. These conditions lead to an environment which is able to maintain high levels of biodiversity. Wind Wind circulation patterns determine the spread of pollutants such as nitrogen and sulfur oxides that cause acid rain. Only wind resistant vegetation can survive in strong winds e.g. along coastal headlands, ridge tops and mountain slopes Persistent winds reduce moisture levels by evaporating more water from the soil and increasing the rate of transpiration from plants LOCATION FACTORSThe proximity of large bodies of water also effects the type of ecosystem existent in an area. Large bodies of water such as oceans and lakes moderate the temperatures of adjoining land masses because water heats and cools more slowly than land. Warm ocean currents -> high levels of evaporation and precipitation -> wet, rainforests Cold ocean currents -> little to no evaporation -> dry, deserts EDAPHIC FACTORSThe main function of soil is to store mineral nutrients and water. The type of soil helps to determine the nature of an ecosystem e.g. sandy = dry, non-porous = wetland Climate also affects the type of soil as a cold climate will lead to permafrost soil found in tundra regions. BIOTIC FACTORSThe biosphere has two different types of organisms: Autotrophic Organisms (Producers) which use light, water, carbon dioxide and nutrients from the soil to manufacture organic compounds that they use as a source of energy and nutrients.  Heterotrophic Organisms (Consumers) include herbivores, carnivores, omnivores and decomposers. TOPOGRAPHIC FACTORSElevation can cause significant differences in plant communities because of the changes in the availability of moisture. Increasing elevation leads to: Decrease in soil depth and air temperature. Increase in wind exposure. Decrease in the number, height, density, and growth rate of plants. Decrease in the length of growing season. This means that there are very different ecosystems on mountains compared to those in the valleys and plains.

Slide 5

    Vulnerability and Resilience
    All ecosystems function in a state of dynamic equilibrium or a continual state of balanced change. Changes to ecosystems occur because of changes in the relationship between four spheres, and this may influence the balance between nutrients, energy, and communities that exist within an ecosystem.Resilience: the ability of an ecosystem (or a component of an ecosystem) to adapt to a changing environment and to restore function and structure following an episode of natural-induced stress.Ecosystem with a GREATER BIODIVERSITY have a GREATER RESILIENCE than those with little biodiversity, as they have a greater ability to recover from both naturally induced stress (e.g. drought and fire) as well as human induced habitat destruction. The more successful a species is able to regenerate and adapt, the less vulnerable it is to changes in its ecosystems. Long term ecosystem degradation occurs when the magnitude and duration of the stress exceeds the ability of the ecosystem to repair itself.Natural sources of stress can play an important role in the functioning of ecosystems. Stress dependent organisms and processes rely on change in the environment to produce or stimulate a growth of their systems. Examples of stress dependent organisms include:  Eucalypt species: rely on fire to initiate a stage in their reproduction cycle Perennial desert plants: rely on the occasional fall of rain to activate their growth cycle

Slide 6

    Causes of Ecosystem Vulnerability
    LOCATIONThe location of an ecosystem affects its functioning. On a global scale, factors such as latitude, distance from the sea and altitude affect climate, and therefore the type of ecosystem that can develop. Latitude: insolation variations Distance from the sea: precipitation (warm or cold ocean currents), sea breezes moderate temperatures Altitude: lower temperatures as altitude rises Proximity to urban areas: pollution affects nearby ecosystems The MICROCLIMATE FEATURES of a location can be significant enough to create a range of distinctive ecosystem types within relatively small areas.  The ASPECT OF A SLOPE is one such microclimate variable.  Some ecosystems occur in environments that are considered extreme e.g. hot and cold deserts/polar and alpine areas/mountain peaks. 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. Examples of such organisms include: coral, polar bears, seals, stone fly nymphs and whales. PROXIMITY TO LARGE CONCENTRATIONS OF PEOPLE contributes to ecosystem vulnerability. As population rises, so does the demand for land. Urban, industrial and agricultural land uses destroy natural ecosystems, while the ocean, rivers and the atmosphere become dumping grounds for pollutants. For coral reef ecosystems e.g. runoff that has been polluted by sewage, agricultural fertilisers and land clearance is a major source of excess nutrients and increased turbidity.EXTENT/SIZE OF ECOSYSTEMSEcosystems that are restricted to relatively small areas or have been subject to extensive disturbance are especially vulnerable. Tropical rainforests for example, has small populations on a very large number of species confined to relatively small, localised community. The loss of even a small area of rainforest can lead to the extinction of plant and animal species. Grasslands on the other hand do not experience this problem because they have large populations spread over large areas.BIODIVERSITY Genetic diversity describes the variety of genetic information contained within individual plants, animals, and micro-organisms. A wider range of genetic diversity allows a species to survive because it increases the chance that some members of the species will have characteristics to aid their survival if the population is subject to stress. Species diversity is a measure of the number of species at each trophic level of an ecosystem. The greater the species diversity, the stronger the ecosystem and the greater the opportunity to adapt to change.This means that if the population of one producer or consumer organism collapses, there are other producers or consumers available to fulfil a similar function in the ecosystem.  Ecosystem diversity refers to the diversity present within ecosystems in terms of habitat differences, biotic communities and the variety of ecological processes. LINKAGESThe greater the level of interdependence, or linkages within an ecosystem, the greater its ability to absorb change. The loss of a primary consumer from the food web for example, is unlikely to have a major impact on secondary consumers as there is a range of alternative primary consumers on which to feed.Ecosystems that have low levels of interdependence are much more vulnerable to change e.g. there are few linkages up through the food chain of the ocean around Antarctica. Krill is the dominant primary consumer and the main source of energy (food) for some species of whale. There are no intermediary stages  in the food chain. Any reduction in the supply of krill e.g. from a large scale commercial harvesting will directly impact on the number of whales that the ecosystem can support. In the same way, many parasitic organisms depend on specific hosts. A parasitic organism is one that lives off another organism, which is known as the host. Eventually, the parasite will kill its host. This makes these organisms vulnerable to disturbances in their ecosystems. Interdependence can take very subtle forms e.g. some flowering plants can be fertilised by one species of insect. The insect may in turn be dependent upon some other organism for part of its life cycle. Any disturbance that jeopardises this third organism therefore will affect the productive success of the flowering plant. CASE STUDY: CORAL Corals are highly specialised organisms that flourish in relatively shallow, nutrient-deficient waters of the tropics. Any increase in nutrients can lead to an increase of algae, subsequently reducing the availability of sunlight for coral growth. Sustained elevation of nutrient levels can lead to corals becoming stressed, which causes reefs to shrink as well as a decline in coral species. Changes in water temperature, even by a few degrees, can cause the coral polyp to die, leaving the white calcium carbonate skeleton. As a consequence of global warming, many coral reef ecosystems are destroyed. Coral reef ecosystems are also prone to runoff that has been polluted by sewage and agricultural fertilisers as well as excess nutrients and increased turbidity caused by land clearing. 

Slide 7

    Importance of Ecosystem Management and Protection
    The Maintenance of Genetic DiversityEcosystems that have a greater genetic diversity have greater resilience and are 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 well-being of people) is put at risk. Natural selection, also known as 'the survival of the fittest', determines the organisms that survive due to their genetic traits and characteristics which they therefore pass on to subsequent generations. The loss of genetic diversity as a result of human-induced stress is referred to as the opportunity cost of an ever-expanding human population.The Census of Marine Life Science announced in 2011 that there are approximately 8.7 million (give or take 1.3 million) species currently inhabiting the world today. In the PLoS Biology published by these scientists, 86% of all land dwelling species and 91% in the water have yet to be discovered and catalogued by science.Evolutionary extinction is thought to account for the loss of approximately one to five species per year. Scientists now predict however, that the current rate of extinction is 1000 to 10,000 times the natural extinction rate, accounting for approximately 12 extinctions per day. The difference between these two rates reflects the impact of the human activities.Utility ValueThe utility value of an ecosystem is its usefulness to the human race. Through the maintenance and protection of ecosystems, we are able to maximise the human's ability to change. The diversity of life represents a vast store of genetic material that humans can use to adapt to change. The loss of a species denies humanity a possible future source of food, medicine, chemicals, fibres, and other materials. At a global scale, the 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 well-being of humanity.Ecosystems also provide humans with: FOOD: Almost all food crops are native to environments at risk in the developing world e.g. wheat is from Afghanistan, potatoes from Peru, sorghum and coffee form Ethiopia and the Sudan. Plant breeders turn to these regions for their genetic material but these resources can only be maintained by preserving their native environments. MEDICINE: Many drugs used nowadays are derived from plants. Micro-organisms are an important source of antibiotics. Various chemicals produced by animals have also led to the discoveries of medically useful substances. Naturally produced chemically based protective mechanisms found in the organisms of tropical rainforests can be constituted as a major pharmacological resource. Medical scientists have estimated that they have only been able to examine about 5,000 of the 250,000 plants that have pharmacological value. WEED KILLERS: Up until the 1960's, synthetic poisons were used to dispose of weeds but these were found to be extremely harmful due to bio-accumulation and the toxins remaining active in the soil for many years. Science addresses this problem by utilising chemical compounds derived from other organisms such as insect sprays derived from a relative of chrysanthemums. This brings about the question: Who owns the genetic resource? Is it the developing country or is it the multinational company that has the technology and money to exploit the resource?The existence value of an ecosystem is defined as the value a community is prepared to place on the ecosystem in its natural state. Many national parks occupy areas that could otherwise be used for agricultural purposes or urban development. They also contain resources such as timber and minerals that could be exploited. The amount that people would be willing to pay for the land and maintenance of these parks is known as its existence value.The option value is the cost of keeping the ecosystem or species in its natural state as opposed to exploiting its resources.The exploitation of the utility value of ecosystems could destroy the environment. Utility value should incorporate appropriate management techniques so as to minimise the risk of environmental degradation.Intrinsic ValuesEcosystems also inherently possess their own intrinsic and ethical value i.e. they are allowed to exist irrespective of their utility value. The biophysical environment provides for many of the inspirational, aesthetic, and spiritual needs of people. By interacting with the elements of ecosystems, humans are reminded that they are part of an interdependent natural world.The aesthetic qualities of ecosystems are valued for their recreational potential e.g. photography, trekking, bushwalking, birdwatching and field studies. The growth of ecotourism is also closely linked to the growing appreciation of the aesthetic and ecological qualities of the natural environment.Throughout the world, Indigenous people derive spiritual strength from their relationship with the biophysical environment e.g. the traditional Aboriginal and Torres Strait Islander people of Australia. They acknowledge that they are responsible for the continuity of their world through their behaviours and beliefs.In a practical context, protection of an area may involve acknowledging its intrinsic value but managing it with utility value for social, political and economic reasons. It may also require public education campaigns to increase public awareness and support.Heritage ValueThe World Heritage Conservation Council considers natural heritage to be "natural features consisting of physical and biological formations or groups of such formations, which are of outstanding value from the aesthetic or scientific point of view". The Australian Natural 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, historical, 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 large areas of pristine wilderness as well as those sites that are more readily accessible to humans. Education has played a critical role in developing public support for heritage listing.The Need to Allow Natural Change to ProceedThe diversity of life forms on Earth is a product of ongoing evolutionary processes. Many environmentalists and ecologists argue that humans have an ethical responsibility, and selfish requirement, to see that this evolutionary process continues relatively unimpeded. To achieve the desired objectives these areas should: Be large enough to protect and conserve intact ecosystems effectively and allow evolutionary processes to continue. Have boundaries that reflect environmental rather than political needs (based off the boundaries of a catchment area). Take into the account of the interests of local people. They need to have access to areas which provide them with the resources they need in order to provide for their families. Be well managed and effectively resourced. Be surrounded by a "buffer zone" where human activity is carefully managed. Changes in areas around protected zones may interrupt breeding and migration patterns and affect air and water quality.

Slide 8

    Evaluation of Traditional and Contemporary Management Strategies
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