2005 HSC - State Rank: Ecosystems At Risk Essay PDF

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State Rank: Ecosystems At Risk Essay (2005 Q)...

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Ecosystems at Risk – 2005 HSC Account for the vulnerability and resilience of ecosystems. – 2005 HSC

According to a recent UN report, 1 million species may be at risk of extinction due to deforestation, overfishing and other human related activates. Ecosystems are fragile environments that can be greatly affected by small factors, with both human impacts and natural impacts, making them vulnerable. Vulnerability is the ecosystem’s sensitively to stresses that can upset the ecological dynamic equilibrium (a state of balance of ecosystem processes). Despite this, ecosystems also have a level of resilience, the ability to adapt to a changing environment and to restore function and structure following an episode of induced stress. Major factors that determine an ecosystem vulnerability and resilience include

the location, extent, biodiversity and linkages within the

ecosystem. By accounting the natural stresses and functioning within ecosystems such as Chernobyl, Avalon Sand Dunes (ASD), Careel Bay Intertidal Wetlands and Mount Saint Helens, we are able to analyse the vulnerability and resilience of ecosystem.

Ecosystem Functioning The countless combinations and variables of the world has led to diverse ecosystems and changes of their functioning to adapt to their biophysical environment. The four spheres (atmosphere, hydrosphere, lithosphere and biosphere) interact with each other to affect how ecosystems develop and function in terms of energy flow & nutrient cycling. Atmospheric factors such

as climate,

temperature

and

rainfall greatly

determine

the

characteristics of all the elements within the ecosystem and the speed at which they function (e.g. moist climates of rainforest ecosystem accelerate the rate of plant growth and decay of the dead material). The

atmosphere also determines the nature of the water cycle in certain areas. Large volumes of rainfall results in high levels of biodiversity, whilst low amounts of water can result in a dry and arid climate, as seen in deserts and polar regions. The lithosphere determines the nature of soil and provides habitats for many of decomposer organisms that recycle the minerals essential to the plants that form the basis of the food web. For organisms to live and ecosystems to function, environmental conditions in the biosphere must enable solar energy to be harvested and plants must be able to produce chemical compounds necessary for life.

Location In a global scale, latitude, distance from sea and altitude can determine the climate and ultimately some ecosystems. However, the location and proximity of an ecosystem near human development can also potentially make an ecosystem vulnerable, placing the ecosystem at risk. This was the case of surrounding ecosystems in Chernobyl, located in the vicinity a nuclear power plant in Ukraine. In 1986, Reactor 4 at Chernobyl Power Plant exploded, releasing large amounts of radioactive material into the surrounding environments, causing the surrounding ecosystems to be at risk. As a result of the human induced stress, surrounding flora and fauna were immediately severely affected by the radioactive material. In the short term, plants and animals within the 30 kilometre exclusion zone, received high doses of radiation, resulting in an increase in mortality rate and a decrease in reproduction over the first few years. Despite such initial damage, the lack of human activity allowed many species to recover in population over the following decades. The resilience of the surrounding ecosystems was demonstrated through the regrowing of vegetation and increased population of animals, such as wolves, suggesting that the food chain is strong and high in population for each trophic level. Thus by accounting the factor of location, we can determine an ecosystem’s vulnerability and resilience.

Extent The extent/size of an ecosystem is also another major determinant of the vulnerability within an ecosystem. Avalon Sand Dunes (ASD) is a dynamic and tidal coastal ecosystem, located 40 kilometres north of Sydney’s CBD and in the Eastern side of the suburb Avalon, next to the Pacific Ocean. The vulnerability of ASD is rather high due to the small extent and isolated nature. of the ecosystem ASD consists of one primary dune, rather than numerous dunes due to human development. The single dune system is approximately 150 metres by 550 metres, covering a relatively small area of 8.4 hectares. As a result, the whole ecosystem is vulnerable if the ecosystem is majorly damaged due to the natural stresses in the area, such as a case of a blowout. Despite all of this, ASD is a highly dynamic ecosystem, subject to constant changes and overall has a relatively high level of resilience. The unstable sands and little foredune vegetation subject to strong winds and waves result in a low level of persistence (the ability to resist change for long periods), high amplitude (significant physical change despite recovery) and malleability. However, the rapid recovery and ecological succession by the keystone species, the spinifex, results in high elasticity.

Biodiversity By accounting the biodiversity within the ecosystem, we can determine its vulnerability and resilience. Careel Bay Intertidal Wetland (CBIW) is a multi-tiered ecosystem, located It is located 32 kilometres north of Sydney CBD, that includes the ecosystems of the mangroves and the saltmarsh. Despite being in such proximity, there are large differences in the vulnerability of each ecosystem. Within the mangrove ecosystem, there is a high level of biodiversity, containing hundreds of species of birds, fish, crustaceans, molluscs, worms, and shellfish. This establishes a strong bond within the food chain and is able to survive even in times of intense

stresses, thus making it resilient and less vulnerable. However, the saltmarsh in the other hand is very limited with low biodiversity. The only prominent plant species there is the low lying sarcoconnia, with minimal amounts of crabs and birds due to the hypersaline conditions. As a result, the saltmarsh ecosystem is very vulnerable, especially to the succession of mangroves, as a result of rising sea levels. Generally, CBIW is quite resilient as a result of the mangrove’s attributes. Mangroves serve as a habitat for local fauna, stabilising soil, absorbing pollutants and filtering excess sediment. As a result, we can deduce that biodiversity is a crucial factor in determining an ecosystem’s vulnerability and resilience.

Linkages Linkages or interdependence is related to species diversity and is another important factor to determine an ecosystem’s vulnerability and resilience. The greater the interdependence within an ecosystem, the greater its ability to absorb change as there is a greater chance for a replacement species if one keystone species lacks or is extinct. This can be seen within the surrounding ecosystems in Mount Saint Helens. In 1980, the volcano erupted, destroying vast amounts of land and vegetation, covering a huge area in infertile debris and ash, and killing hundreds of species and destroying the environment. Despite this, the surrounding ecosystems were able to recover due to its strong linkages, demonstrating its resilience. Lupines, a small flower bush, was one of the first plants to grown on the barren landscape. The lupine held few nutrients in the deep volcanic ash and is able to convert nitrogen into a usable form for plants, enriching the soil. Overtime, lupine patches became biological hotspots facilitating growth of other plant species and attracted numerous insects, birds and small mammals. Pocket gophers and plants such as willow trees that managed to survive the explosion, also played a major role in the rehabilitation and the regrowth and resilience of the surrounding ecosystems. Linkages within an ecosystem play a major role in the resilience and vulnerability of ecosystems.

By accounting numerous factors into consideration, we are about to examine the vulnerability and resilience of an ecosystem. By observing the location, extent, biodiversity and linkages in ecosystems such as in Chernobyl, ASD, CBIW and Mt Saint Helens we are able to analyse the respective vulnerability and resilience of each ecosystem....