LOCATION
The 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 ECOSYSTEMS

Ecosystems 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.

LINKAGES
The 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.

	Created by Lucy Chen about 11 years ago

Summary of HSC Geography Syllabus for Topic 1

Ecosystems at Risk