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ecosystem — English
The plants, animals and microorganisms together with the physical and chemical components of the environment in, and on, which they live constitute an ecosystem. Therefore, ecosystems consist of living organisms, soil, water, air, rocks and any other natural or human-made entity that happens to occur in that specific area at that specific time. In Geography an ecosystem is a spatial concept, that is, it consists of all the above-mentioned, but occupies or exists in a specific, defined space that can be demarcated and mapped (see “demarcation”). This does not mean that ecosystems are closed systems effectively sealed-off from all other ecosystems adjacent to or near them. Individual organisms inhabiting an ecosystem move around and interact with inhabitants and components of other ecosystems. Moreover, all ecosystems receive solar energy, water and air and other physical and organic inputs from the surrounding environment, and both energy and matter leave the system as outputs. Consequently, energy and matter constantly flow into, through and out of all ecosystems. Since ecosystems consist of a variety of organisms that form a food-chain, and inorganic (non-living) components are continually cycled through the system, ecosystems have a high capacity to sustain themselves. Without the variety of organic components and the constant flow of organic and inorganic substances, any ecosystem will eventually collapse and cease to exist. It is a common misconception that ecosystems are completely natural systems somewhere in the rural areas, or in nature reserves, or far away from those of us who live in urbanised regions like Gauteng. This is not at all true, since all cities consist of thousands of small ecosystems (micro-ecosystems). Every single built structure and human-made artefact is part of an ecosystem.
