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Ecosystems Typeit
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The of a species is the maximum population size that the ecosystem can support. Conditions which may affect population size can include:
These are all , or non-living, factors. It is possible that any of these may be the which restricts a population's growth rate. competition (competition within a species), or interactions between different species (involving food, predation or disease) can also have an impact on population size.
To measure the distribution of organisms in an area without studying every individual, a systematic can be taken along a . These often work well when studying , the change in species over time in an area as a result of changes to the landscape. When a pioneer species first attempts to modify an inhospitable environment, this is known as colonisation. Eventually, as more organisms come and go from the area and change the environment, a may be reached, in which the ecosystem becomes stable. If the ecosystem is disturbed, e.g. by fire, grazing or agriculture, before this stage is reached, it is known as .
Humans often have negative impacts on ecosystems, so it is important to protect endangered species and habitats. Methods of aim to keep species and habitats as they currently are, while is a more active process, which aims to maintain or improve the level of biodiversity in an ecosystem. Management must be used to balance these processes with sustainable human activity - for example, is an alternative to fisheries, with a reduced environmental impact.
Ecosystems are dynamic communities which can efficiently recycle nutrients. For example, carbon dioxide in the atmosphere is used by plants in , and the carbon is converted to biomass, which may return to the atmosphere when the plants decay. The nitrogen cycle involves a number of microorganisms which convert nitrogen atoms between various forms. For example, is a free-living bacterium found in the soil which is involved in nitrogen fixation, and is a bacterium found in the soil which converts ammonium ions to nitrite ions.