How Ecosystems Develop
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Many of the eco-zones or
biomes that you are familiar with - the
Boreal Forest, the Rocky Mountains - are
areas where
species have been interacting for many years.
Although living things are always interacting, however, the
relationships between species are not always the same. For instance,
glaciers retreat, leaving a completely different environment in their
wake. Animals and plants adjust and create new relationships with one another in a way that
will sustain the balance of life and growth within their
ecosystem.
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Animals and plants will move into and inhabit a newly formed area. This process is called succession and continues until climax communities develop. In other words, an ecosystem can only support a limited amount of life - be it plant or animal. Anything in excess of this limit will not be able to survive because of natural mechanisms for population control. This ecosystem may support the same species as other ecosystems that have developed in the same ecological region, depending on climate and geographical properties.
There are actually two types of succession -- primary and secondary. Primary succession often takes place when a new piece of land emerges or comes into existence through events like the slow and steady retreat of a glacier or the drying up of a riverbed.
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Secondary succession is generally the result of the
disturbance of an ecosystem. This can occur either through natural
events such as a forest fire, or through man-made destruction such as
clear-cutting.
One similarity between the two types of succession is
that they both lead to an increase in the biomass of the area.