In ecology, a community
refers to a grouping of species living collectively and interactively
with the environment in a specified area, while the term biosphere
refers to the total extent of all of the ecological systems on Earth.
The natural communities in an ecosystem can change in a process
referred to as succession, which can encompass lengths of time ranging
between a few years and centuries. In the biosphere, the totality of
living organisms on Earth have been interacting with each other and the
elements of the hydrosphere, lithosphere and atmosphere for what is
believed to be a span of about 3.5 billion years
