Vegetation
is a general term for the plant life of
a region; it refers to the ground cover
provided by plants, and is, by far, the
most abundant biotic element of the biosphere.
The term vegetation does not, by itself,
imply anything regarding species composition,
life forms, structure, spatial extent,
"naturalness", or any other
specific botanical or geographic characteristics.
It is broader than the term flora which
refers exclusively to species composition.
Perhaps the closest synonym is plant community,
but vegetation can, and often does, refer
to a wider range of spatial scales. Primeval
redwood forests, coastal mangrove stands,
sphagnum bogs, desert soil crusts, roadside
weed patches, wheat fields, cultivated
gardens and lawns; all are encompassed
by the term vegetation. Vegetation serves
several critical functions in the biosphere,
at all possible spatial scales. First,
vegetation regulates the flow of numerous
biogeochemical cycles, most critically
those of water, carbon, and nitrogen;
it is also of great importance in local
and global energy balances.
Such
cycles are important not only for global
patterns of vegetation but also for those
of climate. Second, vegetation strongly
affects soil characteristics, including
soil volume, chemistry and texture, which
feed back to affect various vegetational
characteristics, including productivity
and structure. Third, vegetation serves
as wildlife habitat and the energy source
for the vast array of animal species on
the planet. Vegetation is also critically
important to the world economy, particularly
in the use of fossil fuels as an energy
source, but also in the global production
of food, wood, fuel and other materials.
Perhaps most importantly, and often overlooked,
global vegetation has been the primary
source of oxygen in the atmosphere, enabling
the aerobic metabolism systems to evolve
and persist. Lastly, vegetation is psychologically
important to humans, who evolved in direct
contact with, and dependence on, vegetation,
for food, sheleter, and medicines.
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