SUCCESSION
The observed
changes in a species structure of an ecological community over the period of
time. We know that ecosystem are constantly changing. There are basically two
types of ecological succession.
Primary
succession
Secondary
succession
Primary succession
In this type
the life is created in area where no life existed before. Primary succession
begins in places like sides of volcanos are erupted, landslides an flooding.at
the early stages lichens are established in that area because they usually do
not need any soil to survive. There species are called pioneer species.
When these
lichens die they add organic nutrients in soil. So simple plants lie mosses and
ferns can grow. The simple plant die and add more organic nutrients to the soil
by their decomposition.
The soil
thickens and grasses another plants begin to take over so new plants can now
grow
SECONDARY SUCCESSION
Secondary
succession occurs in areas where previously life is existed but is destroyed by
different disturbances and no life exist on it anymore.
The growth
of species on such kin of areas is called secondary succession.
MECHANISMS
OF SUCCESSION
The
mechanism of succession include facilitation, tolerance and inhibition. The
more capable model is facilation. Facilation and inhibition occurs in
intertidal occurs intertidal succession.
Facilation model
This model
suggests that pioneer species reach and establish on the site where situation
is distributed.thes species modify the land site which become suitable for
further species. Thus further established species eliminate previous species.
This mechanism is repeated until the climax stage is reached.
TOLERANCE MODEL
This concepts
suggests that species in succession are capable to establish on neww disturbed
site. In this model competition intolerant species are relatively successful
early in succession.
Inhibition model
This is the
third mechanism of succession. Some early species make less suitable soil which
is not suitable for development of other species, and in some cases some
species secrete toxic biochemical into soil, which inhibit growth of other
species. So in result inhibitory species die and creates other species to
establish.
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