Download (climax community) is reached is called ecological succession

Succession
http://www.youtube.com/watch?v=55xikeGO6oQ
Start 4:45
http://www.youtube.com/watch?v=bgRnVhbfIKQ
http://www.youtube.com/watch?v=ltlGkDIXu6E
&feature=related
Ecosystem Formation
Ecosystems tend to go
through dynamic change
with time until a stable
system (climax
community in a state of
equilibrium) is attained.
The type of ecosystem
that is formed depends
on the climatic
limitations of a
particular geographical
area.
Succession
The replacement of one
community by another
until a stable stage (climax
community) is reached is
called ecological
succession.
Succession begins with
Pioneer Organisms: the
first plants to populate
an area.
Ex) lichens and algae on
bare rock.
* Starting with
Pioneer organisms,
each community
modifies the
environment.
* Each community
modifies the environment,
often making it more
unfavorable for itself and
more favorable for the
following community.
For example,
As lichens grow and
reproduce, they add organic
matter and moisture to their
substratum, and eventually
it becomes too rich and
moist for the lichen to
survive.
 The lichens die but
produce a richer
substratum that will
support seeds for the
development of grasses and
herbs, the next stage of
succession.
A plant succession
sequence in NY
might be:
deciduous woodlands
(climax)
Conifers (pine trees)
shrubs
grasses
lichens (pioneer)
 Plant species (flora)
dominate in the sense that
they are the most abundant
food sources.
 Plant succession is a
major limiting factor for
animal (fauna) succession.
* Communities are composed
of populations able to exist
under the prevailing
conditions and are identified
by their dominant plant
species – the one that exerts
the most influence over the
other species present.
 Succession ends
with the
development of a
climax community.
Climax Community
is a self-perpetuating
community in which
populations remain stable
and exist in balance with
each other and the
environment.
* A climax community
continues until a
catastrophe or a change in
a major biotic or abiotic
factor alters or destroys it,
thus producing “nonclimax” conditions.
Catastrophic changes
 forest fire
 volcanic eruption
* Succession once
again occurs leading
to another climax
community.
The original climax
community may be
reestablished or a new
climax community may be
established if the abiotic
environment has been
permanently altered.
Pond Succession
 Ponds and small
lakes, for example, fill in
due to the seasonal dieback of aquatic
vegetation and the
erosion of their banks.
 Thus, there is a
gradual succession
from a freshwater to
a terrestrial climax
community.
Old Field Succession
Ex) The oak-hickory
and the hemlockbeech-maple
associations
oak
hickory
cedar
beech
maple
PRIMARY SUCCESSION
Begins from bare rock
PIONEER ORGANISMS
First to inhabit an area
PIONEER ORGANISMS
include lichens and mosses
SECONDARY SUCCESSION
Follows a fire
or
clearcutting
http://www.youtube.com/watch?
v=ltlGkDIXu6E&feature=related
Secondary Succession
occurs more
quickly than Primary
Succession