A Presentation By Mr. Allah Dad Khan Visiting Professor the University of Agriculture Peshawar allahdad52@gmail.com

2. BIODIVERSITY AND ECOLOGICAL
SUCCESSION
BY
MR.ALLAH DAD KHAN

3. ECOLOGICAL SUCCESSION?
 Succession is a series of progressive changes in the
composition of an ecological community over time.
Succession is directional. Different stages in a particular
habitat succession can usually be accurately predicted.
 Ecological successions are the noticeable changes that occur
in an ecological setup over time. These changes are often
predictable and take place in an orderly manner. A prime
example is how vegetation grows bigger and bigger over time.
Drastic alteration of environmental conditions may also bring
about the changes. In an ecological setup, the species
composition and structure changes over time as some species
become more adaptable whereas others gradually disappear.
Other species in the community may become more abundant
while others become less abundant, and some even
completely vanish.

4. ECOLOGICAL SUCCESSION?
 Original species may be able to survive in the
original optimal conditions but as the environment
undergo changes, the initially dominant species
may fail, and new ones may become most
powerful. New species may also invade adjacent
ecological setting thereby alters the original
ecosystems after some time duration. Hence, the
changes realized in an ecological setup over time
are termed as ecological succession. Some of the
influencing environmental factors for ecological
succession include windstorms, landslides,
agriculture, and wildfires.

5. WIKIPEDIA DEFINES ECOLOGICAL SUCCESSION AS,
 “Ecological succession is the process of change in the
species structure of an ecological community over time.
The time scale can be decades (for example, after a
wildfire), or even millions of years after a mass
extinction. It is a phenomenon or process by which an
ecological community undergoes more or less orderly
and predictable changes following a disturbance or the
initial colonization of a new habitat. Succession may be
initiated either by formation of new, unoccupied habitat,
such as from a lava flow or a severe landslide, or by
some form of disturbance of a community, such as from
a fire, severe windthrow, or logging.

6. TYPES OF ECOLOGICAL SUCCESSION
 Succession is largely grouped into two, including
primary and secondary ecological succession. The
categorization is determined by the initiating factors
which may either include the disturbance of an
already existing habitat or the formation of a new
habitat. All the changes and developments have to
undergo a gradual process.

7. PRIMARY SUCCESSION
 It is the type of succession initiated in a completely
new habitat that has never been originally
colonized. It occurs when a series of species enters
into a new habitat that has never supported any
plant or animal community. When the new
community enters such a habitat, significant
changes begin to take place and subsequently alter
the ecological setting completely. The newly
colonized environment is considered to be in its
primary stage as it gradually undergoes fresh
chemical and physical changes.

8. SECONDARY SUCCESSION
 Secondary succession is the reciprocal of primary
succession. It involves the ecological changes that
occur in a previously colonized, but destroyed or
upset habitat. This type of succession is more
frequent compared to primary succession since
most of the contemporary human activities such as
deforestation, agriculture, land clearance, and
pollution often destroys environments after which a
new community moves in.

9. ENDPOINT OF SUCCESSION
 Ecosystems, because of the internal dynamics and
external forces, are in a constant process of change
and re-structuring. Ecological succession is a
predictable process in which a community goes
through the same series of stages. There is a
concept in ecological succession called the “climax”
community. The climax community represents a
stable, unchanging final state of the successional
sequence. Climax community is the final stage.
Succession will not go any further than the climax
community.