Ecological Succession (primary vs secondary)
Summary
TLDRThis script explores ecological succession, using the analogy of U.S. Presidents to explain the concept of succession as a process of following and coming next. It delves into primary succession, the development of life on barren land such as new volcanic rock or retreating glaciers, and secondary succession, the recovery of an ecosystem after a disturbance like a forest fire. The script vividly describes the stages of these processes, from pioneer species like moss and lichen to climax communities, emphasizing the gradual and dynamic nature of ecological change.
Takeaways
- π Ecological succession is the process of ecological development in an area, starting from bare rock to a mature ecosystem.
- πΊπΈ Succession means to follow or come next, as illustrated by the analogy of American presidents succeeding one another.
- π Primary succession begins in a lifeless area such as bare rock created by a volcanic eruption or glacial retreat.
- π± Pioneer species, like moss and lichen, are the first to colonize barren environments, breaking down rock into soil.
- π¨ Moss and lichen arrive via wind-blown spores, starting the soil formation process.
- πΈ Over time, soil builds up, allowing small plants, grasses, and shrubs to grow, followed by herbivores and then carnivores.
- π³ With more time and decomposition, richer soil supports larger plants and trees, leading to a more complex ecosystem.
- π² The climax community is the final stage of ecological succession, where a stable, mature ecosystem is established.
- π₯ Secondary succession occurs after a disturbance in an existing ecosystem, like a fire, and regrowth happens faster due to remaining soil.
- ποΈ Natural disasters like floods, hurricanes, tsunamis, mudslides, and volcanic eruptions can lead to secondary succession, as can human activities like abandoning a town.
Q & A
What is the meaning of 'ecological succession'?
-Ecological succession refers to the process by which an ecosystem changes over time, with different species replacing one another until a stable community is established.
What is the analogy used to explain the concept of 'secession' in the script?
-The analogy used is the succession of American Presidents, where each president 'succeeds' or follows the previous one in office.
What are the two main types of ecological succession discussed in the script?
-The two main types of ecological succession discussed are primary succession and secondary succession.
What is primary succession and how does it start?
-Primary succession is the process of ecosystem development in an uninhabited area, starting from bare rock or newly formed land, and gradually progressing to a mature ecosystem.
How does the process of primary succession begin on a barren rock?
-Primary succession begins on a barren rock when pioneer species like moss and lichen colonize the area, often carried by wind or through spores.
What are some real-world examples of primary succession mentioned in the script?
-Examples of primary succession mentioned include new land formed by volcanic eruptions in the Hawaiian Islands and the retreat of glaciers exposing new barren land.
What role do pioneer species play in primary succession?
-Pioneer species are the first organisms to inhabit new land in primary succession. They help to create a thin layer of soil through decomposition, paving the way for more complex plant life.
What is secondary succession and how does it differ from primary succession?
-Secondary succession occurs after a disturbance in an established ecosystem, such as a forest fire. Unlike primary succession, the soil remains intact, allowing for a faster recovery and regrowth process.
What are some natural disturbances that can trigger secondary succession?
-Natural disturbances that can trigger secondary succession include forest fires, floods, hurricanes, tsunamis, and volcanic eruptions.
How does the script illustrate the process of secondary succession after a forest fire?
-The script illustrates secondary succession after a forest fire by showing a series of pictures taken at different years post-fire, demonstrating the gradual regrowth of vegetation and the return of wildlife.
What is the final stage of both primary and secondary succession called, and what does it represent?
-The final stage of both types of succession is called the climax community. It represents a stable ecosystem where plant and animal populations exist in balance with one another.
Outlines
π± Introduction to Ecological Succession and Presidential Analogy
The video begins with an introduction to ecological succession, using a presidential succession analogy to explain the concept of 'succession' or 'secede,' which means to follow and come next. The analogy outlines the succession of American Presidents from Ronald Reagan to Joe Biden. This sets the stage for understanding ecological succession as a process where ecosystems develop and change over time.
π Primary Succession: From Bare Rock to Ecosystem
The video then discusses primary succession, starting with a barren rock surface that eventually transforms into a rich ecosystem. Using the example of volcanic eruptions in the Hawaiian Islands, it explains how lava cools to form new land that gets colonized by life over time. Glacial retreat is another example where exposed rocky land is eventually inhabited by vegetation. The McCarty Glacier example illustrates how land exposed by retreating glaciers becomes vegetated over time.
π¦ Pioneers of Primary Succession
The next section introduces pioneer species, the first organisms to colonize new land. Analogies to famous pioneers in history help explain the concept. Pioneer species such as moss and lichen, which can colonize bare rock, play a crucial role in creating soil from their decomposed organic matter. This sets the foundation for other plants and eventually larger vegetation to grow.
πΎ Development of Vegetation and Arrival of Herbivores
As more time passes, the thin layer of soil created by pioneer species allows more plants to grow. Seeds arrive through wind or animal droppings, leading to the growth of small flowers, grasses, and shrubs. Herbivores then migrate to the area in search of food, followed by carnivores, creating a growing community. The continual decomposition of plant material enriches the soil, supporting even more plant life.
π³ Formation of Climax Community
Over decades, the soil becomes thicker and more nutrient-rich, allowing trees to take root and grow to full maturity. This creates habitats for various animals, leading to a balanced climax community where plant and animal populations stabilize. The final stage of primary succession results in a mature ecosystem that may take centuries to develop fully.
π₯ Secondary Succession: Regrowth After Disturbance
The video then shifts to secondary succession, which occurs after a disturbance in an established ecosystem, such as a forest fire. Unlike primary succession, the soil remains intact, allowing for faster regrowth. Stages of regrowth occur similarly to primary succession but at an accelerated pace. Examples include forest regrowth after fires, floods, hurricanes, tsunamis, mudslides, volcanic eruptions, and human abandonment of areas like Pripyat after the Chernobyl disaster.
ποΈ Examples and Summary of Secondary Succession
The video provides visual examples of secondary succession, showing how vegetation regrows in stages after a forest fire. It also discusses how life returns after other natural disasters and in abandoned areas. The process of secondary succession is faster because it builds on the existing soil, leading to quicker recovery of the ecosystem. The video concludes with a quiz to test understanding of the concepts covered.
Mindmap
Keywords
π‘Ecological Succession
π‘Primary Succession
π‘Pioneer Species
π‘Climax Community
π‘Secondary Succession
π‘Decomposition
π‘Herbivores
π‘Carnivores
π‘Natural Disasters
π‘Abandoned Areas
π‘Soil
Highlights
The video discusses the concept of ecological succession, using the analogy of American Presidents to explain the term 'secession'.
Primary succession is the establishment and development of an ecosystem in an uninhabited area.
The process begins with bare rock, which over time, develops into a thriving ecosystem through a series of changes.
Volcanic eruptions and glacial retreat are examples of events that lead to primary succession.
Life colonizes new barren land through primary succession, as seen in the Hawaiian Islands where volcanic lava solidifies into new rock.
The process starts with pioneer species like moss and lichen, which are the first organisms to inhabit new land.
Pioneer species are carried by wind and grow on rocks, eventually forming a thin layer of soil.
As time passes, more moss and lichen grow, creating a thick layer that further develops the soil.
Seeds are introduced to the area through bird droppings and wind, leading to the growth of small flowers, grasses, and shrubs.
Herbivores and carnivores migrate to the area as vegetation increases, forming a growing community.
Decomposition of plant material and animal waste continually builds up the soil, enriching it with nutrients.
As the soil becomes richer, more plant life grows, and the community becomes more established.
Decomposition and soil enrichment lead to the growth of trees, which eventually form a climax community.
The climax community is the final stage of primary succession, where plants and animal populations exist in balance.
Secondary succession occurs after a disturbance in an established ecosystem, such as a forest fire.
Unlike primary succession, secondary succession does not start from scratch because the soil remains intact.
Regrowth in secondary succession occurs at a faster pace, often taking just a few decades.
Examples of natural disasters that can lead to secondary succession include floods, hurricanes, tsunamis, and volcanic eruptions.
Abandoned areas, like the city of Pripyat in Ukraine, also undergo secondary succession as nature reclaims the land.
Transcripts
hello everybody so the topic of this
video is going to be ecological
succession let's go ahead and get
started
so what does the word secession even
mean I want to use an analogy with
American Presidents this is President
Ronald Reagan he was President until
1988. who seceded him in 1989. that was
George Bush
who seceded President Bush in 1993. that
was Bill Clinton who seceded Bill
Clinton in 2001 that was George Bush Jr
who seceded him in 2009 that was Barack
Obama who seceded him in 2017 that was
Donald Trump and who seceded him in 2021
that was Joe Biden so I hope you see
secession or secede means to follow and
come next I hope you'll understand why I
chose this analogy as I go through the
slideshow
so let's get into the process of primary
succession first The Establishment and
development of an ecosystem in an
uninhabited area well here's a patch of
bare rock well over time an ecosystem
will develop through a series of changes
and it's subtle at first small
vegetation at first but then the
vegetation grows and gets more hearty
and eventually perhaps you end with a a
large Forest well how does this process
happen let's talk about this in more
detail
so let's look at this example here we
have a volcano erupting and lava is
flowing into the ocean well eventually
this lava will cool down and solidify
into new rock new Barren land now
eventually because of primary succession
life will colonize this area so this is
what we're going to follow a little
later in the slideshow
and this exact scenario is happening in
the Hawaiian Islands volcanoes are
erupting and spewing out lava that lava
is flowing into the ocean and when it
solidifies it makes new uh Barren Rocky
lands that eventually become colonized
through primary succession
you know another scenario that leads to
primary succession is what is called
glacial Retreat as the seasons change as
the planet goes through periods of
warming and cooling glaciers when uh
through warming periods will Retreat and
when that happens new Barren Rocky land
is exposed that eventually becomes
colonized by life
you know here's a nice picture showing
glacial Retreat even though the picture
itself is from 2003 and a little old but
in the blinking line right there this is
where the glacier was in 1985. even now
today I'm sure this Glacier is even
retreated further exposing more land
so here's a good picture of the McCarty
Glacier taken from 1909 and if we if we
compare that to a picture from 2004 the
glacier has retreated but notice the
green hillsides the Green Mountain sides
vegetation has colonized this land
okay so let's actually start the process
now of primary succession starting at
the beginning we're going to use the
volcano lava example so this lava will
eventually cool and Harden into a rocky
Barren Wasteland
and so in my animation here we have some
molten lava that has just gone through
Cooling and now this is just a Barren
Rocky Wasteland let's begin the process
now
so let's go ahead and introduce the
Pioneers now I want to use an analogy
people can be Pioneers these are people
who are Trailblazers they Forge paths
for others to follow you know perhaps
you've heard of Alexander Fleming he was
a Pioneer in medicine he helped to
develop the first ever antibiotic called
penicillin
Amelia Earhart was a Pioneer who helped
uh who was a Trailblazer for women in
aviation uh Elvis Presley was a Pioneer
in rock and roll
a former tennis player Billie Jean King
a Pioneer in women's rights and lgbtq
rights and Muhammad Ali a Pioneer in the
Civil Rights Movement these are people
who are Trailblazers and I hope you'll
understand why I chose this analogy as
we go through pioneer species next
so in primary succession the
Trailblazers are the pioneer species the
first organisms to inhabit this new land
typically you'll see moss which you can
see in this picture growing on rocks and
lichen which you can also see growing on
rock and in this environment that's all
there is this is just a rocky Wasteland
so moss and lichen colonize this new
area
so how do the Moss and lichen even
arrive in this new area well they're
carried by the wind moss and lichen will
release little reproductive cells called
spores the spores of land and ultimately
they begin to grow
now lichen comes in these colors right
here the silvers and reds yellowish
greenish colors kind of these pale
colors here and and this Rusty orange
color right here and so in my animation
I drew the like and as these colorful
squiggly squiggly lines that have begun
to grow on the rock
now over time as the years and years and
years pass the like and will will
multiply and eventually die and the
organic remains forms a real thin layer
of soil over the years and years and
years that pass now is this enough soil
for large sequoia trees and redwood
trees to begin to grow no but it's
enough soil and nutrients for even more
moss and lichen to begin to grow and you
get this real thick Shaggy almost a
thick Shaggy layer of carpet that begins
to grow on the rocky land
so as more time passes as the years and
perhaps decades pass eventually seeds
enter the area you know as birds are
flying overhead seeds often get
deposited in their droppings here's
another bird right here that just went
poop and a seed came out and eventually
was deposited in this area
seeds can also be deposited and
dispersed through wind many seeds are
wind dispersed and can be spread through
the wind and when they land they begin
to germinate into small flowers and
grasses and shrubs begin to grow again
this process can take years and years
and years and decades
so now that there's plans and vegetation
in the area as more time passes
eventually the herbivores begin to
migrate in in the search for food and
shelter and where herbivores migrate
eventually of course carnivores then
follow and we have a growing Community
you know 60 70 years ago perhaps this
was just a rocky Wasteland and as more
time passes decomposition of plant
fallen leaves of plants and mouse
droppings and snake droppings and the
petals that fall off of flowers
decomposition continually builds up the
soil and more and more and more
nutrients are packed away that
eventually help to spawn even more
growth so as more time passes the soil
becomes more rich and more plant life
begins to grow and the community becomes
even more established
so as even more time passes
decomposition again continually builds
the soil notice how the soil just became
thicker as years and years and decades
pass now that the soil is thicker and
more nutrient Rich trees begin to take
root the seeds get deposited by wind and
bird droppings and they grow and it
takes years perhaps decades for trees to
reach their full maturity but eventually
now that there's more habitats and trees
to live in animals migrate in other
animals migrate in and take advantage of
an open Niche that perhaps didn't exist
before and so some insects have flown in
and perhaps some birds and this slow and
steady process can take years and years
and decades but let's say 120 years ago
what was this world it was a rocky
Barren Wasteland
so in the process of primary succession
we finally reach what is known as the
climax community the final stage when
plants and animal populations exist
within a balance of one another and and
they each tend to stabilize again this
can take years and years in in decades
perhaps even centuries
as this process is happening again
decomposition continually builds the
soil trees will shed their leaves animal
droppings add to the nutrients of the
soil and notice how the soil is at its
thickest now and so this means even the
even taller trees can take root and
begin to grow canopy trees will
eventually grow and can out compete and
shade out the smaller plants and
vegetation and over time the smaller
vegetation and plants begins to die off
again it can take decades and decades
for these canopy trees to reach their
full mature height this is a slow and
steady process and with these larger
trees new animals can migrate in and
take advantage of the new habitats maybe
rabbits and owls and think back what was
this area maybe 150 200 years ago this
was a Barren Rocky Wasteland and through
primary succession has become a thriving
forest ecosystem
let's go ahead and shift now to
secondary succession changes that take
place after a disturbance occurs in an
established ecosystem well here in this
picture here is our established
ecosystem perhaps this Forest has been
thriving for hundreds and hundreds of
years and then a disturbance occurs such
as a forest fire here's a lightning
strike which Sparks a forest fire don't
worry no clipart animals have been
harmed in this presentation they all
made it to safety but the perhaps the
trees burned down well ask yourself are
we starting from scratch
is the regrowth process starting from
scratch I hope you see the answers no
the soil remains intact so the regrowth
will be at a faster pace
so during the regrowth the regrowth
still occurs in stages similar stages to
what we saw before small plants and
animals and vegetation and then a little
larger organisms colonize the area and
then eventually again the climax
community the the end result we're
really kind of back to where we started
so you still see the stages where one
stage is followed by another it's
followed by another and this is
secondary succession it's just at an
accelerated Pace instead of taking
perhaps centuries maybe this is a maybe
happens in just a few decades
here are a series of pictures that were
taken after a forest fire here's one
year later
here's two years later notice the ground
vegetation is regrowing here's three
years later
and four years later and five years
later
six years later you can see the
vegetation is getting thicker on the
ground the tall trees a lot of those
trees are dead they have no leaves
eventually they will rot and topple over
well here's seven years later
nine years later ten years later you can
see the vegetation is getting really
thick life is returning to this once
burned area
you know secondary succession and
regrowth happens after other natural
disasters as well after floods After the
flood waters recede and the land dries
out eventually life and Wildlife and
plant life will return to the areas that
were destroyed
same with after hurricanes once the
storm has passed any damage done to
Wildlife and plant life will eventually
begin the regrowth process
same with after a tsunami a large wave
might have washed away a lot of plant
life and animal life but over time life
will repopulate these areas
same with after a Mudslide over time
vegetation and Wildlife will return to
that muddy Hillside that you see
same with after volcano volcano
eruptions eventually life will regrow in
this burned area from a volcano eruption
and we also see this in abandoned areas
such as in this city right here pripyat
in Ukraine this is the location where
the Chernobyl nuclear power plant
accident occurred in 1986 the town of
pripyatz was abandoned in 1986 no one's
lived there since 1986 and so you can
see the forest is breaking through the
sidewalks and the cement structures
because the grounds haven't been
maintained by landscapers or gardeners
ever since people abandoned this town in
1986. uh we you know we see this in
other ghost towns that are you know uh
that are scattered throughout the world
also with you know abandon and here's an
abandoned soccer stadium which I thought
was kind of eerie when I saw this
picture uh you can see the bushes and
vegetation growing in in the stands
where people used to sit and enjoy
soccer matches
so as I wrap up the process of secondary
succession just to repeat the recovery
and the regrowth period is just on a
faster scale because we're not starting
from scratch we're not starting from
bare rock after the natural disaster the
soil has remained intact and so the
growth and Recovery is just sped up on a
much faster time scale
okay so as we wrap this up here's a
little quiz for you to try to see how
much you have understood if you're in my
class write your answers on a separate
sheet of paper I'm happy to check your
answers before class or after class one
day thanks for watching
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