Ecological SuccessionFebruary 18th 2016
Learning Objectives
Describe the process of ecological
succession
Define pioneer species and climax
community
Define primary and secondary succession
Describe the characteristic of species
during early and late succession
Shape of the Day
Lecture/Discussion
Short activity
Story time!
Individual Work time
Surtsey was born
off the coast of
Iceland in 1963
from underwater
volcanic activity.
How did the island
of Surtsey go from
being a barren
rocky wasteland to
the lush island it is
today?
What is Ecological Succession?
Ecological succession the gradual process by which ecosystems change and develop over time.
The story of an ecosystem
Sometimes we start with an ecosystem
AND THEN THERE’S A DISTURBANCE!!
AND THEN THERE’S A DISTURBANCE!!
Disturbance: an
event that causes a
pronounced change
in an ecosystem
Primary succession
Disturbance where soil is either removed or non-existent
Left with bare rock
Secondary succession
Disturbance that may destroy much of the life, but leave behind the soil
But if you just start
with rock (primary
succession) where
does the soil come
from?
What order
do these
species come in?
(5 min)
In the beginning…
Only the hardiest
species survive.
In the beginning…
We call these species pioneer species.
(the first species to colonize after a disturbance)
In the beginning…
Lichen and moss are usually the first to colonize a rocky surface.
They secrete acid that breaks down the rocks and produce the first soil.
Then…
Weedy plants can begin to take root.
As they die, they also decompose and contribute to the soil
Then…
small shrubs and
shade-intolerant
plants
e.g. Red alder
And finally…
Shade tolerant plants
Until we reach the climax community
Western Hemlock and Douglas Fir
And finally…
Climax community: a community that is relatively stable.
The “end stage” of ecological succession.
Old growth forest of BC
What are some
characteristics of plants in
early succession that would
help them to be successful?
Later succession?
What are some
characteristics of plants in
early succession that would
help them to be successful?
Later succession?
Early Stages of Succession Late stages of succession
Weedy Not good at dispersing
Shade intolerant (needs
lots of sunlight)
Shade tolerant
Short lived Long lived
Not good competitors Very good competitors
Can live in harsh
environments
Live in established
environments
Ecological Succession:
The story of how a rock became
an island
Once upon a
time, there
was a slab
of rock
There wasn’t much life on the rock. Actually there was no life at all.
The rock had recently been born from volcanoes under the sea.
The rock wondered
why no one came.
He waited for years.
Just across the sea,
he saw another
island.
This island had lots of tall trees living on it. There were animals galore.
The rock felt a bit jealous. He didn’t even have soil.
“It’s no wonder no one wants
to be with me” he thought.
He started feeling lonely.
Then angry. Who needs
company he thought!
It wasn’t his fault there was
no soil. His heart grew hard
like the rock he was.
One day, a bird flew
toward him. Was this
bird going to land?
He hadn’t finished his
thought before the
bird did what birds do
best.
“Classic…” Thought
the rock. “Not even
a …”
“Hello!” Said a tiny
voice.
“Who said that?!” Said the rock.
“I’m right here!” Said the voice.
It was a small lichen spore.
!
The rock was shocked. “Where did you come from!?”
“I just hitched a ride on that gull.” The spore said. “Say, you’ve got a nice place here, can I stay?”
The rock grumbled. “You won’t like it here. There’s no soil.”
“I don’t need soil!” The lichen said. “Tough places suit me just fine.”
The rock said nothing.
Years passed, and the lichen grew bigger and bigger.
It wasn’t an easy life, and the rock wasn’t an easy friend.
He can be pretty hard nosed. But the lichen didn’t give up.
More lichen stopped
by. They hitched rides
on the wind or other
rude birds.
They settled down
and made a home out
of little, like
pioneers.
Over time the rock
became a little less
lonely.
He didn’t notice at
first, but the lichen
were having the
strangest effect on
him…
As they settled and
grew, the lichen had
been secreting acids into
the rock to break it
down.
Where the lichen
settled, it didn’t look
quite like rock
anymore… it started
looking like…
“Soil!” said a small
voice, different from the
ones before.
It was a dandelion seed.
“I’ve been looking for a
place like this, can I
stay?!”
“There’s not a lot here,”
the rock said, a little shy.
“You sure you want to
stay?”
The dandelion seed
shrugged.
“It’s cool, I don’t like
crowds anyhow.” And the
rock had a new friend
And so the dandelion
stayed. More weeds came
by. They said they liked
the space and lack of
competition.
Many many years passed.
The dandelion’s children
and their children’s
children would pass away.
As they did, they always
left a gift of thanks.
There’s a good amount of
soil on the rock now.
The dandelion and lichen’s
hard work was paying off.
The rock’s hard heart was
softening to soil.
The rock felt softer, less
angry…
Other species noticed the
difference. They started
settling on him too.
First the shrubs came by.
There was enough soil for
them now.
Then trees started settling
down. They needed lots of
soil.
Finally the birds and
animals arrived.
The rock wasn’t a rock
now, he was an island
flourishing with life.
He was in no want of
company, and the species
loved their new home.
One day, the lichen said
to the island that it was
leaving.
“But why?!” said the
island, visibly distraught
“It’s a bit crowded now
for me” said the lichen.
“Besides,” the lichen
beamed. “There’s other
rocks out there that
need a bit of softening
up!”
The island was sad to
watch his friend go.
Over the years,
company came and
went. The shrubs went
when the trees got a
bit too numerous.
Taller trees came to
stay.
But the island never
forgot his first friend
the lichen.
He never forgot the
friend who stayed even
as the going was tough.
And left a soil footprint
in his rock heart.
The end.
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