Ecological Succession February 18 th 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
e.g. Red alder Then small shrubs and shade-intolerant plants
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 Weedy Shade intolerant (needs lots of sunlight) Short lived Not good competitors Can live in harsh environments Late stages of succession Not good at dispersing Shade tolerant Long lived Very good competitors 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.