SUCCESSIONNatural Change Over Time

First, a little review…

ECOLOGYThe study of the interactions between living things and their environments

POPULATIONGroups of organisms, all of the same species, that live in the same area

COMMUNITYAll the organisms (different species) that live in an ecosystem at a given time

ECOSYSTEMThe interacting biological communities and their physical environment (biotic and abiotic factors)

Organization in Ecology

Ecosystem

Community

Population

Organism

Ecology also studies how ecosystems

change over time and how communities

recover from a disturbance.

This is called SUCCESSION.

What Is Succession?

The orderly, natural progression of stages that communities of an ecosystem go through

Stop and Jot

Look at these photos. What do you think this street would look like in 10 years? In 100 years?

Two kinds of SUCCESSION.

There are two kinds of succession, depending on how the ecosystem starts out or how an ecosystem is disturbed

PRIMARY SUCCESSION

The colonization of barren land by communities of organisms

Primary Succession happens when a disturbance destroys the entire community so that there is not even any soil left behind

For example a glacier could melt away to expose bare rock.

Another way to think of primary succession is that it occurs when life enters an area for the first time.

In this case the land is completely devoid of soil and vegetation

PRIMARY SUCCESSION

SECONDARY SECESSION

Sequence of changes that takes place after an existing community is severely disrupted in some way

However, the disturbance was not big enough to remove the soil.

Secondary succession might occur after land is cleared for farming, or after a forest fire.

In secondary succession, the dominant plants in the community are removed, allowing new plants to colonize.

SECONDARY SECESSION

Pair and Share With your partner, discuss what kind of succession

is involved in the following. Then, answer the questions on you activity sheet together.

1) Strong winds blow sand across a valley and cover up all the existing vegetation. Eventually, new plants sprout from the barren sand dunes.

2) A flood carries in the Mississippi Delta destroys all organisms and leaves a sticky mud everywhere.

3) A rock slide buries an ecosystem with 5 meters of broken fragments of rock.

PIONEER SPECIES

The first species that move into a barren or disturbed area

Pioneer Species are tough and can live in conditions that other organisms cannot

Many PIONEER SPECIES create soil. For example, lichen attaches to rocks and breaks them down into soil. Mosses and grasses can also be pioneer species.

Pioneer Species often colonize a new area by seeds being blown by the wind.

Please answer the following questions on your own:

Why are mosses and lichens pioneer species, but pine trees and deer are not?

PIONEER SPECIES

CLIMAX COMMUNITY

A stable, mature community that undergoes little or no change in species

A CLIMAX COMMUNITY is what the community would be like if no disturbances ever occurred.

Some ecosystems contain a climax community for hundreds or thousands of years. In other ecosystems, as soon as a climax community is reached a disturbance becomes much more likely. For example, some climax communities

use up the nutrients in the soil or increase the likelihood of a fire

Another way to think of a climax community is an ecosystem that has a steady amount of TOTAL BIOMASS.

CLIMAX COMMUNITY

#1.6 Aim:How do ecosystems change over time?

AgendaQOD (10)

Lesson: succession (15)

Activity: courtyard scavenger hunt (15)

SummaryShare (5)

HW #5

Pioneer species – the first species to populate an area. These species start making the soil

Climax community – a mature, stable community - what the community would be like if no disturbances ever occurred.

Lichens and mosses are an important pioneer species

Typical forest succession Lichens and mosses

Flowers and weeds

Non-woody plants and grasses

Woody shrubs, grasses, tree saplings

Young forest

Mature treesAs the ecosystem changes, the animals change to accommodate the available food and shelter.

Forests

What does this graph tell us about succession?

Stop and Jot

Take 2 minutes to summarize how forests go through succession. Try to use the vocabulary we’ve discussed: Primary Succession Secondary Succession Disturbance Pioneer Species Climax Community

OK, let’s see if we’ve got it…

For the next example, write down which type of succession you think it represents.

Also, take note of which organisms are the pioneer species, and which are part of the climax community.

#1.6 Aim:How do ecosystems change over time?

AgendaQOD (10)

Lesson: succession (15)

Activity: courtyard scavenger hunt (15)

SummaryShare (5)

HW #5

A gray whale dies, and sinks to the otherwise barren ocean floor…

1st: Decomposers feast on the decaying meat

Which kind of succession is it? (primary or secondary?) What are the

pioneer species? What is

the climax community?

#1.6 Aim:How do ecosystems change over time?

AgendaQOD (10)

Lesson: succession (15)

Activity: courtyard scavenger hunt (15)

SummaryShare (5)

HW #5

2nd: After a year, most of the whale tissue is eaten. The carcass still supports small fishes and other marine animals

As the whale’s body decays, it enriches its surroundings with its nutrients. This makes an oasis that attracts marine worms.

#1.6 Aim:How do ecosystems change over time?

AgendaQOD (10)

Lesson: succession (15)

Activity: courtyard scavenger hunt (15)

SummaryShare (5)

HW #5

3rd: When only the skeleton remains, bacteria begin to decompose the oils inside the whale bones, and support a diverse community of mussels, worms, crabs, and clams.

#1.6 Aim:How do ecosystems change over time?

AgendaQOD (10)

Lesson: succession (15)

Activity: courtyard scavenger hunt (15)

SummaryShare (5)

HW #5

Which kind of succession was that? (primary or secondary?) What were the

pioneer species? What was

the climax community?Primary – starting from

a barren ocean floor…

Pioneer species - decomposers

Climax community: the bacteria decomposing the oils in the whale bones that support all the other species…

Primary or Secondary?

Volcanic Eruption

Clear Cutting

Primary or Secondary?

Tornados Mudslide

The World Without Us

http://www.youtube.com/watch?v=m8CsBMCfu0s&feature=related

http://www.worldwithoutus.com/did_you_know.html

Exit Ticket

1) What is the difference between PRIMARY and SECONDARY succession?

2) How do PIONEER SPECIES help speed up the process of ecological succession?