What is an ecosystem?

What happens if there is a disruption or disturbance

within an ecosystem?

DisturbanceA change or disruption

to a community

• not always a bad

thing

• can alter, slow, or

reset succession

Anthropogenic: plowing, introducing

invasive species, trawling, etc…

(logging in the longleaf pine forest)

Natural: tsunami, flood, fallen trees,

sea-level rise, etc…(fire in longleaf

pine forest)

Natural Disturbances• Some natural disturbances can have greater impact than some anthropogenic

ones.• Can result in large amounts of habitat change, fragmentation, or loss.• Can occur at different time frames:

• Periodic: occur at some-what regular frequency (seasonal drought)• Episodic: occasional, with no regular frequency (hurricanes; pest infestation)• Random: no particular frequency (natural forest fire; volcanic eruption)

• Examples of natural disturbances:• Sea-level variations due to changes in glacial ice• Earth’s climate has changed over geological time• Forest fires, volcanos, floods, etc…

Disturbance: Sea Level Rise

Large degree of habitat change.

Disturbance: Wet/Dry SeasonsPeriodic disturbances that causes migrations to occur, such as

wildebeest migration that follows rains on the African savanna.

Food chain= algae→snail→frog

Intermediate Disturbance Hypothesis

fairly frequent & moderate

disturbances = high

species diversity

Ecosystem Stability

• Ecosystem Resistance = able

to experience significant

disturbances without really

changing

• Ecosystem Resilience = able

to recover from moderate

disturbances

• Methodical approach assisting you to not be overwhelmed with graph at first look.

• Breaks the analysis into three distinct stages:

• First, break down and observe what’s in the graph (identify “What I See”)

• Second, attempt to generate meaning (interpret “What it Means”)

• Third, generate an explanation.

I2 Strategy (Identify & Interpret)

an explanation for the

• First, break down and observe what’s in the graph (identify)

• Only identify & add “What I See” (WIS) comments

• Second, generate meaning (interpret)• Add a “What It Means” (WIM)

comment to each “What I See” (WIM) you previously wrote

• Third, create an explanation.• To demonstrate your understanding,

build a coherent paragraph by joining your WIS/WIM sentences together.

an explanation for the

Range of Tolerance

Range of Tolerance

Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can

endure before injury or death results.

• We want to know exactly how a temperature change affects this fish population.

Initial Final

• At the initial temperature, there were 18 fish.

• At the final temperature, there were 32 fish.

• The fish population increased by what percentage as a result of the temperature change?

To calculate percent change, do FOO:

Final – Original

OriginalX 100

32 – 18

18X 100 = 78%

The fish population increased by 78%.

Initial Final

To calculate percent change, do FOO:

Final – Original

OriginalX 100

4 – 11

11X 100 = -64%

• We want to know exactly how a temperature change affects this fish population.

• At the initial temperature, there were 11 fish.

• At the final temperature, there were 4 fish.

• What was the percent change in the fish population?

The fish population decreased by 64%.

Termite Mounds in the

African Savanna

Conduct I2 analysis:

• Write What I See comments

• Write What It Means comments

• Write a TENTATIVE explanation

How do termite mounds affect the savanna ecosystem?

Dr. Corina Tarnita

How do termite mounds affect the savanna ecosystem?

https://www.youtube.com/watch?v=hRGb9Pq64cU

30

How do termite mounds affect the savanna ecosystem?

Write a three-sentence tentative explanation of what is going on

in the graph.

32

https://www.youtube.com/watch?v=nJGpABrEatc

33

How do termite mounds affect the savanna ecosystem?

Based on what you just saw, revise your explanation.