1. Biology Unit 2, Chapter 16 (Changes in ecosystems)
Thursday, 11th
October, 2012.
Class duration: 70 mins
Class setting: Science laboratory
Topic: Changes in Ecosystems (Intro)
Learning intention:
• To develop understanding of changes to ecosystems over time.
• Recognise the scope, intensity and impact of various natural changes
• Extend awareness of impacts of human-induced changes on ecosystems
• Identify techniques for monitoring and maintaining ecosystems.
Thursday, 11/10/2012
• Unit 1 revision questions
• Group presentation (preparation)
Time (mins) Teacher activity
20 - Intro video
- Discuss frequency of change
- Give example: Climate change (other examples of climate change?)
SLIDE 3
- Pollutants have water vapour adhered to it = man made clouds.
- Clouds hold HEAT in. So no clouds = colder.
- After 9/11, shut down jet traffic in USA for three days.
- Scientists able to observe during that 3 day period, there was about 1*C change over the 3
days.
- This change over a long period = climate change… can impact ecosystems.
SLIDE 4
intergovernmental panel on climate change
- Different countries put their data together
- Study how changes in temperature affect our planet
- Raise in temperature affect arctic ecosystems more than ecosystems closer to equator.
- Impact on the species that have evolved to live in cold temperatures.
SLIDE 5
1ºC change over next 100 years
- All coral becomes bleached.
- Coral made up of two things = a coral (essentially an animal) + algae (plant, lives
mutualistic with them)
- Coral will extrude (force out) the algae, so can’t use photosynthetic process of
algae = bleached.
Increase temperature = warmer.. Affect 10% of world’s ecosystems.
- Affect arctic ecosystems more.
- Species can’t evolve quickly enough to adapt to the change in climate = impacted by
that.
SLIDE 6
2ºC change over next 100 years
SLIDE 7
3ºC change over next 100 years
- 1/2 of nature reserves unable to meet conservation objectives
- Manmade change… Environment impacted by humans.
… Slide 8

2. SLIDE 9
Primary change
Due to human intervention or natural agents
20+10 SLIDE 10 & 11 [ACTIVITY]
PRIMARY CHANGES
- Manmade change: Introduction of exotic/alien-species
o Noxious species, e.g. rabbits, cane toads. Page 510.
- Manmade change: Overharvesting of a biological resource (e.g. fishing too much, hunting
of animals) page 517.
- Natural change agents: Bushfires. Page 528.
o Obligate seeder plants (seeds survive and germinate after fires)
o Vegetative reproducer plants (regrow through means of (epicormic)buds located
under bark or in underground stems/rhizomes)
o Fire is important agent of change in some Australian ecosystems (e.g. page 531
“fire for parrots”)
-
10 SLIDE 12
Primary succession: ecosystem must rebuild after being completely destroyed (including the
soil)
- Main feature of primary ecological succession = soil formation.
- Rock exposed of receding glacier
- New land formed by volcanic explosions
- Mosses and lichens (spore bearing plants) = pioneer organisms…
- Lichens secret toxins into rocks = break down into soil
- Wearing down of rocks by weather/water = form soil
- When mosses and lichens die = biomass degrades into soil
Secondary succession: ecosystem must rebuild with the soil still intact.
- e.g. small bushfire… doesn’t have to go through process of soil formation…
- No pioneer organisms because there are already organisms in and around soil.
- Process of succession stops when a stable community becomes established.
- Stable community = climax community.
10 SLIDE 13: KEY IDEAS
Frequency of change:
Changes in ecosystems may occur regularly, sporadically, or due to one-off events.
(1) Identify a change agent that acts on an ecosystem as follows:
Regularly, sporadically (irregularly), or as a one-of event.
(2) Give an example of change in an ecosystem that is due to:
a. human intervention… b. a naturally-occurring agent of change.
- Invasive exotic species cause negative effects in ecosystems.
- Over-harvesting of a biological resources can cause populations to crash.
- Fire is an important agent of change in some Australian ecosystems.