IB Biology Option C Section 2

1. C2 Communities and Ecosystems
Option C: Ecology and
conservation

2. Understandings Applications/Skills
 Most species occupy
different trophic levels in
multiple food chains.
 A food web shows all the
possible food chains of a
community.
 The percentage of
ingested energy
converted to biomass is
dependent on the
respiration rate.
 The type of stable
ecosystem that will
emerge in an area is
predictable based on
climate.
 In closed ecosystems,
energy, but not matter, is
exchanged with the
surroundings.
 Disturbances influence
 A: Conversion ratio in sustainable
food production practices.
 A: Consideration of one example
of how humans interfere with
nutrient cycling.
 S: Comparison of pyramids of
energy from different
ecosystems.
 S: Analysis of a climograph
showing the relationship between
temperature, rainfall, and type of
ecosystem.
 S:Construction of Gersmehl
diagrams to show the
interrelationship between nutrient
stores and flows between taiga,
desert, and tropical rainforest.
 S: Analysis of data showing
primary succession.

10. In commercial (animal) food production, farmers measure the food
conversion ratio (FCR). It is a measure of an animal's efficiency in
converting feed mass into the desired output. For dairy cows, for example, the output
is milk, whereas animals raised for meat, for example, pigs the output is the mass
gained by the animal.
It is calculated by:
mass of the food eaten
body mass gain
FCR =
http://en.wikipedia.org/wiki/Feed_conversion_ratio
Animal FCR
Beef
Cattle
5 - 20
Pigs 3
Sheep 4 - 5
Poultry 2
Tilapia 1.2-1.6
The lower the FCR the more efficient the method of
food production.
A good (low) FCR is obtained by minimizing the losses of
energy by respiration, for example:
• Restricting animal movement
• Slaughtering the animal at a young age (older animals
have higher FCRs as they grow more slowly)
• Optimizing feed so it is efficiently digested
How ethical are the practices that lead to a low
FCR?
What is more important, efficient food production or
the ethical treatment of animals?

11. New volcanic island in the canary
islands

14. Coastal dunes as an example for primary succession
FOREDUNE
- No soil
- Lyme grass and marram grass (roots help bind sand)
- Little diversity and biomass
http://images.forwallpaper.com/files/images/f/fac8/fac82e28/873673/winter-huron-crescent-state-park-foredune-grass-wallpaper-michigan-marram-lake-
images-landscape-nature-wallpapers.jpg

15. Coastal dunes as an example for primary
succession
YELLOW DUNE
- Some soil
present from
years of plants
dying and
decomposing
- More plants take
root
- Rabbits eat
grass, leave
droppings (adds
nutrients to soil)
http://fc08.deviantart.net/fs71/i/2014/284/d/2/yellow_flowers_and_sand_dunes_stock_photo_dsc_0201_by_annamae22-

16. Coastal dunes as an example for primary
succession
GREY DUNE
- Has a layer of
hummus, which
holds water
- Thick shrubs
MATURE DUNE http://www.friederikeerlinghagen.de/images/6z.jpg
- Final stage
- Can support a forest
- High moisture and soil content
- Insects, birds, and mammals present
http://upload.wikimedia.org/wikipedia/commons/6/62/Mimusops_caffra%2C_op_kusduin%2C_Umhlanga-
strandmeer_NR.jpg

19. http://cispatm.pbworks.com/f/1209212862/biome_graph.jpg
A climograph is a diagram
which shows the relative
combination of temperature and
precipitation in an area.
This modified climograph
(first developed by Robert
Whittaker) shows the
stable ecosystems/biomes
that arise as a result of the
relative combination of
temperature and
precipitation.
It is a graphical
representation of the biome
summary table (last slide).

26. http://commons.wikimedia.org/wiki/File:Nutrient_cycle.svg
When used to analyze a particular
ecosystem:
• Diameter of sinks are
proportional to the mass of
nutrients stored in each sink
• the thickness of the arrows are
proportional to the rate of
nutrient flow
Gersmehl diagrams were first developed in 1976, by P.F. Gersmehl, to show the
differences in nutrient flow and storage between different ecosystems
Flows between the sinks:
• Littering (including withering, defoliation,
excretion, unconsumed parts left over,
dead bodies of animals, and so on)
• Decomposition of the litter into inorganic
nutrients, which are then stored in the soil
• Nutrient uptake by plants
*

27. • Soil is the main store
• Slow rate of nutrient
transfer between stores
(except for the transfer
from biomass to litter)
• Biomass is the main
store (soil is nutrient
poor)
• Fast rate of nutrient
transfer between stores
desert tropical rainforest

28. Create a Gersmehl Diagram
 Taiga
 Litter is the largest store (low rate of decomp due
to low temps)
 High runoff (ground is frozen; snow is melting)
 Relatively low biomass (mainly conifers with only
one layer of needles and no undergrowth)
 High transfer from biomass to litter (needles
constantly falling from trees)
 Low soil stores (poor soil fertility from glacial
deposits)
 Slow weathering of rocks because of the cold

30. Closed Ecosystems
 Ex: mesocosms, space stations
 Energy is exchanged, but not matter
 Waste products of one must be used by another
http://www.portal.environment.arizona.edu/sites/www.portal.environment.arizona.edu/files/air%20300%2

31. Homework
Vocab
Homework
 Second law of
thermodynamics
 Trophic level
 Producers
 Primary consumers
 Secondary
consumers
 Tertiary consumers
 Gross production
 Net production
 Biomass
 Feed Conversion
Ratio (FCR)
 Ecological
 Primary succession
 Pioneer plants
 Secondary succession
 Humus
 Climax community
 Biome
 Biosphere
 Open system
 Closed system
 Disturbance
 Intermediate disturbance
hypothesis
Challenge yourself 16-19, pg 66
Challenge yourself 20, pg 668
Exercises 4-6, pg 670