The Ecosystem

1
The Ecosystem

• An Introduction

2
Ecosystem

• A community of interdependent organisms and the
  interactions with the physical environment in
  which they live.
• It can also be defined as the abiotic and biotic
  factors and the interactions between them.
• The interaction between organisms and the
  environment is the key!

3
Differentiate between the following terms

• Organism
• Species
• Population
• Community
• Niche
• Habitat

4
In your notebook, draw a picture of a bunch of
little organisms

• Label The organisms of the same type (species)
• Circle individuals of the same species
  (Population)
• Draw interactions between the populations
  (Community)

5
Compare the terms habitat and niche

• Sometimes people confuse these terms.
• Figure out the differences between the terms.

6
Niche vs habitat

• A habitat is wear an organism lives. The habitat
  must provide a source of food, water and shelter
  for the organism.
• Niche The role of the organism. This is largely
  to do with the trophic level of the organism.
• For example plants produce food for the rest of
  the food chain. Tigers keep herbivore
  populations under control.

7
Abiotic and Biotic factors

• Biotic Factor A living, biological factor that
  may influence an organism or a system.
• Example predation, disease, competition
• Abiotic factor A non-living, physical factor
  that may influence an organism or a system
• Examples Temperature, salinity, pH, light

8
Which factors are biotic?

• Rabbits
• Cacti
• Daylight hours
• Precipitation
• Moss
• Soil composition
• Bacteria

9
Limiting factors

• An abiotic factor can limit the population size
  if there is too much or too little of it. Even
  if there is the right amount of other factors
• Examples to consider
• Sunlight
• Precipitation
• Salinity
• Nutrients in the soil

10
Trophic levels

• Ecostems are often broken up and described
  according to feeding relationships.
• Trophic level
• The position of an organism in a food chain
• A group of organisms that occupy the same place
  in a food chain

11
Trophic levels in food chains

• Be able to give an example of each!
• Primary producers (autotrophs)
• Primary consumers (herbivores)
• Secondary consumers(carnivores)
• Tertiary consumers (top carnivores)
• Decomposers
• Detrivores
• Scavengers

12
Energy flow and material cycling
13
Producer lAutotroph - self feed lAn
organism that obtains organic food molecules
without eating other organisms but by using
energy from the sun or inorganic molecules to
make organic molecules lRemember This trophic
level supports all of the others lThe role of
producers is to convert energy into a form
useable for other organisms
14
Producers
lMost producers are photosynthetic (e.g. algae,
mosses, diatoms, some bacteria, plants etc.) but
some are chemosynthetic (e.g. hydrothermal vent
bacteria) (H2)
15
Decomposer
lAn organism that obtains energy by breaking
down dead organic matter, including dead plants,
dead animals and animal waste, into more simple
substances lExamples include bacteria and
fungi L Interconnects all trophic levels since
the organic material making up all living
organisms is eventually broken down lRole of
decomposers is to return valuable nutrients to
the system so they can be used again
16
Compare detritus feeders to decomposers
17
Consumer
lHeterotroph - other feed lAn organism that
obtains its nutrition by eating other
organisms lPrimary consumer (herbivore) - eats
producers e.g. sea urchin, copepod lSecondary
consumer (carnivore) - eats primary consumers
e.g. wolf eel, herring lTertiary consumer - eats
secondary consumers e.g. sea otter,
seal lQuaternary consumer - eats tertiary
consumers e.g. killer whale
18
Consumers

• The role of the consumer is to transfer energy
  from one trophic level to the next.
• Notice that consumers have different names,
  depending on what they eat
• Herbivores plant eaters
• Carnivores meat eaters
• Omnivores eat plants and animals

19
Food Chains
20
Food webs
Show energy flow through an ecosystem L An
ecosystems trophic structure determines energy
flow and nutrient cycling
21
Food webs
22
Trophic levels
23
Pyramid of biomass
24
Second Law of Thermodynamics

• There is a tendency for numbers and quantities of
  biomass and energy to decrease along food chains.
• The pyramids become smaller at the top because
  around 90 of the energy is lost between each
  level and only 10 is available in the body of
  the organism for transfer to the next level.

25
Energy transfer in a food chain First law of
thermodynamics
26
The end!