1. Ecosystems

2. Studying organisms in their environment
biosphere
ecosystem
community
population
organism

3. Essential Questions: What limits the production in ecosystems?
How do nutrients move in the ecosystem?
How does energy move through the ecosystem?

4. Ecosystem All the organisms in a community plus abiotic factors
ecosystems are transformers of energy & processors of matter
Ecosystems are self-sustaining
what is needed?
capture energy
transfer energy
cycle nutrients

5. Ecosystem inputs nutrients cycle inputs energy nutrients biosphere
energy flows through
constant input of energy
nutrients cycle
Matter cannot
be created or destroyed
Don’t forget the laws of Physics!
nutrients can only cycle
inputs
energy
nutrients

6. Generalized Nutrient cycling
consumers
consumers
consumers
producers
decomposers
decomposers
nutrients ENTER FOOD CHAIN = made available to producers
nutrients made available to producers
return to abiotic reservoir
Decomposition connects all trophic levels
abiotic reservoir
abiotic reservoir
geologic processes
geologic processes

7. Carbon cycle CO2 in atmosphere Diffusion Respiration Photosynthesis
Plants and algae
Plants
Animals
Industry and home
Combustion of fuels
Carbonates in sediment
Bicarbonates
Deposition of
dead material
Deposition
of dead
material
Fossil fuels
(oil, gas, coal)
Dissolved CO2
abiotic reservoir:
CO2 in atmosphere
enter food chain:
photosynthesis = carbon fixation in Calvin cycle
recycle:
return to abiotic:
respiration
combustion

8. Nitrogen cycle Atmospheric nitrogen Carnivores Herbivores Birds Plants
abiotic reservoir:
N in atmosphere
enter food chain:
nitrogen fixation by soil & aquatic bacteria
recycle:
decomposing & nitrifying bacteria
return to abiotic:
denitrifying bacteria
Nitrogen cycle
Atmospheric
nitrogen
Carnivores
Herbivores
Birds
Plankton with
nitrogen-fixing
bacteria
Plants
Death, excretion, feces
Fish
Nitrogen-fixing
bacteria
(plant roots)
Decomposing bacteria
amino acids
excretion
Ammonifying bacteria
Nitrogen-fixing
bacteria
(soil)
loss to deep sediments
Nitrifying bacteria
Denitrifying
bacteria
soil nitrates

9. Phosphorus cycle Land Plants animals Animal tissue and feces Urine
abiotic reservoir:
rocks, minerals, soil
enter food chain:
erosion releases soluble phosphate
uptake by plants
recycle:
decomposing bacteria & fungi
return to abiotic:
loss to ocean sediment
Phosphorus cycle
Land
animals
Plants
Animal tissue
and feces
Urine
Soluble soil
phosphate
Decomposers
(bacteria and
fungi)
Loss in
drainage
Rocks and
minerals
Phosphates
in solution
Decomposers
(bacteria & fungi)
Animal tissue
and feces
Aquatic
animals
Plants and
algae
Precipitates
Loss to deep sediment

10. Water cycle Solar energy Transpiration Evaporation Precipitation
abiotic reservoir:
surface & atmospheric water
enter food chain:
precipitation & plant uptake
recycle:
transpiration
return to abiotic:
evaporation & runoff
Water cycle
Solar energy
Transpiration
Water vapor
Evaporation
Precipitation
Oceans
Runoff
Lakes
Percolation in soil
Aquifer
Groundwater

11. Transpiration Why does water flow into, up and out of a plant?
We will discuss
process in
detail soon!

12. Breaking the water cycle
Deforestation breaks the water cycle
groundwater is not transpired to the atmosphere, so precipitation is not created
forest  desert
desertification

13. Effects of deforestation
40% increase in runoff
loss of water
60x loss in nitrogen
10x loss in calcium
loss into surface water 80
nitrate levels in runoff 40
loss out of ecosystem!
of nitrate (mg/l )
Concentration 4
Deforestation 2
Why is nitrogen so important?
1965
1966
1967
1968
Year

14. Energy flows through ecosystems
sun
secondary consumers
(carnivores)
loss of energy
loss of energy
primary consumers
(herbivores)
Energy is incorporated into a community by what group?
producers (plants)

15. Productivity
Primary productivity: Term for the rate which producers photosynthesize organic compounds in an ecosystem.
Gross primary productivity: total amount of photosynthetic biomass production in an ecosystem
Net Primary Productivity = GPP – respiration cost

16. Ecosystems with greater productivity are more stable and diverse than ecosystems with less productivity.
Which ecosystems are most productive?

17. Inefficiency of energy transfer
sun
Inefficiency of energy transfer
Loss of energy between levels of food chain
To where is the energy lost? The cost of living!
17%
growth
energy lost to daily living
only this energy moves on to the next level in the food chain
33%
cellular
respiration
50%
waste (feces)

18. Food chains Trophic levels sun feeding relationships
Tertiary consumer
Trophic levels
feeding relationships
start with energy from the sun
captured by plants
1st level of all food chains
food chains usually go up only 4 or 5 levels
inefficiency of energy transfer
all levels connect to decomposers
top carnivore
Level 3
Secondary consumer
carnivore
Level 2
Primary consumer
heterotrophs
herbivore
Level 1
Producer
autotrophs
Fungi
Decomposers
Bacteria

19. Producers & Decomposers
Producers move matter from abiotic sources (air/soil) to biotic sources (food web)
Decomposers move matter
from biotic sources to abiotic
sources

20. Ecological pyramid sun Loss of energy between levels of food chain
can feed fewer animals in each level
10% energy available for next level
Notice only 1% of sunlight energy converted by plants

21. Humans in food chains
Dynamics of energy through ecosystems have important implications for human populations
how much energy does it take to feed a human?
if we are meat eaters?
if we are vegetarian?

22. What you need to be able to do:
Using the laws of conservation of matter and energy to do some basic accounting and determine different aspects of energy and matter usage in a community.
Remember: Inputs have to equal outputs

23. Sample problem
A caterpillar consumes 100 kcal of energy. It uses 35 kcal for cell respiration, and loses 50 kcal as waste. Determine the trophic efficiency for its creation of new biomass.
Total energy = 100 kcal
Lost and Respired: = 85 kcal
Total energy for growth: 15 kcal
Efficiency = part/total = 15/100 = .15 (or 15% or 3/20 as fraction)