1. Ecosystems

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

3. 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

4. The Earth’s Spheres
1. The hydrosphere is the zone of water that covers over three-quarters of the earth.             a. The ability of water to absorb and release great quantities of
heat keeps climate within livable range.
2. The atmosphere is the gaseous layer near earth.             a. The atmosphere is concentrated in lowest 10 kilometers;
extends thinly out to 1,000 km.             b. Major gases are nitrogen, oxygen and carbon dioxide.            
3. The lithosphere is a rocky substratum that extends about 100 kilometers deep.             a. Weathering of rocks supplies minerals to plants and eventually
forms soil.             b. Soil contains decayed organic material (humus) that recycles
nutrients to plants.
4. The biosphere is the thin layer where life is possible between the outer atmosphere and the lithosphere.

5. Ecosystems can range from a microcosm, such as an aquarium
To a large area such as a lake or forest
Regardless of an ecosystem’s size
Its dynamics involve two main processes: energy flow and chemical cycling
Energy flows through ecosystems
While matter cycles within them

6. Factors affecting Ecosystems
Biotic: Living
Abiotic: Nonliving
Clip

7. 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

8. Energy flows through an ecosystem
First law of thermodynamics
energy can neither be created nor destroyed; it can only be changed from one form of energy to another.
Energy in an ecosystem is transformed by the organism and passed through the food chains
Second law of thermodynamics:
when energy is transformed from one form to another, there is always some loss of energy from the system, usually as low grade heat.

9. A terrestrial food chain
Energy flows through an ecosystem:
Food Chains and Webs
A food chain represents passage of energy through populations in a community.
A trophic level is a feeding level of one or more populations in a food web.
All levels connect to decomposers
Quaternary consumers
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
Carnivore
Herbivore
Plant
Zooplankton
Phytoplankton
A terrestrial food chain
A marine food chain
Animation

10. Smaller toothed whales
Energy flows through an ecosystem:
Humans
Baleen whales
Crab-eater seals
Birds
Fishes
Squids
Leopard
seals
Elephant
Smaller toothed whales
Sperm whales
Carnivorous
plankton
Euphausids
(krill)
Copepods
Phyto- plankton
Food Webs
A food web
Is a branching food chain with complex trophic interactions

11. Ecological Pyramids
Shows the trophic structure of an ecosystem and the energy content that is passed to each successive trophic level in a food web.
Pyramid of energy
All of the solar energy that enters an ecosystem is eventually lost as heat

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

13. 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)

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

15. Humans in food chains
Energy dynamics of ecosystems have important implications for human populations
How much energy is available if we are:
carnivores? vegetarians?
Seems to be easier/cheaper to support a large population on grain than on beef!
For example if a man needs 3,000 Calories per day, then 30,000 Cal beef are needed, which in turn need 300,000 Cal of corn, which in turn means 30,000,000 Cal of sunshine. This works out to be 1.5 acres of corn per day per person. If the person ate corn directly then 10 people could be supported by the same 1.5 acres of corn.

16. 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

17. Primary productivity
Rate at which autotrophs capture and store energy within organic compounds over a length of time.
i.e. Amount of light energy converted to chemical energy (glucose)
Net primary production (NPP)
Is equal to GPP minus the energy used by the primary producers for respiration
Only NPP
Is available to consumers

18. Measuring Primary Productivity
Rate of O2 production
Gross primary productivity is the amount available to heterotrophs
GPP is NPP + R
Since some of the O2 is used in respiration:
NPP= GPP - R

19. Ecosystems with greater productivity have more sunlight, water and nutrients.

20. 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

21. Sample problem #1 Total energy output?
.75 kcal
How much is used to build biomass or Secondary Production?
.05 kcal
What % is not being efficiently used for biomass?
93%

22. Sample problem #2
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 consumed = 100 kcal
Lost and Respired: = 85 kcal
Total energy for growth: 15 kcal
Efficiency (%) = 15/100 = .15 or 15%

23. Biological Magnification
PCBs: polychlorinated biphenyls
Concentration of PCBs
Herring
gull eggs
124 ppm
Zooplankton
0.123 ppm
Phytoplankton
0.025 ppm
Lake
trout ppm
Smelt
1.04 ppm
Organisms at higher trophic levels have greater concentrations of accumulated toxins stored in their bodies.
Ex: bald eagle -1950s -DDT
DDT interferes with the deposition of calcium in eggshells
DDT is now outlawed

24. Biogeochemical Cycles
Life on Earth
Depends on the recycling of essential chemical elements
Nutrient circuits that cycle matter through an ecosystem
Involve both biotic and abiotic components and are often called biogeochemical cycles
Hydrologic cycle
Carbon Cycle
Nitrogen cycle
Phosphorus cycle
Clip

25. 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

26. 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

27. 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

28. 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

29. 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

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

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

32. 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