1. Flows of Energy and Matter
Topic 2.3
Flows of Energy
and Matter

2. Significant Ideas:
Ecosystems are linked together by energy and matter flows.
The Sun's energy drives these flows, and humans are impacting the flows of energy and matter both locally and globally.

3. Big questions:
What strengths and weaknesses of the systems approach and the use of models have been revealed through this topic?
How are the issues addressed in this topic of relevance to sustainability or sustainable development?
Why are maximum sustainable yields equivalent to the net primary or net secondary productivity of a system? Why would harvesting biomass at a rate greater than NPP or GPP be unsustainable?
How can systems diagrams of carbon and nitrogen cycles be used to who the effect of human activities on ecosystems? What are the strengths and weaknesses of such diagrams?

4. Energy in living systems:
Obey the laws of thermodynamics
Obey systems laws – input, transfer, transformation, output
Food chains, webs and pyramids, ultimately show energy flow

5. Thermodynamics Review
Universal laws that govern all energy changes in the universe, from nuclear reactions to the buzzing of a bee.
The 1st law: Energy can be transferred and transformed but not created or destroyed
Energy flow in the biological world is unidirectional:
Sun energy enters system and replaces energy lost from heat
Energy at one trophic level is
always less than the previous level

6. Thermodynamics Review
(b) The 2nd law: Energy transformations proceed spontaneously to convert matter from a more ordered, less stable form, to a less ordered, more stable form
Energy lost as heat from each level
Energy at one level less than previous because of these losses

7. Energy Flow in Communities
Energy unlike matter does not recycle through a community it flows
Energy comes from the sun
Converted by autotrophs into glucose

8. The Source of All energy on Earth is the …

10. Energy Flow through the Ecosystem
Conversion of light energy to chemical energy
Transfer of chemical energy from one trophic level to another with varying efficiencies
Overall conversion of ultraviolet and visible light to heat energy by an ecosystem
Re-radiation of heat energy to the atmosphere

11. Transfer and transformation of Energy
Not all solar radiation ends up as biomass. Losses include:
Reflection from leaves
Not hitting chloroplasts
Wrong wavelength
Transmission of light through the leaf
Inefficiency of photosynthesis

12. ENERGY ENTERS THE ECOSYSTEM AS SUNLIGHT
30% solar energy reflected back into space by atmosphere, clouds, ice
20% absorbed by clouds & atmosphere
50% remaining
Warms troposphere and land
Evaporates and cycles water
Generates wind
Only 2% of the light energy falling on plant is used to create energy
< 0.1% captured by producers for photosynthesis
The rest is reflected, or just warms up the plant as it is absorbed

13. Question!
So if sunlight in = sunlight + heat out, what state is the system in?
Stable Equilibrium

14. Transfer and transformation of energy.
Energy comes into the ecosystem as light energy
The light energy is converted into chemical energy by producers.

15. Transfer and transformation of energy.
That chemical energy is transferred as organisms are eaten, with energy being lost as heat and respiration.

16. Summary of solar radiation pathways
Solar radiation comes in, it is then…
Lost by reflection (ice caps) and absorption (soil, water bodies)
Converted from light to chemical energy (photosynthesis in producers)
Lost as chemical energy decreases through trophic levels
Through an ecosystem completely converted from light energy into heat
Reradiated as heat back to the atmosphere

17. Photosynthesis Word equation:
Process where plants use sun light energy to create chemical energy
Word equation:
carbon dioxide + water (+ light energy)  glucose + oxygen
Chemical equation:
6CO2 + 6H2O  C6H12O6 + 6O2
Inputs: light energy, water, carbon dioxide
Outputs: oxygen gas, sugar
Energy transformations: Light to Chemical
respiration backwards!

18. glucose + oxygen  carbon dioxide + water + energy
Respiration
Process by which animals create energy through consumption of organic molecules (sugars)
The breaking down of glucose (and other food) into carbon dioxide and water
Word equation:
glucose + oxygen  carbon dioxide + water + energy
Chemical equation:
C6H12O6 + 6O2  6CO2 + 6H2O + energy
Inputs: oxygen gas, organic molecules (sugars)
Outputs: carbon dioxide, energy in ATP, waste heat
Energy transformations: chemical to heat
Photosynthesis backwards!

19. CO2 O2
Respiration
OUT IN
Photosynthesis

20. Energy Transfers in Ecosystem

21. Energy Flow and Food webs
Biomass = the total dry weight of all organisms in one trophic level
Usable energy is degraded with each transfer
Loss as heat, waste, metabolism

22. Energy Flow through Producers
Producers convert light energy into chemical energy of organic molecules
Energy lost as cell respiration in producers then as heat elsewhere
When consumers eat producers energy passes on to them
In death organic matter passes to saprophytes & detritivores
% transferred = ecological efficiency  ranges from 5-20%
More trophic levels = less energy available at high levels

23. Energy Flow through Consumers
Obtain energy by eating producers or other consumers
Energy transfer never above 20% efficient, usually between 10 – 20%
Food ingested has multiple fates
Large portion used in cell respiration for meeting energy requirements (LOSS)
Smaller portion is assimilated used for growth, repair, reproduction
Smallest portion, undigested material excreted as waste (LOSS)

26. Energy flow through Decomposers
Some food is not digested by consumers so lost as feces to detritivores & saprophytes
Energy eventually released by process of cell respiration or lost as heat

27. Energy Flow Diagrams

28. Conversion of Energy
Conversation of energy into biomass for a given period of time is measured as productivity

29. Biomass and Productivity
Productivity: The conversion of energy into biomass over a given period of time. Measured in g m-2 yr -1 or J m-2 yr-1
Biomass: Living mass of an organism or organisms (sometimes referred to as dry mass). Measured in g m-2
Gross: Refers to the total amount of something
Net: Refers to the amount left over after deductions.
Gross Income: $60,000 per/year
Net Income: $50,000 per/year after taxes, social security, retirement, health care, etc.
Primary Production: to do with plants
Secondary Production: to do with animals

31. Plants Animals Productivity Primary Productivity
Gross Primary Productivity (GPP)
*very difficult to calculate in real life
Net Primary Productivity (NPP)
NPP = GPP – R
*where R is respiratory loss
Secondary Productivity
Gross Secondary Productivity (GSP)
GSP = Food Eaten – Fecal loss
Net Secondary Productivity (NSP)
NSP = GSP – R
[NSP = (Food Eaten – Fecal loss) – Respiratory Loss]
Plants
Animals
…and to account for resp. loss, use this one
Instead we calculate this one

32. Gross vs. Net Productivity
Gross Productivity: Total gain in energy or biomass “assimilated” by an organism per unit area per unit time.
Biomass that can be gained before deductions
Measured in Joules (J)
BUT all organisms have to respire to stay alive so some energy is used up to stay alive instead of used to grow. Therefore…
Net Productivity: Gain energy or biomass per unit area per unity time that remains after deductions due to respiration.

33. Gross productivity continued
Plant (Gross Primary Productivity)
GPP = total gain in energy or biomass (glucose) by autotrophs thru photosynthesis per unit area per unit time
**Almost impossible to calculate because almost as soon as plants create energy (glucose) they use it for respiration (yes, plants respire)
Animals (Gross Secondary Productivity)
GSP = total energy or biomass assimilated (taken up) by consumers minus the fecal loss
Fecal matter doesn’t count because it was never gained in the
first place
GSP = food eaten – fecal loss
Energy is stored in leaf as sugars and starches, which later are used to form flowers, fruits, seeds,

34. Net productivity continued
The energy left over after organisms have used what they need to survive.
All organisms have waste energy and respiratory loss given off as heat, metabolism (R)
Plants and animals have to use some of the energy they capture to keep themselves growing:
They both move water and stored chemicals around
Plants make flowers, fruits, new leaves, cells and stems
Animals create cells and need to move muscles.

35. Net productivity continued
The gain by producers in energy or biomass per unit area per unit time remaining after respiration losses.
Net primary productivity =
Gross primary productivity - Respiration energy
or symbolically:
NPP = GPP - R
The gain by consumers in energy or biomass per unit area per unit time remaining after respiration losses.
Net secondary productivity =
Gross secondary productivity - Respiration energy
or symbolically:
NSP = GSP - R
NSP=

37. A note on NPP*
In theory, any glucose that’s left over after photosynthesis and respiration should be material deposited in and around cells to form new plant matter.
Therefore, NPP is Biomass

38. Energy currency: C-H bonds
Photosynthesis
6 𝐶𝑂 2 +6 𝐻 2 𝑂+𝑙𝑖𝑔ℎ𝑡 𝑒𝑛𝑒𝑟𝑔𝑦→ 𝐶 6 𝐻 12 𝑂 6 𝑔𝑙𝑢𝑐𝑜𝑠𝑒 +6 𝑂 2
Respiration
𝐶 6 𝐻 12 𝑂 6 𝑔𝑙𝑢𝑐𝑜𝑠𝑒 +6 𝑂 2 → 6 𝐶𝑂 2 +6 𝐻 2 𝑂+𝐴𝑇𝑃 (𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦)

39. Therefore…
The least productive ecosystems are those with limited heat and light energy, limited water and limited nutrients.
Example biome:_______________
The most productive ecosystems are those with high temperature, lots of water light and nutrients.
Example biome:__________________
GROSS PRODUCTIVITY
Generally greatest productivity in
Shallow waters near continents
Along coral reefs – abundant light, heat, nutrients,
Were upwelling currents bring nitrogen and phosphorous to the surface
Gnerally lowest
In desert and arid regions with lack of water but high temperatures
Open ocean lacking nutrients and sun only near the surface
NET PRODUCTIVITY
Most amount of NP”
Estuaries, swamps, tropical rainforests
LEAST NP
Open ocean, tundra, desert
Open ocean has low NP but its large area gives it more NP total than anywhere else

40. Look in pearson book for explanation

41. Look in pearson book for explanation

42. Average net primary productivity

44. How to measure primary productivity
Harvest method – measure biomass and express as biomass per unit area per unit time.
CO2 assimilation- measure CO2 uptake in photosynthesis and releases by respiration
O2 production-Measure O2 production and consumption
Radiosotope method-use c14 tracer in photosynthesis.
Chlorophyl measurement- assumes a correlation between the amount of chlorophyll and rate of photosynthesis.

45. Summary: Energy is conserved in ecosystems
First law of Thermodynamics
Chemical energy used by organisms must be less than the chemical energy generated via primary production (plants), due to unavoidable inefficiencies in energy capture.
Photosynthesis is the dominant source of energy in most ecosystems through conversion of light to C-H bonds in organic material.

46. Summary: The flow and fate of carbon is tightly linked to energy flow.
This fact is fundamental to understanding how carbon and energy flow are
linked to other elements and nutrients
support patterns of biodiversity
connect carnivores, herbivores, and plants

47. Experiment to calculate productivity (Light / Dark Rxns)
Use aquatic plants
Measure both photosynthesis and respiration by looking at oxygen levels
In water we must measure dissolved oxygen (DO) = indirect measure
NPP ca be estimated by measuring the increase in DO when in light
GPP can be calculated by measuring the decrease in DO when put in the dark (only respiration (R) will occur)
NPP = GPP – R so GPP = NPP + R
**this is from the adobe powerpoint notes “2.3 flows of energy and matter productivity.pdf”

48. Experiment to calculate productivity (Light / Dark Rxns)
You start with a light bottle / dark bottle measurement on algae species x with 10mg/L of oxygen in both bottles. You let the bottles sit for 1 hour so that the photosynthesis and respiration rates can be calculated. At the end of 1 week, you have 7 mg/L of oxygen in your dark bottle and 12 mg/L of oxygen in your light bottle. What is the NPP, GPP, and respiration?
NPP = 12mg L-1 – 10mg L-1 = 2 mg O2 L-1 wk-1
Loss of dissolved O2: R = 10mg L-1 – 7mg L-1 = 3 mg L-1 wk-1
NPP = GPP – R so GPP = NPP + R
GPP = = 5mg O2 L-1 wk-1
Note to self:
See pdf for 1 additional problem on dissolved oxygen and for more problems calculating GSP, NSP, and R

49. Construct and analyze energy flow diagrams for energy movement through ecosystems
Trophic level boxes are storages – biomass per area (g m-2)
Energy Flow in arrows – rate of energy transfer
(g m-2 day-1)
Calculate W, X, Y, and Z

50. Respiratory loss by decomposers
The data in the table below relate to the transfer of energy in a small clearly defined habitat. The units in each case are in kJ m-2 yr-1
Trophic Level
Gross Production
Respiratory Loss
Loss to decomposers
Producers
60724
36120
477
1° Consumer
21762
14700
3072
2° Consumer
714
576 42
3° Consumer 7 4 1
Respiratory loss by decomposers
---
3120
Construct an energy flow model to represent all these data – Label each arrow with the appropriate amount from the data table above.
Use boxes to represent each trophic level and arrows to show the flow of energy
Calculate the Net Productivity for
NPP for Producers
NSP for 1°Consumers, 2°Consumers, 3°Consumers
NSP for Decomposers

51. ENERGY FLOW MODEL Producers 1 Consumer 2 Consumer 3 Consumer
60724
21762
714 7
Producers
1 Consumer
2 Consumer
3 Consumer
3072 42
477 1
Decomposers
R=3120

52. Productivity Calculations
NPP of Producers:
( )
= kJ.m-2.yr-1
NSP of 1 Consumer
(21762 – 3072)
= 3990 kJ.m-2.yr-1
NSP of 2 Consumer
(714 – 42)
- 576
= 96 kJ.m-2.yr-1
NSP of 3 Consumer
(7 - 1)
- 4
= 2 kJ.m-2.yr-1
NSP of Consumers:
(22483 – 3115)
= 4088 kJ.m-2.yr-10
NSP of Decomposers:
( )
- 3120
= 472 kJ.m-2.yr-1

53. Maximum Sustainable Yield
Equivalent to the NSP or NPP of system.
Important number for farmers who are trying to predict how much money they will get for their product.
Farmers are often paid by how much biomass (often measured by weight/acre) that their crop yields.
Modern agricultural economists spend many months predicting yields which drives prices of the food you buy.
Corn Futures are a good example. People bet on how much corn will be grown in a particular year…even before it is ever planted!

54. Matter Flows
Although energy flows in a one-way direction finally leaving as heat, chemical nutrients circulate through the trophic layers – known as biogeochemical cycles
Matter flows through ecosystems
linking them together. The flow
of matter involves transfers
and transformations.
Carbon Cycle
Nitrogen Cycle

55. Carbon Cycle
Carbon flows through ecosystems through feeding, death and decomposition, photosynthesis, respiration, dissolving, and fossilization.
Carbon is stored in organisms and forests, the atmosphere, soil, fossil fuels, and in the oceans.
Places where carbon is stored are called Carbon Sinks
The oceans are the largest carbon sinks, holding many times more carbon than all the forests on earth combined.
Climate change is affecting how much carbon the ocean can hold.

58. A large amount of carbon is also stored in the oceans
CO2 is dissolved in the actual water.
More complex carbon compounds in sea life.
Huge amounts is stored in the deep ocean as inorganic compounds. (More than any other storage)

59. Storage (sinks) and flows
Photosynthesis
Oceans
Respiration
Death and decomposition
Fossil fuels
Fossilisation
Organisms
Combustion
Feeding
Dissolving
Atmosphere
Soil
Rocks
Sea life
In your books:
Sort the above into two columns, storage and flows
In your books:
How have humans affected the rate of various flows?

60. Annenberg learner interactive labs – carbon lab
_effects_fyc.php

61. Nitrogen Cycle
Nitrogen flows include nitrogen fixation by bacteria and lightning, absorption, assimilation, consumption, excretion, death, decomposition, and denitrification by bacteria in water-logged soils.
Nitrogen is stored in organisms, soil, fossil fuels, atmosphere, and bodies of water.
Places where nitrogen is stored are called Nitrogen Sinks

62. Nitrogen (N) HONC Nitrogen is a main component of proteins and DNA
The most common elements found in living things are Hydrogen, Oxygen, Nitrogen, and Carbon
Nitrogen is a main component of proteins and DNA
Nitrogen (N) along with potassium (K) and phosphorus (P) are the main ingredients of fertilizers.
While fertilizer is good for a plant, too much can kill or damage the plant.

63. Lake
Winnipeg

64. Nitrogen (N) helps plants turn green
Phosphorus (P) helps plants to flower
Potassium (K) is important for overall growth
Too much nitrogen can “burn” or kill a crop as in the case when an animal urinates on your lawn

68. NOTE: Animals can only obtain nitrogen from eating other organisms!
*Organisms can’t absorb nitrogen gas (N2) directly*
Nitrogen atoms must first be pulled out of the air and “fixed”(bonded) to other elements to form new compounds (such as ammonia) with the help of nitrogen fixing bacteria. This process is called nitrogen fixation.
Nitrifying bacteria convert this ammonia into nitrates. Nitrates can be then used by plants for a source of nitrogen. They can also do this from the ammonia from decomposing organisms.
Denitrifying bacteria convert nitrates back into nitrogen gas by a process called denitrification.
NOTE: Animals can only obtain nitrogen from eating other organisms!

69. How do humans affect the nitrogen cycle?
Use the iPads to research how humans can affect the nitrogen cycle.

70. Human Impact on Energy Flows
Human activities such as burning of fossil fuels, deforestation, urbanization, and agriculture impact energy flows as well as the carbon and nitrogen cycle.
How does the burning of fossil fuels or deforestation affect the carbon cycle?
How could urbanization and agriculture affect either the carbon cycle or nitrogen cycle?
Take 5 minutes to write down your thoughts

71. To Do: Calculating Productivity
Pg. 67 of Course Companion, Do question 1, a-e.
Calculating productivity worksheet