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2. Housekeeping Items
Did anyone go to the marine mammal event last night?
Reminder about the talk on putting stickers on gas pumps regarding climate change at 7 tonight in Building 355, Room 203 (Auditorium).
Now that everyone’s had a chance to look at the assignment instructions, any questions?
Any other questions?
Create! Conference. Registration is now open – see
One of you brought my attention to a documentary on the suppression of science in the federal government:

3. Upon completing this chapter, you will be able to:
Describe the fundamental properties of environmental systems and the importance of linkages among environmental systems and processes
Define ecosystem and discuss how living and nonliving entities interact in ecosystems
Outline the fundamentals of landscape ecology, GIS, and the use of modelling in environmental science
Assess ecosystem services and their benefits to us
Summarize the main features of global water, carbon, nitrogen, and phosphorus cycles
Explain how human activity is affecting biogeochemical cycles

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5. Central Case: The Plight of the St. Lawrence Belugas
Decreasing population due to GI cancer from pollutants (PAHs from fossil fuels)
Biomagnification of contaminants through food chain
PAHs come from as far away as the Golden Horseshoe in Ontario
Agricultural development also leads to hypoxia and eutrophication (too many nutrients = depletion of oxygen)
Beluga is classified as “threatened” (there are less 700 left) by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and is an indicator of the health of the Great Lakes – St. Lawrence ecosystem
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6. Earth’s Environmental Systems
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7. Systems are networks of relationships
System = a network of relationships among parts elements or components that interact with and influence one another
exchange of energy, matter, or information
open systems receive inputs of energy and matter, and produce outputs of both
closed systems (i.e. Earth) receive inputs of and produce outputs of energy but not matter
hard to understand and predict
examples of each type?
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8. Forms of feedback are common in environmental systems
Feedback loop = a system’s output serves as input to that same system
Negative feedback loop = output that results from a system moving in one direction acts as input that moves the system in the other direction.
Positive feedback loop = instead of stabilizing a system, it drives it further toward one extreme or another
Dynamic equilibrium = system processes move in opposing directions at equivalent rates, balancing their effects
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9. Negative and positive feedback loops
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10. Homeostasis is a state of balance
Homeostasis = a system maintains constant or stable internal conditions
Resistance refers to the strength of the system’s tendency to remain constant
Resilience is a measure of how readily the system will return to its original state once it has been disturbed

11. A whole may be more than the sum of its parts
Emergent properties = system characteristics not evident in the components alone
“The whole is more than the sum of the parts”
Can’t predict biological behaviour on the basis of chemistry
Can’t predict the behaviour of humans on the basis of other living things

12. Complex systems have multiple subsystems
Environmental entities are complex systems that interact with each other
For example, river systems consist of hundreds of smaller tributary subsystems (Mt. Polley dam break – into Polley Lake, Hazelton Creek, and Quesnel Lake)
To solve environmental problems, all appropriate systems must be considered, something that tends not to happen. Examples?
We will see later what happens when one adopts a silo or “rifle barrel” approach to environmental problems.

13. Complex systems and subsystems: watershed

14. Environmental systems may be perceived in various ways
Categorizing environmental systems helps make Earth’s dazzling complexity comprehensible
For example, the earth consists of structural spheres
Geosphere (or Lithosphere) = rock and sediment
Atmosphere = the air
Hydrosphere = liquid, solid or vapor water
Biosphere = all the planet’s living organisms and the abiotic portions of the environment
Boundaries overlap, so the systems interact

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16. Ecosystems
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17. Ecosystems
Ecosystem = all organisms and nonliving entities that occur and interact in a particular area at the same time
includes abiotic and biotic components
energy flows and matter cycles among these components
Biological entities are highly intertwined with chemical and physical entities
interactions and feedback loops 17

18. Ecosystems are systems of interacting biotic and abiotic components
Energy entering the system is processed and transformed (e.g. food chains)
Matter is recycled within the ecosystem, resulting in outputs such as heat, water flow, and waste products (often in the form of nutrients) 18

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20. Energy is converted to biomass
Primary production = conversion of solar energy to chemical energy by autotrophs
Gross primary production (GPP) = assimilation of energy by autotrophs
Net primary production (NPP) = energy remaining after respiration, and used to generate biomass
Available for heterotrophs
Secondary production = biomass generated by heterotrophs
Productivity = rate at which ecosystems generate biomass 20

21. High net primary productivity = ecosystems whose plants rapidly convert solar energy to biomass

22. Variation in net primary productivity among ecosystems and biomes results in geographic patterns of variation across the globe

23. Nutrient availability limits productivity
Nutrients = elements and compounds required for survival that are consumed by organisms
Macronutrients = nutrients required in relative large amounts (nitrogen, carbon, phosphorus)
Micronutrients = nutrients needed in smaller amounts, such as iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc and molybdenum.
Dramatic growth of algae in water treated with phosphate 23

24. Ecosystems are integrated spatially
Ecosystems vary greatly in size
The term “ecosystem” is most often applied to self-contained systems of moderate geographic extent
Adjacent ecosystems may share components and interact
Ecotones = transitional zones between two ecosystems in which elements of different ecosystems mix. Examples? 24

25. Parkland ecotone in Saskatchewan

26. Ecosystems Where You Live
weighing the issues
Ecosystems Where You Live
Think about the area where you live. How would you describe the ecosystems?
How do these systems interact with one another?
If an ecosystem is greatly disturbed (say, a wetland, forest and bluff complex replaced by a housing development) what impacts might that have on the system and others nearby?
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27. Linley Valley – Before and After

28. Landscape ecologists study geographic patterns
Patches = form the landscape, and are distributed spatially in complex patterns (a mosaic)
Landscape = larger than an ecosystem and smaller than a biome
Land cover surrounding
Madison, WI 28

29. Landscape ecologists study geographic patterns
Metapopulation = a network of subpopulations
Most members stay within patches but may move among patches or mate with those of other patches
Individuals in small patches risk extinction
Conservation biology = studies the loss, protection, and restoration of biodiversity

30. Remote sensing and GIS are important tools
Remote sensing technologies allow scientists to create a complete picture of the landscape
Geographic information system (GIS) = computer software used in landscape ecology research
Can analyze how elements within the landscape are arranged to help make planning and land-use decisions 30

31. Models help scientists understand complex systems
Model = a simplified representation of a complex natural process, designed to help us understand how the process occurs and to make predictions 31

32. What Mother Nature Does for Free32

33. Ecosystem Services 33

34. Biogeochemical Cycles
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35. Nutrients and other materials move in biogeochemical cycles
Nutrient (biogeochemical) cycle = the movement of nutrients through ecosystems
Atmosphere, hydrosphere, lithosphere, and biosphere
Pools (reservoirs) = where nutrients reside for varying amounts of time
Flux = movement of nutrients among pools, which change over time and are influenced by human activities
Sources = pools that release more nutrients than they accept
Sinks = accept more nutrients than they release
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36. Properties of reservoirs
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37. The hydrologic cycle influences all other cycles
Water is essential for biochemical reactions and is involved in nearly every environmental system
Oceans are the main reservoir (97% of water)
Evaporation = water moves from aquatic and land systems to air
Transpiration = release of water vapor by plants
Precipitation = condensation of water vapor as rain or snow
Infiltration= seepage into groundwater tables/ aquifers
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38. The hydrologic cycle

39. The hydrologic cycle influences all other cycles (cont’d)
Aquifers = underground reservoirs of sponge-like regions of rock and soil that hold groundwater
Groundwater = water found underground beneath layers of soil
Water table = the upper limit of groundwater held in an aquifer
Water may be ancient (thousands of years old)
Groundwater becomes exposed to the air where the water table reaches the surface often in the form of a spring

40. Our impacts on the hydrologic cycle are extensive
Damming rivers increases evaporation and infiltration
Altering the surface and vegetation increases runoff and erosion
Spreading water on agricultural fields depletes rivers, lakes and streams
Removing forests and vegetation reduces transpiration and lowers water tables
Emitting pollutants changes the nature of precipitation
The most threatening impact is overdrawing groundwater for drinking, irrigation, and industrial use 40

41. The carbon cycle circulates a vital organic nutrient
Carbon is found in carbohydrates, fats, proteins, bones
Photosynthesis moves carbon from the air to organisms
Respiration returns carbon to the air and oceans
Decomposition returns carbon to the sediment, the largest reservoir of carbon
The world’s oceans are the second largest reservoir of carbon; forests are the first (release occurs when burned or logged) 41

42. The carbon cycle

43. Humans affect the carbon cycle
Burning fossil fuels moves carbon from the ground to the air (from ‘source’ to ‘sink’)
Cutting forests and burning fields moves carbon from organisms to the air
Today’s atmospheric carbon dioxide reservoir is the largest in the past 650,000 years
Is the driving force behind climate change
The missing carbon sink: 1-2 billion metric tons of carbon are unaccounted for
It may be in the plants or soils of northern temperate and boreal forests

44. The nitrogen cycle involves specialized bacteria
Nitrogen is 78% of our atmosphere but N2 gas is inert (not a usable form)
Nitrogen fixation = Nitrogen gas is fixed (made into ammonia) by nitrogen-fixing bacteria on the roots of certain plants (legumes)
Usable form (ammonium ions) for plants
FIGURE 5.18

45. The nitrogen cycle

46. Nitrification and denitrification
Nitrification = bacteria that convert ammonium ions first into nitrite ions then into nitrate ions
Plants can take up these ions
Animals obtain nitrogen by eating plants or other animals
Denitrifying bacteria = convert nitrates in soil or water to gaseous nitrogen, releasing it back into the atmosphere

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48. We have greatly influenced the nitrogen cycle
Haber-Bosch process = synthetic production of fertilizers by combining nitrogen and hydrogen to synthesize ammonia
Humans are fixing as much nitrogen as nature does!
Increased emissions of nitrogen-containing greenhouse gases
Calcium and potassium in soil washed out by fertilizers
Acidified water and soils
Increased transfer from rivers to oceans
Reduced biodiversity of plants adapted to low-nitrogen soils
Changed estuaries and coastal ecosystems and fisheries

49. Eutrophication
The process of nutrient over-enrichment, blooms of algae, increased production of organic matter, and ecosystem degradation

50. Nitrogen Pollution and Its Financial Impacts
weighing the issues
Nitrogen Pollution and Its Financial Impacts
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51. The phosphorus cycle involves mainly the geosphere and ocean
Phosphorus is a key component of cell membranes, DNA, RNA, ATP and ADP
Geology:
Most phosphorus is within rocks and is released by weathering
With naturally low environmental concentrations, phosphorus is a limiting factor for plant growth
Food webs: Plants take up phosphorus when it is dissolved in water

52. The phosphorus cycle

53. We affect the phosphorus cycle
Mining rocks for fertilizer moves phosphorus from the soil to water systems
Wastewater discharge also releases phosphorus
Runoff containing phosphorus causes eutrophication of aquatic systems
Household detergents may contain phosphorus
Potash – i.e. from Saskatchewan – is also useful for plants. The source is buried potassium salts that are mined and used as fertilizers.

54. Conclusion
Thinking in terms of systems is important in understanding Earth’s dynamics
Earth hosts many interacting systems
Understanding biogeochemical cycles is crucial because human activities are causing change the way cycles function
Unperturbed ecosystems use renewable solar energy, recycle nutrients, and are stabilized by negative feedback loops 54

55. QUESTION: Review
The term “system” includes all of the following, except:
A network of relationships among various components
The various components tend to minimize interactions
Energy, matter, and information are exchanged between components
Energy and matter are valuable inputs to the system
Answer: b

56. QUESTION: Review
Which of the following describes a positive feedback loop?
It drives a system towards an extreme
It stabilizes the system
It causes the system to move in opposite directions at the same rates
It causes the system to maintain a constant condition
Answer: a

57. QUESTION: Review Which of the following is a correct statement?
Energy and matter flow in one direction only
Energy and matter both cycle repeatedly
Energy flows in one direction, while matter recycles
Matter flows in one direction, while energy recycles
Answer: c

58. QUESTION: Review What is the definition of “net primary production”?
Assimilation of energy by heterotrophs
Elements and compounds that are required for survival
Energy remaining after respiration that is used to generate biomass
Assimilation of energy by autotrophs
Answer: c

59. QUESTION: Review
Which biogeochemical cycle comprises 78% of our atmosphere, and is contained in proteins, DNA and RNA?
Carbon
Nitrogen
Water
Phosphorus
Answer: b

60. QUESTION: Review
Which biogeochemical cycle is being affected by damming rivers, and altering the surface and vegetation?
Carbon
Nitrogen
Water
Phosphorus
Answer: b

61. QUESTION: Interpreting Graphs and Data
According to this graph, which ecosystem has the warmest temperature and most rainfall?
a) Temperate grassland
b) Boreal forest
c) Savannah
d) Tropical rain forest
Answer: a