GEOG 101 –
Days 2 & 3
Chapter 5: Earth Systems
and Ecosystem Ecology
9 Planetary Boundaries We Must Not Cross (did
anyone read this piece?)
Housekeeping Items
 Does
anyone need a course outline? I would
like to make one correction.
 Does everyone have a textbook?
 I will pass around the sign-in sheet for anyone
not here last time, and also a folder of
potentially interesting articles.
 I have put all of the assignment instructions
up on my web site:
http://web.viu.ca/alexander2 under
“Courses.” You have to pick two out of four
choices: life-cycle analysis, media analysis,
report (to be published on West Linley
Valley), and environmental education unit/
school visit.
Housekeeping Items
 Whatever
assignments you choose, you have
to submit an outline/ proposal by Wednesday
the 26th.
 If you are on the Waitlist, keep trying to add
until tomorrow; we will invariably have a
couple of people
 Please read on your own the very important
speech by author/ activist Paul Hawken:
(http://globalmindshift.wordpress.com/2009/05/21/theunforgettable-commencement-address-by-paul-hawken-tothe-class-of-2009-university-of-portland-may-3-2009/).
 Today
we will start to cover Chapter 5 (we skip
2-4). We will come back to the very important
topic of biodiversity (addressed in Chapters 3
and 4) later in the semester.
But First…
 Chapter
1, in its discussion of science, showed
a strong bias towards positivism. Does anyone
know what positivism is?
 Now that we’ve defined it, what are some
potential arguments against it?
1)
2)
3)
4)
This lecture on Chapter 5 will help you
understand:*
• The nature of environmental systems
• How plate tectonics and the rock cycle
shape the Earth [we will only touch on this
lightly]
• Ecosystems and how living and nonliving
entities interact
• Landscape ecology
• The water, carbon, nitrogen, and
phosphorus cycles
*Please read the textbook yourself. There is way more in there than we can cover in
class!
5-5
Central Case: The Plight of the St. Lawrence
Belugas
• Decreasing population due to GI cancer from pollutants
(polyaromatic hydrocarbons [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
• Beluga is “vulnerable” and
is an indicator of the Great LakesSt. Lawrence ecosystem
image source: Aqua Views
5-6
Systems show several defining properties
• System = a network of relationships among parts
elements or components that interact with and
influence one another
- exchange of energy, matter, or information
- receives inputs of energy, matter, or
information; processes these inputs; and
produces outputs
- hard to understand and predict
• Feedback loop = a system’s output serves as input
to that same system
5-7
Negative feedback loop
• Negative feedback loop = output that results from a system
moving in one direction acts as input that moves the system in
the other direction.
5-8
Positive feedback loop
• Positive feedback loop = instead of stabilizing a system, it
drives it further toward one extreme or another
FIGURE 5.1
5-9
Systems show several
defining properties
• Dynamic equilibrium = system
processes move in opposing
directions at equivalent rates,
balancing their effects
• Homeostasis = a system maintains
constant or stable internal conditions
• Emergent properties = system
characteristics not evident in the
components alone
- “The whole is more than the sum
of the parts”
FIGURE 5.2
5-10
A systems approach
• Environmental entities are complex
systems that interact with each other
- For example, river systems consist
of hundreds of smaller tributary
subsystems
• To solve environmental problems, all
appropriate systems must be
considered
5-11
Complex systems and subsystems:
watershed
5-12
Systems are perceived in various ways
• Categorizing environmental systems helps make Earth’s
dazzling complexity comprehensible
• For example, the earth consists of structural spheres
- 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
5-13
The rock cycle
Since this topic is covered extensively in GEOG 212, I will mostly skip over it.
5-14
The rock cycle
• Rock cycle = The heating, melting,
cooling, breaking and reassembling
of rocks and minerals
• Rocks help determine soil chemistry,
which influences ecosystems
• Helps us appreciate the formation and
conservation of soils, mineral
resources, fossil fuels, and other
natural resources
5-15
Igneous rock
• Magma = the molten, liquid state of rock
• Lava = magma released from the
lithosphere
• Igneous rock = forms when magma cools
• Intrusive rock = magma that cools slowly
well below Earth’s surface (i.e., granite)
• Extrusive rock = magma ejected from a
volcano (i.e., basalt)
5-16
Sedimentary rock
• Sediments = particles of rock are blown by
wind or washed away by water
• Sedimentary rock = dissolved minerals seep
through sediment layers and crystallize and
bind sediment particles together
• Lithification = formation of rock through the
processes of compaction, binding, and
crystallization
5-17
Metamorphic rock
• Metamorphic rock = great heat or pressure
on a rock changes its form
• Temperatures is high enough to reshape
crystals and change its appearance and
physical properties
• Marble = heated and pressurized limestone
• Slate = heated and metamorphosed shale
5-18
Plate tectonics shapes Earth’s geography
• Plate tectonics = process that underlies
earthquakes and volcanoes and that
determines the geography of the Earth’s
surface
• Crust = lightweight thin component of
Earth’s surface
• Mantle = malleable layer on which the
crust floats
• Core = molten heavy centre of Earth
made mostly of iron
5-19
The Earth has 15 major tectonic plates
Movement of these plates influences climate and evolution
FIGURE 5.6
5-20
Plate boundaries
Divergent plate boundaries =
magma surging upward to the
surface divides plates and
pushes them apart, creating new
crust as it cools and spreads
Transform plate
boundary = two plates
meet, slipping and grinding
alongside one another
FIGURE 5.7
5-21
Tectonic plates can collide
• Convergent plate boundaries = where plates collide
• Subduction = one plate of crust may slide beneath another
• Uplift = lift material from both plates
FIGURE 5.7
5-22
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
5-23
Ecosystems are systems of interacting
living and nonliving entities
• Energy entering the system is processed and transformed
• Matter is recycled within ecosystem, resulting in outputs
such as heat, water flow, and waste products
FIGURE 5.8
5-24
Energy is converted to biomass
• Primary production = conversion of solar energy to
chemical energy by autotrophs (plants)
• Gross primary production (GPP) = assimilation of energy
by autotrophs
• Net primary production (NPP) = energy remaining after
respiration (absorption of energy and release of CO2 and
water), and is used to generate biomass
- Available for heterotrophs (animals)
• Secondary production = biomass generated by
heterotrophs
• Productivity = rate at which ecosystems generate biomass
5-25
Net primary productivity
High net primary productivity = ecosystems whose plants rapidly
convert solar energy to biomass
FIGURE 5.9
5-26
Nutrients can limit productivity
• Nutrients = elements and
compounds required for
survival that are consumed
by organisms
• Macronutrients =
nutrients required in
relative large amounts
(nitrogen, carbon,
phosphorus)
FIGURE 5.10
Dramatic growth of algae in
water treated with phosphate
– part of the Experimental
Lakes Area program being
cancelled by the Harper
government
• Micronutrients =
nutrients needed in smaller
amounts (e.g. iron, cobalt,
chromium, copper,
manganese, cobalt, iodine,
selenium, zinc, etc. +
vitamins).
5-27
Nutrient runoff is devastating aquatic
systems – what are its sources?
FIGURE 5.11
5-28
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?)
5-29
Landscape ecologists study geographic areas
with multiple ecosystems
• Patches = form the landscape, and are distributed spatially in
complex patterns (a mosaic)
• Landscape = larger than an ecosystem and smaller than a biome
FIGURE 5.12
5-30
Populations and Biodiversity
• Metapopulation = a network of subpopulations
- Most members of species stay within patches but
may move among patches or mate with those of
other patches
- Individuals in small patches risk extinction
• Conservation biology = study the loss, protection,
and restoration of biodiversity. Considers cores and
corridors, and has been influenced by island
biogeography, which is the study of the relative
abundance of species and sizes of populations on
islands depending on their size and distance from
the mainland.
5-31
Remote sensing helps us applies landscape
ecology
• Remote sensing technologies allow
scientists to create a complete picture
of the landscape
• Geographic information systems
(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
• Here’s an interesting example from a
different discipline:
http://cohort11.americanobserver.net/lato
yaegwuekwe/multimediafinal.html
FIGURE 5.13
5-32
Nutrients circulate via biogeochemical
cycles (more on this soon)
• 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
5-33
The hydrological cycle
FIGURE 5.15
5-34
The hydrological cycle influences all other
cycles
•Water is essential for biochemical reactions and is involved
in nearly every environmental system
•Oceans are the main reservoir
•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
•Run-off= movement of water across the land into
receiving water bodies
•Infiltration= seeping of water into underground aquifers
5-35
Groundwater
• 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
5-36
Human impacts on hydrological cycle
• 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
5-37
weighing
the issues
Your water
• Are you aware of any water shortages or
conflicts over water use in your region?
• What is the quality of your water, and what
pollution threats does it face?
• Given your knowledge of the hydrological
cycle, what solutions would you propose for
water problems in your region?
4-38
The carbon cycle
FIGURE 5.16
5-39
The carbon cycle
• 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
5-40
Humans affect the carbon cycle
• Burning fossil fuels moves carbon from the ground to the
air
• 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
- The driving force behind climate change
• The missing carbon sink: 1-2 billion metric tons of carbon
are unaccounted for
- It may be the plants or soils of northern temperate and
boreal forests
5-41
The nitrogen cycle
FIGURE 5.17
5-42
The nitrogen cycle
• 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
- Usable form (ammonium ions)
FIGURE 5.18
5-43
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
5-44
Humans affect 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
(the ‘Lake Erie’ effect)
5-45
Eutrophication
• The process of nutrient over-enrichment,
blooms of algae, increased production of
organic matter, and ecosystem degradation
FIGURE 5.19
5-46
The phosphorus cycle
FIGURE 5.20
5-47
The phosphorus cycle involves mainly
lithosphere 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
• Plants take up phosphorus when it is dissolved
in water
5-48
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 (another factor in the “death” of
Lake Erie)
5-49
Conclusion
• The hydrologic cycle, the rock cycle, and plate
tectonics lay the groundwork for spreading life across
Earth
• Understanding biogeochemical cycles is crucial
because humans change the way cycles function
• Thinking in terms of systems can teach us how to
avoid disrupting Earth’s processes and how to
mitigate any disruptions we cause
• We can learn about sustainability from natural
systems
5-50
QUESTION: Review
The term “system” includes all of the following,
except:
a) A network of relationships among various
components
b) The various components tend to minimize
interactions
c) Energy, matter, and information are exchanged
between components
d) Energy and matter are valuable inputs to the
system
5-51
QUESTION: Review
Which of the following describes a positive feedback
loop?
a) It drives a system towards an extreme
b) It stabilizes the system
c) It causes the system to move in opposite
directions at the same rates
d) It causes the system to maintain a constant
condition
5-52
QUESTION: Review
Which of the following is a correct statement?
a) Energy and matter flow in one direction only
b) Energy and matter both cycle repeatedly
c) Energy flows in one direction, while matter
recycles
d) Matter flows in one direction, while energy
recycles
5-53
QUESTION: Review
What is the definition of “net primary production”?
a) Assimilation of energy by heterotrophs
b) Elements and compounds that are required for
survival
c) Energy remaining after respiration that is used to
generate biomass
d) Assimilation of energy by autotrophs
5-54
QUESTION: Review
Which biogeochemical cycle is contained in proteins,
DNA and RNA?
a)
b)
c)
d)
Carbon
Nitrogen
Water
Phosphorus
5-55
QUESTION: Review
Which biogeochemical cycle is being affected by
damming rivers, and altering the surface and
vegetation?
a)
b)
c)
d)
Carbon
Nitrogen
Water
Phosphorus
5-56
QUESTION: Review
Which rock is formed from magma; for example, granite
and basalt?
a)
b)
c)
d)
Sedimentary
Igneous
Metamorphic
Phosphorus
5-57
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
FIGURE 5.9
5-58
QUESTION: Interpreting Graphs and Data
What would be created as a
result of this (Figure 5.7)?
• An earthquake-prone area
• A slip-strike fault
• Colliding plates
• New crust
FIGURE 5.7
5-59