unit 2: systems and cycles in nature
TRANSCRIPT
Unit 2: Systems and Cycles in Nature
Description:
Nature is full of complex systems that maintain balance over long periods of time, and in order to
understand them, it is necessary to study entire systems instead of isolated pieces of the puzzle. This unit
examines how the interactions of earth’s atmosphere, hydrosphere, lithosphere and biosphere create
complex cycles that are critical to sustaining life on the planet. We will focus on ecosystems, studying the
relationships that develop between organisms and their environment, and the value of those ecosystems
to humans.
Packet Contents:
Assignment: Due:
1. Chapter 2 vocab 9/15
2. Reading Questions 2A, Video Questions 2A 9/18
3. Reading Questions 2B, Video Questions 2B 9/22
4. Chapter 3 vocab 9/23or 24
5. Reading Questions 3A, Video Questions 3A 9/26
6. Reading Questions 3B, Video Questions 3B 9/29
7. Article #1 “Early Warning Signs” + Analysis Questions Week 1
Date Due Read Tonight RQ/VQ Article
M 9/15 Chapter 2 vocab due p.27-28 2A
#1 “Early Warning Signs” T 9/16 p.29-36
W 9/17 p.36-41
Th 9/18 *DUE: RQ/VQ 2A p.42-43 2B
F 9/19 p.43-46
S/S ”
M 9/22 *DUE: RQ/VQ 2B + Article Questions 3A
T 9/23 DUE: chapter 3 vocab p.57-60
W 9/24 Due: chapter 3 vocab p.60-65
Th 9/25 FRQ In Class Prompt
F 9/26 *DUE: RQ/VQ 3A * Quiz* p.65-76 3B
S/S
M 9/29 *DUE: RQ/VQ 3B Study! Study!
T 9/30 Study! Study!
W 10/1 Study! Study!
Th 10/2 Test Review Study! Study!
F 10/3 *Unit 2 Test (30 MCQ, 1 FRQ) Quizstars due by 8am
Chapter 2 Vocabulary List
Isotopes Capillary Action Power
Radioactive Decay System Analysis First Law of Thermodynamics
Half-Life Steady State Second Law of thermodynamics
Closed System Feedback Energy Efficiency
Inputs Open System Energy Quality
Outputs Negative Feedback Loops Entropy
Positive Feedback Loops Adaptive Management Plan
Reading Questions 2A
Opening Story: A Lake of Salt Water, Dust Storms, and Endangered Species
Earth is a single interconnected system.
All environmental systems consist of matter.
1. Why did Mono Lake develop large mineral structures?
2. What negative environmental consequences occurred as a result of Los Angeles building an
aqueduct to transport water from the lake to the city?
3. The Earth is a single interconnected system, but it can be subdivided into many smaller systems.
How does the nature of the problem to be studied determine the scale of the system chosen?
4. What is the difference between an atom, a molecule, and a compound?
5. How do different isotopes of the same element differ, and what is their significance?
6. How is the half-life of a radioactive element determined, and why is it important?
7. When scientists look for other planets that may have life, they focus on planets that contain water. How do the water’s unique properties make it key for supporting biological processes?
8. Why do coastal areas near lakes and oceans tend to see smaller swings in temperature from hot
to cold?
9. Suppose solution A has a pH of 3, solution B has a pH of 7 and solution C has a pH or 8. If
solution B has 100,000 H+ ions, how many H+ ions do each of solution A and C have?
10. As a tree grows, it’s mass increases. Why is this not a violation of the law of conservation of
matter?
11. Complete the following chart regarding the major types of macromolecules (organic matter):
Defining Characteristics Role in Cell/Organism Examples
Carbohydrates
Proteins
Nucleic Acids
Lipids
APES Video Questions 2A
Watch “Crash Course Chemistry #1: The Nucleus” (http://www.youtube.com/watch?v=FSyAehMdpyI)
Read the Focus Questions in advance to help you catch key information. Take notes while watching,
then summarize and answer the questions when you finish.
Take Notes as you watch:
Summarize Main Ideas
Focus Questions:
1. What are atoms composed of? Describe the properties of each component.
2. What are isotopes? Why are they important?
3. What role does charge play in atomic interactions?
Respond with your own thoughts, questions, connections, and conclusions:
Reading Questions 2B
Energy is a fundamental component of environmental systems.
Energy conversion underlies all ecological processes.
Systems analysis shows how matter and energy flow in the environment.
Natural systems change across space and over time.
Working Toward Sustainability: Managing Environmental Systems in the Florida Everglades
1. How does the Sun transfer energy from millions of miles away to Earth?
2. What is the difference between power and energy?
3. Why do you think we use the term power plants instead of energy plants?
4. What is the difference between potential energy and kinetic energy?
5. Certain chemical reactions give off heat when they occur. Describe what is happening in terms
of potential energy and kinetic energy in such reactions.
6. How is an object’s temperature related to the energy of its molecules?
7. The first law of thermodynamics states that energy can be neither created nor destroyed; do heat-emitting (exothermic) reactions violate this law? Explain.
8. According to the second law of thermodynamics, some energy is always lost as heat during any
energy conversion. Use this concept to explain why lights, engines, computers, muscles, etc. get
hot.
9. How can the efficiency of an energy transformation be calculated?
10. Use the second law of thermodynamics to explain why a barrel of oil can be used only once as a fuel. In other words: why can’t we recycle this high quality energy?
11. The second law of thermodynamics tells us that all systems slowly degrade towards
randomness. However, life on Earth has been incredibly successful at preserving itself and
growing increasingly complex over time. How has life been so successful doing this?
12. Earth is considered an open system for energy and a closed system for matter. Explain what this means.
13. What characterizes a steady state in a system? Are steady states generally a good or bad thing in environmental systems?
14. Explain the difference between a positive feedback loop and a negative feedback loop.
15. Are positive feedbacks necessarily good things? Are negative feedbacks necessarily bad things? Explain.
16. What can inputs, outputs and feedback loops tell us about the health of environmental systems?
APES Video Questions 2B
Watch “Crash Course Chemistry #17: Energy & Chemistry” (www.youtube.com/watch?v=GqtUWyDR1fg)
Read the Focus Questions in advance to help you catch key information. Take notes while watching,
then summarize and answer the questions when you finish.
Take Notes as you watch:
Summarize Main Ideas
Focus Questions:
1. How can molecules contain energy in their bonds, mass and motion?
2. Heat and work are both transfers of energy – what distinguishes them?
3. How do exothermic and endothermic reactions perform energy transformations?
Respond with your own thoughts, questions, connections, and conclusions:
Chapter 3 Vocabulary List
Resilience Gross Primary Productivity (GPP) Limiting Nutrient
Resistance Net Primary Productivity (NPP) Nitrogen Fixation
Restoration Ecology Biomass Leaching
Intermediate Disturbance Hypothesis
Standing Crop Disturbance
Evapotranspiration Ecological Efficiency Watershed
Provisions Trophic Pyramid Instrumental Value
Intrinsic Value
Reading Questions 3A
Reversing the Deforestation of Haiti
Ecosystem ecology examines interactions between the living and the nonliving world.
Energy flows through ecosystems.
1. What happened to the rainforest in Haiti, and why? What effects did it have?
2. What did the US Agency for International Development do to try and correct the problem?
3. Why are both biotic AND abiotic components important to an ecosystem?
4. Why is it difficult to determine what the boundaries to an ecosystem are?
5. Can ecosystems be fully isolated from their surroundings? How does this influence ecosystem
studies?
6. How does most energy enter ecosystems? What types of energy conversion occur within
ecosystems?
7. How are trophic levels related to flow of energy through an ecosystem? What form is this
energy in?
8. What does the productivity of an ecosystem measure?
9. What is the difference between Gross Primary Productivity and Net Primary Productivity? Which
one do you think has more of an influence on an ecosystem, and why?
10. Approximately what percentage of incoming solar energy do plants capture during
photosynthesis? What happens to the rest of it?
11. Which terrestrial and aquatic ecosystems have the highest NPP? Why do you think this is?
12. What is the difference between the standing crop of biomass and productivity in an ecosystem?
13. Why is only a small fraction of energy at each trophic level transferred up to the next trophic
level? Where does the rest of the energy go?
14. As a general rule, the lower the NPP of an ecosystem, the larger the ranges of its top predators
must be. For example, sharks in the open ocean must cover huge distances. Why is this true?
APES Video Questions 3A
Watch “Life in Biosphere 2” (www.ted.com/talks/jane_poynter_life_in_biosphere_2.html)
(Or http://www.youtube.com/watch?v=a7B39MLVeIc)
Read the Focus Questions in advance to help you catch key information. Take notes while watching,
then summarize and answer the questions when you finish.
Take Notes as you watch:
Summarize Main Ideas
Focus Questions:
1. How was Biosphere 2 set up, and what was it intended to study?
2. What were the major problems that developed in Biosphere 2?
3. What can we learn from the “industrial ecosystem” created in Eritrean shrimp farms &
mangrove forests? Could this model be adapted to other situations?
Respond with your own thoughts, questions, connections, and conclusions:
Reading Questions 3B
Matter cycles through the biosphere.
Ecosystems respond to disturbance.
Working Toward Sustainability: Can We Make Golf Greens Greener?
1. What is the difference between a pool (or stock) and a flow in biogeochemical cycles?
2. Hydrologic Cycle
Name of Step What process makes this
happen?
Why is this step important?
Evaporation Solar heating of oceans, lakes,
soils
Water enters atmosphere to be redistributed
3. Carbon Cycle
Name of Step w/ description of change
What organism/process does it? Why is this step important?
Photosynthesis (CO2C6H12O6) Autotrophs (plants) (producers) Converts abiotic CO2 to biomass (base of food chain)
4. Nitrogen Cycle
Name of Step w/ chemical change What organism/process does it? Why is this step important?
Nitrogen Fixation (N2NH3 or NO3) N-fixing bacteria (ie in legume roots) OR fires/lightning OR fertilizer manufacturing
Puts N in to the base of the food chain; fertilizer manufacture
5. Phosphorus Cycle
Name of Step w/ description of change
What process/organism does it? Why is this step important?
Weathering of rock Phosphate PO4 Weathering (by rain, wind, ice, organisms)
Releases P from rocks in to reactive form usable by organisms
6. How does the water cycle help facilitate the other cycles?
7. What human activities cause an impact on the hydrologic cycle? What are these impacts?
8. Explain the difference between the “fast” and “slow” parts of the carbon cycle.
Fast: Slow:
9. Which natural (nonanthropogenic) processes normally return buried carbon to the atmosphere
to balance out the carbon that is buried through sedimentation?
10. Which 2 macronutrients most frequently serve as the limiting nutrient for plant growth in an
ecosystem? Is it different for terrestrial vs. aquatic ecosystems?
11. What are the results of a sudden influx of excess nitrogen or phosphorus in to an ecosystem?
12. How do heterotrophs (consumers) obtain their supplies of macronutrients?
13. Although the most obvious forms of life on our plant are large plants and animals, the vast
majority of life is microbial. Paleontologist Andrew Knoll writes that “Prokaryotic metabolisms
form the fundamental ecological circuitry of life. Bacteria, not mammals, underpin the efficient
and long-term functioning of the biosphere".1 Defend or challenge the truth of this statement,
based on what you know about ecosystems and biogeochemical cycles.
14. When investigating environmental systems, why do scientists often select watersheds as an area
in which to study ecosystems and nutrient/energy cycling?
15. What characteristics do you think give ecosystems high resistance and high resiliency against
change?
16. What is restoration ecology?
17. Suppose ecosystem A experiences very few disruptions, ecosystem B experiences an
intermediate level of disturbances, and ecosystem C experiences very frequent disruptions, but
all 3 have roughly equivalent NPP and stored biomass. Which ecosystem would you expect to
have the highest resistance, and why? Which would have the highest resiliency, and why?
18. What are some environmental concerns that arise from the development of golf courses, and
how can they be addressed?
1 Andrew Knoll, Life on a Young Planet: The First Three Billion Years of Evolution on Earth (Princeton University
Press, 2003), p. 23.
APES Video Questions 3B
Watch “Bozeman Biology: Biogeochemical Cycling” (www.youtube.com/watch?v=09_sWPxQymA)
Read the Focus Questions in advance to help you catch key information. Take notes while watching,
then summarize and answer the questions when you finish.
Take Notes as you watch:
Summarize Main Ideas
Focus Questions:
1. How do the unique properties of each element in CHONPS allow life to build complex
structures?
2. Why are bacteria important to biogeochemical cycling?
3. Why is it significant that the phosphorous cycle lacks an airborne phase, unlike CHONS?
Respond with your own thoughts, questions, connections, and conclusions:
Article #1
Early Warning Signs
Rapid shifts are the hallmark of climate change, epileptic seizures, financial crises, and fishery
collapses. Deep mathematical principles tie these events together.
At a closed meeting held in Boston in October 2009, the room was packed with high-
flyers in foreign policy and finance: Henry Kissinger, Paul Volcker, Andy Haldane, and Joseph
Stiglitz, among others, as well as representatives of sovereign wealth funds, pensions, and
endowments worth more than a trillion dollars—a significant slice of the world’s wealth. The
session opened with the following telling question: “Have the last couple of years shown that our
traditional finance/risk models are irretrievably broken and that models and approaches from
other fields (for example, ecology) may offer a better understanding of the interconnectedness
and fragility of complex financial systems?”
Science is a creative human enterprise. Discoveries are made in the context of our creations: our
models and hypotheses about how the world works. Big failures, however, can be a wake-up call
about entrenched views, and nothing produces humility or gains attention faster than an event
that blindsides so many so immediately.
Examples of catastrophic and systemic changes have been gathering in a variety of fields,
typically in specialized contexts with little cross-connection. Only recently have we begun to
look for generic patterns in the web of linked causes and effects that puts disparate events into a
common framework—a framework that operates on a sufficiently high level to include geologic
climate shifts, epileptic seizures, market and fishery crashes, and rapid shifts from healthy
ecosystems to biological deserts.
The main themes of this framework are twofold: First, they are all complex systems of
interconnected and interdependent parts. Second, they are nonlinear, non-equilibrium systems
that can undergo rapid and drastic state changes.
Consider first the complex interconnections. Economics is not typically thought of as a global
systems problem. Indeed, investment banks are famous for a brand of tunnel vision that focuses
risk management at the individual firm level and ignores the difficult and costlier, albeit less
frequent, systemic or financial-web problem. Monitoring the ecosystem-like network of firms
with interlocking balance sheets is not in the risk manager’s job description. Even so, there is
emerging agreement that ignoring the seemingly incomprehensible meshing of counterparty
obligations and mutual interdependencies (an accountant’s nightmare, more recursive than
Abbott and Costello’s “Who’s on first?”) prevented real pricing of risk premiums, which helped
to propagate the current crisis.
A parallel situation exists in fisheries, where stocks are traditionally managed one species at a
time. Alarm over collapsing fish stocks, however, is helping to create the current push for
ecosystem-based ocean management. This is a step in the right direction, but the current
ecosystem simulation models remain incapable of reproducing realistic population crashes. And
the same is true of most climate simulation models: Though the geological record tells us that
global temperatures can change very quickly, the models consistently underestimate that
possibility. This is related to the next property, the nonlinear, non-equilibrium nature of systems.
Most engineered devices, consisting of mechanical springs, transistors, and the like, are built to
be stable. That is, if stressed from rest, or equilibrium, they spring back. Many simple ecological
models, physiological models, and even climate and economic models are built by assuming the
same principle: a globally stable equilibrium. A related simplification is to see the world as
consisting of separate parts that can be studied in a linear way, one piece at a time. These pieces
can then be summed independently to make the whole. Researchers have developed a very large
tool kit of analytical methods and statistics based on this linear idea, and it has proven invaluable
for studying simple engineered devices. But even when many of the complex systems that
interest us are not linear, we persist with these tools and models. It is a case of looking under the
lamppost because the light is better even though we know the lost keys are in the shadows.
Linear systems produce nice stationary statistics—constant risk metrics, for example. Because
they assume that a process does not vary through time, one can subsample it to get an idea of
what the larger universe of possibilities looks like. This characteristic of linear systems appeals
to our normal heuristic thinking.
Nonlinear systems, however, are not so well behaved. They can appear stationary for a long
while, then without anything changing, they exhibit jumps in variability—so-called
“heteroscedasticity.” For example, if one looks at the range of economic variables over the past
decade (daily market movements, GDP changes, etc.), one might guess that variability and the
universe of possibilities are very modest. This was the modus operandi of normal risk
management. As a consequence, the likelihood of some of the large moves we saw in 2008,
which happened over so many consecutive days, should have been less than once in the age of
the universe.
Our problem is that the scientific desire to simplify has taken over, something that Einstein
warned against when he paraphrased Occam: “Everything should be made as simple as possible,
but not simpler.” Thinking of natural and economic systems as essentially stable and
decomposable into parts is a good initial hypothesis, current observations and measurements do
not support that hypothesis—hence our continual surprise. Just as we like the idea of constancy,
we are stubborn to change. The 19th century American humorist Josh Billings, perhaps, put it
best: “It ain’t what we don’t know that gives us trouble, it’s what we know that just ain’t so.”
So how do we proceed? There are a number of ways to approach this tactically, including new
data-intensive techniques that model each system uniquely but look for common characteristics.
However, a more strategic approach is to study these systems at their most generic level, to
identify universal principles that are independent of the specific details that distinguish each
system. This is the domain of complexity theory.
Among these principles is the idea that there might be universal early warning signs for critical
transitions, diagnostic signals that appear near unstable tipping points of rapid change. The
recent argument for early warning signs is based on the following: 1) that both simple and more
realistic, complex nonlinear models show these behaviors, and 2) that there is a growing weight
of empirical evidence for these common precursors in varied systems.
A key phenomenon known for decades is so-called “critical slowing” as a threshold approaches.
That is, a system’s dynamic response to external perturbations becomes more sluggish near
tipping points. Mathematically, this property gives rise to increased inertia in the ups and downs
of things like temperature or population numbers—we call this inertia “autocorrelation”—which
in turn can result in larger swings, or more volatility. In some cases, it can even produce
“flickering,” or rapid alternation from one stable state to another (picture a lake ricocheting back
and forth between being clear and oxygenated versus algae-ridden and oxygen-starved). Another
related early signaling behavior is an increase in “spatial resonance”: Pulses occurring in
neighboring parts of the web become synchronized. Nearby brain cells fire in unison minutes to
hours prior to an epileptic seizure, for example, and global financial markets pulse together. The
autocorrelation that comes from critical slowing has been shown to be a particularly good
indicator of certain geologic climate-change events, such as the greenhouse-icehouse transition
that occurred 34 million years ago; the inertial effect of climate-system slowing built up
gradually over millions of years, suddenly ending in a rapid shift that turned a fully lush, green
planet into one with polar regions blanketed in ice.
The global financial meltdown illustrates the phenomenon of critical slowing and spatial
resonance. Leading up to the crash, there was a marked increase in homogeneity among
institutions, both in their revenue-generating strategies as well as in their risk-management
strategies, thus increasing correlation among funds and across countries—an early warning.
Indeed, with regard to risk management through diversification, it is ironic that diversification
became so extreme that diversification was lost: Everyone owning part of everything creates
complete homogeneity. Reducing risk by increasing portfolio diversity makes sense for each
individual institution, but if everyone does it, it creates huge group or system-wide risk.
Mathematically, such homogeneity leads to increased connectivity in the financial system, and
the number and strength of these linkages grow as homogeneity increases. Thus, the
consequence of increasing connectivity is to destabilize a generic complex system: Each
institution becomes more affected by the balance sheets of neighboring institutions than by its
own. The role of systemic risk monitoring, then, could simply be rapid detection and
dissemination of potential imbalances, much as we allow frequent underbrush fires to burn in
order to forestall catastrophic wildfires. Provided that these kinds of imbalances can be rapidly
identified, maybe we will need no regulation beyond swift diffusion of information. Having
frequent, small disruptions could even be the sign of a healthy, innovative financial system.
Further tactical lessons could be drawn from similarities in the structure of bank payment
networks and cooperative, or “mutualistic,” networks in biology. These structures are thought to
promote network growth and support more species. Consider the case of plants and their insect
pollinators: Each group benefits the other, but there is competition within groups. If pollinators
interact with promiscuous plants (generalists that benefit from many different insect species), the
overall competition among insects and plants decreases and the system can grow very large.
Relationships of this kind are seen in financial systems too, where small specialist banks interact
with large generalist banks. Interestingly, the same hierarchical structure that promotes
biodiversity in plant-animal cooperative networks may increase the risk of large-scale systemic
failures: Mutualism facilitates greater biodiversity, but it also creates the potential for many
contingent species to go extinct, particularly if large, well-connected generalists—certain large
banks, for instance—disappear. It becomes an argument for the “too big to fail” policy, in which
the size of the company’s Facebook network matters more than the size of its balance sheet.
To be sure, bailing out a large financial institution raises questions of “moral hazard.” The more
compelling reason for caution, however, is that this action could propagate another systemic
collapse elsewhere in the network if there is too much focused subsidy and the benefit is not
spread out (a relevant point for those who are dispensing TARP funds). Excessively favorable
terms between two cooperating agents—say, the Fed and a large financial institution—can lead
to the unintended collapse of other agents and to eventual duopoly.
Another good example is the interdependence of the online auction site eBay and e-payment
system PayPal. PayPal was the dominant method of payment for eBay auctions when eBay
bought it in 2002, strengthening cooperative links between the two companies. This duopolistic
partnership contributed to the demise of competing payment systems, such as eBay’s Billpoint
(phased out after the purchase of PayPal), Citibank’s c2it (closed in 2003), and Yahoo!’s
PayDirect (closed in 2004).
As a final thought, as much as we would like to predict and manage catastrophic change, some
will be inevitable. Instability is a fact of nature. And hard as it may now be to believe,
displacements from climate change will one day dwarf our worries about the economy. As we
become increasingly aware of the ways in which our actions are speeding us toward climate
tipping points, perhaps our greatest asset will be our ability to anticipate these changes soon
enough to avoid them or, at the very least, prepare for their consequences.
Analysis Questions for “Early Warning Signs”
1. Why are humans especially prone to underestimating the speed, scale and nature of
changes in complex systems?
2. What do events as different as the recent economic crisis, climate change and ecosystem
disruptions have in common from a systems analysis perspective?
3. What is the difference between linear systems and nonlinear systems? Which ones are
more complex and unpredictable, and why?
4. What properties lead to systems being more vulnerable to a dramatic shift, such as a
collapse or a transition from one stable state to another?
5. What can we learn from this study of complex system dynamics to help us better
understand, manage and respond to changes in natural systems?
Article #2: From Scientific American - "Ecosystems on the Brink"
Analysis Questions:
1. Why did the addition of largemouth bass so dramatically transform Peter Lake? Describe
the changes that occurred and why a small change caused such a large systemic shift.
2. Why is it advantageous to represent food webs as complex mathematical systems that can
be simulated on a computer? How can this be done? And what makes this difficult?
3. How can human actions produce dramatic changes in natural systems so quickly, and
what are some examples?
4. What are some of the common signs of a system that is close to a tipping point? How can
this information help us?
5. What can we learn from this study of complex system dynamics to help us better
understand, manage and respond to changes in natural systems?
Article #3 from National Geographic: "Fixing the Global Nitrogen Problem"
Analysis Questions:
1. Explain what the Haber-Bosch process is, and why it is so significant.
2. Describe a situation in which Nitrogen can be extremely beneficial, and one in which it
can be extremely harmful. How can one element play both a helpful and harmful role?
3. What is Nitrogen’s role in climate change and biodiversity loss?
4. What are the most important solutions to the “global nitrogen problem”?
5. What can we learn from this study of complex system dynamics to help us better
understand, manage and respond to changes in natural systems?