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Notes/ Study Guide

by: Aubrey Rogers

Notes/ Study Guide BIO 123-001

Aubrey Rogers

GPA 3.4

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Anything you could want to cover Human Ecology. Whole semester put into an organized set of notes.
Human Ecology - NS
Charles Acosta
Class Notes
Human Ecology, Bio
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This 77 page Class Notes was uploaded by Aubrey Rogers on Wednesday April 13, 2016. The Class Notes belongs to BIO 123-001 at Saint Leo University taught by Charles Acosta in Spring 2016. Since its upload, it has received 20 views. For similar materials see Human Ecology - NS in Biology at Saint Leo University.

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Date Created: 04/13/16
A major task of human ecology – contribute to the re- imagination and rearrangement of social – ecological systems -> Humane, sustainable, worthwhile future the broader community will accept/embrace 1.4 Conclusion: a systems approach to sustainability 4 thematic areas of human ecology 1) Ethical priorities 2) Social-ecological interactions 3) Learning and behavior change 4) Meeting/changing expectations built into dominant belief systems 5) -> Systems approach – understand interplay between the various aspects under investigation and how the parts of social – ecological system drive change in each other. a.Where change is unsustainable Systems approach -> leverage points – effective intervention Leverage point – place within a complex system where a small shift in one thing can produce big changes in everything  System redesign to develop more acceptable patterns of behavior o Theoretical structure – help human ecology evolve as a comprehensive, disciplined form of inquiry and practice Chapter 2: Water Conflicts in the Snowy Mountains 2.1 Example of how environment changes as different groups of people try to obtain resources from it. - to avoid conflict and manage sustainably, must consider issues of justice and fairness Snowy Mountains – Australia - Finite water resources o Landscape scale conservation – site-based conservation  Holistic approach:  Biodiversity  Local economies and agriculture  Health and social benefits of the environment  Geodiversity  Eco-tourism  Need a comprehensive framework to understand complex social – ecological system 2.2 The Australian Snowy Mountains – SE Australian continent - millions of years of erosion -> rounded, soil covered hills Prolonged weathering – gentle slopes with rivers in deep valleys Soils - fragile, acidic, poor in nutrients, shallow + flat tablelands 2.3 Aboriginal people: at home in the High Country - High-country ecosystem – relatively small alpine area characterized by severe weather, low nutrient stocks, and short growing seasons -> naturally low in productivity - management strategies – included setting fires But main strategy – understanding behavior of environment  Intergenerational cultural learning o Relocate to places where the environment could readily absorb the impacts of their presence with few lasting effects on its productive capacity - moved in phase with ecological cycles – to wherever there was sufficient food and water to support them 2.4 New arrivals: stockmen and graziers - even though Snowy Mountains were not fertile, like the European soils they were used to, the stockmen put the Snowy Mountains land to similar uses – had grazing animals in the High Country for as much of the year as the weather allowed. - harnessing environmental resources -> value -> size of the population of the High Country was called on to support was much greater than it had been under Aboriginal management - plus export of resources => high demand for resources from this environment that was not very fertile, etc. - big grazing animals – brought in from Europe cattle and sheep – no co-evolutionary relationship with environment, - grazing animals depleted the environment – ate grass, drank from bogs, broke down the sides – allowed draining out of the bogs – causing them to dry up - changed plant community by selectively eating certain plants o Set fires to try to restore vegetation, but that would destroy soil -> less fertile -> less vegetation  Also, removing plants, nothing for soil to hang on to  -> erosion o -> soil ended up downhill in streams and rivers of lowlands  -> conflict with inland irrigators 2.5 Inland irrigators Australia – large continent – 7.7 million km2 – fractionally larger than the contiguous U.S.  Low and unreliable volumes of rainfall  Land area: 5% of world’s total  Only 1% of total rainwater runoff  Most reliable rainfall – narrow coastal st strip along SE Australia = 1 occupied area  Mid 1900’s – next occupied – wide inland plains o Problem – rainfall variability  Drought -> cattle died in thousands  = hardship for settlers How to get the environment to yield meats and grains that European-style diets required? And support exports to British Empire Inland plains (vs Snowy Mtn settlers)  Brought water to stock (vs driving cattle to water)  Impoundments and diversions of water o At expense of downstream neighbor  -> conflict Major Drought (Federation Drought 1895 – 1902)  Need for large, more properly administered irrigation schemes  Political imperative overruled scientific advice (additional water could bring salts to surface) o Government-funded irrigation projects along the Murrumbidgee and Murray Rivers  Dams, supply channels - removed the natural variability of rainfall  Pasture irrigation  Grains, horticultural produce  Unintended consequence: bringing salt to surface -> barren Another Problem for waterways – soil eroding from High Country Soil entered waterways, accumulated on floors of reservoirs  Decreasing volume of water stored (capacity) o -> decrease in water security for irrigators By 1930s – government reports strongly linking grazing and burning with downhill siltation o -> inevitable conflict with irrigators 2.6 Changing Flows: the Snowy Hydro Scheme - irrigation projects along Murray and Murrumbidgee Rivers drew more settlers and more farms converting to irrigation -> though reliable, the water resources became fully allocated - now they want to increase inflows: Snowy River Snowy River – upper reaches – rocky gorge country not suitable for farming o To farmers – this is “wasted” water 1945 – “left”- leaning government  Centralized programs, large-scale infrastructure, welfare schemes  Used war revenue-raised money to build public works o -> water diversion project, generating hydro-electric power  Electricity generation: money earned to refund money advanced for project and cover costs  Dammed Snowy River  Diverted water for storage in reservoirs in High Country o Release when needed  Fall from considerable height -> hydropower stations at outlet point – capture energy of water and convert of electricity  Diverted water from Snowy River – delivered in equal parts Murray and Murrumbidgee Rivers -> irrigation communities – 2x the flow volume Construction: required tunneling through 150 km mountain, impoundments – storage of water = 2 years average precipitation  Never tried before – brought Australia to first world status Politics – Hydropower station weakened the Coal Miners Union, and established Australia as outpost of Europe  Opposition to stockmen: “standing in the way of national progress” – lost fight to maintain way of life – from late 1940s on – decreases in stock numbers due to catchment protection, conservation and recreation interests o By 1970’s – no more grazing  Stockmen’s perspective – lost fight for their way of life -> enduring sense of injustice -> anger, resentment to this day 2.7 New expectations – new pressures Health of alpine landscape  Soil conservation  “bushwalking” (hiking) o -> park system  Intrinsic value  Skiing  Economic contribution o Commercial operators  Restaurants, etc Park entry fees  Major source of revenue for Parks and Wildlife Service  Potential conflicts:  Skiiers vs wilderness seekers  Must be managed by parks service Other conflicts with conservation concerns:  Return flows to Snowy River o Environmental health of river and wellbeing of old riverside communities o Irrigators: don’t favor returning flow: food security  60% consumers overseas 2.8 Conclusion: Snowy Mountain Water Conflict - different groups acting based on dominant worldview (ex: harnessing nature for human uses vs leaving nature natural – conservation) Chapter 3 – Thinking together Comprehensive – interplay between different cultural and natural processes in human situations and the principles relevant to this interplay 3.1 Introduction - no one person can see the “whole elephant” - contrast between different perspectives can be a source of valuable new insights - work together – mesh different views of cause and effect to generate a new understanding of driving forces of system behavior - comprehensive – integrative, systematic approach - values expertise of people drawn from many walks of life Systems approach – begins when you first see the world through the eyes of another person cognitive science – how people perceive and conceptualize the world governs their behavioral policies and actions takes into account:  Anthropology, computer science, linguistics, neurophysiology, philosophy, psychology, sociology Early cognitive scientists – “thought” as a disembodied logical process involving serial signal-processing  Brains as digital computer, thought as computation Today’s cognitive scientists – mind as “embodied”  Human understanding is based on real- world experience  Study language use -> studies of mental processes -> insights into nature human conceptual systems  erms: o Concept o Mental model o Conceptual framework o Powerful idea o Shared understanding 3.2 Mental models and predictions: Humans build mental models of themselves and their environment  Predict future, base decisions and actions on these predictions o Ex: generalizations – people are untrustworthy o Ex: complex theory – why members of family act the way they do Mental models: 1.Are active – they shape how we act a.They affect what we do because they affect what we see i. We observe selectively (not very objective) ex: two people with different mental models can observe same event and describe it differently because they looked at different details 2.Make up understanding of event/behavior  Models of cause and effect o Imagine potential outcomes of alternative courses of action -> select action that you judge produces your favored outcome Ability to anticipate future events -> mental models 3.Conscious vs tacit knowledge tacit – cannot be adequately articulated by verbal means  Transfer requires extensive personal contact, regular interaction, and trust 4.Never completely adequate a.Limited and idiosyncratic b.Hard to improve (“locked-in”) i. Ignore things – hard to learn new things from experience Scientific method – counter this natural shortcoming o -> make models as reliable as possible As connections between cause and effect become more complex, cause and effect models become less adequate  Diminished ability to anticipate the results of an action 3.3 Conceptual metaphor, understanding, and reasoning Mental models are metaphorical structures o Understand and experience one kind of thing in terms of another Literal vs metaphorical concept: Literal concept = abstraction that summarizes the common properties of a number of superficially different concrete things or actions Common properties – allow the individual items to be classified as examples of the concept Ex: concept “coffee mug” – literal: formed by separating: a) Essential characteristics of a large number of coffee mugs b) Their individual characteristics Superficial differences between individual real coffee mugs – are irrelevant to forming concept “coffee mug “coffee mug” is an abstract concept that captures the essential attributes of all coffee mugs o Abstract point of view – coffee mug:  ~cylindrical  Open top  Rigid material  Insulation  Handles – sure grip, insulation o Capture invariant aspects of things and actions – present in all instances of the concept  Value: speed and sharpen your perceptions by allowing you to ignore detail o Used unconsciously o Almost everyone understand them the same way Metaphorical concepts – aka “metaphor” - More common than literal concepts 1) Not necessarily understood in the same way by everyone Ex: “Fish stocks are falling in the North Sea” o Literally – makes no sense o Sensical meaning: your understanding involves imagination and metaphor  Used: “more is up, less is down” metaphor o Primary metaphor – based on simple physical correlation  (see Fig. 3.1 glasses of water) – level of water in the glass increases as the amount of water in glass increases  -> correlation between level and amount 2) More than a mere matter of words, they are a way for people to use their common perceptions and experiences of physical movements (sensimotor experiences) as basis for understanding and reasoning about how the world works. 3) Human conceptual systems contain a large number of metaphorical concepts a.Organized into ~coherent structure -> set of complex metaphors built on foundation of primary metaphors and image schemata Image schema = simple cognitive structure that captures and summarizes a commonly experienced pattern of sensorimotor experiences Ex: path schema (fig. 3.2) o A moving entity (trajector, T) travels along a path toward destination (D) or goal.  Starting point = S  Force that induces T to move = F  Path already traversed = continuous curve  Path yet to be traveled = dashed line  L = one of the locations T already passed o Basic structure of the Path Schema  Elaborated metaphorically in a wide variety of ways (a lot of different experiences)  Intellectual or physical journey  Giving something to someone else  Change of entity from one state to another  - something moves (changes) under the action of some driving force, from one place (initial state) to another place (final state) o Each schema has basic logic -> inference about any metaphorical elaboration of the schema  Ex: course of study  S = admissions office  F = ambitions  L = various assessments  D = degree awarded  - the path schema = basic logic for “a formal study is a journey” metaphor o = complex metaphor  Depends on correlation between two sets of concepts: source and target concepts Source concepts – embodied (based on sensimotor experience) – people’s everyday bodily experiences as abstracted in the path schema o Relate to fundamental sensorimotor experiences, therefore everyone will have ~same understanding of words used (to label them) o Conceptual source domain = set of concepts around metaphor  Ex: path schema: concepts built around the path schema -> formal study is a journey metaphor Target concepts o In this example, target concepts are set of concepts concerning the process of formal study o More abstract, therefore can be more difficult to understand  Different experiences -> different understanding of processes involved  This example: the connections comprising the metaphor terminate on concepts to do with “studying”- this set of concepts is called the conceptual target domain  - ex: path schema – the language you use to talk about your experiences sends a clear signal that the path schema is involved path schema – captures a basic pattern common to all journeys = different individuals tend to have similar mental models of how journeys work - ex: love is a journey metaphor – crossroads in relationship - burnt our bridges - no going back - smooth sailing cary tight logic – reason and communicate about love Often more than one metaphorical way to represent a key concept: Ex: “idea” (Box 3.2 p. 44) – acquiring ideas is eating metaphor: eating healthy foods => healthy body -> acquiring good ideas => well- functioning mind 4) metaphorical concept is defined as unidirectional mapping - between conceptual source domain and conceptual target domain a) selective – not all source domain concepts are mapped into the target domain b) selective, because must make sense in the target domain c) provides way to use inferential logic of source domain as inferences in target domain (fig. 3.3) = “analogy” “B is metaphorically A” an item in A => an item in B = this item in the source domain A corresponds to this item in the target domain B, or “this item in A maps to this item in B” 3.4 Categories – classical and fuzzy categorization – used to simplify flood of information - build concepts without being distracted by different details - utilize categories when you say “kind” of thing (chair, nations, illness, emotions) or utilize “kind” of action ex: iron clothes, hammer with hammer - never done exactly the same way, yet despite differences, are same type of movement speech – any utterance = dozens/hundreds of categories: speech sounds, words, phrases, clauses, conceptual categories understanding how we categorize is central to any understanding of how we think/function = central to understanding what makes us human category – defined by properties common to all its members - no one member of a classical category can be a better example of the category (concept) than any other member - many of our everyday categories don’t work this way - “graded membership” = fuzzy categories - some members are good examples, others poor examples of the category - fig. 3.4 – classical vs radial categories radial - graded membership – shaded in radial direction – dark at center, light at rim -> “fuzzy” – objects at center are best examples objects whose representative points fall close to center are better examples of category than those toward edge of bounded area - important in human ecology: exploration of a range of possible meanings of a given term ( such as “system”) is a part of the work required to establish a shared theoretical framework - each meaning can be sharply defined, by describing the corresponding metaphor, and the most useful one selected for any given discussion 3.5 The Conduit metaphor and communication comprehensive approach – effective communication between people from different walks of life: need practical procedures for bridging the gap between individuals’ worldviews - your conceptual system is not arbitrary – reflects way your body works and your experience of activity in your local environment – there will always be some commonality between your conceptual system, and those of others who share your world - no one person can see the whole of a social – ecological system – that’s why differences of perception and understanding are invaluable to building better theoretical frameworks - but using different metaphors to understand and talk about a given situation  ambiguity and confusion, misunderstanding (to be expected in normal human communication but counter to popular belief because most people assume that, in normal conversation, exchange of meaning is automatic and trouble free) - rests on unconscious use of the conduit metaphor - language as conduit (pipe or channel) that can be used to convey ideas directly from one mind to another – you put your ideas into words then give the words to your friend – takes your ideas, unchanged, out of the words – “I gave you that idea” - based on assumption that thoughts are objects that can exist outside the thinker’s head – externalized  bundled up in words and passed easily from person to person  view that communication is automatic, little effort - however, many good reasons that opposite is true: communication is chancy process, requires a lot of time and energy to be successful – major implications for subjects that require comprehensive approach, like human ecology: - explained by Information Theory: difference between a concept and its name: concept = an idea name = a sound, a mark on paper (assoc. with idea) - same name heard or seen each time an example of a concept is encountered -> name is mistaken for concept itself - words do not carry meaning, they are just physical signals (ex: learning a new language) - high level abstract concepts (human ecology) are better thought of as hierarchical clusters of concepts – (“concept” = hierarchical cluster of concepts) To express your new ideas in words, you (unconsciously) take the following steps: 1. select relevant concepts from your conceptual repertoire and assemble them in an ordered (non- random) sequence that captures your idea 2. use your concept <-> name code to assemble a sequence of words (concept names)that matches your ordered list of concepts 3. generate an ordered set of physical signals (sounds, marks on paper) corresponding to your list of words and transmit the signals to your friend. - accurate communication is possible only when you and your friend have identical conceptual repertoires and use identical concept <-> name codes - ex: “The conduit metaphor violates the entropy law” (entropy = entropy law = in every real process the sum of the entropies of participating bodies is increased) People cannot fully understand each other’s ideas unless they have: a) overlapping conceptual repertoires b) identical concept<-> name codes  ‘a priori shared context’ for communication - if no a priori shared context: human ecologists need a generally agreed conceptual framework to achieve productive comprehensive work 3.6 Powerful ideas George Bernard Shaw: “the single biggest problem in communication is the illusion that it has taken place” “The view that human communication is automatically effective, that words effortlessly carry unambiguous meanings along conduits that connect mind to mind, leads to the tacit conclusion that a deliberate construction of a shared theoretical framework is not necessary.” = we think we automatically understand each other because we exchange words, therefore we think we don’t need a theoretical framework Development of a mutual understanding is an iterative process 1. you have idea you want to share 2. initiate the 3 steps in section 3.5 3. friend receives signal, and applies her own concept <-> name code, and generates an ordered sequence of concepts from her repertoire 4. – doesn’t make sense to her, so she rearranges it, (removing /adding concepts) to produce new sequence (S2) 5. friend applies her own concept <-> name code to S2 to generate physical signal, then transmits her signal to you 6. you receive her signal, apply your concept <-> name code -> third ordered sequence of concepts you consider to represent her understanding of your new idea. 7. Compare S3 with S1; if they match well, mutual understanding has been achieved. 8, If not, assemble new sequence of concepts  new loop Methods for building a shared understanding of new concepts: a) idea analysis: investigation of the cross- domain mappings that underlie a given metaphorical concept a.your understanding of the concept and the meaning you ascribe to the words that you use to label that concept, depends on your source domain of the defining metaphor b.different source -> different understandings -> different word meanings o -> conflict over meaning of term signaled “powerful idea” – metaphor whose source domain is relatively simple and understood in much the same way by people from a wide variety of backgrounds 3.7 Conclusion Chapter 3 – Initial step toward development of theoretical framework to support comprehensive work in human ecology - based on ideas from modern cognitive science - no one person can have expert knowledge of the whole of a complex social-ecological system – need collaboration between individuals from many walks of life – success depends on articulation and communication of explanations of causation - how humans build mental models of causal mechanisms – use them to anticipate outcomes of their own decisions and actions - mental models are constructed metaphorically metaphor (conceptual metaphor) = mapping from a conceptual source domain to a conceptual target domain - shared understanding can only exist if people have “shared metaphors” - barriers to development of shared understanding: - multiple metaphors for a single concept - fuzzy categories - conduit metaphor - crisp definitions are essential for effective communication - conduit metaphor –> communication works automatically because words carry meaning – misleading (message into words, words to friend, friend takes message (unchanged) out of words – this is not what happens in reality – to understand each other, must have a priori shared context for communication (conceptual repertoires overlap, use same words to represent concepts) - may occur in everyday situations, where people have similar experience-based concepts, but not often where concepts are based on highly technical or idiosyncratic experience --- helpful here is “powerful idea”: relatively simple conceptual metaphor, of fundamental importance in a wide range of disciplines and circumstances Chapter 4 – System dynamics I: Stocks and flows 4.1 Introduction System (feedback system) – set of parts (components, agents) that interact to constrain each other’s behaviour - interact = influence each other (two-way) - a change in the value of any one variable will eventually cause a change in the values of all the other variables - these changes then “feed back” to influence the value of the variable that was initially changed -> counterintuitive behavior of social-ecological systems - importance of feedback system theory: understand how and why things change (causation) Dynamical systems theory - dynamics (physics) = the way that material bodies move under the influence of applied forces - helps us understand how systems of different kinds change from one state to another - dynamical systems theory concepts are generic and simple => “powerful ideas” - expressed in terms of easily understood metaphors -> effective way to build shared understanding - changing state in response to forces: endogenous: internally generated exogenous: externally generated - accumulation = “stock” - processes that change the amount accumulated – “flows” 4.2 Accumulation and the Water Tank metaphor accumulation – most concrete form – material collecting in, and draining from, containers - accumulation of water in lakes, tanks, tubs = good conceptual metaphor - powerful: simple and generic (everyone has experience filling and draining containers, so logic of process is easily understood) Water Tank metaphor: at any given time a water tank holds a certain amount of water (‘stock’) inflow and outflow processes change amt of water accumulated (state change processes) = ‘flows’ stock and flow diagram – identifies some of the flows associated a dynamical system (ex: water tank, Fig. 4.2, Box 4.1 – uses STELLA) water tank = stock and flow structure – therefore effective source domain for metaphor – apply to wide range of real-world contexts (Table 4.1) (- metaphor = mapping – project inferential logic of source domain into target domain; basis for understanding phenomena in target domain) ex: experienced-based water tank logic: -> as long as water is flowing out of a tank faster than it is flowing in, the water level in the tank will fall -> it takes time to fill/drain tank metaphor: it will always take time to change the level of a stock -> delays in a system’s response to changed conditions –> “system inertia” water tanks as buffers: decouple outflows from inflows – less impacted by natural variability of local rainfall patterns (can store excess water for use during dry periods) – makes water-supply system workable by smoothing out variations => using water tank metaphor, can infer that stocks play critical roles as buffers in all systems ex: practical experience: body stores excess food energy freeing us from need to eat continually ex: just-in-time manufacturing system: very little buffering stocks – any break in flows of materials to factory brings whole manufacturing process to a halt – reduce vulnerability by increasing size of inventory (stock) of raw materials systems dynamics terminology: accumulation = ‘stock’ processes that affect amounts accumulated = ‘flows’ types of stocks: material (water, inventory of goods, number of frogs in pond, amount of money in account) non-material or intangible (stress and emotions: fear, anger, happiness – build up and drain away over time – also real biochemical states in real containers (human brain) thus easily thought about as material - other examples: political will, economic growth any material or non-material thing (even if it cannot be measured) that takes time to accumulate or dissipate under the influence of one or more causal process – can be thought about in terms of ‘stock- and-flow’ must distinguish between: container holding stock, name of stock (kind of thing accumulated), and amount accumulated ex: tank = container, water = name of stuff accumulated, volume of water = amount accumulated - name of accumulation doesn’t change over time – nouns (water) - amount accumulated does change over time (V(t)) exceptions: word labels both stock & level of stock (accumulation) ex: population (stock and number of individuals) 4.3 Stocks control flows, flows change stocks Stocks and flows interact: - flows change levels of stocks (amount accumulated) - levels of stocks control flow rates (rate = amt./time)  feedback behavior of dynamical systems Net flow rates: moment-to-moment differences between the inflow and outflow rates (F (tin F (outor F ,in )out - net inflow increases level of stock - net outflow decreases “ “ “ ex: water tank with one inflow and one outflow (Fig. 4.3) V(t) – volume of stock accumulated at specific time t Fig. 4.3(a): both pumps stopped – no water flowing in or out The relationship between changes in flow rates and associated changes in stock levels (Fig. 4.4): F inremains constant over time period considered F outjumps between 3 different levels (a, b, c) S(t) (stock level) changes over time in response to net flow rate (Fnet= F inF )out a) F out< F in F netis positive and S(t) rises steadily b) F out> F in F netis negative and S(t) falls steadily c) F out<< F sinF netis more positive and S(t) rises more steadily sudden changes in net flow rate produce sudden jumps in S(t) - at each point in time the state of a dynamical system can be described by listing the levels of its stocks – interactions between stocks drive changes in levels of stocks – - stocks don’t affect each other directly, but by influencing the flow rates of each other’s state-change processes Basic Rule of System Dynamics: Stocks and flows always alternate along a causal chain Box 4.2 – mathematical note – stocks integrate net flows Change in stock over time = net flow rate dV(t)/dt = F net= F in) – F out A stock integrates the difference between its inflows and outflows over time. The stock of water accumulated in a tank at time t is therefore given by the integral equation: V(t) = V +  t(F () – F ())d 0 =0 in out Where V i0 the volume of water in the tank at time  = 0 4.4 Causal diagrams - simplified view of interplay between the variables of a system-of- interest - illustrate feedback structures and present dynamic hypothesis – causal structure proposed to explain the behavior of a system in terms of endogenously generated feedback effects ex: stock and flow map – Fig. 4.5 – agricultural production - hypothetical food-supply system of farming family: 3 stocks: Area farmed, food Reserves, consumers N levels of stocks A(t), R(t), N(t) - looking at flows that increase/reduce R(t) - rate of replenishment F = in y(t)A(t) y(t) = time-dependent average yield per unit area  Rate of consumption (F out c(t)N(t))  Fig 4.7 - three cases: – different y(t) (slope) - A(t) increases by same amount at time t - N(t) & c(t) (per capita consumption) constant -> F outonstant Fig. 4.7 (a): R(t) decreases throughout time span because y ia so low that F in< F outat all times - increase in A(t) – slows rate of decrease of R(t) - at time t2, R(t) is an amount ∂ greater than it would have been if A(t) had not increased Fig. 4.7(b): R(t) decreases until time t -1increases thereafter - because y cbuses F netto change from negative to positive after t1 - increase in A(t) – changes direction of the of change in R(t) - size of increase in A(t) is same as in (a), therefore value of R(t) increases by same amount ∂ at time t 2 Fig. 4.7(c): R(t) increases throughout time span because y ic so high that F in> F outat all times - increase in A(t) - speeds up rate of increase of R(t) - size of increase in A(t) is same as in (a), therefore value of R(t) increases once again by same amount ∂ at time t 2 Causal diagram link polarities: (+): increase in rate of replenishment -> increase in Food Reserves (R(t)) decrease in rate of replenishment -> decrease in (R(t)) (positively correlated) (-): increase in rate of consumption -> decrease in (R(t)) decrease in rate of consumption -> increase in (R(t)) (inversely correlated or negatively correlated) Caution: Causal loop diagrams: increase in rate of inflow increases rate at which level of stock increases; if rate of inflow falls to 0, then level of stock stops increasing and remains constant. A change in inflow rate cannot reduce the level of the stock. Influence diagram = causal diagram without polarities - useful when not possible to unambiguously assign link polarities - early stages of investigation - complex causal structure 4.5 Stocks and states In systems dynamics terminology: change – described in terms of variations in levels of a system’s stocks ‘stocks’ and ‘state variables’ = different names for same things ‘level’ of stock = ‘size’, ‘magnitude’, ‘value’ of state variable ‘value’ = numerical amount, magnitude, or quantity ex: increase in the value of the state variable = increase in quantity represented by the state variable in question also: “value” = importance or preciousness of something ‘behavior’ of dynamical system = way the levels of its component stocks change over time ‘state descriptions’ - characterize world as sensed = ‘stocks’ ‘process descriptions’ – characterize world as acted upon = ‘flows’ Chapter 5: System dynamics II: Feedback 5.1 Introduction Feedback loops – another fundamental system dynamics concept  Endogenous point of view of system Links concepts of: Control and self-reinforcement Stability and instability Structure and behavior Mutual causality Interdependence Ideas in natural, social and behavioral sciences - feedback thinking is rare in human society, but essential in human ecology ex: Ragweed pollen and hay fever (fig. 5.1) - ragweed needs open soil to establish itself - using broad spectrum herbicides kills other plants (perennials)  open soil  increased ragweed  increased prevalence of allergies (“the ragweed boomerang) – example of reinforcing feedback loop management interventions in social- ecological systems: 1 - must consider the behavior of the system as a whole, not individual parts in isolation 2 – always include unintended outcomes majority – unexpected, undesirable, even catastrophic often delayed – occur at places distant from center of management activity, difficult to identify cause- effect links 5.2 Feedback and endogenous behavior There are just 2 types of feedback: 1) ‘reinforcing’ (‘positive’) feedback loop – amplifies change 2) ‘balancing’ (‘negative’) feedback loop – opposes change ex: Fig. 5.2: causal loop diagrams R = reinforcing, B = balancing Balancing loop – all else being equal, increase in individual’s hunger  increase in discrepancy between actual and desired level of hunger = increase in gap  increase in amount of food eaten  reduction in level of hunger (parallel lines = delayed response - allows eater to over-indulge) - encircled B = balancing feedback loop – this example: works to maintain individual’s hunger at an acceptable level (provided food is available) - always goal seeking - behavior driven by gap between goal state and actual state of system (in interest of clarity, book will sometimes omit goal and gap in drawing influence and causal loop diagrams) - ‘positive’ and ‘negative’ feedback labels can be misleading - do not signal ‘good’ or ‘bad’ feedback – desirability of feedback effect depends on context: ‘positive’ – amplifies change – helpful where you want change, but unhelpful when you don’t want change Importance of focusing on endogenous behavior: 1) draws attention to role feedback plays in behavior of real- world systems Fig. 5.3: real world is not linear, but either reinforcing ( runaway change) or balancing ( resisting change) feedback system 2) provides a way to deal with complexity (2 types): - detail complexity - many variables & possible combinations  challenge: select optimal arrangement from large number of possibilities - dynamic complexity: caused by feedback interactions - counterintuitive, oscillations, overshoot and collapse  policy resistance: efforts to solve problem may give rise to endogenous forces that counteract those efforts - policies that don’t take feedback into account may even exacerbate the target problem ex: antibiotic resistance 3) evidenced by system archetypes = simple generic feedback structures - occur in many guises, many situations - give rise to commonly observed patterns of behavior - “nature’s templates” – reoccur in many fields of knowledge: biology, psychology, family therapy, economics, political science, ecology, management - invariant, cross-disciplinary  foundation for integrative theoretical framework for human ecology 5.3 Basic feedback dynamics 3 fundamental cases: 1) exponential growth 2) goal seeking 3) exponential decay (more cases in chapter 6) 1) Exponential growth (Figs. 5.4, stock and flow diagram): = reinforcing feedback - fractional growth rate – sets speed of growth = ‘gain’ of feedback loop - relates rate of inflow (F ) to stock S(t) in - F = fractional growth rate * S(t) in ‘gain’ - sensitivity of F to changes in S in (Stock S increases by amount determined by fractional growth rate) - influence link from S to F in -> reinforcing feedback loop ex: growth of balance in interest-bearing bank account (interest reinvested, no withdrawals): fractional growth rate = interest rate Fig. 5.5: time-series graphs of exponential growth: - graphs of S(t) and F hine same shape, both depend on fractional growth rate - growth is very slow at first, then speeds up - when S(t) is low, F inll also be low and S(t) will increase only slowly -  S(t)   Fin  faster  S(t)  faster  Fin  S(t) even more - growth continues to accelerate – graphs of S(t) and Finecome even steeper until limit is reached - exponential growth cannot continue indefinitely in a finite world - Fig. 5.6 – China GDP, 1969 - 2011 - limit not yet in sight 2) “Goal seeking” - refers to balancing feedback loops – operate to maintain level of a stock close to a specific target value (Fig. 5.7) gap = goal – S(t)  F =inractional growth rate * (goal – S(t)) = fractional growth rate * gap Fig. 5.7: - influence link from Stock via gap to inflow establishes balancing feedback loop - fractional growth rate – sensitivity of F in changes in gap and thus to changes in S(t) ex: growth of well-established tree: goal = mature size of tree growth rate slows as tree approaches mature size - approaches maximum size asymptotically: grows more & more slowly as gap between actual & eventual mature size decreases Fig. 5.8: time-series: Goal seeking behavior: F in mirrors S(t): big gap between S(t) & goal -> F ingh S(t) increases rapidly as S(t) rises, Finill decrease  S(t) will rise more slowly as S(t) slows down, F grins more slowly  S(t) slows down even more => graphs become more and more horizontal = asymptotic growth - S(t) never reaches its goal; in real world – goal actually reached in finite time, sometimes even surpassed (ex: Fig. 5.9: male baby head circumference, section 6.4: carrying capacity) 3) Exponential decay - special case of goal seeking: initial stock is high, goal is zero - fractional decay rate: sets speed of decay (Fig. 5.10) Fout - fractional decay rate * S(t) - minus sign because outflow is a negative flow: reduces level of stock - large stocks will decay faster than small stocks ex: leakage of water from tank, hole on bottom: - high level – high pressure -> rapid outflow -> water level will drop quickly - as water level drops, pressure at hole reduces, flow slows, water level falls more slowly - water level = 0  water pressure at hole = 0, flow ceases - Fig. 5.11: graphs of Foutand S(t) are mirror images: - when S(t) is high, Foutwill also be high, and S(t) will decrease rapidly - as S(t) falls,outdecreases  S(t) falls more slowly - decay continues to slow, graphs of S(t) and Fout become more and more horizontal as S(t) approaches 0 ex: Fig. 5.12 – radioactivity of Protactinium 5.4 System archetypes = simple generic structures with characteristic behavior patterns ex: exponential growth and decay, limits to growth (sec 6.4), Fixes that Fail archetype (ragweed boomerang (Fig. 5.1); Fig. 5.13) = any situation where there is a basic problem with unwelcome symptoms - individuals/communities try to fix symptoms rather than underlying problem; with delay, fix makes problem worse: Fig. 5.13 – loop B – balancing: - as symptom grows stronger, more of fix is applied  symptom reduced - as symptom decreases, amount of fix is reduced  symptom grows stronger - response delays  oscillation (fig. 6.7) -- loop R - reinforcing: - basic problem, symptom and fix interact in reinforcing loop (ex: fig. 5.14) (discrimination  depression  substance abuse) - extent of symptom depends on extent of problem  as problem gets worse, symptoms worsen  more intensive application of fix  makes problem worse  worsens symptoms  worsens problem more = runaway situation, until natural limit reached Fig. 5.13b, fig. 5.14: At start, problem and symptom at moderate levels Concern about symptoms  moderate application of fix  (delay) reduction of symptom  reduction of application of fix  increase in symptom  increased application of fix == oscillation symptom/fix (loop B) at same time, application of fix (substance abuse)  increased severity of problem (discrimination)  ^ symptom  ^ fix  ^ problem (loop R) - problem more severe  ^ levels of symptom, fix, problem until something catastrophic occurs, or direct actions taken to reduce severity of problem discussion of system archetypes => appreciation of power of endogenous worldview Senge’s archetypes: feedback structures named Limits to Growth, Tragedy of the Commons, Success to the Successful, Fixes that Fail, Accidental Adversaries, Shifting the Burden, Escalation, Drifting Goals, Growth and Underinvestment 5.5 Cross-sector feedback – an invisible force feedback dynamics of social-ecological systems: causal links are cross-disciplinary, thus management actions in one sector can produce significant changes in a second sector, and feedback can occur to undercut aims of original action ex: annual ragweed problem (sec. 5.1, Fig. 5.16) = social subsystem overlapping an ecological subsystem variables of social subsystem – management action of human community variables of ecological subsystem – reaction of plant community Fixes that Fail feedback structure: cross-sector feedback: Identifying increase in perennial vegetation cover as sustainable solution to ragweed problem complex ex: Fig. 5.17: cross-sector feedback in an urban setting: causal structures that link urban planning, global climate change, public health and wellbeing Invisibility of feedback loops: human decision making oversight results in undermining management initiatives, unexpected and unwanted outcomes What contributes to peoples’ inability to see cross-sector feedback structures? - process is not usually noticed and thought about consciously as “feedback”  people not inclined to look for feedback loops - feedback effects delayed by accumulation – stocks take time to fill and drain  long timescales (decades to hundreds of years) - managers/policy makers tend to seek proximal causes – overlooking triggering events – fail to make feedback connections - fragmented management of social-ecological systems sector-based management silos – isolated, do not share info - hide cross-sector feedback loops - feedback structures can be hard to identify, hidden within complicated network of causal links (Fig. 5.18: single feedback loop embedded in moderately complicated causal context) - search for feedback structure – examine behavior-over-time of selected variables; observation of archetype behaviors Identification of dominant cross-sector feedback structures requires collaborations and investigations that mesh the knowledge and mental models of people with widely different worldviews (powerful ideas). Chapter 6: Systems and sustainability 6.1 Introduction Sustainable system = a system that continues to function adequately throughout time Question: meaning of "function adequately”: - different people  different ideas ex: sustainable growth vs. sustainable development sustainable growth: 1 - economic growth is necessary, despite planetary limits 2 - society can use new technologies to "do more with less": operate within planetary limits despite continued growth in consumption sustainable development: 1 - achievements through technology are limited 2 - continued growth is not possible on a finite planet - human consumption of energy and matter must eventually be stabilized at rates that can be accommodated indefinitely by the planet - social sustainability: important practical ethical and equity issues - cannot be solved by techno- fixes or continued economic growth Comprehensive approach to sustainability: - uses "operational definition" of sustainability = what a society has to DO to be sustainable = how society must act to influence rates of critical social and biophysical processes  sustainability = flow management = controlling rates of processes that alter resource and pollution


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