Midterm review BSC 417

Outline Major points Question formats Study tips

Major topics Theory and purpose of environmental modeling Systems thinking & why it is important Basic STELLA nomenclature & structures Mathematical relationships – All types covered in detail Feedback loops, synergy Sensitivity analysis Case analysis

Concepts/things you should know Dimensional analysis and how it relates to environmental modeling – Working with units The basic layout (STELLA) of each behavior pattern Difference equations Rate equations Key features of examples from homework/class discussions Vocabulary from text

Behavior patterns Linear growth/decay Exponential growth/decay Logistic growth Overshoot and collapse Oscillation Know equations, recognize patterns, know how patterns are influenced by the inputs, know steady state conditions Be able to cite (and describe in detail) examples for each

Linear Rate equation: dR(t)/dt = k Solution: R(t) = R0 + kt K is the slope K = sum of inflows – sum of outflows

Exponential Rate equation: dR(t)/dt = kR(t) Solution: R(t) = R0 x e kt K = inflow rate – outflow rate

Logistic Rate equation: dR(t)/dt = k(t) x R(t) Solution: R(t) = cc/(1+Ae -unconst.gr.rt x t ) K(t) = unconstrained growth rate x (1-(R(t)/cc) Cc = carrying capacity A = (carrying capacity – R0)/R0

Overshoot and collapse Rate equation (population): dP(t)/dt = ((B-(1- R(t)/R0)) x P(t) Rate equation (resource): dR(t)/dt = -C x P(t) P(t) = population at time = t R(t) = resource reservoir at time = t B = per capita birth rate in population per unit time C = per capita consumption rate of resource per unit time R0 = initial value in reservoir Solution to rate equations: depends – system of differential equations

Oscillation Rate equation (consumer): dC(t)/dt = G x R(t) - D Rate equation (resource): dR(t)/dt = W – Q x C(t) G = consumer growth rate D = consumer deaths per unit time W = resource growth per unit time Q = resource consumption rate Equilibrium oscillation for the consumer: W/Q Equilibrium oscillation for the resource: D/G Solution to rate equations: depends – system of differential equations

Problem types you should be prepared to face Short answer Multiple choice Simple calculations 1-2 questions involving application of systems thinking to a hypothetical problem – Basic model set up and analysis

Study tips Straightforward assessment of your understanding of the basics of modeling – No surprises, but comprehensive Application of those basics to hypothetical problems Everything in Chapters 1-3 in text Class notes and homework

About the exam In room 229, Biology Closed book/notes Bring a calculator One hour, 15 minutes to complete

Questions?