ESM 221 Lecture 5 Monday, April 17, 2017 Core concepts from the reading Discussion Models to address these Hypotheses, models Population dynamics Variability Density dependent factors Extinction/ irreversible loss of biodiversity Biodiversity loss – strong sustainability would avoid this because it can never be recovered or substituted

Key concepts from the text Should see some of this in Biology courses also

Population dynamics Be able to define these terms: Population size Population distributions Be able to define these terms: Population size Population density Population distribution Clumped Uniform Random Sex Ratio Age Structure Why do these matter to population growth & stability?

Keystone species Create favorable environmental conditions for other species Impact beyond just their community production rate (i.e. growth rate) Examples: Beavers Elephants Alligators

Succession Predictable pattern of plants in a community that varies over time Earlier species “replaced” with later species Prepare the environment for them to be successful Primary – on rock Secondary – disturbance eliminates plants but leaves soil

Human population dynamics Factors that control growth rate Demographic transition Demographic trap Multiple interacting factors – complex behavior http://web.pdx.edu/~rueterj/courses/objects/demographic-transition.html Malthus prediction Importance of innovation (Schumpeter) I = PAT

5-1 Draw the classical “Demographic Transition”

Discussion What can environmental science and science-based policy say about human population and control? Why is the Malthusian limit concept so important? Does innovation in agriculture really solve the problem of impact from high populations? What are some of the alternative models or paths for sustainable human society?

Population dynamics and management 5-2 Draw logistic growth curves (N vs. time) Low r, low K Low r, high K High r, low K High r, high K

How do we use models and hypotheses http//web.pdx.edu/~rueterj/courses/objects/models-hypotheses.html