ECOSYSTEM DYNAMICS KGA172 Space, Place and Nature Presented by Associate Professor Elaine Stratford Semester 2

LOOKING BACK, LOOKING FORWARD Part 1

Revising Lecture Define ecosystem. Explain its etymology. In terms of helping us understand nature, why might it matter that ecosystem has the same origins [derivation] as household – from the Greek oikos? 2.How does Eugene Odum specifically describe ecology and in what ways is the idea of exchange important in that description? 3.What is meant by ‘open system’ in relation to ecosystems? Can you draw such a system accounting for abiotic and biotic elements? 4.How would you explain to someone completely unfamiliar with the subject the links between and among biomes, limiting factors and ecotones? Give examples. 5.What are the main distinctions between gross and net primary production? What are the main determinants of those distinctions? 6.Describe in fulsome detail the components and relationships one might find along a terrestrial and an aquatic food chain. What do food chains reveal about ecosystems as integrated phenomena? Auguste Rodin, A man thinking

Learning Objectives Module 2 Lecture 3 Be able to – describe and explain interactions between species the meaning of the concepts of disturbance and succession – describe and critique classical succession theory contemporary understanding of vegetation dynamics – make links between these ideas and the larger question of how we understand nature KGA172 Know and be able to (a) employ basic geographical terminology and concepts, (b) find, evaluate, analyse and reference appropriate literature, (c) contribute to debates about development and sustainability Comprehend and be able to explain spatial patterns, generate basic maps, field sketches and graphs, and communicate in written and graphical forms Apply key academic skills and (a) engage in critical thinking, discussion and listening, and in self-reflection and reflection upon the viewpoints of others and (b) research, plan and conduct fieldwork to collect data Analyse and interpret basic spatial, numerical and qualitative information Synthesize and integrate knowledge of social and Earth systems

Textbook Reading Continue to mine Bergman and Renwick (2008) Critical reading 1. What is the author’s purpose? 2. What key questions or problems does the author raise? 3. What information, data and evidence does the author present? 4. What key concepts does the author use to organize this information, this evidence? 5. What key conclusions is the author coming to? Are those conclusions justified? 6. What are the author’s primary assumptions? 7. What viewpoints is the author writing from? 8. What are the implications of the author’s reasoning? [from Foundation for Critical Thinking]Foundation for Critical Thinking A man in a library

INTERACTION Part 2

Basic Types of 2-species interaction InteractionSpecies 1Species 2 Neutral00 Competition__ Consumption+_ Commensalism+0 Mutualism++

Competition

Consumption

Commensalism

Mutualism

COMPETITION Part 3

Exploitative Competition Competition for light, water and nutrients

(Greg Unwin)

Competition for light R.E. Ricklefs (1990) Ecology. 3 rd ed. Freeman & Co.

Competition for carbohydrates and/or protein Single visits to flowers by bumblebees resulted in less than 10% as many seeds as did single visits by swift parrots Hingston et al. (2004) Australian Journal of Botany 52,

Pre-emptive competition Dominance: first grab on resources (Chris Servheen)

Overgrowth competition pre-emptive competition for light (+ other resources)

(Greg Unwin)

Interference competition - chemical interference (allelopathy) (facultyengineering.ucdavis.edu) (R.E. Ricklefs (1990) Ecology. 3rd ed. Freeman & Co.)

Territorial interference (science.howstuffworks.com) (

Principle of competitive exclusion (Paul Colinvaux (1993) Ecology 2. Wiley).

CONSUMPTION Part 4

predators kill prey, usually smaller than themselves parasites feed off other organisms, usually larger than themselves, usually without killing them grazers and browsers eat part or all of primary consumers consumers can reduce populations to below carrying capacity Predation, parasitism and grazing (Ricklefs, 1990, Ecology)

(Colinvaux, 1993, Ecology 2) Consumer-prey relationships can result in sharp population fluctuations

COMMENSALISM AND MUTUALISM Part 5

Commensalism (

Mutualism (symbiosis) fungal (mycorrhizal fungi, lichen) bacterial (nitrogen-fixing) pollination and co-evolution facilitation of predation of parasites or grazers the dangers of specific interdependence (P. and E. Grey (2001) Fungi down under ( (

DISTURBANCE AND SUCCESSION Part 6

Disturbance – an environmental event (or events) that results in a change in biomass or the resources that support species at a rate that is faster than normal change Exogenous [external] disturbance … allogenic disturbance response

Endogenous [internal] disturbance … autogenic succession response

Exogenous or endogenous?

Fire – exogenous and endogenous disturbance (Greg Unwin)

Colinvaux Ecology 2 Traditional succession theory (Clements and Tansley)

Edaphic and flood disclimax

Primary and secondary succession

(G L Unwin)

Relay floristics (Bowman Australian Rainforests

(Greg Unwin)

Cyclic succession (Greg Unwin)

(Colinvaux Ecology 2) Some theoretical generalisations Ruderals (R strategists) to Competitors to Stress tolerators (K strategists)

(Colinvaux Ecology 2) Productivity trends during succession