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ECOSYSTEM DYNAMICS
KGA172 Space, Place and Nature
Presented by Associate Professor Elaine Stratford
Semester 2
Part 1
LOOKING BACK, LOOKING
FORWARD
Revising Lecture 2.2
1. 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
KGA172
•
•
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
•
•
•
•
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]
A man in a library
Part 2
INTERACTION
Basic Types of 2-species interaction
Interaction
Species 1
Species 2
Neutral
0
0
Competition
_
_
Consumption
+
_
Commensalism
+
0
Mutualism
+
+
Competition
Consumption
Commensalism
Mutualism
Part 3
COMPETITION
Exploitative
Competition
Competition
for light, water
and nutrients
(Greg Unwin)
Competition for light
R.E. Ricklefs (1990) Ecology. 3rd 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, 371-379
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)
(R.E. Ricklefs (1990) Ecology. 3rd ed. Freeman & Co.)
(facultyengineering.ucdavis.edu)
Territorial interference
(www.wolaver.org)
(science.howstuffworks.com)
Principle of competitive exclusion
(Paul Colinvaux (1993) Ecology 2. Wiley).
Part 4
CONSUMPTION
• predators kill prey,
usually smaller than
themselves
Predation, parasitism
and grazing
• 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
(Ricklefs, 1990, Ecology)
Consumer-prey relationships can result in sharp
population fluctuations
(Colinvaux, 1993, Ecology 2)
Part 5
COMMENSALISM AND MUTUALISM
Commensalism
www.thefishsite.com
(www.tas.gov.au)
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
(www.myrmecos.net)
(www.anu.edu.au)
Part 6
DISTURBANCE AND SUCCESSION
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)
Traditional succession theory (Clements and Tansley)
Colinvaux Ecology 2
Edaphic and flood disclimax
Primary
and
secondary
succession
(G L Unwin)
Relay floristics
(Bowman Australian Rainforests
(Greg Unwin)
Cyclic succession
(Greg Unwin)
Some theoretical generalisations
Ruderals (R strategists) to Competitors to
Stress tolerators (K strategists)
(Colinvaux Ecology 2)
Productivity trends during
succession
(Colinvaux Ecology 2)