Download Communities I Intro

Communities I
Definitions and Components
I. History
A. Plant Ecology
Concern with community structure
1. What species are present?
2. What species are dominant?
3. What are the characteristic combinations or groupings of species in a community?
4. Methods in plant community ecology
i. Pattern analysis
ii. Gradient analysis
iii. Ordination
B. Animal Ecology
1. Trophic structure of communities (Elton)
2. Energy flow through communities (Lindeman)
3. Processes
i. competition
ii. predation
iii. parasitism, disease, symbiosis etc.
II Definition(s) of a community
A. Minimum
‘All populations living in an area”
B. Bells and whistles
1) Groups of species populations
2) Living in a specific area
3) That interact with each other
4) In defined and regulated ways
III Features of communities
A. Species composition
1) Number of species
2) Species list
3) At the community level populations are the building blocks
B. Diversity
1) Evenness
2) Diversity indices
3) Influences on diversity
a. Latitude
b. Area
C. Trophic structure
1) ‘Real organisms’ really eating each other
2) Actual food webs
D. Dynamics of communities
1) Succession
a. the ‘climax community concept
b. primary succession
c. secondary succession
2) Cyclic
3) Stochastic
a. scale
b. the “intermediate Disturbance Hypothesis’
IV The “Balance of Nature”
A.What is balance
C. What is balanced?
Diamond, J. and T. J. Case. 1986 Community Ecology Harper & Row.
Lewin, R. 1989. Sources and sinks complicate ecology Sci. 243: 477- 478.
Pimm, S. L. 1991. The Balance of Nature? Univ. Chicago Press
Tansley, A. G. The early history of modern plant ecology in Britain. J. Ecol. 35: 130 – 137.
Wilson, D. S. 1997. Biological communities as functionally organized units. Ecol. 78: 2018 –
2024.