COMMUNITY AND ECOSYSTEM BIOLOGY

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COMMUNITY AND ECOSYSTEM BIOLOGY

• Biology 302

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FIELDWORK IN DANGEROUS PLACES
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• THIRD YEAR ECOLOGY
• FALL Population ecology (BIOL 303)
• SPRING Community ecology ( ecosystems)
• Community structure
• Succession
• Productivity
• Biodiversity
• Nutrient cycling etc.

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COMMUNITY STRUCTURE
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READINGS for this lecture series KREBS cpt 20.
The Nature of the Community KREBS cpt 12. Pp
190 - 199 KREBS cpt 23. Predation Competition
(selected) KREBS cpt 24. Disturbance Pp 485 - 501
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COMMUNITY ECOLOGY COMMUNITY STRUCTURE   Doing
science at the community level presents daunting
problems because data bases may be enormous and
complex.        
Krebs Fig 23.4 p464
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• FIRST STEP is to DESCRIBE by searching for
  PATTERNS in community structure and composition.
• recognition of patterns is a big first step is
  all sciences.

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• FIRST STEP is to DESCRIBE by searching for
  PATTERNS in community structure and composition.
• recognition of patterns is a big first step is
  all sciences.

2. Recognition of pattern leads to formulation
of HYPOTHESES ABOUT THE CAUSES of the pattern

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• FIRST STEP is to DESCRIBE by searching for
  PATTERNS in community structure and composition.
• recognition of patterns is a big first step is
  all sciences.

2. Recognition of pattern leads to formulation of
HYPOTHESES ABOUT THE CAUSES of the pattern
3. Hypothesis testing by doing EXPERIMENTS or
making further observations.
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THE NATURE OF THE COMMUNITY Krebs general read
of cpt. 20
1. What is a community?
2. How to describe a community?
3. Does a community have boundaries?
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1. Is the community real?
abstraction?   2. Can you tell when you leave one
community and enter another? prairie and
deciduous forest of eastern USA (world map.
Krebs p395 Fig. 20.6) at Lytton on the
Hope/Cache Creek Rd.   3. Or, do communities
generally change along some environmental
gradient?
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1. Is the community real?
abstraction?   2. Can you tell when you leave one
community and enter another? prairie and
deciduous forest of eastern USA (world map.
Krebs p395 Fig. 20.6) at Lytton on the
Hope/Cache Creek Rd.   3. Or, do communities
generally change along some environmental
gradient?
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WORLD VEGETATION MAP
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Krebs Fig. 20.6 p395
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1. Is the community real?
abstraction?   2. Can you tell when you leave one
community and enter another? prairie and
deciduous forest of eastern USA (world map.
Krebs p395 Fig. 20.6) at Lytton on the
Hope/Cache Creek Rd.   3. Or, do communities
generally change along some environmental
gradient?
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Alternative models for vegetation organization
along an environmental gradient (Krebs Fig. 20.5
p394)
Organismic concept
Resource partitioning model
Individualistic concept
Resource partitioning model with several layers
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Alternative models for vegetation organization
along an environmental gradient (Krebs Fig. 20.5
p394)
Organismic concept
Resource partitioning model
Individualistic concept
Resource partitioning model with several layers
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Alternative models for vegetation organization
along an environmental gradient (Krebs Fig. 20.5
p394)
Organismic concept
Resource partitioning model
Individualistic concept
Resource partitioning model with several layers
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Alternative models for vegetation organization
along an environmental gradient (Krebs Fig. 20.5
p394)
Organismic concept
Resource partitioning model
Individualistic concept
Resource partitioning model with several layers
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Arthur Tansley 1871 - 1955
Frederic Clements 1874 - 1945
Henry Gleason 1882 - 1975
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CLEMENTS (1916, 1928) ORGANISMIC CONCEPT GLEASON (1926, 1927) INDIVIDUALISTIC CONCEPT
Closely integrated system with birth, growth, maturation, development, death Homeostasis Repair Random assemblages of species that happen to have same growth requirements They may interact
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CLEMENTS (1916, 1928) ORGANISMIC CONCEPT GLEASON (1926, 1927) INDIVIDUALISTIC CONCEPT
Predictable development Climax Predictable, stable Convergence to sameness Randomness of seed dispersal, establishment etc. Climax Disturbance prevents it Different end points
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• THE MODERN SYNTHESIS
• quite close to Gleasons view of community
  structure and dynamics.
• However, we do get some sharp boundaries
• Environmental (Lytton)
• Soils
• Serpentine soils of northern Oregon
• Moisture
• Competition

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Krebs Fig. 7.9 p95