Biol 302 Introduction1 COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302.

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COMMUNITY AND COMMUNITY AND ECOSYSTEM BIOLOGYECOSYSTEM BIOLOGY

Biology 302Biology 302

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FIELDWORK IN DANGEROUS PLACESFIELDWORK IN DANGEROUS PLACES

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Who’se de boss?

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THIRD YEAR ECOLOGYTHIRD YEAR ECOLOGY

FALL Population ecology (BIOL 303)

SPRING Community ecology (& ecosystems)

• Community structure

• Succession

• Productivity

• Biodiversity

• Nutrient cycling etc.

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COMMUNITY COMMUNITY STRUCTURESTRUCTURE

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READINGS for this lecture series: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 ECOLOGY & COMMUNITY STRUCTURECOMMUNITY 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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1. 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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1. 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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1. 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 COMMUNITYTHE NATURE OF THE COMMUNITY

Krebs: general read of cpt. 20Krebs: 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

Individualistic concept

Resource partitioning model

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

Individualistic concept

Resource partitioning model

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

Individualistic concept

Resource partitioning model

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

Individualistic concept

Resource partitioning model

Resource partitioning model with several layers

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Frederic Clements 1874 - 1945

Henry Gleason 1882 - 1975

Arthur Tansley 1871 - 1955

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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:THE MODERN SYNTHESIS:

• quite close to Gleason’s 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