Biol 302 Introduction1 COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302

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7 FIELDWORK IN DANGEROUS PLACES

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Biol 302 Introduction14 Who’se de boss?

Biol 302 Introduction15 THIRD YEAR ECOLOGY FALLPopulation ecology (BIOL 303) SPRINGCommunity ecology (& ecosystems) Community structure Succession Productivity Biodiversity Nutrient cycling etc.

Biol 302 Introduction16 COMMUNITY STRUCTURE

Biol 302 Introduction17 READINGS for this lecture series: KREBS cpt 20. The Nature of the Community KREBS cpt 12.Pp KREBS cpt 23. Predation & Competition (selected) KREBS cpt 24.Disturbance Pp

Biol 302 Introduction18 COMMUNITY ECOLOGY & COMMUNITY STRUCTURE 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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Biol 302 Introduction20 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.

Biol 302 Introduction21 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

Biol 302 Introduction22 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.

Biol 302 Introduction23 THE NATURE OF THE COMMUNITY Krebs: general read of cpt What is a community? 2. How to describe a community? 3. Does a community have boundaries?

Biol 302 Introduction24 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?

Biol 302 Introduction25 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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Biol 302 Introduction27 WORLD VEGETATION MAP

Biol 302 Introduction28 Krebs Fig. 20.6; p395

Biol 302 Introduction29 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?

Biol 302 Introduction30 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

Biol 302 Introduction31 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

Biol 302 Introduction32 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

Biol 302 Introduction33 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

Biol 302 Introduction34 Frederic Clements Henry Gleason Arthur Tansley

Biol 302 Introduction35 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

Biol 302 Introduction36 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

Biol 302 Introduction37 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

Biol 302 Introduction38 Krebs Fig. 7.9; p95