Biol 302 Introduction1 COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302

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Biol 302 Introduction11 THIRD YEAR ECOLOGY FALLPopulation ecology (BIOL 303) SPRINGCommunity ecology (& ecosystems) Community structure Succession Productivity Biodiversity Nutrient cycling etc.

Biol 302 Introduction12 COMMUNITY STRUCTURE

Biol 302 Introduction13 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 Introduction14 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

Biol 302 Introduction15 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 Introduction16 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 Introduction17 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 Introduction18 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 Introduction19 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 Introduction20 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 Introduction22 WORLD VEGETATION MAP

Biol 302 Introduction23 Krebs Fig. 20.6; p395

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 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 Introduction26 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 Introduction27 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 Introduction28 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 Introduction29 Frederic Clements Henry Gleason Arthur Tansley

Biol 302 Introduction30 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 Introduction31 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 Introduction32 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 Introduction33 Krebs Fig. 7.9; p95