COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302 Biol 302
COMMUNITY AND ECOSYSTEM BIOLOGY Biology 302 Biol 302 Introduction 1
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FIELDWORK IN DANGEROUS PLACES Biol 302 Introduction 6
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THIRD YEAR ECOLOGY FALL Population ecology (BIOL 303) SPRING Community ecology (& ecosystems) • Community structure • Succession • Productivity • Biodiversity • Nutrient cycling etc. Biol 302 Introduction 11
COMMUNITY STRUCTURE Biol 302 Introduction 12
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 Biol 302 Introduction 13
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; p 464 Biol 302 Introduction 14
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 Introduction 15
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 Introduction 16
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 Introduction 17
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? Biol 302 Introduction 18
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 p 395 Fig. 20. 6) · at Lytton on the Hope/Cache Creek Rd. 3. Or, do communities generally change along some environmental gradient? Biol 302 Introduction 19
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 p 395 Fig. 20. 6) · at Lytton on the Hope/Cache Creek Rd. 3. Or, do communities generally change along some environmental gradient? Biol 302 Introduction 20
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WORLD VEGETATION MAP Biol 302 Introduction 22
Krebs Fig. 20. 6; p 395 Biol 302 Introduction 23
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 p 395 Fig. 20. 6) · at Lytton on the Hope/Cache Creek Rd. 3. Or, do communities generally change Biol 302 along some environmental gradient? 24 Introduction
Alternative models for vegetation organization along an environmental gradient (Krebs Fig. 20. 5; p 394) Organismic concept Individualistic concept Biol 302 Introduction Resource partitioning model with several layers 25
Alternative models for vegetation organization along an environmental gradient (Krebs Fig. 20. 5; p 394) Organismic concept Individualistic concept Biol 302 Introduction Resource partitioning model with several layers 26
Alternative models for vegetation organization along an environmental gradient (Krebs Fig. 20. 5; p 394) Organismic concept Individualistic concept Biol 302 Introduction Resource partitioning model with several layers 27
Alternative models for vegetation organization along an environmental gradient (Krebs Fig. 20. 5; p 394) Organismic concept Individualistic concept Biol 302 Introduction Resource partitioning model with several layers 28
Arthur Tansley 1871 - 1955 Frederic Clements 1874 Biol 302 1945 Introduction Henry Gleason 1882 - 1975 29
CLEMENTS (1916, 1928) ORGANISMIC CONCEPT • Closely integrated system with birth, growth, maturation, development, death – Homeostasis – Repair Biol 302 Introduction GLEASON (1926, 1927) INDIVIDUALISTIC CONCEPT • Random assemblages of species that happen to have same growth requirements – They may interact 30
CLEMENTS (1916, 1928) ORGANISMIC CONCEPT • Predictable development • Climax – Predictable, stable – Convergence to Biol 302 sameness Introduction GLEASON (1926, 1927) INDIVIDUALISTIC CONCEPT • Randomness of seed dispersal, establishment etc. • Climax – Disturbance prevents it 31 – Different end points
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 Introduction 32
Krebs Fig. 7. 9; p 95 Biol 302 Introduction 33
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