1. Biol 302 Introduction1 COMMUNITY STRUCTURE (cpt. 20) Biological structure: composition and abundance temporal changes (succession) relationships between species (interactions, dominance, Keystone’s etc.)

2. Biol 302 Introduction2 COMMUNITY STRUCTURE (cpt. 20) Biological structure determines how the community functions: Productivity Trophic levels Nutrient cycling etc.

3. Biol 302 Introduction3 VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE: 1.LIFE FORMS 2.HORIZONTAL STRUCTURE 3.VERTICAL STRUCTURE

4. Biol 302 Introduction4 VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE: 1.LIFE FORMS 2.HORIZONTAL STRUCTURE 3.VERTICAL STRUCTURE

5. Biol 302 Introduction5 LIFE FORMS In the 1920’s, a Danish botanist, Raunkiaer, provided a classification (1934) based on the position of the perennating tissue (buds, bulbs, seeds etc.). This can be used to characterize a community because certain life forms are dominant in certain environments.

6. Biol 302 Introduction6 Christen C. Raunkiaer 1860-1938

7. Biol 302 Introduction7 RAUNKIAER’S LIFE FORMS Phanerophytes (trees) Chamaephytes (shrubs) Hemicryptophytes (perennial herbs) Cryptophytes (bulbs etc.) Therophytes (annuals)

8. Biol 302 Introduction8 The great biomes of the world show a remarkable degree of convergence in their “physical appearance”, despite wide variation in the species involved. It is difficult to distinguish between: chaparral of California and Chile nutrient-poor heaths of S. Africa and Australia Arctic and Antarctic fell fields rain forest in Brazil and SE Asia These divergences are vivid testimony of the importance of climatic factors as agents of natural selection.

9. Biol 302 Introduction9 LIFE FORMS IN DIFFERENT BIOMES

10. Biol 302 Introduction10 Phanero phytes (trees) Chamae phytes (shrubs) Hemicrypto phytes (perennial herbs) Crypto phytes (bulbs etc.) Thero phytes (annuals) World or Normal 46926613 LATITUDE Tropical rain forest 9622 Sub tropical forest 65172510 Warm temperate forest 5492494 Cold temperature forest 101754127 Tundra 12260152

11. Biol 302 Introduction11 Phanero phytes (trees) Chamae phytes (shrubs) Hemicrypto phytes (perennial herbs) Crypto phytes (bulbs etc.) Thero phytes (annuals) World or Normal 46926613 MOISTURE Mesophytic forest 34833232 Oak woodland 30233656 Dry grassland 112631014 Semi-desert 591427 Desert 417673

12. Biol 302 Introduction12 SEVERAL POINTS EMERGE FROM THESE COMPARISONS SEVERAL POINTS EMERGE FROM THESE COMPARISONS: 1.Where there is no unfavorable season, or the less favorable is not too severe, then tree-like plants (phanerophytes) predominate in the flora as a whole. 2.Under ideal growth conditions (constant warmth and moisture) trees are dominant, simply because the competitive spoils go to the tallest individuals. 3.In less equable climates, trees may still be the dominant plants in most communities, but the flora as a whole is made up predominantly of other life forms (hemicryptophytes in northern temperate latitudes)

13. Biol 302 Introduction13 Where the summer is arid (as in deserts and Mediterranean climates), there is a preponderance of annual plants (which avoid drought by passing the dry period as dormant seeds) and geophytes (which avoid drought by die-back of their above-ground parts and survive by means of underground storage organs). Other desert plants that tolerate drought may appear to be dominant if the vegetation is surveyed during the dry season (xerophytic shrubs and stem succulents) 4.Where the summer is arid (as in deserts and Mediterranean climates), there is a preponderance of annual plants (which avoid drought by passing the dry period as dormant seeds) and geophytes (which avoid drought by die-back of their above-ground parts and survive by means of underground storage organs). Other desert plants that tolerate drought may appear to be dominant if the vegetation is surveyed during the dry season (xerophytic shrubs and stem succulents)

14. Biol 302 Introduction14 5. Where extreme cold and exposure characterize the unfavorable season, there is a shift towards cushion-forming plants and other species whose buds are held close to the ground surface (chamaephytes). Many Arctic plants have their perennating buds protected by the dead leaf-bases of last year's shoots, because both the exposed aerial environment and the frozen soil are extremely inhospitable conditions for bud survival.

15. Biol 302 Introduction15 VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE: 1.LIFE FORMS 2.HORIZONTAL STRUCTURE 3.VERTICAL STRUCTURE

16. Biol 302 Introduction16 HORIZONTAL STRUCTURE HORIZONTAL STRUCTURE: 1.Random Probably never occurs 2.Regular or Systematic Plantations of crops Behavioural interactions 3.Aggregated or Clumped

17. Biol 302 Introduction17 HORIZONTAL STRUCTURE: 1.Random Probably never occurs 2.Regular or Systematic Plantations of crops Behavioural interactions 3.Aggregated or Clumped

18. Biol 302 Introduction18 RANDOM ARRANGEMENT

19. Biol 302 Introduction19 HORIZONTAL STRUCTURE: 1.Random Probably never occurs 2.Regular or Systematic Plantations of crops Behavioural interactions 3.Aggregated or Clumped

20. Biol 302 Introduction20 REGULAR [OR SYSTEMATIC] ARRANGEMENT ARRANGEMENT

21. Biol 302 Introduction21 REGULAR, OR SYSTEMATIC, ARRANGEMENT

22. Biol 302 Introduction22 HORIZONTAL STRUCTURE: 1.Random Probably never occurs 2.Regular or Systematic Plantations of crops Behavioural interactions 3.Aggregated or Clumped

23. Biol 302 Introduction23 AGGREGATED: ants and termites fish and phytoplankton plants distribution from parent environmental heterogeneity species interactions

24. Biol 302 Introduction24 AGGREGATED: ants and termites fish and phytoplankton plants distribution from parent environmental heterogeneity species interactions

25. Biol 302 Introduction25 AGGREGATED: ants and termites fish and phytoplankton plants distribution from parent environmental heterogeneity species interactions

26. Biol 302 Introduction26 Solidago canadensis Solidago nemoralis

27. Biol 302 Introduction27 Buttercup (Ranunculus sp.)

28. Biol 302 Introduction28 Bullrush Cattail

29. Biol 302 Introduction29 Krebs Fig. 7.9; p94,95,137 Chthamalus Balanus

30. Biol 302 Introduction30 VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE VARIOUS WAYS TO DESCRIBE COMMUNITY STRUCTURE: 1.LIFE FORMS 2.HORIZONTAL STRUCTURE 3.VERTICAL STRUCTURE

31. Biol 302 Introduction31 VERTICAL STRUCTURE: Forest (usually associated with light diminution) Warblers in a coniferous forest Aquatic systems Soil layers Root systems

32. Biol 302 Introduction32

33. Biol 302 Introduction33 WARBLERS (Krebs Fig. 12.15; p193)

34. Biol 302 Introduction34 (Krebs Fig. 12.15; p193)

35. Biol 302 Introduction35

36. Biol 302 Introduction36