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Chap.28 Community Development

Chap.28 Community Development. Ecology 2000. Community Development. 28.1 succession follows an orderly pattern of species replacements. 28.2 Primary succession develops in habitats newly exposed to colonization by plants and animals.

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Chap.28 Community Development

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  1. Chap.28 Community Development Ecology 2000

  2. Community Development • 28.1 succession follows an orderly pattern of species replacements. • 28.2 Primary succession develops in habitats newly exposed to colonization by plants and animals. • 28.3 The intensity and extent of disturbance influence the pattern of secondary succession. Ecology 2000

  3. 28.4 Succession results from variation in the ability of organisms to colonize disturbed areas and from changes in the environment following the establishment of new species. • 28.5 Succession in old fields and glacial areas illustrates the development of the sere. • 28.6 Analytical models of succession are based on transitions from one successional stage to the next. • 28.7 The character of the climax is determined by local conditions. Ecology 2000

  4. 28.1 succession follows an orderly pattern of species replacements. • Primary succession and secondary succession • autogenic succession and allogenic succession • climax and seres • continuum index: (Fig. 28-4) Ecology 2000

  5. Fig. 28-1 Stages of succession leading to an oak-horneam forest in southern Poland. • (a) the time just after clear-cutting Ecology 2000

  6. (b) after 7 years. Fig. 28-1 Stages of succession leading to an oak-horneam forest in southern Poland. Ecology 2000

  7. (c) After 15 years Fig. 28-1 Stages of succession leading to an oak-horneam forest in southern Poland. Ecology 2000

  8. (d) after 30 years Fig. 28-1 Stages of succession leading to an oak-horneam forest in southern Poland. Ecology 2000

  9. (e) after 95 years Fig. 28-1 Stages of succession leading to an oak-horneam forest in southern Poland. Ecology 2000

  10. (f) after 150 years Fig. 28-1 Stages of succession leading to an oak-horneam forest in southern Poland. Ecology 2000

  11. Fig. 28-2 An old field on the Piedmont of North Carolina. Such habitats develop after abandonment of agricultural land. Ecology 2000

  12. Fig. 28-3 Initial stages of plant succession on sand dunes along the coast of Maryland. (a) Beach grass. Ecology 2000

  13. Fig. 28-3 Initial stages of plant succession on sand dunes along the coast of Maryland. (b) Invasion back Ecology 2000

  14. Fig. 28-4 Relative importance of several tree species in forest communities, arranged along a continuum index. Soil moisture, exchangeable calcium, and pH increase toward the right of the continuum index. Ecology 2000

  15. 28.2 Primary succession develops in habitats newly exposed to colonization by plants and animals. • 冰河退去，或是火山爆發過後，都可有新生地。新生地的生物群落之發展，就稱為primary succession。 • 早期就進入的生物物種，即稱為 pioneer species。 Ecology 2000

  16. 28.3 The intensity and extent of disturbance influence the pattern of secondary succession. • Physical disturbance and biological disturbance • Disturbed sites are colonized from three sources. • 1. The area surrounding the disturbance. • 2. Pools of dispersants. • 3. The buried seeds or eggs (原本存在). Ecology 2000

  17. Succession in Marine Epifaunal habitats • Keough investigated the colonization of artificially created patches, ranging in size from 25 to 2,500 cm2, by various subtidal encrusting invertebrates that grow on hard surfaces. • The major epifaunal taxa vary considerably in their colonizing abilities and competitive abilities, which are generally inversely related (Table 28-1) Ecology 2000

  18. Succession in Marine Epifaunal habitats Ecology 2000

  19. Bryozoans and polychaetes are disturbance-adapted species, what botanists call weeds. • They get into open patches quickly, mature and produce offspring at an early age, and then often are eliminated by more slowly colonizing but superior competitors. • Such weedy species require frequent disturbances to stay in the system. Ecology 2000

  20. Succession in rocky intertidal algal communities • Rabbits rarely feed far from the cover of brush or trees to avoid being seen by predators far from safety. • Limpets similarly do not venture far from the safety of mussel beds to feed on algae. • Because this behavior limits their foraging range (Fig. 28-5), densities of limpets in the small patches exceeded those in the large patches. Ecology 2000

  21. Fig. 28-5 A natural cleared patch in a bed of mussels. The patch about 1 m across and has been colonized by a heavy growth of the green alga. Ecology 2000

  22. Succession after disturbance by fire • The intensity of a fire is determined by a number of factors, including the types, amount, and location of available fuel, moisture conditions, and the direction and strength of winds. • A fire in the crown of stands of the trees opens the cones, releasing the seeds, a phenomenon called serotiny. Ecology 2000

  23. 28.4 Succession results from variation in the ability of organisms to colonize disturbed areas and from changes in the environment following the establishment of new species. • Two factors interact to determine the position of a species in a sere: • 1. the life history characteristics of the species and • 2. the nature of the changes that occur through the course of succession. Ecology 2000

  24. 1. Life history features and succession Ecology 2000

  25. Fig. 28-6 Relationship between seed weight and mortality of seedlings after 3 months under shaded conditions. • The survival of seedlings in shade is directly related to seed weight. Ecology 2000

  26. 2. Effects of species on one another • Connell and Slatyer (1977) suggested three mechanisms by which the presence of one species affects the others. • (1) Facilitation • (2) Inhibition • (3) Tolerance Ecology 2000

  27. 28.5 Succession in old fields and glacial areas illustrates the development of the sere. • Three mechanisms and the life history characteristics of species are important in every sere. • Succession in an old field (Fig. 28-8) (Fig. 28-9) • Succession in an area of glacial retreat (Fig. 28-10) (Fig. 28-11) Ecology 2000

  28. Fig. 28-8 Schematic summary of the life histories of five early successional species of plants that colonize abandoned fields in North Carolina. Ecology 2000

  29. Fig. 28-9 Growth response of aster (dry weight) and soil water content as a function of distance from broomsedge plants in an old field. Ecology 2000

  30. Fig. 28-10 A valley exposed by a receding glacier, visible at the top center, in North Tongass National Forest, Alaska. Ecology 2000

  31. Succession in an area of glacial retreat • Four different successional stages have been identified in the glacier area. • 1. A pioneer stage, consisting of blue-green algal mats, lichens, liverworts, some forbs, and a scattering of willows, cottonwoods, and spruce, along with a mat-forming dwarf shrub that is capable of fixing nitrogen. Ecology 2000

  32. 2. A second stage characterized by a thick mat of Dryas, interspersed with a few willows, cottonwoods, alder, and spruce, that emerges about 30 years after deglaciation. This stage is referred to as the Dryas stage. • 3. A third stage, featuring alder, that appears after about 50 years, called the alder stage. • 4. A spruce climax stage, appearing after about 100 years. Ecology 2000

  33. Fig. 28-11 Diagram showing the complex influences of early successional stages on the establishment of spruce seedlings at Glacier Bay, Alaska. Ecology 2000

  34. 生態體系的演進(succession) • (1) 它是一種有次序的過程，且是具有方向性的，因此是可以預測的。 • (2) 它是由於群落(群落是在某一地區內，各種生物種類的集合)對於其生存環境的改變所造成的。雖然其生存環境決定演進的形態、演進的速率以及限制演進最終所能達到的界線，然而演進過程卻是由生態體系中的生物本身(即是群落)所控制。 • (3) 演進的最高峰是一個穩定的生物體系，在其內的所有生命體能共同生活且其內的能量遞移及物質的循環效率達到最高。它們均在增加控制其生活環境的能力以及維持其生活環境平衡的能力。因而使保護生命的能力達到最高且使整個體系免於動盪不安。 Ecology 2000

  35. 28.6 Analytical models of succession are based on transitions from one successional stage to the next. • Fig. 28-12 Markov process model. A state vector, N, and matrix transition probabilities, P, in a system in which two species (A and B) colonize open space (O) or replace each other. Ecology 2000

  36. Fig. 28-13 Transition probabilities for successional systems behaving according to different models of species interaction.(a) Facilitation model. Ecology 2000

  37. Fig. 28-13 Transition probabilities for successional systems behaving according to different models of species interaction.(b) Inhibition model. Ecology 2000

  38. Fig. 28-13 Transition probabilities for successional systems behaving according to different models of species interaction.(c) Tolerance model. Ecology 2000

  39. Fig. 28-13 Transition probabilities for successional systems behaving according to different models of species interaction.(d) Cyclic model. Ecology 2000

  40. Fig. 28-14 Diagram of the relationships between the three states of the Larrea-Ambrosia communities of the deserts of Arizona.Markovian Dynamics in a desert plant community. Ecology 2000

  41. McAuliffe used a variety of information about plant densities, mortality rates, wood decay rates, and recruitment to calculate transition probabilities for a simple Markov transition matrix (Table 28-3) Ecology 2000

  42. The results of this analysis show considerable concordance between the predictions of the Markov model and the communities observed. Ecology 2000

  43. Markovian dynamics in a forest community Ecology 2000

  44. Fig. 28-15 Predicted transitions in a deciduous forest community near Princeton based on the probabilities shown in Table 28.5. (a) The thickness of the arrows are proportional to the transition probabilities. (b) The sizes of the circles represent the relative abundances of each species. Ecology 2000

  45. 28.7 The character of the climax is determined by local conditions. • In the absence of strong disturbance, succession eventually leads to a situation in which environmental conditions change slowly and newly invading species are not able to replace existing species at a site. • The end of successional change does not mean the end of community development. Ecology 2000

  46. Fig. 28-16 Composition of a forest undisturbed for 67 years. Ecology 2000

  47. Nature of the Climax • Monoclimax theory • sub-climax, preclimax, postclimax • polyclimax theory • pattern-climax theory • transient climaxes • cyclic climax • stable cyclic climaxes Ecology 2000

  48. Fig. 28-17 (a) A stand of longleaf pine in North Carolina shortly after a fire. Ecology 2000

  49. (b) their growing shoots are protected by the dense, long needles, shown on an unburned individual (c) Ecology 2000

  50. Fig. 28-18 Zebras and Thompson's gazelles feed side by side in the Serengeti ecosystem, but utilize different food plants. Ecology 2000

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