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Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
Biogeo lec 5   the distribution of communities
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Biogeo lec 5 the distribution of communities

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  • 1. THE DISTRIBUTION OFTHE DISTRIBUTION OF COMMUNITIESCOMMUNITIES
  • 2. Biogeographic PerspectivesBiogeographic Perspectives • Ecological Communities - complex associations of species • To what extent are species distributed together as interdependent communities as opposed to being distributed essentially independently of one another?
  • 3. Biogeographic PerspectivesBiogeographic Perspectives • Life zones, Ecoregions or Biomes - specific kinds of animals and microorganisms are associated with specific vegetation formations associated with particular climates
  • 4. Communities and EcosystemsCommunities and Ecosystems • Definitions – – Community – Community structure – Community function – Ecosystem – Microcosm – Biosphere
  • 5. Communities and EcosystemsCommunities and Ecosystems • Definitions - • Community -consists of those species that live together in the same place
  • 6. Communities and EcosystemsCommunities and Ecosystems • Community structure - static properties including diversity, composition, and biomass of species in a community
  • 7. Communities and EcosystemsCommunities and Ecosystems • Community function - all the dynamic properties and activities that affect energy flow and nutrient cycling
  • 8. Communities and EcosystemsCommunities and Ecosystems • Ecosystem - includes all the species inhabiting a place as well as all the physical features of the physical environment
  • 9. Communities and EcosystemsCommunities and Ecosystems • Microcosms - small, relatively self- contained ecosystems
  • 10. Communities and EcosystemsCommunities and Ecosystems • Biosphere - largest and only complete ecosystem -> encompasses the entire earth
  • 11. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Basal metabolic rate - varies with body mass
  • 12. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Body mass - most important variable to measure –> larger the organism the more energy it requires for maintenance, growth and reproduction
  • 13. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Larger animals have greater reserves and therefore greater potential to withstand prolonged stresses such as starvation, dehydration, and subfreezing temperatures
  • 14. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Smaller organisms require fewer resources per individual than large ones, use smaller areas, can be more specialized, and still maintain population densities high enough to avoid extinction
  • 15. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Any geographic area contains a greater number of small-bodied species than large ones AND • Large organisms are constrained to have broad geographic ranges
  • 16. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Trophic Status - influences role in the community structure
  • 17. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Ecological Pyramids - successively higher trophic levels tend to have less than 10% the rate of energy uptake of the level below them, and usually contain proportionately lower biomass and fewer individuals and species
  • 18. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy)
  • 19. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy) • –> lower for successively higher levels
  • 20. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy) • –> lower for successively higher levels • –> predictable characteristics that affect ecological roles and geographic distributions
  • 21. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy) • –> lower for successively higher levels • –> predictable characteristics that affect ecological roles and geographic distributions • –> fewer species of carnivores than herbivores
  • 22. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy) • –> lower for successively higher levels • –> predictable characteristics that affect ecological roles • and geographic distributions • –> fewer species of carnivores than herbivores • –> tend to feed on several species
  • 23. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy) • –> lower for successively higher levels • –> predictable characteristics that affect ecological roles • and geographic distributions • –> fewer species of carnivores than herbivores • –> tend to feed on several species • –> broad habitat requirements
  • 24. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Carrying Capacity - (measured in units of usable energy) • –> lower for successively higher levels • –> predictable characteristics that affect ecological roles • and geographic distributions • –> fewer species of carnivores than herbivores • –> tend to feed on several species • –> broad habitat requirements • –> wide geographic distributions • (Ex: Mountain lion, Puma concolor)
  • 25. Community Organization :Community Organization : Energetic ConsiderationsEnergetic Considerations • Productivity varies greatly among different habitats –> widespread highly productive habitats such as rain forests and coral reefs have higher diversity of specialized species –> small, isolated areas (such as small islands) and widespread unproductive habitats (such as boreal forests and tundra) contain fewer specialized species and more generalized species
  • 26. Terrestrial BiomesTerrestrial Biomes • Terrestrial communities are classified on the basis of the structure of the vegetation
  • 27. Terrestrial BiomesTerrestrial Biomes • Observed that similar climate regimes do tend to support • structurally and functionally similar vegetation in disjunct • areas throughout the world • –> these similarities may result from convergence • –> unrelated plant species in geographically isolated • regions have evolved similar forms and similar • ecological roles under similar selective pressures
  • 28. Terrestrial BiomesTerrestrial Biomes • Six major forms of terrestrial vegetation recognized: • 1.) Forest • 2.) Woodland • 3.) Shrubland • 4.) Grassland • 5.) Scrub • 6.) Desert
  • 29. Terrestrial BiomesTerrestrial Biomes • 1.) Forest - a tree-dominated assemblage with a fairly continuous canopy
  • 30. Terrestrial BiomesTerrestrial Biomes • 2.) Woodland - a tree-dominated assemblage in which individuals are widely spaced, often with grassy areas or low undergrowth between them bare
  • 31. Terrestrial BiomesTerrestrial Biomes • 3.) Shrubland - a fairly continuous layer of shrubs, up to several meters high
  • 32. Terrestrial BiomesTerrestrial Biomes • 4.) Grassland - an assemblage dominated by grasses and forbes
  • 33. Terrestrial BiomesTerrestrial Biomes • 5.) Scrub - a mostly shrubby assemblage in which individuals are discrete or widely spaced
  • 34. Terrestrial BiomesTerrestrial Biomes • 6.) Desert - an assemblage with very sparse plant cover in which most of the ground is bare
  • 35. Terrestrial BiomesTerrestrial Biomes • Twelve common terrestrial biomes are recognized – correspond to the distribution of climatic zones – latitude and elevation reflect influence of local climate and soil type
  • 36. Terrestrial BiomesTerrestrial Biomes • Tropical rain forest - richest and most productive • covers approximately 6% of surface • approximately 50% of species • low elevations at tropical latitudes (10o N to 10o S) • abundant rainfall (>180 cm annually) • rainfall tends to be seasonal • temperatures nearly uniform year-round (over 18o C)
  • 37. Terrestrial BiomesTerrestrial Biomes • Tropical rain forest (continued)– • dominant plants are large evergreen trees that form a closed canopy (30 to 50m) • convergent morphology of trees (buttressed bases, straight trunks, broad leaves with smooth edges) • also characterized by lianas (woody vines) and epiphytes (orchids, ferns and New World bromeliads) • very little light reaches the forest floor which is open and devoid of vegetation
  • 38. Tropical rain forestTropical rain forest
  • 39. Terrestrial BiomesTerrestrial Biomes • Tropical deciduous forest - occur in hot lowlands outside the equatorial zone (between 10o and 30o latitude) • rainfall is more seasonal • dry season is more pronounced • canopy is low and more open • trees and shrub shed their leaves during the dry season • flowering and fruit maturation occurs during the dry season
  • 40. Tropical deciduous forestTropical deciduous forest Synchronous blooming at the start of the dry season Madagascar Puerto RicoCeiba trees in Ecuador
  • 41. Terrestrial BiomesTerrestrial Biomes • Thorn woodland - tropical and subtropical • hot semiarid lowlands • small spiny or thorny shrubs and trees are the dominant form • Members of the genus Acacia are common on all continents • succulents such as cacti (Cataceae) in the New World and convergent forms of Euphorbia (Euphorbiaceae) in Africa are common • often found on drier sites adjacent to tropical deciduous forests
  • 42. Terrestrial BiomesTerrestrial Biomes • Tropical savanna - dominated by a nearly continuous layer of xerophytic grasses and sedges and scattered with fire-resistant trees and shrubs • low to intermediate elevations at intertropical latitudes (between 25o N and 25o S) • one or two rainy seasons followed by intense droughts • weather patterns driven by seasonal shifts in the Intertropical Convergence Zone
  • 43. Terrestrial BiomesTerrestrial Biomes • Tropical savanna (continued) - • annual rainfall varies from 30 to 160 cm • 3 common factors: • 1) seasonally intense precipitation • 2) fire during the dry season • 3) migratory or seasonal grazing • intertropical Africa (most extensive savannas) • support the most diverse community of large grazing mammals in the world
  • 44. Tropical SavannaTropical Savanna Africa Australia
  • 45. Terrestrial BiomesTerrestrial Biomes • Desert - hot deserts and semideserts occur around the world at low to intermediate elevations • --> especially in belts of dry climates (30o to 40o N and S) • --> rain is seasonal and unpredictable (often less than 25 cm per year) • --> amount of rainfall is less than the evaporative potential
  • 46. DesertDesert
  • 47. Terrestrial BiomesTerrestrial Biomes • Sclerophyllous woodland (and Chaparral) - mild temperate climates • --> moderate winter precipitation • --> long, usually hot, dry summers • --> broad variety of xeric woodlands (Ex. - Pinon-juniper, sandhill pine woodlands, pine flatwoods)
  • 48. ChaparralChaparral King Sugar Bush Californis Blue Oak, Iron Oak Aardwolf
  • 49. Terrestrial BiomesTerrestrial Biomes • Sclerophyllous woodland (continued) - • --> dominant plants have sclerophyllous (hard, tough, evergreen) leaves • --> can receive up to 100 cm rain per year • --> areas that receive less than 60 cm of rainfall per year have low, shrubby vegetation -> Sclerophyllous scrubland (Chaparral)
  • 50. Terrestrial BiomesTerrestrial Biomes • Subtropical evergreen forest - also called Oak-laurel forests or Montane forests • --> common in subtropical mountains at intermediate elevations • --> China, Japan, disjunct areas of the Southern Hemisphere and southeastern U.S. • --> most dominant species are dicotyledons with broad, sclerophyllous evergreen leaves (Ex. - laurels, oaks, and magnolias)
  • 51. Terrestrial BiomesTerrestrial Biomes • Temperate deciduous forest - temperate latitudes • --> also called Summer-green Deciduous Forests • --> variable in their structure and composition across eastern North America, western Europe, and parts of eastern Asia
  • 52. Temperate deciduous forestTemperate deciduous forest
  • 53. Terrestrial BiomesTerrestrial Biomes • Temperate rain forest - uncommon, found along the western coast of continents where precipitation exceeds 150 cm per year and falls during 10 months of the year • --> cool temperatures predominate year round • --> always above freezing • --> epiphyte diversity is high consisting of mosses, lichens, epiphyllous fungus and some ferns • --> renowned for world’s oldest and largest trees
  • 54. Temperate rain forestTemperate rain forest
  • 55. Terrestrial BiomesTerrestrial Biomes • Temperate grassland - situated geographically and climatically between the deserts and the temperate forests • --> most extensive in the interior plains of the Northern Hemisphere • --> markedly seasonal, substantial annual variation in temperature and rainfall • --> vegetation dominated by grasses, sedges, and other herbaceous plants (single stratum) • --> tall grasslands to shortgrass plains • --> vegetation growth is stimulated by fire and grazing
  • 56. Temperate GrasslandTemperate Grassland
  • 57. Terrestrial BiomesTerrestrial Biomes • Boreal forests – “swamp forest”, broad band across northern North America, Europe, and Asia in regions of cold temperatures • --> extends southward into temperate latitudes at high elevations (i.e., into southern Mexico) • --> dominated by a few species of coniferous trees (Ex. - spruce and firs)
  • 58. Terrestrial BiomesTerrestrial Biomes • Boreal forests (continued) - • --> decomposition rates are slow because of cool temperatures and waterlogged soils • --> results in the accumulation of peat and humic acids • --> soil nutrients unavailable for plant growth • --> acidic soils and cool temperatures limit diversity and productivity
  • 59. Boreal forestsBoreal forests
  • 60. Terrestrial BiomesTerrestrial Biomes • Tundra - treeless biome found between the boreal forests and the polar ice caps • --> also at high elevations on tall mountains (Alpine tundra) • --> temperatures below freezing for at least 7 months of the year • --> precipitation less than many deserts • --> soils more nutrient poor than boreal forests environment
  • 61. Terrestrial BiomesTerrestrial Biomes • Tundra (continued) - • --> single, dense stratum of vegetation • --> high productivity during short growing season • --> heavily grazed by migratory mammals such caribou (Rangifer tarandius), muskox (Ovibus moshatus) and Dall sheep (Ovis dalli) • --> fragile environment
  • 62. TundraTundra

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