L03 Ecosystems Biomes
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L03 Ecosystems Biomes

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L03 Ecosystems Biomes L03 Ecosystems Biomes Presentation Transcript

  • Ecosystems – what types are there, and where are they located?
  • Types of Ecosystems
    • estuaries
    • swamps and marshes
    • tropical rain forest
    • temperate forest
    • northern coniferous forest (taiga)
    • savanna
    • agricultural land
    • woodland and shrubland
    • temperate grassland
    • lakes and streams
    • continental shelf
    • open ocean
    • tundra (arctic and alpine)
    • desert scrub
    • extreme desert
    Miller Ch 4 Fig 4.21)
  • Biomes (Miller Ch 4 Fig 4.8); Cotgreave & Forseth Ch 2)
    • large regions of the ecosphere containing ecosystems and communites which are similar in vegetation structure
    • occur in similar overall environments (climate)
    • species composition is different in the same biome in different parts of the world
  • BIOMES - WORLDWIDE PATTERNS OF DIVERSITY at a world scale the vegetation is clumped into a few major types called BIOMES, based on abiotic factors
    • BIOME boundaries tend to run east-west around the earth, and they reflect the climatic changes which occur from the POLES to the EQUATOR
    • the pattern of BIOME distribution is determined by GROSS CLIMATE and occurs over thousands of kilometres of latitude
      • day-length
      • temperatures
      • rainfall distribution
    • HIGH LATITUDES are characterised by TUNDRA
    • LOW TEMPERATURE
    • LOW RAINFALL
    • EXTREMES of DAY LENGTH
    • (short “growing season”)
    • and characteristic groups of plants are dominant
    SEDGES and DWARF TREES LICHENS MOSSES TUNDRA
    • moving towards the equator (LOW LATITUDES) the
          • rainfall increases
          • temperatures rise
          • day length increases
    and the vegetation which characterize the BIOMES changes high latitudes high latitudes low latitudes (equator)
  • TAIGA ( BOREAL FOREST ) BIOME large areas of boreal forest - conifer forests - only in northern hemisphere
  • TEMPERATE DECIDUOUS or EVERGREEN FOREST BIOME (eg. Eucalyptus ) evergreen deciduous
  • DESERT BIOMES occur wherever RAINFALL is low and unpredictable deserts
  • GRASSLAND BIOMES occur where rainfall is higher and reliable high but unreliable rainfalls result in SAVANNA BIOMES tropical grassland & savanna temperate grasslands
    • as a general rule, the diversity of species in a biome declines with increasing severity of climate
    • eg. TROPICAL BIOMES - mild climate - only 7% of land mass, but contain
          • 50% terrestrial plants
          • 30% birds
          • 50% vertebrates
          • 90% insects
    tropical biome
    • BUT high species diversity CAN be found in BIOMES in severe climates
        • eg. reptile diversity in Australian DESERT BIOME is HIGH
    Threats to TROPICAL BIOMES have received most attention, but BIODIVERSITY is in serious decline in most BIOMES
  • BIOME orientation can be altered by mountain ranges running north-south Rockies (USA) Andes (South America) Great Dividing Range (Australia)
  • Biome types can be altered by secondary processes such as fire, or grazing - HEATH & DRY SCLEROPHYLL (Australia), GARIQUE (Mediterranean Europe), FYNBOS (Southern Africa), CHAPARRAL (USA - California) Heath in Australia – high endemic diversity is maintained by fire
  • World-scale Plant and Animal Distributions
    • species and ecosystems can be examined in terms of compositional properties as well as structural properties
    • the study of distributions shows that biomes and ecosystems with similar structures can have very different compositions , reflecting different evolutionary histories
      • Lydekkers line  eastern limit of oriental elements
    • Wallacaea
      • zone of mixing between Australian and Oriental realms mostly in last 15 million years
      • Wallaces line  western limit of Australian elements
  • Oriental and Australian avifauna in Wallacaea  ali Lombok Sumbawa flores Alor 87-13 72-28 68-32 63-37 57-43 Oriental Australian 
  • World Patterns of Plant Distribution
    • distribution patterns can indicate
      • environmental requirements of the taxon
      • dispersal ability
      • areas of origin or diversification
      • evolutionary and pre-history of the taxon
  • Types of plant distributions
    • the terms we use to describe distributions can imply processes, constraints, history
      • Cosmopolitan species (e.g., Drosera spp.)
      • Relictual families ( Cycadaceae )
      • Gondwanan families ( Restionaceae )
      • sub-antarctic ( Nothofagus spp.)
      • disjunct species ( Eucalyptus aggregata )
      • endemic genus ( Isophysis tasmanica )
    Macrozamia communis NSW
  • Regional biodiversity hotspots
    • “ hotspot” - a region where high biodiversity and high endemism are found, and high threat (risk of loss) sometimes coincide
    • development of ‘hot-spot’ regional biotas
      • in situ development (e.g. SW Australia, southern Africa)
      • survival of ancient forms (e.g. New Caledonia, Madagascar)
      • mixing of elements (e.g. Oriental and Australasian bird species in Wallacaea)
      • isolated islands
  • Regional plant diversity for selected areas * area in thousands of square kilometres