Life on land p2

• Desert


  • Major bands at 30o N and 30o S latitude
  • Occupy about 20% of earth's land surface
  • Water loss usually exceeds precipitation
  • Soil usually extremely low in organic matter
  • Plant cover ranges from sparse to absent
  • Animal abundance low, but biodiversity may be high
  • Strong behavioral adaptations
  • Human intrusion increasing
• Desert characteristics


  • Very little precipitation: < 250 mm
  • Predominant plants: Succulents (Cacti, Crassulaceans)

  
• Deserts


  • Sonoran desert
  • Dubai Desert
• Adaptations to life in the desert

  Shown in video
• Mediterranean Woodland and Shrubland

  • Occur in all continents except Antarctica
  • Usually along the coast
  • Climate cool and moist in fall, winter, and spring, but can be hot and dry in summer
  • Fragile soils with moderate fertility
  • Trees and shrubs typically evergreen
  • Fire-resistant plants due to fire regime
  • Long history of human intrusion
  • Cleared for agriculture
• Mediterranean Woodland and Shrubland

  • Shown in videos
• Temperate Grassland


  • Also called 'prairie' (especially North America)
  • Extremely widespread distribution—outside the Tropics (most: 30o to 60o N & S)
  • Annual rainfall 300 - 1,000 mm
  • Experience periodic droughts
  • Soils tend extremely nutrient rich and deep
  • Thoroughly dominated by herbaceous vegetation
  • Large roaming ungulates: Bison, cattle, wild horses (herbivores)
  • Agriculture has caused loss of organic matter
• Temperate Grassland


  • National Bison Range

  
• Temperate Forest (Old Growth)

  • Majority lie between 40o and 50o latitude
  • Rainfall averages 650 - 3,000 mm
  • Predominant plants: evergreen (coniferous) AND deciduous trees
  • Fertile soils
  • Biomass production can be very high
  • Many major human population centers
• Temperate Forest (Old Growth)

  • Predominant plants: evergreen (coniferous) AND deciduous trees
  • Long growing seasons dominated by deciduous plants
  • Conifers more abundant when growing season is short
• Temperate Forest (Old Growth)


  • Shown in videos
• Temperate rainforest


  Characteristics shown in video
• Boreal Forest (Taiga)


  • Confined to Northern Hemisphere: subarctic climate
  • Covers 11% of earth's land area
  • Winters are long, summers are short
  • Precipitation is moderate
  • Predominant plants: Conifers (evergreen trees): pine, spruce, larch, birch
  • Thin, acidic soils low in fertility
  • Relatively high animal density, including migratory species
  • Historically, low levels of human intrusion
• Tundra


  • Covers most of lands north of Arctic Circle
  • Climate typically cool and dry with short summers
  • 200 - 600 mm precipitation
  • Low decomposition rates
  • Permafrost: soil (20 – 90 cm) frozen permanently…so no trees!
  • Dominated by perennial herbaceous plants
  • Supports high numbers of native mammals
  • Human intrusion historically low, but increasing as resources become scarce
• Tundra plants


  • Mosses, liverworts, lichens
• Tundra


  • Shown in videos
• Biosphere 2


  • American Earth System Research Facility located in Oracle, Arizona
  • The world's largest Earth Science Experiment
• Terrestrial ecoregions
• Worldview


  • Websites to view satellite imagery of Earth