Organism and its Environment 2

• Abiotic factors


  Non-living components of the environment that can limit the distribution and abundance of organisms
• Soil


  • Serves as the reservoir of nutrients
  • Plants obtain nutrients from water often in soil then animals get nutrients from plants
  • Availability of nutrients is dependent on soil properties
  • Soil harbors thousands of organisms in every handful

  
• Soil formation


  1. Physical weathering

  2. Biological weathering

  
• Rhizospheres


  Aggregations of microbes around roots
• Soil horizons


  • A (Eluvial): dead plants and animals reduced to organic material by humification
  • A-0: litter; organic matter
  • A-1: humus
  • A-3: leached zone
  • B (Illuvial): mineral soil (mineralization)
  • C: unmodified parent material

  
• Soil types


  • Mollisol: Soft, dark; Calcification; grassland
  • Spodosol/podzol: Ash, gray; acid soil; Podzolization; Tropical Rainforest (TRF)
  • Oxisol: Reddish soil (FeO3); Laterization; SubTRF, TRF
  • Aridisol: Salty, no organic matter; Caliche formation; desert
  • Gley soil: Black ("peat"); Gleization; Marshy, boggy
  • Anthrosol: 25% "fill" with lots of pulverized concrete, dust, and debris; more nitrogen and lime runoff; Anthropogenic; Human-created urban soil

  
• Soil composition


  • Gravel (> 2.0 mm)
  • Sand (0.05-2.0mm); feels gritty
  • Silt (0.002-0.05); looks like flour
  • Clay (<0.002); too small and fine; colloidal

  
• Cation-Exchange Capacity (CEC)


  Order of adherence of ions: Humid regions: H+ and Ca2+ > Mg2+ > K+ > Na+; Arid regions: Ca2+ and Mg2+ >K+ and Na+> H+
• Soil pH


  • < pH 5: Deficiencies of P, Fe, Cu and Zn; Toxicity of Boron
  • >pH 7.5: Deficiencies of P, Ca, Mg, K, and Mo; Toxicity of aluminum

  
• Water


  Essential for all life; "Hydride of oxygen"; Covalently bonded hydrogen and oxygen atoms; Extraordinarily stable; Forms hydrogen bonds with other water molecules
• Properties of water


  • Has 3 phases on earth
  • High specific heat capacity & heat of vaporization
  • High enthalpy of fusion
  • High surface tension
  • Moderately viscous
  • Temperature-dependent density
  • Miscible with liquids & (in gaseous form) with air
• Water as a limiting factor


  Very pronounced among terrestrial organisms
• Water as a limiting factor


  • Limits aquatic plant
  • Animal adaptations: Whiskered Tern birds, African ungulates, Couchs Spadefoot Toad
  • Limits animals
  • Limits animals due to salt concentrations
• Temperature


  Controls metabolic processes
• Temperature and water


  Influencing plant adaptation
• Plant adaptations to temperature and water loss


  • Dormancy
  • Structures: bulliform cells, trichomes, sunken stomates, thick cuticle, Transfusion tissue
  • Heat shock proteins
• Temperature regulation


  • Endothermy: Heat from within, Homeothermy, Warm-blooded
  • Ectothermy: Heat from without, Poikilothermy, Cold-blooded
  • Heterothermy: Employ both ectothermy and endothermy, Temporal heterotherms
• Homeothermy


  • Maintain body temp form oxidizing glu and energy-rich molecules
  • Sustenance of high levels of physical activity
  • Cell respiration: rate of respiration is proportional to body mass (body mass0.75)
• Homeothermy adaptations


  • Reflective fur
  • Evaporative cooling: sweating & panting
  • Wallow in water
  • Insulation: Body fat, Fur/ Feathers, Preening, Feather ball/ fluffing
• Poikilotherms


  • Low metabolic rate
  • High ability to maintain heat exchange between environment (high conductivity)
  • Fishes, Amphibians, Reptiles, Insects, other invertebrates
• Crown fires/ Wildfire


  Intense and out of control; Destroy vegetation and some soil organic matter; Reset successional processes
• Surface fires


  Exert a more selective effect; Supplement bacterial action; Favor fire-tolerant ecosystem; Relieve competition
• Ionizing radiation


  Intense energy that produces ion pairs; From radioactive materials (radionuclides/radioisotopes); Cosmic rays: Radiation from outer space
• Flooding


  • Agent of disturbance; Biotic processes: decomposition, dispersal
  • Abiotic factors: temperature, humidity, currents
• Wind


  • Agent of disturbance; Biotic processes: growth, dispersal
  • Abiotic factors: nutrient availability