1. conditions
    • physicochemical features of the environment
    • may be altered by other organisms
    • never consumed
  2. resources
    • forms of energy, chemical compounds
    • consumed
  3. photosynthesis
    carbon dioxide + water + light --> sugar + oxygen
  4. photosynthetic rate
    • amount of C fixed/ unit time
    • varies depending on light and environment
    • quality: wavelengths present
    • intensity
  5. light effects
    • quality: light varies depending on environment which plants must make due
    • intensity: more light increases photosynthetic rate (increases till CO2 is limited)
  6. leaf management
    • upright and many layers allows for a lot of sun capture for sun plants
    • single layer and very horizontal allows for maximum light capture for shade plants
  7. O2
    need to conduct aerobic respiration, never limiting since they produce it (except for maybe roots)
  8. CO2
    • 400pm in atmosphere, not limited
    • enters leaf thru stomates
    • diffuses thru intercellular spaces in leaf then into photosynthesizing cells
    • need for feeding
  9. water
    • potentially limiting resource
    • water can evaporate out of leaf cells (thru stomata)

  10. physiological tradeoff
    balence of CO2 entry and water loss thru stomata
  11. drought tolerance
    • need to minimize water loss but maximize CO2 intake
    • can survive drought conditions

    ex. waxy cuticle, upright leaf, hairy leaves, stomata on underside, deep root systems, organs for water storage
  12. drought avoidance
    being physiologically active during dry times

    • live thru dry times as seeds rather than photosynthesizing individuals
    • germination triggered when water is available
    • becomes seed before drought begins

    leaves lose a lot of water, so leaves are lost
  13. plant resources
    light, O2, CO2, water, nutrients, space, food
  14. nitrogen
    most common limiting nutrient

    • N2 is dominant, but still limiting since plants can only use ammonium (NH4) and nitrate (NO3)
    • Nitrogen must be fixed
    • abiotic: lightening
    • *biological*: N-fixing bacteria (free living or symbiotic), uses enzymes

    carnivorous plants found most often in low N areas since insects bodies have N

    humans fixing N: fossil fuels, nitrogen fixing crops, fertilizer
  15. Harber Process
    • he nitrogen fixation reaction of nitrogen gas and hydrogen gas to make ammonia
    • energy inputs required, fossil fuel consumption
  16. phosphorus
    • limiting resource
    • from breaking down of rocks and soil and decomposition of particles from elsewhere
    • exists as PO4
    • plants associate with mycorrhizae (fungus) to increase access to P

    • in water plants:
    • P is limiting because it causes algal growth, makes insoluble compounds
    • algae dies, bacteria and fungi break it down, use up O2 in water for respiration
  17. space and food
    • space: for growth, access resources, limiting on plant survival
    • food: parasitic plants (using roots to tap into another plant for food)
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