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Ecosystem Energetics and Primary Production

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이 집합의 용어 (20)

  • What are the three main points of view to describe complex terrestrial and aquatic ecosystems?
    Trophic interactions, nutrient cycling, and energy flow.
  • What is the main source of energy in natural ecosystems?
    Light from the sun provides energy in the form of photons.
  • What role do photosynthetic organisms play in energy transformation?
    They transform light energy into chemical bond energy stored in carbon-based compounds.
  • State the first law of thermodynamics in the context of ecosystems.
    Energy is neither created nor destroyed; it can change forms and move, but total energy remains constant.
  • What does the second law of thermodynamics imply about energy transfers in ecosystems?
    Energy transfers increase entropy; some energy is lost as heat and cannot do work.
  • Define Gross Primary Productivity (GPP).
    The total rate of photosynthesis by autotrophs, including energy used for their own respiration.
  • Define Net Primary Productivity (NPP) and its formula.
    NPP is the energy stored as organic molecules after autotroph respiration; \(\mathrm{NPP} = \mathrm{GPP} - R\).
  • How is NPP commonly measured in aquatic ecosystems?
    Using the light/dark bottle method to measure oxygen production and consumption.
  • What are the primary controls on net primary productivity in terrestrial ecosystems?
    Climate factors (temperature and precipitation) and nutrient availability.
  • How does precipitation affect primary productivity in terrestrial ecosystems?
    More precipitation increases water availability for transpiration, supporting photosynthesis and leaf growth.
  • What is Liebig's Law of the Minimum in relation to nutrient availability?
    Primary productivity is limited by the scarcest essential nutrient, even if others are abundant.
  • What limits net primary productivity in aquatic ecosystems?
    Light availability (photosynthetically active radiation) and nutrient availability.
  • What is the compensation depth in aquatic ecosystems?
    The depth where gross primary productivity equals respiration, so net primary productivity is zero.
  • What is the difference between autochthonous and allochthonous organic carbon in aquatic ecosystems?
    Autochthonous carbon is produced within the ecosystem by photosynthesis; allochthonous carbon comes from outside, such as terrestrial inputs.
  • How does energy allocation to plant tissues affect primary production?
    Greater allocation to photosynthetic tissues (leaves) increases net carbon gain and plant growth.
  • How does primary production vary with time in ecosystems?
    It varies seasonally and with ecosystem age, influenced by climate and plant life span.
  • What limits secondary production in ecosystems?
    Primary productivity limits secondary production by controlling the energy available to consumers.
  • What is secondary production?
    The net energy allocated to growth and reproduction of heterotroph biomass over time.
  • What are the two major food chains in ecosystems?
    The grazing food chain (energy from living plants) and the detrital food chain (energy from dead organic matter).
  • What is trophic efficiency and its typical value?
    The ratio of productivity between trophic levels; typically about 10% of energy is transferred to the next level.