5 - energy in agroecosystems

5 - Energy in Agroecosystems
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Unformatted text preview: Energy in Agroecosystems Carbon and Energy in Ecosystems Movement of carbon and energy through ecosystems is closely linked. Organic compounds: contain carbon sources of potential energy Therefore, we can track carbon and energy simultaneously. Photosynthesis 2 6 12 6 light 2 2 O 6 O H C O H 6 CO 6 + + Organic molecules contain: C Energy Both now incorporated into living plant system O H 6 CO 6 O 6 O H C 2 2 2 6 12 6 + + Respiration Energy is released (for use by organisms) C is released as CO 2 C and energy cycles are completed Energy Tracks Similar to Carbon Flow in Ecosystems Energy in Ecosystems Energy is a common denominator to all individuals in an ecosystem. All living organisms and their products (wood, oil, etc.) contain various amounts (kcal) of potential energy stored in their tissues. Can standardize for comparisons in terms of energy. Removing water from organisms yields biomass from which you can calculate its energy equivalent. 1. Energy or Trophic Pyramid Plant often less than 1-2% efficient at harvesting light Sunlight Production Respiration Primary Producer Plant = primary producer Gross primary production (GPP) = total energy captured by plant during photosynthesis. GPP is used for: Respiration (R) to maintain life functions of the plant. Production (P) = Net primary production (NPP) for plants = energy which is stored in plant tissues (growth, etc.) -- estimated from dry biomass produced over time. Note that GPP = NPP + R. Energy Transfer Efficiency Efficiency of transfer of energy from solar energy to NPP is low (<4%). ...
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