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.
• Efficiency of transfer of energy from solar energy to NPP is low (<4%). Price, 1997. Insect Ecology; see also Tivy, 1992.
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