Download Flow of energy and matter

FLOWS OF ENERGY
AND MATTER
2.3
Energy Budget:
• Only a very small part of the
total sunlight reaching the
Earths surface is ever
transformed into energy
used by living organisms.
• A study of an Illinois
cornfield suggested only
1.6% was actually used by
the corn.
Boxes and Circles represent Storage and Arrow
thickness represents magnitude of flow
Pathways of radiation through
ecosystem
■ Conversion of light energy to chemical energy
■ Transfer of chemical energy from one trophic level to
another (efficiency varies)
■ Overall conversion of ultraviolet and visible light to
heat energy by organisms in ecosystem
■ Re-radiation of heat energy to the atmosphere
Energy currency: C-H bonds
photosynthesis
■ 6𝐶𝑂2 + 6𝐻2 𝑂 + 𝑙𝑖𝑔ℎ𝑡 𝑒𝑛𝑒𝑟𝑔𝑦 → 𝐶6 𝐻12 𝑂6 𝑔𝑙𝑢𝑐𝑜𝑠𝑒 + 6𝑂2
respiration
■ 𝐶6 𝐻12 𝑂6 𝑔𝑙𝑢𝑐𝑜𝑠𝑒 + 6𝑂2 → 6𝐶𝑂2 + 6𝐻2 𝑂 + 𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦
Summary:
■ Energy is conserved in ecosystems
– First law of Thermodynamics
■ Chemical energy used by “buffalo and bacteria” must be
less than the chemical energy generated via primary
production, due to unavoidable inefficiencies in energy
capture.
■ Photosynthesis is the dominant source of energy in most
ecosystems through conversion of light to C-H bonds in
organic material.
Summary:
■ The flow and fate of carbon is tightly linked to energy
flow.
■ This fact is fundamental to understanding how
carbon and energy flow are
– linked to other elements and nutrients
– support patterns of biodiversity
– connect carnivores, herbivores, and plants
Work Cited
■ Beman, J. (2010) Energy Economics in Ecosystems. Nature Education
Knowledge 3(10):13