FLOWS OF ENERGY AND

MATTER2.3

Energy Budget:

Boxes and Circles represent Storage and Arrow thickness represents magnitude of flow

• 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.

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 bondsphotosynthesis

■6

respiration

■ 6

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