1. Biological Communities

2. Food Webs
The biota of an ecosystem are tied together in complex networks – food webs - that reflect feeding relationships

3. Community Energy Energy enters biotic communities via photosynthesis
transferred between organisms in feeding
used for growth, energy via respiration

4. Energy transfer
Inefficient: only a small fraction of energy, in the form of biomass, is available to the next trophic level
~10%
Where’d the rest go?
Recall the energy transfer POGIL
Biomass is transferred, but the organisms used some, lost some as heat in transformations, excreted some, etc.
biomass

5. Eco pyramids energy transfer numbers of organisms
Hence, the pyramid shape
A large base needed to support the levels above
amount of biomass