The Flow of Energy: Higher Trophic Levels

Take home message:

Ecological efficiency will get us in the end. 

Main Terms:

Trophic levels

Assimilation, ingestion, and excretion

Secondary production

Homeotherm vs. poikilotherms

Assimilation efficiency vs. net production efficiency vs. ecological efficiency

Pyramids of biomass, energy, and numbers

Main Concepts:

·        What is the fate of NPP?; What can you conclude about the fate of NPP in our world?

·        What are the “rules” for energy transfer in trophic levels.

·        Understand the principles behind calculating assimilation, net production, and ecological efficiency.

·        What are the relationships among these different efficiencies, and what do each of them actually mean?

·        Understand how pyramids of biomass, energy, and numbers are constructed, and the typical shapes of these pyramids. 

·        Know or be able to calculate the relative residence time of energy for various ecosystems; what does the residence time mean or indicate in this example?

·        Have a general understanding of how much energy humans consume; the notes present three scenarios estimating human appropriation of the world’s NPP (focus on how the highest, and most realistic, estimate is calculated and what terms go into the calculation). 

·        What processes control ecosystem function? (Top down versus bottom up)