12.3

• Mutualism with three players:
  Nitrogen fixing bacteria, plants, and mycorrhizae fungi

Community Structure

• Species richness: number of species in a community

• Species evenness: the degree to which individuals among species are evenly distributed

Succession

• Experiment with rabbits and lynx is important

• Clements argued that in community there is one stable equilibrium, climax community

• Communities are like a “super organism”. If there’s a disturbance, we can predict what the climax community will look like through time. It will look the same as it springs up after disturbances.

• Gleason argued that communities were not so predictable. There’s too many other abiotic factors. A climax community is disturbed, and you could have an entirely different climax community could spring back due to outside factors.

Energy Systems and Global Ecology

• GPP = Gross Primary Productivity

• NPP = Net Primary Productivity

• NPP = GPP - R

• R = cellular respiration and heat

• How efficient are photosynthesizers at photosynthesizing? I’m going to end my shit

• NPP is like 45% of GPP. 55% is lost to respiration, waste, heat loss

• It’s worse as you move up the chain. Only about 10% of energy gets transferred to biomass at the next level.

• Which trophic level is most efficient at supporting humans? Primary producers! So stuff like vegetables and crops