Energy loss The further up the food chain the less food and therefore less energy.
Energy Flow in an Ecosystem Biomass Ecological efficiency Pyramid of energy flow
Fig. 3-18, p. 49 Secondary consumers (perch) 10 100 1,000 10,000 Usable energy available at each tropic level (in kilocalories) Heat Producers (phytoplankton) Tertiary consumers (human) Primary consumers (zooplankton) Pyramid of Energy Flow Decomposers
Biomass Productivity Gross primary productivity (GPP) Net primary productivity (NPP) NPP and populations
Fig. 3-19, p. 49 Energy lost and unavailable to consumers Respiration Growth and reproduction Sun Photosynthesis Gross primary production Net primary production (energy available to consumers) Differences between GPP and NPP
Primary productivity Primary productivity is the amount of carbon (organic matter) produced by organisms –Mostly through photosynthesis Energy source = solar radiation –Also includes chemosynthesis Energy source = chemical reactions
Fig. 3-20, p. 50 Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean Terrestrial Ecosystems 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 Average net primary productivity (kcal/m 2 /yr) Net Primary Productivity in Major Life Zones and Ecosystems
Net Productivity Some of GPP used to stay alive, grow and reproduce NPP is what’s left Most NPP –Estuaries, swamps, tropical rainforests Least NPP –Open ocean, tundra, desert Open ocean has low NPP but its large area gives it more NPP total than anywhere else