1. Ch. 3 Ecosystems GPP & NPP

2. The amount of energy available in an ecosystem determines how much life an ecosystem can support.

3. Some ecosystems produce plant matter faster than others do Variation in productivity on Earth High productivity -- green Low productivity -- yellow

4. Estuaries Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland Temperate grassland Lakes and streams Continental shelf Open ocean Tundra (arctic and alpine) Desert scrub Extreme desert 8001,6002,4003,2004,0004,8005,6006,4007,2008,0008,8009,600 Average net primary productivity (kcal/m 2 /yr) Fig. 4.25, p. 88 Estimated annual average of NPP per unit area in major life zones and ecosystems

5. Converting Sunlight into Chemical Energy is NOT Efficient

6. Gross Primary Productivity Gross Primary Productivity (GPP) - Rate at which an ecosystem ’ s producers convert solar energy into chemical energy as biomass GROSS = TOTAL

7. Net Primary Productivity The rate at which energy for use by consumers is stored in new biomass (cells, leaves, roots, and stems) UNITS –Units of energy (Kcal) or biomass available/specified area (m 2 )/given time

8. Net Primary Productivity Net Primary Productivity (NPP) Rate at which producers store energy as biomass (produced by photosynthesis) Rate at which producers use chemical energy stored as biomass (through aerobic respiration) = _

9. GPP & NPP

10. FORMULAS GPP = NPP + Respiration NPP = GPP – Respiration Respiration = GPP - NPP

11. ANALOGY GPP = Paycheck NPP = Amount take home Respiration = Taxes

12. Practice The net primary productivity of an ecosystem is 1 kg C/m 2 /year, and the energy needed by the producers for their own respiration is 1.5 kg C/m 2 /year. The gross primary productivity of such an ecosystem would be ________________. 2.5 kg C/m 2 /year

13. Practice The GPP of an ecosystem is 3 kg C/m 2 /year and 0.5 kg C/m 2 /year is used for respiration. What is the NPP of this ecosystem? 2.5 kg C/m 2 /year

14. Why do we care about productivity? NPP limits the number of consumers that can survive on earth Measuring tool of biosphere production Can be used to measure human impact

15. NPP Lab

16. Hints for the Lab Dissolved Oxygen (DO) = Concentration of dissolved oxygen in water/air

17. Calculating GPP Indirectly

18. Nomogram: water temperature, Oxygen mg/L, % Saturation