Ecosystems

1. Ecosystems AP Biology

3. Tertiary consumers LE 54-2 Microorganisms and other detritivores Secondary consumers Primary consumers Detritus Primary producers Heat Key Chemical cycling Sun Energy flow

5. Concept 54.2: Physical and chemical factors limit primary production in ecosystems • Primary production in an ecosystem is the amount of light energy converted to chemical energy by autotrophs during a given time period

6. Gross and Net Primary Production • Total primary production is known as the ecosystem’s gross primary production (GPP) • Net primary production (NPP) is GPP minus energy used by primary producers for respiration • Only NPP is available to consumers • Ecosystems vary greatly in net primary production and contribution to the total NPP on Earth

8. 3,000 Tropical forest LE 54-8 2,000 Net primary production (g/m2/yr) Temperate forest 1,000 Mountain coniferous forest Desert shrubland Temperate grassland Arctic tundra 0 1,500 0 500 1,000 Actual evapotranspiration (mm/yr)

9. 300 LE 54-9 N + P 250 200 Live, above-ground biomass (g dry wt/m2) N only 150 100 Control P only 50 0 0 August 1980 June July

10. Concept 54.3: Energy transfer between trophic levels is usually less than 20% efficient • Secondary production of an ecosystem is the amount of chemical energy in food converted to new biomass during a given period of time

11. LE 54-10 Plant material eaten by caterpillar 200 J 67 J Cellular respiration 100 J Feces 33 J Growth (new biomass)

12. Pyramids of Production • A pyramid of net production represents the loss of energy with each transfer in a food chain

13. Tertiary consumers 10 J LE 54-11 Secondary consumers 100 J Primary consumers 1,000 J Primary producers 10,000 J 1,000,000 J of sunlight

14. Pyramids of Biomass • In a biomass pyramid, each tier represents the dry weight of all organisms in one trophic level • Most biomass pyramids show a sharp decrease at successively higher trophic levels

15. LE 54-12a Trophic level Dry weight (g/m2) Tertiary consumers Secondary consumers Primary consumers Primary producers 1.5 11 37 809 Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida.

16. Certain aquatic ecosystems have inverted biomass pyramids: Primary consumers outweigh the producers

17. LE 54-12b Trophic level Dry weight (g/m2) 21 4 Primary consumers (zooplankton) Primary producers (phytoplankton) In some aquatic ecosystems, such as the English Channel, a small standing crop of primary producers (phytoplankton) supports a larger standing crop of primary consumers (zooplankton).

18. Pyramids of Numbers • A pyramid of numbers represents the number of individual organisms in each trophic level

19. LE 54-13 Trophic level Number of individual organisms Tertiary consumers Secondary consumers Primary consumers Primary producers 3 354,904 708,624 5,842,424

20. LE 54-14 Trophic level Secondary consumers Primary consumers Primary producers

21. LE 54-17a Transport over land Solar energy Net movement of water vapor by wind Precipitation over land Precipitation over ocean Evaporation from ocean Evapotranspiration from land Percolation through soil Runoff and groundwater

22. CO2 in atmosphere LE 54-17b Photosynthesis Cellular respiration Burning of fossil fuels and wood Higher-level consumers Primary consumers Carbon compounds in water Detritus Decomposition

23. LE 54-17c N2 in atmosphere Assimilation Denitrifying bacteria NO3– Nitrogen-fixing bacteria in root nodules of legumes Decomposers Nitrifying bacteria Ammonification Nitrification NH3 NH4+ NO2– Nitrogen-fixing soil bacteria Nitrifying bacteria

24. LE 54-17d Rain Geologic uplift Weathering of rocks Plants Runoff Consumption Sedimentation Plant uptake of PO43– Soil Leaching Decomposition

25. LE 54-23 Herring gull eggs 124 ppm Lake trout 4.83 ppm Concentration of PCBs Smelt 1.04 ppm Zooplankton 0.123 ppm Phytoplankton 0.025 ppm