Biomass Productivity

1. Biomass Productivity • Gross primary productivity (GPP)rate at which producers in an ecosystem convert sun into food • Net primary productivity (NPP)= GPP - Respiration • NPP and populationsNPP limits the number of consumers that can live on earth

2. Differences between GPP and NPP Sun Photosynthesis Energy lost and unavailable to consumers Respiration Gross primary production Net primary production (energy available to consumers) Growth and reproduction

3. Net Primary Productivity in Major Life Zones and Ecosystems Terrestrial Ecosystems 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 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/m2/yr) Fig. 3-11, p. 48

4. Ecosystems: What Are They and How Do They Work? Chapter 3 Sections 5-7

5. Matter Cycling in Ecosystems: Biogeochemical Cycles • Nutrient (biogeochemical) cycles • Hydrologic (water) cycle • Carbon cycle • Nitrogen cycle • Phosphorus cycle • Sulfur cycle

6. Simplified Hydrologic (Water) Cycle Condensation Rain clouds Transpiration Evaporation Precipitation to land Transpiration from plants Precipitation Precipitation Evaporation From ocean Evaporation From ocean Surface runoff (rapid) Precipitationto ocean Rapid Surface runoff (rapid) Infiltration and percolation Groundwater movement (slow) Ocean storage

7. Human Interventions in the Hydrologic Cycle • Large withdraw of surface and ground waters • Clearing vegetation / wetland destruction -  runoff,  infiltration,  groundwater recharge,  flood risk,  soil erosion & landslides • Pollution - addition of nutrients

8. The Carbon Cycle (Marine) Diffusion between atmosphere and ocean Combustion of fossil fuels Carbon dioxide dissolved in ocean water aerobic respiration photosynthesis Marine food webs Producers, consumers, decomposers, detritivores incorporation into sediments uplifting over geologic time death, sedimentation sedimentation Marine sediments, including formations with fossil fuels

9. The Carbon Cycle (Terrestrial) Atmosphere (most carbon is in carbon dioxide) Combustion of fossil fuels volcanic action combustion of wood (for clearing land; or fuel) aerobic respiration photosynthesis Terrestrial rocks deforestaion Land food webs Producers, consumers, decomposers, detritivores weathering Soil water (dissolved carbon) Peat, fossil fuels death, burial, compaction over geologic time leaching, runoff

10. High projection Low projection Human Interferences in the Global Carbon Cycle Clearing Vegetation Burning Fossil Fuels potential consequences? Fig. 3-26, p. 56

11. Gaseous Nitrogen (N2) in Atmosphere Nitrogen Fixation by industry for agriculture Food Webs on Land uptake by autotrophs uptake by autotrophs excretion, death, decomposition Fertilizers Nitrogen Fixation bacteria convert N2 to ammonia (NH3); this dissolves to form ammonium (NH4+) Denitrification by bacteria NO3– in Soil Nitrogenous Wastes, Remains in Soil Ammonification bacteria, fungi convert the residues to NH3; this dissolves to form NH4+ 2. Nitrification bacteria convert NO2– to nitrate (NO3–) NH3, NH4+ in Soil 1. Nitrification bacteria convert NH4+ to nitrite (NO2–) NO2– in Soil loss by leaching loss by leaching The Nitrogen Cycle

12. Human Interferences in the Global Nitrogen Cycle Add nitric oxide (NO) to atmosphere - can form acid rain Add nitrous oxide N2O to atmosphere via anaerobic decomposition & inorganic fertilizers - greenhouse gas Nitrate in inorganic fertilizers can leach thru soil & contaminate groundwater Release large quantities of N into troposphere via habitat destruction Upset aquatic ecosystems from excess nitrates in ag. runoff & sewage- eutrophication

13. The Phosphorus Cycle mining Fertilizer Guano excretion agriculture uptake by autotrophs uptake by autotrophs Land Food Webs Dissolved in Soil Water, Lakes, Rivers leaching, runoff Dissolved in Ocean Water Marine Food Webs death, decomposition weathering weathering settling out sedimentation uplifting over geologic time Rocks Marine Sediments

14. Human Interventions in the Phosphorus Cycle Mining of phosphate rock Clearing tropical forests reduces available phosphate in tropical soils Phosphates from runoff of animal wastes, sewage & fertilizers disrupts aquatic ecosystems - eutrophication“Since 1900, human activities have increased the natural rate of phosphorous release to environment by about 3.7 fold”

15. The Sulfur Cycle Water Ammonia Acidic fog and precipitation Sulfur trioxide Sulfuric acid Ammonium sulfate Oxygen Hydrogen sulfide Sulfur dioxide Plants Volcano Dimethyl sulfide Animals Industries Ocean Sulfate salts Metallic Sulfide deposits Decaying matter Sulfur Hydrogen sulfide

16. How Do Ecologists Learn about Ecosystems? • Field research • Remote sensing • Geographic information system (GIS) • Laboratory research • Systems analysis

17. Geographic Information System (GIS) Critical nesting site locations USDA Forest Service USDA Forest Service Private owner 1 Private owner 2 Topography Forest Habitat type Wetland Lake Grassland Real world Fig. 3-31, p. 61