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Plants and Carbon

Photosynthesis:. 6CO 2 + 6H 2 O + solar radiation → C 6 H 12 O 6 + 6O 2 sugars. Respiration:. C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + chemical energy sugars. Plants and Carbon. Biomass:. GPP = gross primary production NPP = net primary production R a = respiration.

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Plants and Carbon

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  1. Photosynthesis: 6CO2 + 6H2O + solar radiation →C6H12O6 + 6O2 sugars • Respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + chemical energy sugars Plants and Carbon • Biomass: GPP = gross primary production NPP = net primary production Ra = respiration GPP – Ra = NPP 1

  2. Land Use • Fossil fuel utilization Net addition of Carbon in the cycle from fossil fuels Reduced sequestration: Global forest biomass reduction when deforested (land use) Landfills only partially compensate 2

  3. Carbon Pools and the Flux Rates of Carbon Biomass Wastes – in landfills Soil Storage of Carbon–COMPLEX CARBON COMPOUNDS OR ORGANIC MATTER >100 years Decomposition Plant Tissues– COMPLEX CARBON COMPOUNDS CONVERTED TO CARBON GASES AND ORGANIC MATTER 10 – >100 years Atmosphere – CARBON GASES 10 – >100 years Seconds to Minutes Plant Growth and Biomass – FORM COMPLEX CARBON COMPOUNDS Minutes to Days Millions of years –CARBON IN BIOMASS TO OIL, NATURAL GAS, COAL FOSSIL FUELS Wood Products – COMPLEX CARBON COMPOUNDS STORED IN HUMAN CONSTRUCTS 50 -100 years 3

  4. Table 6.1.Estimates of the carbon pools in various global reservoirs. (modified from Siegenthaler and Sarmiento 1993, Schimel et al. 1995, Sundquist 1993) 4

  5. Forest C Soil C Carbon in the World’s Forests and Soils 5

  6. Early Soil Scientists! 6

  7. O A E B C Soil Profile and Horizons 7

  8. 8

  9. Carbon in Soils Coniferous Forest Soil Young Riparian Forest Soil Tropical Forest Soil Deciduous Forest Soil 150 Mg C 320 Mg C 65 Mg C 30 Mg C 9

  10. Biosphere 2 in Arizona 10

  11. 11

  12. 12

  13. Biosphere 2 13

  14. 14

  15. Tropical forest soils are generally acidic • Native soil is alkaline, so add OM to soil • Decomp of OM creates organic & carbonic acids in soil decreasing pH of soil • However too much OM, so microbes continue decomp, releasing CO2 and using O2 15

  16. Problems • CO2 increases to 2000 ppm but levels off around 800-1500 ppm • O2 decreases from 21% to 15% and continued decreasing 16

  17. CO2 was absorbed by the artificial rock formations and concrete 17

  18. Carbon components of forest materials:-simple sugars -starch -cellulose -lignin 18

  19. Sugar C6H12O6 Cellulose C6H12O6 + C6H2O6 + C6H12O6 Paper = Cellulose (remove lignins and sugars) 19 http://babylon.u-3mrs.fr:10085/~www-pol/cell.html

  20. CELLULOSE Polymers from cellulose: plastics, motion picture film, clear lacquer coating, rayon (fabrics) http://www.psrc.usm.edu/macrog/proposal/dreyfus/outcome/plascot/cellace.htm 20

  21. Chemical composition of jeans is same as what the MICROBES EAT DURING COMPOSTING Jeans = equivalent to paper, bags, cardboard (some lignin still left) Apply sulfuric acid – what happens to jeans? c H2SO4 http://www.us.levi.com/spr03a/levi/home/l_home.jsp 21

  22. Six-carbon ring structure (benzene) – same structure as pesticide Makes plants woody Very resistant to decay Complex enzymes needed to break down Removed from wood to make paper, what is left after composting LIGNIN http://www.eng.rpi.edu/dept/chem-eng/Biotech-Environ/FUNDAMNT/lignin.htm 22

  23. What is composting doing to plant materials? What is the product left at the end of composting? What is its chemical composition? What is eaten up by microbes in composting? What is the chemical similarity of COMPOSTING to forest materials that decompose? 23 http://www.gardenaction.co.uk/images/compost_bin_very_simple_mine.jpg

  24. Forests and recycling - today - recycle paper - construction wood – re-use untransformed - wood wastes from making products or from forest activities -- burn to make steam and energy or composted by mixing with animal wastes 24

  25. Stored Carbon 25

  26. LIFE-CYCLE for FORESTS: United States Forest Products: paper, building materials, packing materials, furniture, clothing 82% FORESTS ~18% Fuelwood 16% 4) Burned 57% 27% In US, 38% of fiber in paper is recycled fibers 1) Landfill 2) Composting 3) Recycling 26

  27. Carbon Cycle –managed to increase/decrease storage • Factors Increase C sequestration: • Land fills (-/+) • Wood Products • Afforestation (plant more trees) • Decrease C loss in agricultural soils and in forests when not cut trees • Factors Reduce C sequestration: • Land-use changes (Deforestation) • Combust Fossil fuels • Forest fires http://www.marietta.edu/~biol/102/ecosystem.html#CarbonCycle10 27

  28. Total US Energy Sources Is this GOOD? EU mandating 25-30% Little wood used to produce energy? Renewables only partitioning of energy sources 28

  29. Technological breakthroughs facilitating development of new biomass energy systems • New C neutral chemical transformation processes for biomass conversion to methanol • Developments in hydrogen fuel cells 29

  30. DIVERSITY OF NON-TRADITIONAL PRODUCTS POSSIBLE FROM WOOD TODAY Transportation Biofuels Pharmaceutical Precursors Bio-oils Electricity using Hydrogen Fuel Cells and Chemical Industry Precursors Chemicals Methanol 30

  31. Case 6.2.Carbon Sequestration in a Boreal Forest in Iceland: Effects of Foreign and Exotic Species 31

  32. Estimated forest cover 1100 years ago (25%) Current forest cover (1%) 32

  33. In a grazed birch forest, all leaves from lowest brances get grazed, otherwise abundant basal sprouts (imp for regen.) are grazed awayand most of /all seedlings are grazed. Trunks get damaged by abration by sheep horns and from scratching. Sheep wool 33

  34. Forest floor 1875 1477 Iceland has: Native forest: Mountain Birch is the single forest forming tree species Soils: mostly uniform aeolian andisols w/ ash layers (good for dating), or entisols (fresh glacial till or eroded soils) 34

  35. What to plant? • Exotic or native species? • Native species for conservation? • Species to maximize carbon sequestration? • What are the constraints and opportunities? 35

  36. Betula pubescens 36

  37. Larix sibirica 37

  38. Pinus contorta 38

  39. Results • Exotic species sequester more carbon • But exotic species may alter disturbance regimes and ecosystem processes • Exotic species alter the biodiversity of understory communities 39

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