Plants and Carbon• Photosynthesis:

6CO2 + 6H2O + solar radiation → C6H12O6 + 6O2

sugars

• Respiration:C6H12O6 + 6O2 → 6CO2 + 6H2O + chemical energy sugars

GPP = gross primary productionNPP = net primary productionRa = respirationGPP – Ra = NPP

• Biomass:

1

A ir

L an dW ater

C O 2

F o ss il F u e lsL im e s to n e

C a r b o n

Land Use Fossil fuel utilization

Reduced sequestration: Global forest biomass reduction when deforested (land use)

Net addition of Carbon in the cycle from fossil fuels

Landfills only partially compensate

2

FOSSIL FUELS

Millions of years –CARBON IN

BIOMASS TO OIL, NATURAL GAS,

COAL

10 – >100 years

10 – >100 years

Minutes to Days

Atmosphere – CARBON

GASES

Seconds to Minutes

Decomposition Plant Tissues– COMPLEX CARBON COMPOUNDS CONVERTED TO CARBON GASES AND ORGANIC

MATTER

>100 years

Plant Growth and Biomass – FORM

COMPLEX CARBON

COMPOUNDS

Wood Products – COMPLEX CARBON COMPOUNDS STORED IN HUMAN

CONSTRUCTS

Soil Storage of Carbon–COMPLEX CARBON

COMPOUNDS OR ORGANIC MATTER

Biomass Wastes – in landfills

50 -100 years

Carbon Pools and the Flux

Rates of Carbon

3

Table 6.1. Estimates of the carbon pools in various global reservoirs.

(modified from Siegenthaler and Sarmiento 1993, Schimel et al. 1995, Sundquist 1993)

Global Pools of Carbon(or Reservoirs)

Amount of Carbon(billion metric tons)

Percentage of Total (%)*

Atmospheric 750 1.8

Oceanic 39,000 93.4

Vegetation 550 1.1

Soils 1,500 3.7

100.0

Recoverable Fossil Fuel > 4,000 -

Geological Substrate (marine sediments, sedimentary rocks)

> 65,000,000 -

4

Forest CSoil C

Carbon in the

World’s Forests

and Soils

5

Early Soil Scientists!

6

Soil Profile and HorizonsOA

E

B

C

A

O

E

B

C

7

8

Carbon in SoilsDeciduous Forest Soil

Coniferous Forest Soil

Tropical Forest Soil

Young Riparian Forest Soil

150 Mg C 320 Mg C 65 Mg C 30 Mg C 9

Biosphere 2 in Arizona

10

11

12

Biosphere 2

13

14

• 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

Problems

• CO2 increases to 2000 ppm but levels off around 800-1500 ppm

• O2 decreases from 21% to 15% and continued decreasing

16

CO2 was absorbed by the artificial rock formations and concrete17

Carbon components of forest materials:

-simple sugars -starch -cellulose -lignin

18

http://babylon.u-3mrs.fr:10085/~www-pol/cell.html

SugarC6H12O6

Paper = Cellulose (remove lignins and sugars)

CelluloseC6H12O6 + C6H2O6 + C6H12O6

19

http://www.psrc.usm.edu/macrog/proposal/dreyfus/outcome/plascot/cellace.htm

Polymers from cellulose: plastics, motion picture film, clear lacquer coating, rayon (fabrics)

CELLULOSE

20

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?

http://www.us.levi.com/spr03a/levi/home/l_home.jsp

H2SO4

c

21

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

http://www.eng.rpi.edu/dept/chem-eng/Biotech-Environ/FUNDAMNT/lignin.htm

LIGNIN

22

http://www.gardenaction.co.uk/images/compost_bin_very_simple_mine.jpg

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

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

Stored Carbon

25

LIFE-CYCLE for FORESTS: United States

FORESTSForest Products:paper, building materials, packing materials, furniture, clothing

1) Landfill

2) Composting 3) Recycling

Fuelwood

82%

57% 4) Burned

~18%16%

27%In US, 38% of fiber in paper is recycled fibers

26

Carbon Cycle –managed to

increase/decrease storage

http://www.marietta.edu/~biol/102/ecosystem.html#CarbonCycle10

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 27

SOURCE PERCENTAGE

Petroleum 39

Coal 23

Natural Gas 23

Nuclear 8

Renewables 7

Hydroelectric 50

Biomass 43

Geothermal 5

Solar 1

Wind <0.5

Total US Energy Sources

Renewables only

partitioning of energy sources

Is this GOOD? EU mandating 25-30%

Little wood used to produce energy?

28

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

Bio-oils

Chemicals

Methanol

Transportation Biofuels

Pharmaceutical Precursors

Electricity using Hydrogen Fuel Cells and Chemical Industry Precursors

DIVERSITY OF NON-TRADITIONAL PRODUCTS POSSIBLE FROM WOOD TODAY

30

Case 6.2. Carbon Sequestration in a Boreal

Forest in Iceland: Effects of Foreign and Exotic Species

31

Estimated forest cover 1100 years ago (25%)

Current forest cover (1%)32

Sheep wool

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

33

Forest floor

1875

1477Iceland 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

What to plant?• Exotic or native species?

• Native species for conservation?

• Species to maximize carbon sequestration?

• What are the constraints and opportunities?

35

Betula pubescens

36

Larix sibirica

37

Pinus contorta

38

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