Foreste e ciclo del carbonio

1. Topic 1, Slide 1 of 47
USAID-CIFOR-ICRAF Project
Assessing the Implications of Climate Change for USAID Forestry Programs (2009)
Foreste e ciclo del carbonio
Parte 1
Giorgio Vacchiano
giorgio.vacchiano@unito.it

2. Topic 1, Slide 2 of 47
Indicators of the Human Influence
on the Atmosphere during the Industrial Era

3. Topic 1, Slide 3 of 47
To solve the climate change
problem we need to
reduce atmospheric
concentrations of
greenhouse gases to a
safe level

4. Topic 1, Slide 4 of 47
IPCC 2007 Summary for Decision Makers
Fig SPM.11: Global C02 emissions 1940-2000
To stabilize at 450ppm requires global emissions to be
around zero by 2070

5. Topic 1, Slide 5 of 47
The carbon cycle
Surface water
1 020
Intermediate
and deep water
38 000 - 40 000
Coal deposit
3 000
Oil and gas deposit
300
Marine sediments
and sedimentary rocks
66 000 000 - 100 000 000
Sources: Center for Climatic Research, Institute for Environmental
studies, University of Wisconsin at Madison; Okanagan University
College in Canada, Department of Geography; ,
November-December 1998; Nature.
Marine
organisms
3Dissolved
organic carbon
700
Surface sediment
150
Terrestrial
vegetation
540 - 610
Plant growth
and decay
Fossil fuel
emissions
Atmosphere
750
Soils and
organic matter
1 580
Fires
Speed of exchange processes
Very fast (less than 1 year)
Fast (1 to 10 years)
Slow (10 to 100 years)
Very slow (more than 100 years)
Storage and flux of carbon in gigatonnes (Gt)
Arrows are proportional to the volume of carbon.
Flux figures express the volume exchanged each year
Fossil fuel and
cement production
Exchange
ocean - atmosphere
Exchange
surface water - deep water
Exchange
soil - Atmosphere
Gas Hydrates

6. Topic 1, Slide 6 of 47
Grey carbon is the carbon stored in fossil fuel (coal, oil and gas deposits
in the lithosphere)
Green carbon is the carbon stored in terrestrial ecosystems (there is also
green carbon in the oceans)
Brown carbon is the carbon stored in industrialized forests, including
plantations, inclusive of the carbon emissions from the associated land
use, transportation and industrial production
Blue carbon refers to the inorganic carbon stored in the atmosphere
(carbon dioxide, CO2) and oceans (carbonate, CO3
2-)
So, our carbon accounting is
currently “colour blind”, and
fails to see the green carbon
in natural forests

7. Topic 1, Slide 7 of 47
Global scale: The carbon cycle
Atmospheric increase 4.1
Fossilcarbon
emissions
Ocean
uptake Deforestation
Residualland
sink
7.2 2.6
2.2
1.6

8. Topic 1, Slide 8 of 47
§ Examples from daily life footprint
• Flying one way from Rome to New York =
1 tCO2/person
• Driving an average car = 5.4 tCO2/year
§ National averages
• One person in the USA = 25 tCO2/yr
• One person in Italy = 18 tCO2/yr
• One person in India = 1 tCO2/yr
www.epa.gov/climatechange/emissions/ind_calculator.html
www.nature.org/initiatives/climatechange/calculator/
What is a tonne of CO2?

9. Topic 1, Slide 9 of 47
Carbon emissions and uptakes since 1800
(Gt C)
180
110
115
265
140
Land use
change
Fossil
emissions
Atmosphere
Oceans
Terrestrial

10. Topic 1, Slide 10 of 47
IPCC 2007Summary for Decision Makers
Fig SPM.3: Global anthropogenic GHG emissions

11. Topic 1, Slide 11 of 47
Forest scale: Stocks and fluxes
A forest = carbon stocks
1 kilogram of dry wood ≈ 0.5 kg of carbon
Tropical wet forest (IPCC, 2003):
§ Aboveground biomass: 65 to 430 tC/ha
§ Soils: 44 to 130 tC/ha
Leaves
Branches
Dead wood
and litter
Soils
Roots
Trunks
Understory
A forest = carbon fluxes
Atmospheric CO2
Products
Photosynthesis
Respiration
Mortality
Mineralisation
Humification
∑= Net
Absorption
Flux

12. Topic 1, Slide 12 of 47
Source: FAO 2006a.
Map produced by Emmanuelle Bournay.
North
America
South
America
East
and South
Africa
North Africa
Europe
South and
Southeast
Asia
Oceania
Central
America
West
and Central
Africa
Caribbean
East
Asia
West
and Central
Asia
91 Gt
Carbon in tree and plant biomass
Giga tonnes (Gt)
50
25
5
Forest carbon stock per region
36 VITAL FOREST GRAPHICS

13. Topic 1, Slide 13 of 47
High: 6.5
Low: –1
No data
Carbon density
(Mg C/ha)
0–20
21–40
41–60
61–80
81–100
101–120
121–140
141–160
161–180
181–200
>200
b
www.annualreviews.org • The World’s Forests 609

14. Topic 1, Slide 14 of 47
Forest Floor
Down Dead
Understory
Standing Dead
Live Tree
Soil
Example:
75-year-old stand of
northern hardwoods
(sugar maple, beech,
and yellow birch) in
the Lake States
Data from: Smith et al. 2006
Amount of C varies by forest type and region
Total = 112.8
Mg C per acre
Forest Carbon – Where is it?

15. Topic 1, Slide 15 of 47
nd either be respired back into the atmosphere or made into soil carbon.
in
y to
ns
for
or
Figure 2: The forest carbon cycle
,
s
an essentially permanent form of storage. Only 10 to 30 percent of the
nsumed by a fire; the majority remains on-site. Live trees will continue their

16. Topic 1, Slide 16 of 47
How long does carbon stay
in a tree?
Some carbon goes right back into the atmosphere
as the tree respires (breathes out); but, if it stays,
then it may remain sequestered in the tree
throughout its life—whether that is 10 or 500
years.

17. Topic 1, Slide 17 of 47
How long does carbon remain
in the soil?
Carbon is returned daily to the atmosphere when it is decomposed and
respired by soil organisms. But, much of it remains in complex
chemical forms that resist decomposition and persist for hundreds to
thousands of years.
Soil carbon is an important carbon storehouse. It
accounts for as much carbon as is presently found in
plants and the atmosphere combined.

18. Topic 1, Slide 18 of 47
What is the role of fire in
the forest carbon cycle ?
10-30 % of the biomass in a forest is actually consumed by a
fire; the majority remains on-site as live or dead biomass.
Regrowth after a fire will recapture carbon from the
atmosphere, reversing the fire’s emissions.
1-10% of biomass is converted to charcoal, a uniquely stable
form of carbon that will persist for thousands of years.

19. Topic 1, Slide 19 of 47
Undisturbed forests
§ An undisturbed forest:
• A large stock
• But not a large sink
§ +/- equilibrium (climax)
§ Scientific debate on this point
• Measurement: sinks (CO2 fertilisation,
recuperation from past disturbances,
spatial sampling)
• Even if an undisturbed forest does not
absorb GhG from the atmosphere, it is
better to conserve it than to convert it
to other uses
Carbon
Years

20. Topic 1, Slide 20 of 47
Comparing scenarios
Years
Carbon
A
For climate change mitigation, which is the better alternative?
• Conserving an undisturbed forest (A)
• Converting this forest to forest plantation (B)?
Carbon emitted into the atmosphere
under scenario B compared with A =
Carbon that contributes to climate
change
Answer: A
Years
Carbon
Years
Carbon
B

21. Topic 1, Slide 21 of 47
Years
Carbon stock
Years
Carbon stock
Years
Carbon stock
Years
Carbon stock
Years
Carbon stock
Years
Carbon stock
Tree plantation
Conserved
primary forest
Forest to
plantation
Unsustainably
managed forest
Deforested
Non forested

22. Topic 1, Slide 22 of 47
The correct base line for carbon
accounting in natural forests is NOT
necessarily the current stock of
carbon in a forested landscape, as
this can reflect land use history
The correct base line is called the
“carbon carrying capacity”
“The mass of carbon able to be stored in a forest ecosystem under
prevailing environmental conditions and natural disturbance regimes,
but excluding disturbance by human activities (Gupta and Rao
1994).”

23. Topic 1, Slide 23 of 47
To calibrate “dynamic carbon accounting
models” in natural forests requires specific, hard-
to-get data. Using the wrong data results in badly
calibrated models and erroneous output
GPP:NPP?
Partitioning
co-efficients?
Turnover
Rates?

24. Topic 1, Slide 24 of 47
1. Our natural forests can store a lot1. Our natural forests can store a lot
more carbon than previousmore carbon than previous
international and nationalinternational and national
estimates suggestestimates suggest

25. Topic 1, Slide 25 of 47
2. The carbon stored in our natural2. The carbon stored in our natural
forests is a significant component of ourforests is a significant component of our
national carbon accountsnational carbon accounts

26. Topic 1, Slide 26 of 47
Links between stock and flux
If the stock decreases…If the stock increases….
Flux: Outbound
Atmospheric CO2: Increasing (more climate change)
Process: C emission
Forest: C source
Example: Decaying or burning forest
Flux: Inbound
Atmospheric CO2: Decreasing (less climate change)
Process: C fixation, absorption,removal
Forest: C sink
Example: Growing forest

27. Topic 1, Slide 27 of 47 IPCC 2007
Regional carbon balance (MtCO2), 1855-2000.
World Forests in the Carbon Cycle
Globally, at least 17% of emissions are from the forestry
sector: deforestation and land use change.

28. Topic 1, Slide 28 of 47
Forests, carbon and global climate 1577
total: 123 PgC
cropland
68%
harvest
16%
pasture
13%
shifting cultivation
3%
total: 2.1 PgC yr -1
cropland
61%
harvest
14%
pasture
16%
shifting cultivation
9%
(a) (b)
Figure 7. (a) Estimated total net carbon emissions from land-use change 1850{1990; (b) esti-
mated annual emissions from land-use change in the year 1990. Data from Houghton (1999) and
R. A. Houghton (2002, personal communication).
trial activity, and the net carbon emissions from deforestation more di¯cult to quan-
tify, there is greater uncertainty in this ≠gure than in ≠gure 5. Houghton estimates
that a total of 124 GtC was emitted between 1850 and 1990. There are remarkable
variations over time. In particular, temperate deforestation rates have slowed greatly
and there has even been a recent net expansion of forest cover in North America

29. Topic 1, Slide 29 of 47
June 2012 NPP
(g C/m2/day)
High: 6.5
Low: –1
No data
a
January 2012 NPP
(g C/m2/day)
High: 6.5
Low: –1
No data

30. Topic 1, Slide 30 of 47
0
100
200
300
400
500
600
700
800
0 5 10 15 20 25 30 35
b
Whittaker & Likens (1973)
Asymptotic
Quadratic
TemperateTemperate
rainforestsrainforests
Temperate
rainforests
Abovegroundbiomass(Mgha–1)
Aboveground NPP (Mg ha–1 year–1)
8

31. Topic 1, Slide 31 of 47
1900 1950 2000 2050 2100
Netecosystemproductivity,GtCyr–1
Sink
Source
4
2
0
–2
Predicted effects of changes in climate and atmospheric CO2 on
the global net uptake of carbon by terrestrial ecosystems --
this model shows the sink maximizing in about 2050 and
declining to zero by 2100 -- other models tend to show
constant or less of a decline after 2050
Global Net Ecosystem Productivity

32. Topic 1, Slide 32 of 47

33. Topic 1, Slide 33 of 47
Forest Sector Carbon Cycle
Atmosphere
Live Vegetation
Down Wood &
Forest Floor
Soil
Standing Dead
Vegetation
Modified from Heath et al. 2003 and EPA 2007

34. Topic 1, Slide 34 of 47
Forest Sector Carbon Cycle
Atmosphere
Live Vegetation
Down Wood &
Forest Floor
Soil
Standing Dead
Vegetation
Harvested
Wood
Landfills
Modified from Heath et al. 2003 and EPA 2007
Wood
Products
Wood
Energy

35. Topic 1, Slide 35 of 47
Carbon and forest management
18 April 2008
Forest carbon management options

36. Topic 1, Slide 36 of 47
Options for Responding
PEOPLE
Greenhouse
Gases
Climate
Change
CC Impacts

37. Topic 1, Slide 37 of 47
Mitigation: Forest Carbon Mgmt.
Mitigation includes human actions to
reduce the effects of climate change by
reducing sources and enhancing sinks of
greenhouse gases
Three broad categories:
1) Sequestration
2) Emission avoidance
3) Substitution
IPCC 2007, Brown 1999, Maness 2009

38. Topic 1, Slide 38 of 47
Mitigation #1: Sequestration
Use management in forest ecosystems to
sequester additional carbon

39. Topic 1, Slide 39 of 47
Mitigation #1: Sequestration
Example: Afforestation (create forest)
McKinley et al. 2011

40. Topic 1, Slide 40 of 47
Annual C sequestration potential (GtC/y)
Transformation between cover types
0 0.1 0.2 0.3 0.4 0.5
Croplandtograssland
Degraded agriculturetoagroforest
Wetlandrestoration
Degraded landrestoration Annex 1 Global
Annual C sequestration potential (GtC/y) - change
in cover type - new activities since 1990

41. Topic 1, Slide 41 of 47
Y. Malhi, P. Meir and S. Brown
0
5
10
15
20
25
2000 2020 2040 2060 2080 2100
year
emissionsrate(GtCyr-1)
business as usual
low emissions scenario (B1)
required
emissions
reductions
(a)
0
40
80
120
160
2000 2020 2040 2060 2080 2100
year
percentagecontributionofCsink
(b)

42. Topic 1, Slide 42 of 47
Mitigation #1: Sequestration
Example: Forest management for
increased carbon storage
Increased forest growth:
Enhanced regeneration
Competition control
Fertilization
Improved/superior stock
Wood Products:
Products in use
Landfills
Ryan et al. 2010

43. Topic 1, Slide 43 of 47
Mitigation #2: Emission Avoidance
Prevent carbon from being emitted into
the atmosphere

44. Topic 1, Slide 44 of 47
Mitigation #2: Emission Avoidance
Example: Avoided deforestation/degradation
Figure from UCS 2007

45. Topic 1, Slide 45 of 47
Mitigation #2: Emission Avoidance
Example: Mgmt. for reduced emissions
Reduced harvest levels
Longer harvest intervals
Reduced emissions from machinery, etc.
Ryan et al. 2010, Mika and Keeton 2012

46. Topic 1, Slide 46 of 47
I
0 0.1 0.2 0.3
Forest management
Cropland management
Grazing land management
Agroforestry
Rice Paddies
Urban land management Annex 1 Global
Contains a best estimate of the rate of uptake of these
activities by 2010 (varies between 3% to 80%) -- current text
would inhibit investment in forest management under Article
Annual C sequestration potential (GtC/y)
improvement of management within cover type -
new activities since 1990

47. Topic 1, Slide 47 of 47
Mitigation #3: Substitution
Replace fossil fuels with wood-based
energy and products

48. Topic 1, Slide 48 of 47
Forest products
Energy
CO2CO2
Wood
Energy
CO2
§ Forest products can substitute for:
• Materials, such as steel and
aluminium, whose production
emits a lot of greenhouse
gases
• Energy, such as oil, coal and
gas
§ Fuelwood:
• There is a low CO2 balance if
harvesting is sustainable and
the yield is high.

49. Topic 1, Slide 49 of 47
Mitigation #3: Substitution
Example: Renewable energy production
from biomass in place of fossil fuels
Percent reduction in lifecycle greenhouse gas emissions
Figure data from EPA 2007
9%
22%
23%
29%
47%
56%
68%
91%
0% 20% 40% 60% 80% 100%
Methanol
Corn Ethanol
Liquified Natural Gas
Compressed Natural Gas
Electricity
Sugar Ethanol
Biodiesel
Cellulosic Ethanol

50. Topic 1, Slide 50 of 47
Mitigation #3: Substitution
Example: Wood used in place of more
energy or emissions intensive materials
Figure from Glover et al. 2002
Embodied energy in three different types of houses.

51. Topic 1, Slide 51 of 47

52. Topic 1, Slide 52 of 47
Forest Carbon Markets
Carbon sequestration in forests is used to
“offset” emissions produced elsewhere
$237 million in 2011
Compliance markets
California, British Colombia, elsewhere…
Voluntary markets
Small, but growing

53. Topic 1, Slide 53 of 47
How can the forest sector mitigate climate change?
§ Producing biomaterials and bioenergy
§ Reducing emissions caused
by forest activities Less energy,oil, fertilisers...
§ Increasing carbon stocks
Reducing
deforestation
Developing
agroforestry
Creating
plantations
§ Avoiding losses of carbon stocks
Forest
Energy
(It is NOT a political definition)
Years
Carbon
Project
Baseline
Benefit
Years
Carbon
With conservation
Baseline (Deforestation)
Benefit

54. Topic 1, Slide 54 of 47
Forest Mitigation Complexity
1) Location and situation specific
Ecosystem, Management goals, Condition
2) Determining ‘baseline’
3) Multiple scales
Time, Space
4) Life cycle emissions
Upstream, Downstream