• The Car bon Conundr um
• The global car bon cycle
• The f or est car bon cycle
2
Keeling, CD and TP Whorf
Fossil Fuel combust ion is t he main sour ce of CO2
Marland et al., 2007
2
• Dir ect Plant Ef f ect s
• The Gr eenhouse Ef f ect
• Global War ming
2
• The f ut ur e is
uncer t ain
• Developing mar ket s f or C sequest r at ion is a
pr oact ive act ion in t he f ace of uncer t aint y
• The long-t er m st or age of car bon in:
– The t er r est r ial biospher e
– Deep Under gr ound (Car bon Capt ur e and St or age)
– Oceans
http://earthobservatory.nasa.gov/Library/CarbonCycle/carbon_cycle4.html
• Global t ot al ~10 23 g C
• Most is in Sediment ar y r ocks
– 8 x 10 22 g C (or ganic compounds and
car bonat es)
• I n t he near sur f ace
– ~40 x 10 18 g C
Component
Ocean
Gt C (10 15)
38100
Soil
1580
At mospher e
750
Plant
610
• Ter r est r ial ecosyst ems (lar gely f or est s)
• Oceans
Component
Gt C (10 15)
Plant Upt ake
121.3
Ocean Upt ake
92
Plant
Respir at ion
Soil Respir at ion
60
Ocean Release
90
60
Human per t ur bat ions t o t he global C cycle
(sour ces)
CO2 sources
Fossil f uel
combust ion and
cement pr oduct ion
Land-use change
Tot al emissions
1980- 1989
19891998
Gt C yr -1
5.5 ± 0.5
6.3 ±0.6
1.6 ±0.8
1.6 ±0.8
7.1 ±1.3
7.9 ±1.4
Human per t ur bat ions t o t he global C cycle
(sinks)
CO2 sinks
Gt -C/ yr
St or age in t he at mospher e
3.3 ±0.2
Upt ake by t he ocean
2.2 ±0.8
For est r egr owt h
0.7 ±0.5
Unknown sinks
1.7 ±1.5
Tot al sinks
7.9 ±3.0
• Emissions known well
• At mospher ic pool incr easing
• Ocean sink cr it ical but appar ent ly
limit ed
• Land-use change est imat es cont inually
impr oving
• Ref or est at ion and unknown sinks, ar eas
of high f ocus
34-yr-old loblolly pine forest
Contents
kg/ha
Foliage
Branches
3000
21000
Stem
99700
Forest Floor
34900
Roots
17000
Soil
96000
Richter et al., 1995
16 yr-old loblolly pine forest
Photosynthesis 41240 kg ha-1 yr-1
Plant respiration
20680 kg ha-1 yr-1
Foliage
Branches
Soil respiration 6940 kg ha-1 yr-1
Stem
Forest Floor
Roots
Soil
Kinerson et al.
The Car bon balance of a f or est ecosyst em
• Gr oss Pr imar y Pr oduct ivit y (GPP)
– Phot osynt hesis: f ixat ion of at mospher ic C
– H 2 O + CO2 + light ener gy
C6 H 12O6 + O2 + H 2 O
• Some f ixed C is used f or r espir at ion
– C6 H 12O6 + O2 + enzyme
CO2 + H 2 O + ener gy
– Bot h Plant maint enance (Rm) and
st r uct ur al gr owt h (Rs)
• NPP= GPP-(Rm + Rs)
• NEP is t he amount of car bon gain in t he
ecosyst em
– NEP account s f or t hat C r espir ed by
secondar y pr oducer s (i.e. het er ot r ophs: Rh)
– NEP = NPP – Rh
• GPP= Pg (gr oss phot osynt hesis)
• NPP=GPP-Ra (aut ot r ophic r espir at ion)
• NEP=NPP-Rh (het er ot r ophic r espir at ion)
• NEP def ines annual (or long-t er m) car bon
sequest r at ion
Barnes et al.
Component
GPP
I mmat ur e
Mat ur e For est
For est
kg/ ha/ yr
12200
45000
Ra (plant respiration)
4700
32000
NPP
7500
13000
Rh
4600
13000
2900
0
(Heterotrophic
respiration)
NEP
Modified from Odum
• How do forest C pools change in response
to forest disturbance?
• Four phases of accumulation
– Reorganization
– Aggradation
– Transition
– Steady state
• Relatively brief period of time depending
on climate (5-20 yr)
• Total C mass declines due to high
decomposition although living biomass
is accumulating
– GPP < RA+ RH
• Relatively long period in which total
biomass accumulates and reaches a
peak (~100 yr)
• Strong biotic control
– GPP > RA + RH
– In other words, NPP and NEP are high
• Variable in length of time
• Loss in overstory biomass as pioneers die off
• Structure shifts from even aged to uneven
aged
• This transition period has not been well
studied since globally we have a few old
forests and many young forests but not many
forests we have allowed to succeed to older
age
• Total carbon fluctuates about a relatively
stable mean
• NEP=0
Waring and Schlesinger
Car bon Accumulat ion dur ing Old Field Succession
34-yr-old loblolly pine stand
350
Fol i a ge
Li v e B r a nc h
300
D e a d B r a nc h
S t e m ba r k
250
S t e m wood
Ta p R oot s
200
La t e r a l R oot s
S oi l
15 0
10 0
50
0
0
1
5 2
3
10
4
15
20
St and A g e
5
6
25
30
7
34
8
Richter and Markewitz
• Focus on net balance of input s and out put s
• I n f or est s, f ocus on biomass and soil
change
Cit at ions:
•
Barnes, BV, DR Zak, SR Denton, and SH Spurr. 1998. Forest Ecology 4th edition. John Wiley and Sons,
Inc., New York
•
Keeling, C.D. and T.P. Whor f . 2005. At mospher ic CO2 r ecor ds f r om sites in the SIO air sampling
network. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis
Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
•
Kinnerson, RS, CW Ralston, and CG Wells. 1977. Carbon cycling in a loblolly pine plantation. Oecologia
29:1-10.
•
Marland, G., T.A. Boden, and R. J. Andres. 2007. Global, Regional, and National CO2 Emissions. In
Tr ends: A Compendium of Dat a on Global Change. Carbon Dioxide Information Analysis Center, Oak
Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A
•
Odum, EP. 1971. Fundamentals of Ecology. WB Saunders, Philadelphia.
•
Richter, DD and D Markewitz. 2001. Understanding Soil Change. Cambridge University Press, New
York.
•
Richter, D.D., D. Markewitz, C.G. Wells, H.L. Allen, J. Dunscomb, K. Harrison, P.R. Heine, A. Stuanes, B.
Urrego, and G. Bonani. 1995. Carbon cycling in an old-field pine forest: Implications for the missing
carbon sink and the concept of soil. p. 233-252. In W. McFee and J.M. Kelly (eds.), Carbon forms and
functions in forest soils. Soil Science Society of America Publishers, Madison, WI.
•
Waring, RH and WH Schlesinger . 1985. For est Ecosyst ems: Concept s and Management. Academic
Press, Florida.
This document was created with Win2PDF available at http://www.win2pdf.com.
The unregistered version of Win2PDF is for evaluation or non-commercial use only.
This page will not be added after purchasing Win2PDF.