4/5/2013
Carbon, Part 3,
Net Ecosystem Production
• Carbon Balance of Ecosystems
• NEP,NPP, GPP
• Seasonal Dynamics of Ecosystem Carbon
Fluxes
• Carbon Flux Partitioning
• ‘Chain-saw’ and ‘Shovel’ Ecology
Dennis Baldocchi
ESPM
UC Berkeley
ESPM 111 Ecosystem Ecology
ESPM 111 Ecosystem Ecology
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4/5/2013
Carbon Cycle:
Above and Below Ground Links
Law and Ryan, Biogeochemistry, 2005
ESPM 111 Ecosystem Ecology
Active Carbon/Water Flux Measurement Sites
www.fluxdata.org
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What is the Range of Gross Primary Productivity?
Published Data, April, 2011
0.06
0.05
pdf
0.04
0.03
0.02
0.01
0.00
0
500
1000
1500
2000
2500
3000
3500
4000
GPP (gC m-2 y-1)
ESPM 111 Ecosystem Ecology
Upper Limits of GPP
GPPmax
PAR
gC m 2
LUE fpar
 Rg
Rg
mole  C
7000 * MJ m-2 y-1 * (4.6/2) * 0.02 * 0.9 * 12 = 3477 gC m-2 y-1
Rg: incoming short wave radiation
PAR: photosynthetically active radiation, 0.4 to 0.7 micron
LUE: light use efficiency
fpar: fraction of absorbed PAR
ESPM 111 Ecosystem Ecology
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Potential and Real Rates of Gross Carbon Uptake by Vegetation:
Most Locations Never Reach Upper Potential
GPP at 2% efficiency and 365
day Growing Season
tropics
GPP at 2% efficiency and
182.5 day Growing Season
FLUXNET 2007 Database
How much Carbon do Ecosystems take up?
Probability Distribution of Published NEE Measurements, Integrated Annually
Published Data, April, 2011
0.016
0.014
0.012
n = 973
-2 -1
mean = -165 +/- 253 gC m y
pdf
0.010
0.008
0.006
0.004
0.002
0.000
-1000
-500
0
500
1000
NEE (gC m-2 y-1)
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Luyssaert et al. 2007, GCB
ESPM 111 Ecosystem Ecology
NEP is the balance between two large fluxes
GPP and ecosystem respiration
Chapin et al.
ESPM 111 Ecosystem Ecology
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Seasonal change in daily NEE for a temperate deciduous forest
Harvard Forest: 1991-2000
100
-1
-1
NEE (kg ha d )
50
0
-50
-100
0
50
100
150
200
250
300
350
400
Day
Data of Wofsy et al; Urbanski et al 2007 JGR
ESPM 111 Ecosystem Ecology
Season Course in Daily
GPP and Reco for a
temperate deciduous
forest
H a rv a rd F o re s t, 1 9 9 2 -2 0 0 2
-1 4 0
GPP (kgC ha d )
-1 2 0
-1
-1
-1 0 0
-8 0
-6 0
-4 0
-2 0
0
0
50
100
150
200
250
300
350
400
day
100
-1
-1
Reco (kgC ha d )
80
60
40
20
0
0
50
100
150
200
250
300
350
400
day
Data of Wofsy et al; Urbanski et al. JGR 2008
ESPM 111 Ecosystem Ecology
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Seasonal Patterns Vary with Plant Functional Type
4
FN (gC m-2 d-1)
2
0
-2
Deciduous forest
Evergreen forest
Macchia
Perennial grassland
Annual grassland
Crop (wheat)
Tundra
-4
-6
-8
0
50
100
150
200
250
300
350
Day
ESPM 111 Ecosystem Ecology
Net Ecosystem Carbon Exchange of Deciduous Forests
Scales with Length of Growing Season
Temperate and Boreal Deciduous Forests
Deciduous and Evergreen Savanna
200
-200
-2
-1
FN (gC m yr )
0
-400
-600
-800
-1000
50
100
150
200
250
300
350
Length of Growing Season, days
Baldocchi, Austral J Botany, 2008
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Does Net Ecosystem Carbon Exchange Scale with Photosynthesis?
1000
750
FN (gC m-2 y-1)
500
250
0
-250
-500
-750
-1000
0
500
1000
1500
2000
2500
3000
3500
4000
FA (gC m-2 y-1)
Ecosystems with greatest GPP don’t necessarily experience greatest NEE
Baldocchi, Austral J Botany, 2008
Ecosystem Respiration Scales with Ecosystem Photosynthesis,
But with an Offset by Disturbance
4000
Undisturbed
Disturbed by Logging, Fire, Drainage, Mowing
3500
2500
-2
-1
FR (gC m y )
3000
2000
1500
1000
500
0
0
500
1000
1500
2000
-2
2500
3000
3500
4000
-1
FA (gC m y )
Baldocchi, Austral J Botany, 2008
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Interannual Variations in Photosynthesis and Respiration are Coupled
Interannual Variability in FN
1000
Coefficients:
b[0] -4.496
b[1] 0.704
r ² 0.607
n =164
d FR/dt (gC m-2 y-2)
750
500
250
0
-250
-500
-750
-750
-500
-250
0
250
500
750
1000
d FA/dt (gC m-2 y-2)
Baldocchi, Austral J Botany, 2008
GPP and Climate Drivers
Climate explains 70% of variation in GPP
Luyssaert et al. 2007, GCB
ESPM 111 Ecosystem Ecology
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NPP and Climate Drivers
Climate explains 35% of variation in NPP
Luyssaert et al. 2007, GCB
ESPM 111 Ecosystem Ecology
NEP and Climate Drivers
Climate explains 5% of variation in NEP
Luyssaert et al. 2007, GCB
ESPM 111 Ecosystem Ecology
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Disentangling roles of Age, Climate and N deposition
Magnani et al 2007 Nature
ESPM 111 Ecosystem Ecology
Net Ecosystem C Exchange is a Function of
Time Since Disturbance
Harvard Forest
1800
Carbon Flux (gC m-2 y-1)
1600
1400
1200
FN
1000
0
FA
FR
-200
-400
-600
1990
1992
1994
1996
1998
2000
2002
2004
2006
Year
Urbanski et al. 2007, JGR
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Net Primary Production and Stand Age
He et al. 2012 GBC
ESPM 111 Ecosystem Ecology
On to Ecosystem Respiration
ESPM 111 Ecosystem Ecology
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The Ratio between Plant Respiration and Photosynthesis is Constant:
Regardless of Plant Size, Treatment etc
Emerging and Useful Ecological Rules
Gifford, 1994, Australian J Plant Physiol
ESPM 111 Ecosystem Ecology
Fundamentals of Soil Respiration
Kyuzakov
ESPM 111 Ecosystem Ecology
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Soil Respiration and Temperature
Note how
Variance
increases with T,
especially after
Ps starts!
deForest et al 2006 IntJ Biomet
ESPM 111 Ecosystem Ecology
Soil Respiration, Temperature and Soil Moisture
Xu and Qi, 2001, Global Change Biology
ESPM 111 Ecosystem Ecology
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Soil Respiration and Soil Moisture
Xu and Qi, 2001, Global Change Biology
ESPM 111 Ecosystem Ecology
Roles of Drought and Temperature on Soil Respiration
Reichstein et al. 2003, GBC
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Environmental Controls on Respiration:
Temperature, Soil Moisture, Growth/Reproduction, Rain-Induced
Microbial Activity
2.0
Fast growth
period data
Reco/Rref
1.5
Rain pulse
1.0
0.5
0.0
0.0
0.1
0.2
0.3
0.4
-3
Soil volumetric water content (m3 m )
Xu + Baldocchi, 2003 AgForMet
ESPM 111 Ecosystem Ecology
Respiration: Temperature and acclimation
Respiration of a cold
Boreal Ecosystem, at 10 C,
Is similar to a warm Temperate
Ecosystem at 20 C
Enquist et al. 2003, Nature
ESPM 111 Ecosystem Ecology
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Respiration and Temperature:
A role for fast-photosynthesis
Tonzi Open areas
Tonzi Under trees
0.50
1.7
14:50h
0.45
12:50h
Under trees
DOY 211
1.6
12h
0.40
1.5
0.35
16h
10h
1.4
0.30
20h
1.3
Fo=0.037e0.0525T, Q10=1.69, R2=0.95
0.25
6h
6h
1.2
0.20
0.15
30
35
40
45
50
24h
0.0479T
2
Fu=0.337e
, Q10=1.61, R =0.80
1.1
25
30
o
35
Soil temperature (oC)
Soil tempreture ( C)
Tang, Baldocchi, Xu, 2005, GCB
ESPM 111 Ecosystem Ecology
On Annual Scales Soil Respiration Scales with Photosynthesis
Raich 2000 Tellus
Janssens et al 2001 GCB
ESPM 111 Ecosystem Ecology
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Rain Pulses: Heterotrophic Respiration
5
C Efflux (gC m-2 d-1)
4
8 mm
12.7 mm
61 mm
12 mm
3 mm
3
2
1
0
-10
-5
0
5
10
15
20
25
30
Days After Rain Pulse
Xu, Baldocchi, Tang, 2004, GBC
ESPM 111 Ecosystem Ecology
Photodegradation
Austin et al 2010 PNAS
ESPM 111 Ecosystem Ecology
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Concluding Points
GPP scales with Available Sunlight
so there are upper Limits to GPP, set by Length of Growing Season,
Temperature and Water
Most (80%) Assimilated Carbon is lost by
Autotrophic and HeterTrophic Respiration
Net Carbon Fluxes are a Function of Weather, Structure and Function
And Time Since Disturbance
Soil Respiration tied to Temperature and Moisture,
and recent Photosynthesis…Rain can Induce Pulses!
ESPM 111 Ecosystem Ecology
‘Chain-Saw’ Carbon Balance, 101
C
 Gains  Losses
t
Gains  GPP
Losses  Re spiration  LitterFall
 Herbivory  RootTurnover 
VOC _ Emissions  Fire  Harvest )
C
|annual ~ WoodC  SoilC
t
ESPM 111 Ecosystem Ecology
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Carbon Allocation of Forests
Litton et al., 2007
ESPM 111 Ecosystem Ecology
But Partitioning of Carbon is Poorly related to Biomass
Litton et al., 2007
ESPM 111 Ecosystem Ecology
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NPP Biometry
• NPP=GPP-Ra
• NPP=Live mass increment (L) + Detritus (D) +
Herbivory (H)
• NEP = (L + D +H)-Rhetero
• Soil Carbon Store=Detritus-Rhetero
• dCarbon = Wood Increment + Soil Carbon Store
• NEP ~ dCarbon
– H=0
ESPM 111 Ecosystem Ecology
Caveat Emptor
• Few of the NPP components are measured, or
measured well, in practice
–
–
–
–
–
–
–
Litterfall
Bole Increment
Labile Carbon is not measured in wood increment
ANPP
Convert bole increment to gC
Small diameter trees ignored, < 10 cm diameter
Below ground components often ignored
ESPM 111 Ecosystem Ecology
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Biometry and Eddy Covariance NEP converges on Long Time Scales
Gough et al 2008 AgForMet
ESPM 111 Ecosystem Ecology
•NEP,ec=GPP-Reco
NEP = (L + D +H)-Rhetero
Curtis et al, 2002, AgForMet
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Chapin et al
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