wfc 09 carbon cycling in tree plantations of temperate and subtropical south america. e.g. jobbágy...
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CARBON CYCLING IN TREE PLANTATIONS
OF TEMPERATE AND SUBTROPICAL SOUTH AMERICA
.E.G. Jobbágy
G. Piñeiro
R.B. Jackson
S.T. Berthrong
P. Eclesia
M.D. Nosetto
Grupo de Estudios Ambientales – IMASL, CONICET &
Universidad Nacional de San Luis – ARGENTINA
IFEVA, CONICET & Facultad de Agronomía
Universidad de Buenos Aires - ARGENTINA
Department of Biology & Nicholas School of the
Environment – Duke University – U.S.A
WFC 09WFC 09Tree plantations in South America
Fast growing species for commercial purposeseucalypts, pines, poplar-willows
First wave in the 70s, second wave in the 90sdeclining native resourcessubstitution of importspublic subsidiesglobalization of markets
Ecological & economic opportunity very high productivity (high yield / short shifts) suitable land with low opportunity cost
afforestationfoci
in the subtropical & temperate zone
grasslands emerge as THE key “forestry” biome (!)
EXAMPLE: Output of forest products in Argentina (statistics for 2002)
native forests → ~1 M Tn y-1 on 34 M Haplanted forests on grasslands → ~1 M Tn y-1 on 0.5 M Ha
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HarvestFireHerbivory
Decomposition
FireErosionHerbivory / Decomposition
biomass
C uptake (NPP)
soil organicmatter
forest floor
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biomass
C uptake (NPP)
soil organicmatter
forest floor
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Media histórica 1982-1999
dry forest
Subtrop humid forest
temp grasslandtrop grassland
temp humid forest
Net primary production TREE PLANTATION vs. PREVIOUS COVERas suggested by NDVI from AVHRR-NOAA
Baldi et al. 2008. Ambiencia (Brasil)Nosetto et al. 2008. Global Biogeochemical Cycles
Jobbágy et al. Agrociencia 2006
BR
BR
BR BR
VZ EC
CH
CH
CH
BR
AR
AR-UR
BR
AR
ND
VI
tre
e p
lan
tati
on
NDVI adjacent zones (control)
LONG TERM AVERAGE 1982-1999
Independent field data suggests a 2-3 fold increase of aboveground NPP
NPP rates are by far the highest of any other cultivated land use
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biomass
C uptake (NPP)
soil organicmatter
forest floor
Jobbagy & Jackson 2003 – BiogeochemistryLaclau 2003 – Forest Ecology & Management
Nosetto et al. 2006 – Journal of Arid EnvironmentsPiñeiro et al – unpublished data
Gains under commercial, high density, fastest growing species schemes: 5-15 Tn/Ha/yr in humid zones1-3 Tn/Ha/yr in semiarid zones
Shorter shifts than in the Northern Hemisphere: 10-20 yrs in warm/humid zone
Still under expanding face (planted area > harvested area)
Net gains under steady state conditions??
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biomass
C uptake (NPP)
soil organicmatter
forest floor
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SOC differences in paired standsnative grassland vs. eucalypt plantation ppt gradient (Argentina-Uruguay)
Relationship of Effect of Afforestation on TotalSoil C with Age and MAP 0-10 cm soil
Plantation Age (Years)
0 10 20 30 40 50 60
Ln R
espo
nse
Rat
io(t
otal
C g
/m2)
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1500mm MAP
1300mm MAP
1100mm MAP
900mm MAP
700mm MAP
soil organicmatter
Isotopic (13C) evidence points to lower inputs to SOCcompared to grasslands
(a) higher aerial vs. belowground inputs causing lower humification rates
seem more important than
(b) lower biomass quality (just small) or (c) higher SOC decomposition rates (not seen at all)
Berthrong et al. in preparation
(-)
(=)100%
50%
20%
-20%
-40%
same
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0
20
40
60
80
100
0 20 40 60 800
20
40
60
80
100
0 20 40 60SOM - Kg C / m3 SOM - Kg C / m3
differences p<0.05
grassland
plantation
CASTELLI (50 years) GUERRERO (97 years)
de
pth
(cm
)
0
100
-32-28-24-20-16
∂13C ‰
(new C)
-28-24-20-160
100
∂13C ‰
(new C)
de
pth
(cm
)
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biomass
soil organicmatter
forest floor
(+)
(-)
(?, but possibly ++)
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biomass
C uptake (NPP)
Declining water yields in small watersheds of increasing relative importance towards drier climates
High groundwater consumption and localized salinization in flat sedimentary regions (Pampas)below ~1200 mm/yr of precipitation
Jobbágy & Jackson 2004 Global Change BiologyJackson et al. 2005 – Science
Farley et al. 2006 – Global Change BiologyNosetto et al. 2008 – Global Biogeochemical Cycles
trade-off 1: water
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biomass
soil organicmatter
forest floor
4
5
6
7
8
4 5 6 7 8pH grassland
pH
tre
e p
lan
tati
on 1:1 line
mean pH drop
High Ca demand, sequestration, and export leads to soil acidification. eucalypts >> pineswet & sandy/weathered contexts: stream acidification
Jobbágy & Jackson 2003 – BiogoechemistryJobbágy & Jackson - Ecology
Berthrong et al. 2008 – Ecological ApplicationsFarley et al. 2008 – Water Resources Research
Piñeiro et al. unpublished data
Review of paired soil studies (plantation vs. grassland)
trade-off 2: calcium redistribution
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Guess where our best C stock is
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Solución 100% analítica, exacta, sin parámetros ajustables
En nuestro caso, para tiempo = 0 (establecimiento)y para tiempo = X (edad al muestreo)conocemos S y S*Además conocemos rI (I*/I)
Queremos averiguar I y k, y así proyectar S en otras tiempo/condiciones
Para 12C
dS/dt = I – k S(t)
Para 13C
dS*/dt = I* – k S*(t)
rI =
1
1
1ln
1
o
X
o
X
o
X
rS
rS
rSrI
rSrI
S
S
Xk
)exp(1
)exp(..
kXrI
kXrSSrSSkI ooXX
rS
WFC 09WFC 09Aplicación del modelo
• Descenso de I en profundidad (en Guerrero 480, 219, 103, 42, 25 y 16 g/m3 por estrato)
• I es menor en Guerrero (monte de baja densidad sujeto a cosecha…)
• Muy bajos Ingresos respecto a los valores conocidos de producción
En 0-20, I = 450-900 Kg C/Ha/año Productividad primaria neta aérea de aprox 5000 Kg C/Ha/año Biomasa raíces (<0.5 cm diámetro) 4500 Kg. C/Ha/año
• Tiempo de renovación mas rápido en superficie
• Valores similares en ambos sitios
Estrato Ingreso (I) t renov. (1/k)
(cm) (KgC/Ha/año) (años)
Castelli Guerrero Castelli Guerrero
0-5. 477 240 106 80
5-10. 147 109 181 194
10-20. 276 103 242 206
20-35. NC 63 NC 144
35-50. NC 38 NC 117
50-75. NC 41 NC 236
75-100. NC NC NC NC