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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

WFC 09WFC 09

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Nosetto et al. 2006 – Journal of Arid EnvironmentsPiñeiro et al – unpublished data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