WFC 09 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.

Presentación del tema: "WFC 09 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."— Transcripción de la presentación:

1 WFC 09 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

2 WFC 09 Tree plantations in South America Fast growing species for commercial purposes eucalypts, pines, poplar-willows First wave in the 70s, second wave in the 90s declining native resources substitution of imports public subsidies globalization of markets Ecological & economic opportunity very high productivity (high yield / short shifts) suitable land with low opportunity cost afforestation foci 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 Ha planted forests on grasslands ~1 M Tn y -1 on 0.5 M Ha

3 WFC 09 Harvest Fire Herbivory Decomposition Fire Erosion Herbivory / Decomposition biomass C uptake (NPP) soil organic matter forest floor

4 WFC 09 biomass C uptake (NPP) soil organic matter forest floor

5 WFC 09 Media histórica 1982-1999 dry forest Subtrop humid forest temp grassland trop grassland temp humid forest Net primary production TREE PLANTATION vs. PREVIOUS COVER as 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 VZEC CH BR AR AR-UR BR AR NDVI tree plantation 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

6 WFC 09 biomass C uptake (NPP) soil organic matter forest floor Jobbagy & Jackson 2003 – Biogeochemistry Laclau 2003 – Forest Ecology & Management Nosetto et al. 2006 – Journal of Arid Environments Piñeiro et al – unpublished data Gains under commercial, high density, fastest growing species schemes: 5-15 Tn/Ha/yr in humid zones 1-3 Tn/Ha/yr in semiarid zones Shorter shifts than in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??

7 WFC 09 biomass C uptake (NPP) soil organic matter forest floor

8 WFC 09 SOC differences in paired stands native grassland vs. eucalypt plantation ppt gradient (Argentina-Uruguay) soil organic matter Isotopic ( 13 C) evidence points to lower inputs to SOC compared 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

9 WFC 09

10 biomass soil organic matter forest floor (+) (-) (?, but possibly ++)

11 WFC 09 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 Biology Jackson et al. 2005 – Science Farley et al. 2006 – Global Change Biology Nosetto et al. 2008 – Global Biogeochemical Cycles trade-off 1: water

12 WFC 09 biomass soil organic matter forest floor High Ca demand, sequestration, and export leads to soil acidification. eucalypts >> pines wet & sandy/weathered contexts: stream acidification Jobbágy & Jackson 2003 – Biogoechemistry Jobbágy & Jackson - Ecology Berthrong et al. 2008 – Ecological Applications Farley et al. 2008 – Water Resources Research Piñeiro et al. unpublished data Review of paired soil studies (plantation vs. grassland) trade-off 2: calcium redistribution

13 WFC 09 Guess where our best C stock is

14 WFC 09 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=rS

15 WFC 09 Aplicación 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 EstratoIngreso (I)t renov. (1/k) (cm)(KgC/Ha/año)(años) CastelliGuerreroCastelliGuerrero 0-5.47724010680 5-10.147109181194 10-20.276103242206 20-35.NC63NC144 35-50.NC38NC117 50-75.NC41NC236 75-100.NC