Director Centro de Cambio Global UC Flujos de Vapor y Carbono: Avances en el monitoreo para la gestión de la huella ecológica en Agricultura Dr. Francisco J. Meza Director Centro de Cambio Global UC fmeza@uc.cl Tercer Seminario Regional Agricultura y Cambio Climático Septiembre , 2012

Source: Millenium Ecosystem Assessment

Regional and global trends in population (Upper Left), crop production (Upper Right), crop area (Lower Left), and fertilizer use (Lower Right), 1961–2005. Burney J A et al. PNAS 2010;107:12052-12057 ©2010 by National Academy of Sciences

Paradigma de una Intensificación Sostenible while emissions from factors such as fertilizer production and application have increased, the net effect of higher yields has avoided emissions of up to 161 gigatons of carbon (GtC) (590 GtCO2e) since 1961 Burney J A et al. PNAS 2010;107:12052-12057

Net Primary Productivity

Net Ecosystem Exchange Intercambio ( Flujo) de CO2 entre la atmósfera y el ecosistema Fotosintesis Respiración The exchange of carbon between the atmosphere and the ecosystem is known as net ecosystem exchange (NEE) at any particular point in time (Moncrieff et al., 2000). NEP and NEE are widely used as indicators of the amount of carbon accumulated or lost (medium-term storage) by an ecosystem. However, not all these carbon remain NEP = Net ecosystem productivity= (-)NEE

Huella del agua de un producto Huella Verde ► Volumen de agua de lluvia evaporado o incorporado en el producto. Huella Azul ► Volumen de agua superficial o subterránea evaporado, incoporado en el producto o retornado en otra área o en el mar. Huella Gris ► Volumen de agua contaminado en el proceso de producción. Green water footprint – Volume of rainwater consumed during the production process. This is particularly relevant for agricultural and forestry products (products based on crops or wood), where it refers to the total rainwater evapotranspiration (from fields and plantations) plus the water incorporated into the harvested crop or wood. Blue water footprint – Volume of surface and groundwater consumed as a result of the production of a good or service. Consumption refers to the volume of freshwater used and then evaporated or incorporated into a product. It also includes water abstracted from surface or groundwater in a catchment and returned to another catchment or the sea. It is the amount of water abstracted from groundwater or surface water that does not return to the catchment from which it was withdrawn. Grey water footprint – The grey water footprint of a product is an indicator of freshwater pollution that can be associated with the production of a product over its full supply chain. It is defined as the volume of freshwater that is required to assimilate the load of pollutants based on natural background concentrations and existing ambient water quality standards. It is calculated as the volume of water that is required to dilute pollutants to such an extent that the quality of the water remains above agreed water quality standards. Source: Hoekstra, A.Y., Chapagain, A.K., Aldaya, M.M. and Mekonnen, M.M. (2011) The water footprint assessment manual: Setting the global standard, Earthscan, London, UK. See page 187, 189, 190. 7

Calculando entonces, la Huella Verde es: Donde: H: Huella Hídrica (m3/ha/Unidad de Producción) ET: Evapotranspiración del cultivo (mm) RHC: Requerimientos hídricos del cultivo (mm/ha) PPef: Precipitación efectiva (mm)

Y la Huella azul… Donde: Blue water use refers to the volume of irrigation water (withdrawn from surface or ground water) that evaporates from a crop field during the growing period. The distinction between green and blue water has been introduced by Malin Falkenmark, Swedish hydrologist. Donde: H: Uso de agua por el cultivo (m3/ha/Unidad de producción) RR: Riego (mm/ha) RRef: Riego efectivo

Requerimientos del Cultivo Método de Penmann-Monteith Modelos Otros

Flujo de Vapor/Evapotranspiración Gran Problema es que en pocas circunstancias se mide el flujo de vapor Ecuación de Penman Monteith es la más completa desde el punto de vista teórico, pero al momento de aplicarla la llevamos a su nivel más simple ETo El uso de estaciones meteorológicas automáticas permite el cálculo de ETo (pero no la medición de la ET)

Medidas Directas

Medidas Directas

Medidas Directas

Metodología Eddy Covariance Ampliamente usada para medición de flujos de gas y energía en la atmósfera. (Capa Límite). Método de medición directo, no afecta el medio de medición. Matemáticamente complejo y requiere de instrumental sofisticado

Cierre Balance Energético La formulación y justificación del EBC radica en la primera ley de la termodinámica adaptada por los micrometeorólogos y que estipula que la energía incidente sobre un ecosistema debe ser transformada y/o utilizada en distintos procesos que ocurren en el ecosistema. LE H Rn EBC ha sido aceptado como uno de los más importantes para validar los datos de eddy covariance, por lo que su aplicación resulta formar un procedimiento estándar en la aplicación de esta metodología S the rate of change of heat storage (air and biomass) between the soil surface and the level of the eddy covariance instrumentation, and Q the sum of all additional energy sources and sinks. (Wilson et al., 2002) Respiración Asimilación CO2 G (Wilson et al., 2002)

Fundamentos Campbell Sci, 2006.

Capa límite atmosférica Atmospheric Boundary Layer (ABL) The lowest layer of the atmosphere that is in direct contact with Earth’s surface. Conditions and processes within the ABL will react to changes at the surface within a period of less than an hour and within a distance of less than 100 km Troposfera libre zi = 1400 m Capa de Mezcla Eddy por convección térmica 4.5 ms-1 Schmidt H. 2003. Micrometeorology, Biosphere-Atmosphere Exchange. Teachers Notes, Indiana University . Tarong, Queensland (AUS), stack height: 210 m, zi = 1400 m, w* = 2.5 ms-1. Photo: Geoff Lane, CSIRO (AUS)

Flujo turbulento Baldocchi, D. 2001. Wind and Turbulence, Surface Boundary Layer. Teachers Note. University of California, Berkeley.

Burba and Anderson, 2003. Burba and Anderson, 2003. Introduction to the Eddy Covariance method, General Guidelines and Conventional Workflow. Li-Cor Bioscience.

Instrumentación Anemómetro Sónico Open path Gas Analyzer Higrómetro Termocupla Datalogger

Cierre del Balance de Energía

Flujos de CO2/Intercambio de Carbono -182.9gC m-2 y-1≈1.829tC ha-1 y-1 In temperate ecosystems, seasonal trend in CO2 exchange (FN) follows the seasonal cycle of the sun, with qualifications. In temperate coniferous forests, seasonal patterns of FA and FR are in phase, causing FN to peak (most negative values, indicating uptake) when FA and FR do. In cold regions, temperate conifer forests lose carbon in the winter and gain it during the frostfree, growing season. And in milder regions, such as the Pacific North-west, south-western France and the south-eastern part of the United States, temperate conifer forests can be net carbon sinks year-round. In contrast, FR is delayed compared with FA in temperate deciduous and boreal coniferous forests. This lag is attributed to cold spring-time soils, which restrict FR and enable FN to be most negative then. Arid and semi-arid systems, such as Mediterranean and tropical savannas and annual grasslands, are water-limited. Consequently, the most negative rates of net carbon exchange occur during the wet winter and spring in Mediterranean-type climates and during the summer wet period for tropical savannas. Perennial grasslands, growing in temperate climates, experience summer rainfall, so their annual cycle of carbon exchange is moderated by the freeze-free period of the year, changes in leaf area index and vapour-pressure deficits. The greatest rates of carbon uptake occur for C4, C3 and mixed C3–C4 grasslands during the summer growing season. Agricultural crops achieve the highest short-termrates of carbon uptake. But, ironically, their net annual uptake is not the greatest. Spring-sown crops, such as soybeans and corn, experience a short season of effective net carbon uptake because they must grow from seed The ranking of FN, at annual time scales, is not explained well by variations in climate variables, plant functional type or photosynthetic potential (Law et al. 2002; Arain and Restrepo- Coupe 2005; van Dijk et al. 2005; Reichstein et al. 2007b). A step-wise, multiple regression analysis revealed that only 45% of the variance in annual FN, for forests across central and northern Europe, is explained by a combination of sunlight, leaf area index and air temperature (van Dijk et al. 2005). More productive ecosystems (those with greater values of FA), which occur under wetter and warmer climates, do not necessarily produce large values of FN because FR scales linearly with available light, moisture and temperature (Arain and Restrepo-Coupe 2005; van Dijk et al. 2005; Reichstein et al. 2007b). This point is illustrated with data in Fig. 5,which shows that variations inFA explain only 42% of the variation in FN. Consequently, it is better to partition FN into its components FA and FR, and relate the components to abiotic and biotic drivers, as is shown below. Baldocchi, 2008 FN <0 representan una pérdida de CO2 de la atmósfera y ganancia por la superficie en estudio (Hutley et al. 2005; Baldocchi et al. 2001; Paw U et al. 2004; Sellers et al. 2010)

Sitio de Estudio Ubicación geográfica: (33°02'S 70°44'O 660 m.s.n.m), Clima Mediterráneo Suelo franco arcilloso, C:N = 12 Precipitación Media: 233 mm T° media: 15.6 Pp 2010: 132mm Pp 2011 : 103 mm El sitio de estudio se encuentra en la Región Metropolitana de Chile, 33º02'S 70º44'O 660 m.s.n.m.

Eddy Covariance Adaptación de Burba and Anderson, 2010.

Resultados (Bravo et al., in prep)

Otros Ejemplos Comparison between estimated (LEe) and observed (LEo) latent heat flux over a drip-irrigated Merlot vineyard. The solid line represents the 1:1 line. S. Ortega-Farias , C. Poblete-Echeverr?a , N. Brisson Parameterization of a two-layer model for estimating vineyard evapotranspiration using meteorological measurements Agricultural and Forest Meteorology Volume 150, Issue 2 2010 276 - 286

Desafíos Nuevas Hipótesis: Cómo las fluctuaciones climáticas (Tº,pp, Rn) bajo ciertas condiciones (sequías, heladas, eventos extremos), afectan el flujo de CO2 y la fotosíntesis. (Baldocchi, 2008) Medición de otros gases traza en la atmósfera. Combinar métodos: LIDAR, mediciones aéreas. Expansión de redes de medición para mediciones globales: distintos ambientes y países…