Progress and opportunities for monitoring greenhouse gases fluxes in Mexican ecosystems: the MexFlux network

Abstract

RESUMENPara entender los procesos de los ecosistemas desde un punto de vista funcional es fundamental entender las relaciones entre la variabilidad climática, los ciclos biogeoquímicos y las interacciones superficie-atmósfera. En las últimas décadas se ha aplicado de manera creciente el método de covarianza de flujos turbulentos (EC, por sus siglas en inglés) en ecosistemas terrestres, marinos y urbanos para medir los flujos de gases de invernadero (p. ej., CO 2 , H 2 O ) y energía (p. ej., calor sensible y latente). En diversas regiones se han establecido redes de sistemas EC que han aportado información científica para el diseño de políticas ambientales y de adaptación. En este contexto, el presente trabajo delimita el marco conceptual y técnico para el establecimiento de una red regional de medición de flujos de gases de efecto invernadero en México, denominada MexFlux, cuyo objetivo principal es mejorar nuestra comprensión de la forma en que la variabilidad climática y la transformación ambiental influye en la dinámica de los ecosistemas mexicanos ante los factores de cambio ambiental global. En este documento se analiza primero la importancia del intercambio de CO 2 y vapor de agua entre los ecosistemas terrestres y la atmósfera. Después se describe brevemente la técnica de covarianza de flujos turbulentos para la medición de éstos, y se presentan ejemplos de mediciones en dos ecosistemas terrestres y uno urbano en México. Por último, se describen las bases conceptuales y operativas a corto, mediano y largo plazo para la continuidad de la red MexFlux. 325-336 (2013) Atmósfera 26(3), 326 R. Vargas et al. ABSTRACTUnderstanding ecosystem processes from a functional point of view is essential to study relationships among climate variability, biogeochemical cycles, and surface-atmosphere interactions. Increasingly during the last decades, the eddy covariance (EC) method has been applied in terrestrial, marine and urban ecosystems to quantify fluxes of greenhouse gases (e.g., CO 2 , H 2 O) and energy (e.g., sensible and latent heat). Networks of EC systems have been established in different regions and have provided scientific information that has been used for designing environmental and adaptation policies. In this context, this article outlines the conceptual and technical framework for the establishment of an EC regional network (i.e., MexFlux) to measure the surface-atmosphere exchange of heat and greenhouse gases in Mexico. The goal of the network is to improve our understanding of how climate variability and environmental change influence the dynamics of Mexican ecosystems. First, we discuss the relevance of CO 2 and water vapor exchange between terrestrial ecosystems and the atmosphere. Second, we briefly describe the EC basis and present examples of measurements in terrestrial and urban ecosystems of Mexico. Finally, we describe the conceptual and operational goals at short-, medium-, and long-term scales for continuity of the MexFlux network.

A modeling approach reveals differences in evapotranspiration and its partitioning in two semiarid ecosystems in Northwest Mexico

“…[] described the precipitation, soil moisture, and vegetation at a nearby site, and detailed simulations have not been conducted at the site. Both the ST and MW EC systems form part of a growing network of flux measurements in Mexico [ Vargas et al ., ]. Figure shows the seasonal evolution of rainfall and surface soil moisture ( SM , top 10 cm) for the 2004–2009 summers in the ST and MW sites as bi‐weekly averages and ±1 standard deviations.…”

Contrasting precipitation seasonality influences evapotranspiration dynamics in water‐limited shrublands

“…In contrast, this hypothesis may not prevail at the WP site where there is a decoupling between precipitation and available energy (i.e., radiation and temperature) and has a longer rainy season characteristic of Mediterranean ecosystems [ Rana and Katerji , ]. The novelty of this study is that these hypotheses have not been simultaneously tested across sites at similar latitudes that are influenced by similar regional climate patterns [ Arriaga‐Ramírez and Cavazos , ] but with different timing of precipitation. Finally, this study represents the first collaborative effort toward syntheses studies across the MexFlux network [ Vargas et al ., , ].…”

Carbon fluxes above a deciduous forest in Greece

“…More detailed information about the partitioning of CO 2 flux in terrestrial ecosystems is given by Vargas et al (2013). CO 2 absorption was strongly related with R net and absorbed PAR, even in an hourly basis (Fig.…”

“…When soil moisture is adequate, increases in temperature (up to a certain level) enhance net CO 2 absorption (Sacks et al, 2007). Therefore, for the soil moisture effect on carbon fluxes, it is found that the changes in soil moisture, due to changes in precipitation patterns, can substantially affect carbon uptake by the ecosystems (Thomey et al, 2011;Vargas et al, 2012Vargas et al, , 2013.…”

“…The general principles of the technique are fully described in Burba and Anderson (2006) and a synoptic description is presented in Vargas et al (2013). The method uses simultaneous measurements from three dimensional wind velocity and gas analyzer data, allowing calculation of representative Table I.…”