Unraveling the origin behind the stem CO2 efflux in Quercus ilex and Quercus faginea trees
Researcher:
Ferrio Díaz, Juan Pedro
Congress:
XVI Congreso Nacional de la AEET
Participation type:
Comunicación oral
Other authors:
Ana López-Ballesteros (speaker); José Javier Peguero-Pina; José Victor dos Santos Silva; Rubén Martín-Sánchez; Domingo Sancho-Knapik; Eustaquio Gil-Pelegrín; Juan Pedro Ferrio
Year:
2023
Location:
Almería
Publication:
Ana López-Ballesteros (speaker); José Javier Peguero-Pina; José Victor dos Santos Silva; Rubén Martín-Sánchez; Domingo Sancho-Knapik; Eustaquio Gil-Pelegrín; Juan Pedro Ferrio. Unraveling the origin behind the stem CO2 efflux in Quercus ilex and Quercus faginea trees. Comunicación oral presentada en el XVI Congreso Nacional de la AEET (Almería, 6-20 octubre 2023)
The contribution of stem respiration to the overall forest carbon balance is currently uncertain due to the difficulty to directly measure it. Recent research has demonstrated that not all the CO2 produced by respiration in woody tissues escapes immediately to the atmosphere. Instead, it can be partially stored inside in the tree or dissolved and transported within the xylem. Furthermore, the CO2 respired within soil by heterotrophs can even move upwards and contribute to the measured CO2 efflux at a given height of the tree stem. In order to disentangle this complex process, we have developed an automated system to quantify and trace the metabolic origin of stem CO2 efflux. This system is composed by dynamic steady-state stem chambers were the CO2 efflux and its 13C and 18O stable isotopes are measured in real time together with plant transpiration, photosynthetic active radiation, vapor pressure deficit, and soil, stem, and air temperature.
By using this system, we have investigated stem respiratory fluxes of two Quercus species with contrasting traits that are extensively distributed across the Iberian Peninsula, Quercus ilex subsp. rotundifolia and Quercus faginea. While the evergreen Quercus ilex subsp. rotundifolia has a water-saver strategy with greater stomatal conductance regulation, the deciduous Quercus faginea can reach high transpiration rates even under stress conditions. Given that the CO2 transport within and outside the stem depends on xylem sap velocity and morphology of woody tissues, we hypothesize that both the magnitude and isotope signal of stem CO2 efflux will differ between species as well as its relationship with ambient variables.
In this work, we will present preliminary results of a mesocosm experiment we performed in autumn 2022 to test our hypothesis, where we monitored three trees of each species under a broad range of ambient conditions.
The contribution of stem respiration to the overall forest carbon balance is currently uncertain due to the difficulty to directly measure it. Recent research has demonstrated that not all the CO2 produced by respiration in woody tissues escapes immediately to the atmosphere. Instead, it can be partially stored inside in the tree or dissolved and transported within the xylem. Furthermore, the CO2 respired within soil by heterotrophs can even move upwards and contribute to the measured CO2 efflux at a given height of the tree stem. In order to disentangle this complex process, we have developed an automated system to quantify and trace the metabolic origin of stem CO2 efflux. This system is composed by dynamic steady-state stem chambers were the CO2 efflux and its 13C and 18O stable isotopes are measured in real time together with plant transpiration, photosynthetic active radiation, vapor pressure deficit, and soil, stem, and air temperature.
By using this system, we have investigated stem respiratory fluxes of two Quercus species with contrasting traits that are extensively distributed across the Iberian Peninsula, Quercus ilex subsp. rotundifolia and Quercus faginea. While the evergreen Quercus ilex subsp. rotundifolia has a water-saver strategy with greater stomatal conductance regulation, the deciduous Quercus faginea can reach high transpiration rates even under stress conditions. Given that the CO2 transport within and outside the stem depends on xylem sap velocity and morphology of woody tissues, we hypothesize that both the magnitude and isotope signal of stem CO2 efflux will differ between species as well as its relationship with ambient variables.
In this work, we will present preliminary results of a mesocosm experiment we performed in autumn 2022 to test our hypothesis, where we monitored three trees of each species under a broad range of ambient conditions.