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Plants adjust leaf water potential and hydraulic conductance when confronted with drought, reducing sap-flow and protecting their tissues from extensive water loss. Leaf and xylem water potentials directly influence cell turgor pressure, affecting in turn xylem cell division and differentiation and thus stem radial growth and xylem structure. Potential xylem hydraulic conductivity, on the other hand, depends mainly on the size and number of conduits. Xylem formation at the beginning of the vegetative period may thus have long-lasting consequences for whole canopy water and carbon fluxes throughout the rest of the year, as proper xylem formation is essential for sufficient supply of water to the canopy. Understanding how xylem formation and anatomical features interplay with water fluxes in their response to climatic conditions is therefore essential to improve models on the water flux-growth-climate interaction and assess trees’ responses to climate change. The objective of our research is to study the coupling between xylem formation and tree water fluxes in Fagus sylvatica L., by easuring the intra-annual dynamics of xylem production using wood- formation-monitoring techniques, stem water movement using sap-flow sensors and carbon and water flux measurements from an Eddy covariance flux tower located at the long-term monitoring site Hesse (Lorraine, France). The measurements are related to meteorological data to assess the relationships between environmental factors and intra-annual dynamics of the assessed traits. The proposed research will provide, moreover, new insights into the biological processes governing the water cycle of an ecosystem, improving our understanding of its responses to drought in the short (growth dynamics), medium (legacy effects), and long term (forest functioning). Such information is essential to further develop dynamic vegetation models, to improve the representation of climate- water and climate-carbon interactions and, therefore, better simulate the impact of climatic change on the terrestrial biosphere.
Throughout my research career I have developed a great interest in understanding how environmental factors, particularly drought, drive tree physiology, phenology and overall tree performance, as this knowledge is essential to assess species and, thus, forest response to ongoing changing environmental conditions. I earned a Master of Forest Conservation from the University of Toronto (Canada) in 2009 and a PhD in Ecology, Ecosystem Conservation and Restoration from the University of Alcalá (Spain) in 2016. I hold my PhD thesis at the Forest Research Center (INIA-CIFOR, Spain) together with short-term research visits at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL, Switzerland), the Los Alamos National Laboratory (USA), the Université du Québec à Chicoutimi (Canada) and the Centre de Recherche et d’Enseignement de Géosciences de l’Environnement (CEREGE, France). It focused on the physiological response of trees to climate and competition at different temporal scales, from intra-annual growth dynamics and instantaneous leaf gas exchange to long-term tree-ring growth and δ13C trends.
As an AgreenSkills+ postdoctoral fellow at INRA Grand EstNancy, I am currently studying the feedbacks among xylem formation and anatomy, tree water fluxes and climatic factors.
Fernández de Uña L., Aranda I., Rossi S., Fonti P., Cañellas I., Gea-Izquierdo G. (2018) Divergent phenological and leaf gas exchange strategies of two competing tree species drive contrasting responses to drought at their altitudinal boundary. Tree Physiology, 38: 1152-1165
Fernández de Uña L., Rossi S., Aranda I., Fonti P., González-González B.D., Cañellas I., Gea-Izquierdo G., 2017. Xylem and leaf functional adjustments to drought in Pinus sylvestris and Quercus pyrenaica at their elevational boundary. Frontiers in Plant Science, 8: 1200.
Fernández de Uña L., McDowell N.G., Cañellas I., Gea-Izquierdo G., 2016. Disentangling the effect of competition, CO2 and climate on intrinsic water-use efficiency and tree growth. Journal of Ecology, 104: 678-690.
Fernández de Uña L., Cañellas I., Gea-Izquierdo G., 2015. Stand competition determines how different tree species will cope with a warming climate. PLoS ONE: 10(3): e0122255.
Gea-Izquierdo G., Fernández de Uña L., Cañellas I., 2013. Growth projections reveal local vulnerability of Mediterranean oaks with rising temperatures. Forest Ecology and Management, 305: 282-293.