Extreme drought triggers parallel shifts in wood anatomical and physiological traits in upper treeline of the Mediterranean Andes

• Autores: Santini, Luiz; Craven, Dylan; Ortega Rodríguez, Daigard Ricardo; Quintilhan, Manolo Trindade; Gibson Carpintero, Stephanie; Aravena Torres, Cristina; Roig Junent, Fidel Alejandro; Muñoz, Ariel A.; Venegas Gonzalez, Alejandro
• Año de publicación: 2024
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: DENDROANATOMY; XYLEM VULNERABILITY; DROUGHT; CLIMATE CHANGE
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Background Treeline ecotones of Mediterranean ecoregions have been affected by the increasing intensity and severity of droughts. Even though the effect of droughts on forest dynamics has been widely documented, knowledge is relatively scarce of how extreme climate episodes affect the hydraulic structure and, therefore, the phys‐ iology of woody plants. The Mediterranean Andes have experienced an uninterrupted period of drought since 2010, including an extremely dry year in 2019 with approximately 80% rainfall deficit. Here, we investigated shifts in wood anatomical and physiological traits of Kageneckia angustifolia, an endemic treeline species, in response to this drought period.Methods We evaluated the xylem plasticity of three K. angustifolia populations across their natural distribution (31–35° SL) based on anatomical (vessel structure and distribution) and physiological (intrinsic water‐use efficiency) variables in the tree rings. We focused on the period 2000–2020 that corresponds to before the megadrought (2000– 2007), (ii) megadrought (2008–2018) and (iii) hyperdrought (2019–2020). The variables were annualized and analyzed by linear mixed‐effects models.Results Our results provide insights to the anatomical and physiological mechanisms underlying the resilience of treeline forests to persistent droughts in central Chile. We found that the extreme drought in 2019–2020 triggered shifts in vessel size and frequency that increased hydraulic safety. These significant shifts in vessel traits occurred in parallel with a decrease in pit aperture area and an increase in water‐use efficiency, further increasing the resilience of K. angustifolia to extreme drought stress.Conclusions Our results revealed coordinated shifts in vessel size and frequency and water‐use efficiency in response to the megadrought, thereby reducing vulnerability to hydraulic failure. The apparent resilience of K. angustifolia to extreme droughts suggests that this adaptation to drought stress may increase its ability to tolerate novel climatic conditions of treeline environments of the Mediterranean Andes, although it is not clear whether these adaptations will be sufficient to persist in scenarios that predict intensification of climate stress. Finally, our results provide empirical evidence that integrating wood anatomical and physiological traits facilitates the understanding of resilience mechanisms that treeline forests develop in the face of increasing drought stress.
Fil: Santini, Luiz. Universidad Mayor; Chile
Fil: Craven, Dylan. Universidad Mayor; Chile
Fil: Ortega Rodríguez, Daigard Ricardo. Universidade do Sao Paulo. Escola Superior de Agricultura Luiz de Queiroz; Brasil
Fil: Quintilhan, Manolo Trindade. Universidade Estadual de Campinas. Instituto de Biología; Brasil
Fil: Gibson Carpintero, Stephanie. Universidad Nacional Autónoma de México; México
Fil: Aravena Torres, Cristina. Universidad Mayor; Chile
Fil: Roig Junent, Fidel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina
Fil: Muñoz, Ariel A.. Pontificia Universidad Católica de Valparaíso; Chile
Fil: Venegas Gonzalez, Alejandro. Universidad Mayor; Chile. Universidad Bernardo O? Higgins;