Ana I García-Cervigón1, Alex Fajardo2, Cristina Caetano-Sánchez3, J Julio Camarero4, José Miguel Olano5. 1. Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, Móstoles, Spain. 2. Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Camino Baguales s/n, Coyhaique, Chile. 3. Departamento de Biología-IVAGRO, Universidad de Cádiz, Campus Río San Pedro s/n, Puerto Real, Spain. 4. Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Montañana, Zaragoza, Spain and. 5. iuFOR-EiFAB, Universidad de Valladolid, Campus Duques de Soria, Soria, Spain.
Abstract
BACKGROUND AND AIMS: Plants have the potential to adjust the configuration of their hydraulic system to maintain its function across spatial and temporal gradients. Species with wide environmental niches provide an ideal framework to assess intraspecific xylem adjustments to contrasting climates. We aimed to assess how xylem structure in the widespread species Nothofagus pumilio varies across combined gradients of temperature and moisture, and to what extent within-individual variation contributes to population responses across environmental gradients. METHODS: We characterized xylem configuration in branches of N. pumilio trees at five sites across an 18° latitudinal gradient in the Chilean Andes, sampling at four elevations per site. We measured vessel area, vessel density and the degree of vessel grouping. We also obtained vessel diameter distributions and estimated the xylem-specific hydraulic conductivity. Xylem traits were studied in the last five growth rings to account for within-individual variation. KEY RESULTS: Xylem traits responded to changes in temperature and moisture, but also to their combination. Reductions in vessel diameter and increases in vessel density suggested increased safety levels with lower temperatures at higher elevation. Vessel grouping also increased under cold and dry conditions, but changes in vessel diameter distributions across the elevational gradient were site-specific. Interestingly, the estimated xylem-specific hydraulic conductivity remained constant across elevation and latitude, and an overwhelming proportion of the variance of xylem traits was due to within-individual responses to year-to-year climatic fluctuations, rather than to site conditions. CONCLUSIONS: Despite conspicuous adjustments, xylem traits were coordinated to maintain a constant hydraulic function under a wide range of conditions. This, combined with the within-individual capacity for responding to year-to-year climatic variations, may have the potential to increase forest resilience against future environmental changes.
BACKGROUND AND AIMS: Plants have the potential to adjust the configuration of their hydraulic system to maintain its function across spatial and temporal gradients. Species with wide environmental niches provide an ideal framework to assess intraspecific xylem adjustments to contrasting climates. We aimed to assess how xylem structure in the widespread species Nothofagus pumilio varies across combined gradients of temperature and moisture, and to what extent within-individual variation contributes to population responses across environmental gradients. METHODS: We characterized xylem configuration in branches of N. pumilio trees at five sites across an 18° latitudinal gradient in the Chilean Andes, sampling at four elevations per site. We measured vessel area, vessel density and the degree of vessel grouping. We also obtained vessel diameter distributions and estimated the xylem-specific hydraulic conductivity. Xylem traits were studied in the last five growth rings to account for within-individual variation. KEY RESULTS: Xylem traits responded to changes in temperature and moisture, but also to their combination. Reductions in vessel diameter and increases in vessel density suggested increased safety levels with lower temperatures at higher elevation. Vessel grouping also increased under cold and dry conditions, but changes in vessel diameter distributions across the elevational gradient were site-specific. Interestingly, the estimated xylem-specific hydraulic conductivity remained constant across elevation and latitude, and an overwhelming proportion of the variance of xylem traits was due to within-individual responses to year-to-year climatic fluctuations, rather than to site conditions. CONCLUSIONS: Despite conspicuous adjustments, xylem traits were coordinated to maintain a constant hydraulic function under a wide range of conditions. This, combined with the within-individual capacity for responding to year-to-year climatic variations, may have the potential to increase forest resilience against future environmental changes.
Authors: Alex Fajardo; Cecilia Martínez-Pérez; María Angélica Cervantes-Alcayde; Mark E Olson Journal: New Phytol Date: 2019-11-28 Impact factor: 10.151
Authors: Patrizia Trifilò; Piera M Barbera; Fabio Raimondo; Andrea Nardini; Maria A Lo Gullo Journal: Tree Physiol Date: 2014-01-30 Impact factor: 4.196
Authors: José M Olano; Noelia González-Muñoz; Alberto Arzac; Vicente Rozas; Georg von Arx; Sylvain Delzon; Ana I García-Cervigón Journal: Tree Physiol Date: 2017-11-01 Impact factor: 4.196
Authors: Ana I García-Cervigón; María A García-López; Nuria Pistón; Francisco I Pugnaire; José Miguel Olano Journal: Ann Bot Date: 2021-06-24 Impact factor: 4.357