Climate change-related growth improvements in a wide niche-breadth tree species across contrasting environments

FAJARDO, ALEX; GAZOL, ANTONIO; MEYNARD, PAULO MORENO; MAYR, CHRISTOPH; MARTÍNEZ PASTUR, GUILLERMO J; PERI, PABLO L; CAMARERO, J JULIO

ANNALS OF BOTANY

OXFORD UNIV PRESS

Año: 2023 vol. 131 p. 941 - 951

0305-7364

• Background and Aims The vulnerability and responsiveness of forests to drought are immensely variable acrossbiomes. Intraspecific tree responses to drought in species with wide niche breadths that grow across contrasting climaticallyenvironments might provide key information regarding forest resistance and changes in species distributionunder climate change. Using a species with an exceptionally wide niche breath, we tested the hypothesis thattree populations thriving in dry environments are more resistant to drought than those growing in moist locations.• Methods We determined temporal trends in tree radial growth of 12 tree populations of Nothofagus antarctica(Nothofagaceae) located across a sharp precipitation gradient (annual precipitation of 500–2000 mm) in Chileand Argentina. Using dendrochronological methods, we fitted generalized additive mixed-effect models to predictthe annual basal area increment as a function of year and dryness (De Martonne aridity index). We also measuredcarbon and oxygen isotope signals (and estimated intrinsic water-use efficiency) to provide potential physiologicalcauses for tree growth responses to drought.• Key Results We found unexpected improvements in growth during 1980–1998 in moist sites, while growthresponses in dry sites were mixed. All populations, independent of site moisture, showed an increase in their intrinsicwater-use efficiency in recent decades, a tendency that seemed to be explained by an increase in the photosyntheticrate instead of drought-induced stomatal closure, given that δ18O did not change with time.• Conclusions The absence of drought-induced negative effects on tree growth in a tree species with a wideniche breadth is promising because it might relate to the causal mechanisms tree species possess to face ongoingdrought events. We suggest that the drought resistance of N. antarctica might be attributable to its low stature andrelatively low growth rate.