Masting creates sex-specific growth patterns in Araucaria araucana tree-rings

HACKET-PAIN, ANDREW; HADAD, MARTÍN A.; FIDEL A. ROIG; ARCO MOLINA, JULIETA

Lund

Congreso; TREE RINGS IN ARCHAEOLOGY, CLIMATOLOGY AND ECOLOGY (TRACE 2021); 2021

University of Lund

Araucaria araucana is a dioecious evergreen conifer endemic to temperate forests of South America. It is a long-lived species (maximum age > 1000 years), with high potential for tree-ring based climate reconstructions. However, the species' dioecious habit (individuals are either male or female) is associated with distinct sex-specific growth patterns. This introduces novel challenges in the interpretation of their tree-ring chronologies. We used a network of 10 chronologies from northwest Patagonia (Argentina) to analyse sex-specific growth patterns in A. Araucana. For the first time, we show that differences in the growth patterns of male and female trees resulted from their contrasting responses to mast events (years with high seed production). During mast events, the growth of females was strongly and significantly reduced relative to male trees. A growth response of similar magnitude was found in male trees in the previous year, corresponding to the year of pollination. The sex-specific growth responses associated with mast events resulted in a strong and distinct signal in a RWI male-RWI female chronology. Despite masting-related differences, male and female tree-ring chronologies shared a strong common climate signal. Our results indicate that sex-specific tree-ring signals can be leveraged to isolate mast events in A. araucana chronologies, providing an opportunity to develop multi-century reconstructions of large mast events, and improve dendroclimatic calibration for this species.