Sex-related climate sensitivity of Araucaria araucana Patagonian forest-steppe ecotone

• The effect of dioecy on growth patterns and climate relationships in Araucaria araucana is assessed.
• Male trees are more sensitive to land precipitation during September of the current growing period while female trees are more sensitive to air surface temperature during the prior period of growth.
• Future intensification of climate change may be determinant in particular responses of tree growth, seed production, and tree recruitment.

Dioecious species offers the possibility to discern plant development in relation to sex. However, there is little information of the incidence of sex on tree-growth sensitivity to seasonal variations in climate. In this study we aim to examine the relationship between the climate and tree growth variability from Araucaria araucana inferred from independent male and female tree-ring chronologies derived from old growth forests growing on the xeric environments of NW Patagonia in Argentina. The analysis included 186 standing trees (93 males and 93 females) distributed in five forest stands. After applying a Generalized Linear Mixed Models (GLMMs), result suggests significant differences between tree-ring width related to both sex and climatic conditions. When considering the relationships between tree growth and climate, sensitivity of tree-ring variability to climate appeared to be sex-dependent. While male trees are more sensitive to land precipitation during part of the current growing period, female trees appears to be more sensitive to air surface temperature during the prior period of growth. At atmospheric circulation scales, male trees are more sensitive to the Southern Annular Mode index during the current period of growth. The reported differences in the sensitivity of the response to climate from both male and female trees can be attributed to different mechanisms in the use of the environmental resources. In relation to recent trends in climate experienced in northern Patagonia, these changes, if continued, may compromise the growth and reproductive fitness of the A. araucana forests.