Common garden trial reveals altitudinal differentiation in phenology among populations of a southern beech.

EL MUJTAR, V.; PASTORINO, M.J,; DUBOSCQ-CARRA VG; LETOURNEAU F; ARIAS RIOS, JA; MARCHELLI P

Bariloche

Conferencia; International Conference ?Adapting forests ecosystems and wood products to biotic and abiotic stress?; 2019

INTA - INRA

Phenological traits are crucial for understanding adaptation to climate change due to their genetic control and association with abiotic factors. In temperate forest trees, phenology is driven by a balance between survival and productivity. Nothofagus alpina is a key species of the temperate forests of Patagonia, very appreciated for its high wood quality. We aimed to analyze the variation among and within natural populations of N. alpina in two phenological traits: bud burst and foliar senescence, which determine the longitude of the growing and productive period of the plants, and also studied the relation of those variables with the seasonal growth. We registered phenology in 86 open pollinated families of eight Argentinean natural populations installed in a common garden trial. Apical buds and foliar senescence were observed every three days in 6-years-old (6YO) plants (N= 453), and again three years later (9YO) in the same plants. Julian days (JD) until bud burst (BB) and the beginning and the end of foliar senescence were measured. Degree days to BB were calculated with a basal temperature equal to 7°C. All variables were analyzed by a linear mixed effects model. Significant differences among populations and years in JD to BB were found. The family factor explained 16 % of the total variance. Analysis in 9YO plants showed a similar variation pattern and correlation between lateral and apical buds, what allows following bud phenology through lateral buds in tall trees. The analyzed models for foliar senescence did not show significant differences among populations but the family factor was significant, although they only explained a minimum part of the total variance (beginning of senescence: 3 %; end of senescence: 1 %). Analysis in terms of degree days are still missing, but preliminary analyses show that degree days varied among populations but not between years. The correlation between the altitude from the original site of each population and the mean JD to BB was high and positive. These results reveal the genetic control of BB phenology and the importance of using different populations and families to plant N. alpina at different sites. We will also analyze the relationship between the seasonal growth in height and diameter and the longitude of the vegetative period.