Seed response to temperature of three Nothofagus species distributed across an altitudinal gradient in the South Andes

ARANA VERONICA; GONZALES-POLO M; MARTINEZ-MEIER A; GALLO, L; SANCHEZ RODOLFO; ROBERTO LUIS BENECH-ARNOLD; DIEGO BATLLA

Mar del Plata

Congreso; XXIX Reunión Argentina de Fisiología Vegetal; 2012

Sociedad Argentina de Fisiología Vegetal

Seed germination is the earliest event in plant life cycle, and therefore it constitutes a relevant process for adaptation since it sets the environmental context for subsequent development and natural selection. Across the South Andes Mountains, it is possible to distinguish several environmental gradients although the pluviometric and altitudinal ones are probably exerting the stronger influence in the distribution and abundance of the tree species of the region. In the western Andes, three Nothofagus species, N. obliqua (Roble), N. nervosa (Raulí), and N. pumilio (Lenga) are distributed across a clear altitudinal range; Roble: 600-900 meters over the sea level (msl), Raulí: 800-1100 msl and Lenga: 1000-1700 msl. Temperature is the environmental factor that shows the stronger association with altitude, suggesting the existence of different thermal niches. The aim of this work is to study germination behavior of Roble, Raulí and Lenga, in order to evaluate the possible contribution of this trait to the species’ distribution across the altitudinal range. Using a threshold modeling approach, we compared thermal population parameters between species, as indicative of differential responses of seeds to temperature. In addition, we studied dormancy loss in the field, to validate the models and unravel differences in seed behavior between these species’ under natural conditions. Data will be discussed in the context of possible adaptation in germination to thermal environments and its potential contribution to emergence patterns across the altitudinal range.