Evidence of genetic determination in the growth habit of Nothofagus pumilio (Poepp. & Endl.) Krasser at the extremes of an elevation gradient

ABSTRACT

In temperate mountainous regions, altitudinal clines in tree size and growth habit develop from a gradual adjustment of multiple traits to tolerate harshening conditions with altitude. We perform a common garden trial with seedlings from two stands of Nothofagus pumilio: low altitude, tall forest (1200 m a.s.l) vs. high altitude, shrubby forest (1560 m a.s.l), to determine whether the contrasting growth habits observed in the forest have a genetic basis, which expresses in the juvenile tree life stage. Growth habit syndrome was assessed including size, phenology, growth rhythm and architecture traits. Shrubby archetypes, i.e. small densely-branched plants with codominant axes, were more frequent between plants from higher altitude. Instead, large single-stemmed, slender morphotypes prevailed between plants from the lower stand. These contrasting frequencies between both extremes of the elevation gradient could be explained by differences in cumulative effects in multiple underlying traits, giving clues that there could be genetic determination in the growth habit of N. pumilio. Based on our findings, we recommend that the sampling strategy of future study systems of N. pumilio genetic variation, should encompass multiple elevation gradients along its distribution. Meanwhile, altitudinal zoning seems a precautionary advice for ongoing restoration plans.

KEYWORDS:

• Cold adaptation
• phenology
• tree architecture
• southern beeches

Acknowledgements

We thank Mario Huentú for his technical assistance in the nursery, Nahuel Huapi National Park authorities for granting us permission to carry out seed collection, M. Victoria Lantschner for the preparation of the map of the studied area, Javier Puntieri for kindly providing the plant drawing and María Marta Azpilicueta for valuable comments on an early version of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

CS and AGA conceived and designed the research, performed the data collection and wrote the manuscript. AGA lead the statistical analyses.

Availability of data and materials

The datasets analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This work was funded by the National Forest Program of INTA (Instituto Nacional de Tecnología Agropecuaria); specific project PNFOR 1104063 “Domestication of native forest tree species.”