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.

在温带山区，树木的大小和生长习性的垂直变化趋势是通过逐步调整多种性状以适应海拔高度的苛刻条件而发展起来的。我们用Nothofagus pumilio的两个看台上的幼苗进行普通的花园试验：低海拔高大森林（1200 m asl）与高海拔灌木丛森林（1560 m asl），以确定在森林中观察到的相反生长习惯是否具有遗传基础，该遗传基础在幼树生命阶段表达。评估了生长习惯综合征，包括大小，物候，生长节律和建筑特征。矮矮胖胖的原型，即带有共轴的小型密集分支植物，在海拔较高的植物之间更为常见。取而代之的是，低位植物在植物之间普遍存在较大的单茎细长形态型。海拔梯度的两个极端之间的这些相反频率可以通过多个潜在特征的累积效应差异来解释，从而提供线索，可以确定是否存在遗传确定的N. pumilio习性。。根据我们的发现，我们建议未来的N. pumilio遗传变异研究系统的采样策略应沿其分布包含多个海拔梯度。同时，纵向分区似乎是正在进行的恢复计划的预防性建议。