Growth and branching in Nothofagus alpina and Nothofagus obliqua (Nothofagaceae) under different light conditions

Growth and branching in Nothofagus alpine and Nothofagus oblique (Nothofagaceae) under different light conditions. Architectural traits of entire main branches and their growth units (GUs) were assessed for trees of Nothofagus alpine and N. oblique developed at three sites with different levels of natural shading (low: roadside, intermediate: nursery, and high: understory). The hierarchical structure of main branches was evaluated by means of: (1) the ratio between the diameters of the secondary branches and that of the parent main branch, and (2) the angles formed between secondary branches and main branches. Understory trees had GUs with less leaves and a thinner and shorter stem compared to those of trees at the less shaded sites. These differences were less notable for more recently-extended GUs. Branching systems became less hierarchical as they aged, but were not significantly different in their hierarchical structure among sites. Main branches of understory N. alpine and N. oblique trees may develop for years by producing small and scarcely branched GUs. Main branches of N. oblique trees tend to develop less hierarchical branching systems and to be more negatively affected by shading than those of N. alpine.