The particularities of the growth of Siberian fir (Abies sibirica Ledeb.) in the first stages of ontogeny in conifer forests (Ufa plateau, Pre-Ural)

Abstract

Fir undergrowth under forest canopy forms the xylorhizome, which allows a long time to exist in pessimal conditions and to compete with nemoral species. This work is devoted to studying features of Siberian fir (Abies sibirica Ledeb.) in the first stages of ontogeny in different forest conditions. We have shown that in determining biological (exact) age of the plant, researchers should consider the xylorhizome formation. While studying the growth dynamics of the shoot, we identified three periods of accelerated growth, which correspond to increased competition from different layers of grassy vegetation. The change in fir growth rates was associated with the growth of the lateral and pseudo-whorl shoots, leading to the increased assimilating surface of the needles. These regularities of growth and development of fir in the first stages of ontogeny reflect specific adaptations of fir that allow this species to compete with understory nemoral species. The xylorhizome formation is one of the structural–functional adaptations for the ontogeny protection, allowing to fir undergrowth a long time exist in pessimal conditions under the forest canopy.