New Biological Rhythm in Cambia of Trees – “Music of Trees” Revisited 50 Years After the Discovery of Cambial Morphogenetic Waves

Abstract

Among periodic patterns having origin in cambium and recorded in figured wood, the tangential waviness has been the first to be discovered and thoroughly characterized. Yet another pattern, manifested in the rippled surface of some tree trunks, has remained basically undescribed. This work is the first attempt to provide information on its morphology, dynamics, and relation to the tangential waviness. Developmental analysis of the annual ring widths on the transverse surface of the stem showed that crests and throughs forming a ripple pattern result from a highly controlled proliferation of cambial cells. These cells’ activity regularly oscillates in time and space between an increased and a reduced state at approximately 10-year intervals, independently of the environmental cues considered in dendrochronological studies. This rhythm leads to the development of radial waviness and is a major factor affecting wood ring width. Radial waviness is dynamic; it propagates along the stem axis and is often synchronized with tangential waviness in a nonrandom manner. Possible causes of radial pattern emergence based on auxin waves, the role of other phytohormones, and recent discoveries of MADS-box genes that regulate cambial cell proliferation are discussed.