Storeyed structure of cambium as an adaptive strategy to environmental conditions in trees forming the canopy and the emergent layer of the tropical rain forests

Abstract

In a given environment, organisms capable of optimizing the utilization of the resource available as a limiting factor, dominate. In tropical rainforests, during first few years of growth of trees light is a limiting factor in understorey strata. The individuals that reach the canopy first, win the struggle for light. However the height of trees is limited by the mechanical properties of the trunk which depend on its anatomical structure, especially the structure of wood which in turn depends on the structure and activity of vascular cambium. High mechanical strength is provided by the interlocked grain of wood. The formation of interlocked grain is based on a fast cyclical change in orientation of the fusiform cambial initials. Such a fast cell rearrangement is possible only in the storeyed cambium. It is hypothesized that the presence of the storied cambium has an adaptative value for the fast growing trees. It seems to be an important evolutional achievement which facilitates fast cell rearrangement in the cambium without excessive expenditure of energy on such events as intensive intrusive growth, frequent oblique anticlinal divisions and rapid eliminations of excessive fusiform initials which are characteristic of a nonstoreyed cambium.