Changes in the intensity of heartwood formation in Scots pine (Pinus sylvestris L.) ontogenesis

What is it about?

The formation of xylem structural elements (tracheids, axial and radial parenchyma cells) is a complex process that includes division of cambial initials, their growth by stretching, thickening of the cell wall, and in the case of tracheids, programmed cell death. In most tree species, the final stage of xylem development is the heartwood formation. The heartwood formation is considered as an aging process of sapwood, in which the cells of the radial and axial parenchyma die, as a result of which physiological activity stops and a non-functional xylem is formed in the center of the trunk. Living cells of the parenchyma participate in respiratory processes; provide storage of nutrients and their movement through the conducting tissues of the plant. Identification of the functionally active sapwood proportion in the total trunk biomass is necessary for large-scale assessments of respiration and transpiration of woody plants. The presence of heartwood largely determines the tree's resistance to weather influences (storm winds) and the quality of wood (humidity, color, resistance to biodegradation). Understanding the mechanisms that regulate the transition of sapwood to heartwood is relevant both from the point of view of global studies of the carbon cycle and the production of wood with special properties.

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