Regeneration of Scots pine stem after wounding

Stem regeneration after wounding was studied in 110-year-old trees of Pinus sylvestris L. over a period of 30 years. The changes of cambial surface are shown as 3D models. For construction of the models ArcGIS and geodesic Surfer programs were applied. The trees responded to stem injury by increasing the cambial activity near the wound edge. The result was longitudinal rolls or spindles which gradually covered the wounded stem surface. The successively formed tree rings changed their orientation to perpendicular with respect to the wound surface. The disturbances of wood formation near the wound edge were manifested by oblique orientation of xylem rays with respect to annual ring boundaries. The spatial distribution of the xylem ray orientation is presented on the Surfer contour maps. Near the fusion of the wound spindles there were some areas consisting of irregularly oriented xylem cells. The cellular ordering of the xylem tissue in these areas was measured by applying digital image analysis software. Measurements shown on color-coded maps revealed that the tracheid orientation (seen on tangential sections) deviated between 0 and 90 degrees from the stem axis. In some areas a circular pattern of tracheid orientation was visible. Crooked and forked tracheids were also present. These results support the view that the adaptive growth occurring in the case of deep wounding is analogous to that observed when an inanimate body is in lateral contact with a tree stem. The intensive growth and accumulation of newly deposited tissue in the wound spindles seems to be the most effective mechanism for the tree stem regeneration to restore its biomechanical and transport functions. This could be considered as an illustration of Wolff’s law that the shape of an organ follows its function.