%0 Research article
%T Histochemical and geometric alterations of sapwood in coastal Douglas-fir following mechanical damage during commercial thinning
%A Kiser, Jim
%D 2011
%J Silva Fennica
%V 45
%N 4
%R doi:10.14214/sf.447
%U https://silvafennica.fi/article/447
%X Histochemical and geometric alterations to sapwood in mechanically  damaged Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) trees were  quantified 14 years after thinning.  Discoloration and decay were  measured in felled damaged and undamaged trees. Compartmentalized walls  were identified and measured macroscopically. Sapwood to heartwood ratio  was measured incrementally along the boles. Results showed a distinct reaction zone forming at the time of injury.  Compartmentalized walls 1–3 were less distinct and heavily resinous  streaking was evident in extant tissues, particularly in the axial  direction. Post-damaged sapwood was burl-like for 4–6 years and  tracheids contained resin-filled lumina. Damaged wood volumes were  modeled by multiple regression. Wound depth, wound area, and diameter  inside bark (DIB) accounted for 73% of the discolored volume (p = 0.02).  DIB alone accounted for just over 55% of the response. Post-damaged  sapwood averaged 15 mm (SE = 2.3 mm) greater in width on the side  opposite the damage along the length of the boards. Wound area explained  just over 65% of this response (p = 0.003). Sapwood area was not  significantly different between damaged and control trees (p = 0.56).  Results indicate that wounded Douglas-fir trees may slow conversion of  sapwood to heartwood on the bole side opposite the wound, possibly as a  response to maintain sapwood area necessary for physiological  maintenance of the existing crown. About 19% of the lower bole volume in  damaged trees was affected by discoloration and secondarily by  structural changes. Reduction in value of the lower log can be as high  as 19% by conventional bucking practices. Alternatives are presented to  reduce the value loss to between 2.5% to 3.5%.