Sapwood Width Research Articles

Vertical variation of sapwood thickness in Pinusbanksiana Lamb. and Larixlaricina (Du Roi) K. Koch

Variation of sapwood thickness, in terms of a linear measurement (sapwood width) and a growth ring count (sapwood ring), in relation to age, height, aspect, and radial growth rate was studied in jack pine (Pinusbanksiana Lamb.) and tamarack (Larixlaricina (Du Roi) K. Koch). In general, jack pine has more sapwood rings and a greater sapwood width than tamarack. In jack pine, the number of sapwood rings steadily declined with increasing height, but in tamarack, the number of sapwood rings at first increased and then declined with increasing height. Sapwood width tended to show a species-specific constant thickness along the trunk, but both species exhibited a slight increase at the base and at the crown. The number of sapwood rings shows strong correlation with age, height, and sapwood radial growth rate, but not with sapwood width. In both species, the south aspect of the tree has wider sapwood and fewer sapwood rings than the north aspect. There is no statistical relationship between sapwood width and the number of sapwood rings.

Thinning and nitrogen fertilization effects on sapwood development and relationships of foliage quantity to sapwood area and basal area in Douglas-fir

A 24-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand was treated with various levels and combinations of nitrogen fertilization and thinning. Over a period of 5–9 years after treatments, trees were sampled to determine effects on foliage quantity and sapwood characteristics at different stem heights together with their relationships. Sapwood width remained relatively constant up the stem where heartwood was present, but the number of annual rings it contained decreased with height. The sapwood width at breast height (bh) increased with stem diameter; treatments had little effect on percent sapwood at bh. The ratio of foliage mass to sapwood cross-sectional area changed for different portions of the crown and was lower when based on sapwood area at bh than at base of live crown. Significant linear relationships of foliage mass and area to sapwood area at bh were found, but relationships of foliage to basal area (bh) were just as close for all treatments; treatments significantly affected these relationships with control trees having the lowest regression slopes.