%0 Research article
%T Wood density within Norway spruce stems
%A Jyske, Tuula
%A Mäkinen, Harri
%A Saranpää, Pekka
%D 2008
%J Silva Fennica
%V 42
%N 3
%R doi:10.14214/sf.248
%U https://silvafennica.fi/article/248
%X We studied the variation in average wood density of annual rings,  earlywood density, and latewood density in addition to ring width and  latewood percentage within Norway spruce (Picea abies (L.) Karst.) stems  from the pith to the bark, and from the stem base towards the stem  apex. Moreover, the variation in wood density within annual rings was  studied at the different heights and radial positions in the stem. The  material consisted of 85 trees from central and south-eastern Finland.  Variation between the annual rings accounted for 11–27% of the total  variation in wood density. Only small differences (3–6%) in wood density  were found between different heights in the stem. The largest (49–80%)  variation in wood density was found within the annual rings. The  difference in wood density between earlywood and latewood was smaller in  the rings near the pith than in the outer rings. The increasing wood  density from the pith outwards was related to increasing latewood  density and latewood percentage, whereas the earlywood density increased  only slightly from the pith outwards. In a given cambial age (i.e.,  given rings from the pith), the average wood density of annual rings  increased with increasing stem height. In contrast, in the rings formed  in the same calendar years (i.e., given rings from the bark), the  average wood density of annual rings decreased with increasing stem  height. The results of this study verify our knowledge of wood density  variation and can further contribute to creating models to predict wood  density.