%0 Research article
%T The effects of site and stand factors on the tree and wood quality of Sitka spruce growing in the United Kingdom
%A Moore, John R.
%A Lyon, Andrew J.
%A Searles, Gregory J.
%A Vihermaa, Leena E.
%D 2009
%J Silva Fennica
%V 43
%N 3
%R doi:10.14214/sf.195
%U https://silvafennica.fi/article/195
%X The extent and sources of variation in the wood quality of Sitka spruce  (Picea sitchensis (Bong.) Carr.) were quantified using data collected  from 64 stands in northern Britain. These stands were selected on the  basis of elevation, latitude, longitude, yield class, initial spacing  and the presence or absence of thinning. Dynamic modulus of elasticity  (MOE) was calculated from measurements of stress wave velocity made on  standing trees and qualitative descriptions were made of stem form.  Dynamic MOE of individual trees ranged from 3.81 kN/mm<sup>2</sup> up to 12.29 kN/mm<sup>2</sup>, with a mean of 7.71 kN/mm<sup>2</sup>.  Approximately 55 percent of the variation in dynamic MOE was due to  differences between individual trees within a site, while 35 percent was  due to differences between sites. The remaining 10 percent was due to  differences between the measurements made on opposite sides of each  tree. Variation in dynamic MOE at the site level was significantly  influenced by yield class, elevation as well as by a number of the  interactions between these factors and latitude, longitude and initial  spacing. A multiple regression model incorporating these variables was  able to explain 45 percent of the variation in dynamic MOE. Ramicorn  branches were the most commonly recorded defect (37.2% of all live  trees), followed by stem scarring and basal sweep (6.9% and 6.3%,  respectively). Dynamic MOE was not influenced by stem straightness (p =  0.10) which indicates the utility of stress wave velocity measurements  for segregating Sitka spruce stands based on potential grade recovery.