This consensus document addresses the biology of Sitka spruce (Picea sitchensis (Bong.) Carr.). Sitka spruce is an ecologically important species of the north temperate coastal rain forest of western North America. It is a valuable species for both pulp and lumber. Its wood offers unique qualities for manufacture of the highest quality sounding boards and tops for many musical instruments. As well, an outstanding strength-to-weight ratio made Sitka spruce strategically important during both World Wars for construction of aircraft (Brazier, 1987). While its natural range is not extensive and the species' economic importance ranks far below that of other western conifers, it is a keystone species in some of the most productive ecosystems of North America, particularly in the Queen Charlotte Islands of British Columbia (Peterson et al., 1997). Outside its natural range, Sitka spruce has played an important role in plantation forestry, particularly in Northern Europe (Hermann, 1987). In Great Britain, the species now accounts for almost 70% of the annual conifer planting stock (Malcolm, 1997) and plantations cover over 20% of the forest/woodland area (Cannell and Milne, 1995). Sitka spruce is also a primary plantation species in Brittany, where productivity of stands is similar to that in Britain (Vaudelet, 1982; Serrière-Chadoeuf, 1986; Guyon, 1995).