Although a lack of thermal acclimation of photosynthesis seems to be common to all boreal tree species (Way and Sage, 2008a; Dillaway and Kruger, 2010), thermal acclimation of dark respiration was reported to be moderate to strong for several tree species of the boreal forest, including white spruce (Tjoelker et al., 1999, 2009; Dillaway and Kruger, 2011; Reich et al., 2016; Wei et al., 2017). It seems that the firm acclimation of Rd (predominantly by the downshift in Q10) could reduce the negative impact of rising temperatures on photosynthesis under climate change (Atkin et al., 2005; Reich et al., 2016). In accordance with the recent results of Reich et al. (2016) for white spruce and the results of Tjoelker et al. (1999) for black spruce, we showed evidence for type II acclimation of Rd, as indicated by a downshift of Rd10 with increasing plantation site temperature. However, we could not show consistent evidence for type I acclimation of Rd (Fig. 4) as in Reich et al. (2016), and Tjoelker et al. (1999) for different white spruce and black spruce seed sources. The average Q10 value (1.50 ± 0.15) observed in this study was similar to that obtained with a white spruce population from northern Minnesota, USA (Reich et al., 2016). The small change noted in Q10 was not congruent with the important change in climate observed from site to site. Whether this lack of change in Q10 is related to the regional temperature gradient and seed sources tested in the present study, or to intrinsic species physiological performance needs to be examined (Wei et al., 2017).