Xylogenesis in Black Spruce Trees of Canadian Boreal Forests
Lugo, J.B., Deslauriers, A. and Rossi, S. 2012. Duration of xylogenesis in black spruce lengthened between 1950 and 2010. Annals of Botany 110: 1099-1108.
In an attempt to begin filling this research void, Lugo et al. monitored the timing of xylogenesis (wood formation) in black spruce (Picea mariana) trees for nine years on a weekly basis at four sites in the boreal forest of Quebec, Canada. This they did in order to reconstruct the onset, duration and ending of xylogenesis in trees of this species between 1950 and 2010, as well as the relationships of these phenomena to chronologies of maximum and minimum air temperatures. So what did their measurements reveal?
The three researchers first report that "all sites exhibited increasing trends of both annual and May-September temperatures, with the greatest changes observed at the higher latitudes," after which they state that "phenological events in spring were more affected than those occurring in autumn, with cambial [growth] resumptions occurring 0.5-0.8 days/decade earlier." Given such observations, "if the observed trend is maintained unaltered in the long term," in the words of Lugo et al., "the demonstrated advancement of cambial activity could dramatically modify the short time window for growth of boreal species and markedly affect cell production of the secondary meristem," with the result that "long-term increases in temperature can substantially extend wood formation and, consequently, the dynamics and productivity of cold ecosystems, by removing the thermal constraints to the activity of carbon sinks in trees."