In this study, we examine variation in C concentration, including
the total and the volatile fraction, of bark and stemwood tissues
across a range of tree sizes for the major tree species of North
America’s boreal forest, including jack pine (Pinus banksiana
Lamb.), trembling aspen (Populus tremuloides Michx.), white birch
(Betula papyrifera Marsh.), black spruce (Picea mariana [Mill.] B.S.
P), white spruce (Picea glauca [Moench] Voss), and balsam fir (Abies
balsamea [L.] Mill.). We sought to test the following hypotheses
concerning C concentrations in our target tree species: (1) bark tissue
has higher total and volatile C concentration than stemwood
tissue; (2) total and volatile C concentrations vary among tree species;
(3) total and volatile C concentrations change with tree size,
but this size-dependent effect in total C concentration is influenced
by size-related changes in volatile C concentration; (4) the sizeassociated
relationships of total and volatile C concentrations are
dependent on shade tolerance.