Constraints to growth of boreal forests

Understanding how the growth of trees at high latitudes in boreal forest is controlled is important for projections of global carbon sequestration and timber production in relation to climate change. Is stem growth of boreal forest trees constrained by the length of the growing season when stem cambial cells divide1, or by the length of the period when resources can be captured2? In both cases, the timing of the thaw in the spring is critical:...