PubMed · 2026-06-02
Scientists warmed entire forest plots by up to 9°C and found that when trees leaf out earlier in spring and hold their leaves longer in fall, they build wider, more water-conducting wood — with black spruce and tamarack larch responding differently. This reveals a clear link between seasonal leaf timing and the internal plumbing trees use to grow and survive.
Warming of up to +9°C extended growing seasons in black spruce, indirectly boosting growth by widening late-season wood water channels (latewood hydraulic diameter).
Tamarack larch showed greater sensitivity to elevated CO2 (+500 ppm) in adjusting leaf timing and wood anatomy than black spruce, revealing species-level divergence in climate response.
A phenology-tracheid-growth trade-off was identified: earlier leaf-out and longer seasons favor wider, faster-conducting wood cells, while later leaf-out correlates with thicker-walled, structurally safer cells.
