Leaf phenology affects wood anatomy in an ecosystem warming experiment.
Song Y, Pivovaroff AL, Richardson AD, Warren JM, Hanson PJ
Climate Adaptation
The tamarack larches turning gold in northern bogs each October are quietly rewiring their wood grain in response to shifting seasons — and those structural changes ripple out to how much water the whole boreal forest cycles into the atmosphere.
Trees don't just grow in spring and stop — the timing of when they first sprout leaves and when those leaves drop shapes the very structure of the wood they build inside. Researchers cranked up temperatures and CO2 in real forest plots and found that longer leafy seasons led trees to build wider internal water channels, boosting growth. The catch: not all trees respond the same way, and pushing too far toward speed trades away the structural toughness that helps trees survive drought.
Key Findings
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.
chevron_right Technical Summary
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.
Abstract Preview
Leaf phenology may influence the development of wood structure and hydraulic function across growing seasons, yet the roles of green-up, green-down, and growing season length in regulating xylem an...
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