UC Santa Cruz

Forests are experiencing dieback due to drought, making it imperative to understand the mechanisms of drought-induced mortality to better predict and manage forests under a changing climate. My research goal was to capture the link between xylem function and cambial viability in Sequoia sempervirens saplings under drought. Greenhouse-grown saplings were exposed to water potentials known to cause 50% and 88% loss of water transport due to air expansion in the xylem cells (embolism). These water potentials were identified as levels of mild and severe stress. Xylem water transport and cambial viability were assessed at these targets, and compared against well-watered controls. The cambium was viable under mild drought and able to recover under rewatering regime, but not under severe drought stress. The cambium produces new growth rings each year, so understanding its ability to recover from drought will provide a critical mechanistic link between xylem function and potential for recovery.