UC Davis

Like many plants, coast redwoods (Sequoia sempervirens), are capable of absorbing water directly into their leaves. Foliar water uptake may be important for surviving the hot, dry summers frequently found within Sequoia’s range and influence ecosystem-level water acquisition. However the role of foliar uptake in water-stress recovery, the balance of leaf wetness and photosynthesis, and the vulnerability of foliar uptake rate to environmental perturbation are unknown. Using samples collected from throughout the crowns of tall Sequoia trees, this series of studies addresses these knowledge gaps and through an experimental conservation physiology approach, adds mechanistic and ecological context by incorporating a range of both high-tech and classical anatomical trait analyses. These studies together show that Sequoia trees can absorb up to 48 kg of water per hour across their leaf cuticles, and can use absorbed water to repair drought-damaged leaves. Foliar dimorphism allows uptake specialization in axial leaves, but wax and stomatal density cause hydraulic resistance at the leaf surface, leading to variation in uptake capabilities under different environmental conditions.