Fig. 2

Physiological events triggered at various water table depths in Prosopis tamarugo Phil. Tamarugo maintains its water status to a groundwater depth of approximately 10 m by decreasing water demand through partial defoliation and decreased twig growth. Beyond this depth, the trees start to decrease their predawn water potentials. A drop in water offer negatively affects tamarugo water status and triggers the tamarugo water stress response sequence (TWSRS). Tamarugo faces drought with partial stomatal closure. Early senescence and twig growth diminishment are the first mechanisms in the sequence, followed by twig death caused by xylem cavitation. This biomass reduction strategy contributes to reduce water demand. Tamarugo drawing taken from Sudzuki (1969)