An investigation into the underlying cause of Banksia decline in south-western Australia: adaptive hydraulic traits and vulnerability to drought stress

Maintenance of plant water status above safe operating physiological thresholds is crucial for plants in drying soils, and stomatal control of water loss is the main regulatory process over short to medium timeframes. Co-occurring tree species in a Western Australian woodland differ, both diurnally and seasonally, in the regulation of water use in response to soil and atmospheric drought, and have corresponding distinct species-specific thresholds for physiological functioning. In this seasonally dry woodland, heavy reliance on stomatal control to maintain high water status appears associated with hydraulic vulnerability in dry and hot summers after below-average winter rainfall.