Drought resistance in two populations of invasive Tamarix compared using multiple methods

Area of Science:

• Plant physiology
• Ecology
• Wood anatomy

Background:

• Intra-specific variability and plasticity in xylem traits are crucial for plants colonizing diverse habitats.
• Tamarix, a non-native woody plant, is successful across various arid environments.

Purpose of the Study:

• To investigate population differences in Tamarix hydraulic conductivity, embolism vulnerability, and vessel anatomy.
• To determine water potentials linked to crown dieback during drought.
• To compare micro-computed tomography (microCT) and hydraulic methods for quantifying hydraulic conductivity loss.

Main Methods:

• Measured hydraulic conductivity (Ks), embolism vulnerability curves, and vessel anatomy (length, diameter).
• Conducted a season-long drought experiment on field-grown Tamarix.
• Quantified percentage loss in hydraulic conductivity (PLC) using both microCT and hydraulic methods.

Main Results:

• No significant differences in measured xylem traits were found between Tamarix populations grown in a common environment.
• Tamarix exhibited vulnerability to embolism, with larger vessels showing increased susceptibility.
• The microCT method overestimated theoretical conductivity and underestimated PLC compared to the hydraulic method.
• Water potentials associated with crown dieback aligned with hydraulic method results.

Conclusions:

• Plasticity in xylem traits, rather than genetic differentiation, likely contributes to Tamarix's success in diverse habitats.
• Xylem trait plasticity is a key factor for Tamarix adaptation in arid regions.
• Hydraulic methods are more reliable than microCT for assessing embolism-induced hydraulic impairment.