Patterns of Tamarix water use during a record drought

Area of Science:

• Hydrology
• Plant Ecology
• Invasive Species Management

Background:

• Record drought conditions in southwest Kansas during 2006.
• Shallow, unconfined aquifer system with invasive Tamarix ramosissima.

Purpose of the Study:

• Assess groundwater dynamics and plant water sources.
• Investigate physiological responses of Tamarix to drought.
• Understand invasive species' adaptation strategies.

Main Methods:

• High-frequency monitoring of water table fluctuations.
• Assessment of plant water sources using isotopic methods.
• Measurement of volumetric water content and plant physiological responses.

Main Results:

• Diel water table fluctuations indicated early evapotranspirative groundwater consumption.
• Water table dropped to record lows, diminishing fluctuations despite increased evapotranspirative demand.
• Evidence of a shift from groundwater to vadose-zone water reliance by Tamarix.
• Potential re-intensification of fluctuations suggests deeper groundwater uptake later in the season.

Conclusions:

• Tamarix ramosissima rapidly shifts water sources in response to declining water tables.
• Utilizing multiple water sources minimizes leaf-level water stress during drought.
• Previous hydrologic conditions influence root establishment depth.
• High-frequency hydrologic data are crucial for interpreting plant water sources.