Abstract Title

Environmental Drivers of Plant Water Use Variability in a Non-Perennial Mountainous Watershed

Additional Funding Sources

This project was supported by NSF EAR-1653998 and Idaho State University.

Abstract

In an intermittent stream, which dries for a portion of the year, it is vital to understand how geology, meteorology, and land cover interact to determine the water balance to predict when and where streams will dry. The relationship between evapotranspiration (ET) and streamflow has been an understudied portion of the hydrological balance in these systems. Vapor pressure deficit (VPD) and soil moisture are known to drive ET, but are difficult to study together because sensitivity to these variables changes seasonally and with elevation. In this study, I aim to characterize how the sensitivity of plant water use to fluctuations in VPD and soil moisture change seasonally and over an elevation gradient in a watershed drained by an intermittent stream. To answer this, I am collecting Douglas Fir sap flow velocity, VPD, soil moisture, and photosynthetically active radiation (PAR) data at three sites spanning an elevation gradient in the Gibson Jack watershed in southeastern Idaho. Preliminary results suggest that the relationships between these drivers vary dynamically with elevation. My work suggests that in situ measurements across gradients are necessary to understand linkages between the water balance of intermittent streams and plant water use across elevations.

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Environmental Drivers of Plant Water Use Variability in a Non-Perennial Mountainous Watershed

In an intermittent stream, which dries for a portion of the year, it is vital to understand how geology, meteorology, and land cover interact to determine the water balance to predict when and where streams will dry. The relationship between evapotranspiration (ET) and streamflow has been an understudied portion of the hydrological balance in these systems. Vapor pressure deficit (VPD) and soil moisture are known to drive ET, but are difficult to study together because sensitivity to these variables changes seasonally and with elevation. In this study, I aim to characterize how the sensitivity of plant water use to fluctuations in VPD and soil moisture change seasonally and over an elevation gradient in a watershed drained by an intermittent stream. To answer this, I am collecting Douglas Fir sap flow velocity, VPD, soil moisture, and photosynthetically active radiation (PAR) data at three sites spanning an elevation gradient in the Gibson Jack watershed in southeastern Idaho. Preliminary results suggest that the relationships between these drivers vary dynamically with elevation. My work suggests that in situ measurements across gradients are necessary to understand linkages between the water balance of intermittent streams and plant water use across elevations.