Intraspecific variation in surface water uptake in a perennial desert shrub

Despite broad recognition that water is a major limiting factor in arid ecosystems, we lack an empirical understanding of how this resource is shared and distributed among neighboring plants. Intraspecific variability can further contribute to this variation via divergent life-history traits, including root architecture. We investigated these questions in the shrub Artemisia tridentata and hypothesized that the ability to access and utilize surface water varies among subspecies and cytotypes.
We used an isotope tracer to quantify belowground zone of influence in A. tridentata, and tested if spatial neighborhood characteristics can alter plant water uptake. We introduced deuterium-enriched water to the soil in plant interspaces in a common-garden experiment and measured deuterium composition of plant stems. We then applied spatially-explicit models to test for differential water uptake by A. tridentata, including intermingled populations of three subspecies and two ploidy levels. 
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