1. 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.
2. 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.
3. The results suggest that lateral root functioning in A. tridentata is associated with intraspecific identity and ploidy level. Subspecies adapted to habitats with deep soils generally had a smaller horizontal reach, and polyploid cytotypes were associated with greater water uptake compared to their diploid variants. We also found that plant crown volume was a weak predictor of water uptake, and that neighborhood crowding had no discernable effect on water uptake.
4. Intraspecific variation in lateral root functioning can lead to differential patterns of resource acquisition, an essential process in arid ecosystems in the contexts of changing climate and seasonal patterns of precipitation. Altogether, we found that lateral root development and activity is more strongly related to genetic variability within A. tridentata than to plant size. Our study highlights how intraspecific variation in life strategies is linked to mechanisms of resource acquisition.

Data Use
License
CC0-1.0
Recommended Citation
Zaiats, Andrii et al. (2020), Intraspecific variation in surface water uptake in a perennial desert shrub, Dryad, Dataset, https://doi.org/10.5061/dryad.pk0p2ngjm

Funding
US National Science Foundation and Idaho EPSCoR: OIA-1757324