Precipitation events are becoming more intense around the world, changing the way water moves through soils and plants. Plant rooting strategies that sustain water uptake under these conditions are likely to become more abundant (e.g., shrub encroachment). Yet, it remains difficult to predict species responses to climate change because we typically do not know where active roots are located or how much water they absorb. Here, we applied a water tracer experiment to describe forb, grass, and shrub root distributions. These measurements were made in 8 m by 8 m field shelters with low or high precipitation intensity. We used tracer uptake data in a soil water flow model to estimate how much water respective plant root tissues absorb over time. In low precipitation intensity plots, deep shrub roots were estimated to absorb the most water (93 mm yr-1) and shrubs had the greatest aboveground cover (27%). Grass root distributions were estimated to absorb an intermediate amount of water (80 mm yr-1) and grasses had intermediate aboveground cover (18%). Forb root distributions were estimated to absorb the least water (79 mm yr-1) and had the least aboveground cover (12%). In high precipitation intensity plots, shrub and forb root distributions changed in ways that increased their water uptake relative to grasses, predicting the increased aboveground growth of shrubs and forbs in these plots. In short, water uptake caused by different rooting distributions predicted plant aboveground cover. Our results suggest that detailed descriptions of active plant root distributions can predict plant growth responses to climate change in arid and semi-arid ecosystems.

Author ORCID Identifier

Andrew Kulmatiski

Karen H. Beard

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.zip, .xlsx, .csv, .docx

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Utah Agricultural Experiment Station


Utah State University


Percent cover by visual estimation determined in 9, 1m x 1m fixed plots located in each of 14 experimental plots (each plot was 8 m x 8m) . Vegetation was surveyed by species one to three times per year between 2016 and 2021.

Volumetric water content and soil water potential measured using Decagon EC-5 and Campbell Scientific 229 sensors, respectively. Daily average values reported for measurements made in one control and one treated plot at depths of 10, 20, 30, 60, 90 and 100 cm.

BEI 9605 spring return linear sensors were fixed to sagebrush stems in each plot. Values reported are mm of stem diameter over time. Values are the average from six sensors in low intensity plots and five sensors in high intensity plots.

1mL of 70% Deuterium oxide was injected in a 15 cm by 15 cm grid to the indicated target depth. Xylem water was collected and analyzed for deuterium concentrations two days after injections. Injections were performed in May and July 2020.

Referenced by

Root distributions predict shrub-steppe responses to precipitation intensity. Kulmatiski A., Holdrege M.C., Chirvasa, C., and Beard K.H. Biogeosciences. Special issue: Ecosystems experiments as a window to future carbon, water, and nutrient cycling in terrestrial ecosystems.

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41° 36' 53" N, 111° 34' 1" W



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This work is licensed under a Creative Commons Attribution 4.0 License.



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