15 Feb 2023
 | 15 Feb 2023
Status: this preprint is currently under review for the journal BG.

Root distributions predict shrub-steppe responses to precipitation intensity

Andrew Kulmatiski, Martin C. Holdrege, Cristina Chirvasa, and Karen H. Beard

Abstract. Precipitation events are becoming more intense around the world, changing the way water moves through soils and plants. Plants that have, or create, roots that absorb more water 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 used water tracer injections in a field experiment to describe forb, grass, and shrub root distributions under low and high precipitation intensity treatments. To estimate how much water different active rooting distributions can absorb over time, we used a soil water flow model, and we compared our estimates of water uptake to aboveground plant growth. 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 % cover). In high precipitation intensity plots, shrub and forb roots moved 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.

Andrew Kulmatiski et al.

Status: open (until 12 Apr 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2023-13', Anonymous Referee #1, 16 Mar 2023 reply
    • CC1: 'Reply on RC1', Andrew Kulmatiski, 22 Mar 2023 reply
  • RC2: 'Comment on bg-2023-13', Anonymous Referee #2, 17 Mar 2023 reply
    • CC2: 'Reply on RC2', Andrew Kulmatiski, 22 Mar 2023 reply
      • RC3: 'Reply on CC2', Anonymous Referee #2, 23 Mar 2023 reply
        • CC3: 'Reply on RC3', Andrew Kulmatiski, 24 Mar 2023 reply

Andrew Kulmatiski et al.

Andrew Kulmatiski et al.


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Short summary
Warmer air and larger precipitation events are changing the way water moves through the soil and into plants. Here we show that detailed descriptions of root distributions can predict plant growth responses to changing precipitation patterns. Shrubs and forbs increased growth while grasses showed no response to increased precipitation intensity and these responses were predicted by plant rooting distributions.