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Xylem and soil water extraction via centrifugation in a sub-tropical urban green space
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  • Erica Almance,
  • Suprina Shrestha­,
  • Sánchez-Murillo, R,
  • Brooke Byerley Best,
  • Oscar Rojas-Carrillo,
  • María Poca,
  • Christian Birkel
Erica Almance
The University of Texas Arlington Department of Earth and Environmental Sciences
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Suprina Shrestha­
The University of Texas Arlington Department of Earth and Environmental Sciences
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Sánchez-Murillo, R
The University of Texas Arlington Department of Earth and Environmental Sciences

Corresponding Author:[email protected]

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Brooke Byerley Best
Fort Worth Botanic Garden
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Oscar Rojas-Carrillo
Universidad Nacional de Costa Rica
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María Poca
Instituto de Matematica Aplicada San Luis
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Christian Birkel
Universidad de Costa Rica
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Abstract

Extracting water from discrete xylem and soil samples and continuous (long-term) monitoring of water vapor across the soil-plant-atmosphere continuum remains challenging and under a large debate. Here, we present a detailed one-year study in the Fort Worth Botanic Garden (north-central Texas) to evaluate the analytical robustness of the centrifugation extraction method and understand water sourcing from three common urban tree species (Elderberry, Sambucus canadensis; Cherry Laurel, Prunus caroliniana; and Boxelder Maple, Acer negundo). Xylem (N=110) isotope ratios (δ 18O and δ 2H) are compared to local precipitation (N=498), throughfall (N=33), and soil water (N=105) at different depths (0-38 cm). Complementary soil water samples were obtained from cup suction lysimeters (N=42) (0-38 cm). Soil and xylem water extraction volumes ranged from 100 µL to 7.5 mL in plant samples and from 100 µL to 10.5 mL in soil samples. Extraction success rates were 68.8% and 75.2% for xylem and soil samples, respectively. The minimum sample total water content for effective extractions was determined as 10.6% (soil) and 17.8% (xylem). Xylem mean narrowband and broadband (proxy for organic contamination) were 0.23±0.40 (-) and 1.00±0.01 (-), respectively. These values agree with mean narrowband and broadband metrics from throughfall and soils, which highlight the non-invasive nature of centrifugated extractions. Annual mean soil δ 18O compositions (-3.6±1.7‰) corresponded with the throughfall input (-3.6±2.4‰). Xylem δ 18O compositions exhibited a strong temporal enrichment trend at the end of the winter, summer, and fall seasons. Mean spring xylem δ 18O (-2.85‰) was less variable and close to soil mean compositions (-2.82‰). For this season, Bayesian mixing analysis showed source water contributions from distinct soil depths: 0 cm to 12.7 cm for Boxelder Maple, 12.7 cm to 25.4 cm for Cherry Laurel, and 12.7 cm to 38.1 cm for Elderberry. Our results offer a standardized and effective protocol for centrifugation extractions and reveal plant water uptake preferences in a highly altered urban green space during an unprecedented warm year.
31 May 2024Submitted to Ecohydrology
04 Jun 2024Review(s) Completed, Editorial Evaluation Pending
15 Jul 2024Reviewer(s) Assigned
05 Sep 2024Editorial Decision: Revise Major