DOI: 10.5061/dryad.sf7m0cggx
title: Data from: Plasticity in plant hydraulic traits: An evaluation of a common-taxa experiment across a climatic gradient in the Western U.S.

description: Drought impacts plant productivity, ecosystem function, and the global
 carbon cycle, with many species-level responses remaining unknown.
 Variable responses to water availability exist among plant species and
 across biomes. This research utilized a coordinated water deficit
 experiment of horticultural taxa across three sites in the Western U.S. to
 assess taxa-level plasticity to water availability and location. Four taxa
 (*Cercis occidentalis, Cercis canadensis, Physocarpus ‘*Diabolo’, and
 *Physocarpus ‘*Little Devil’) were measured for physiological and
 morphological traits affecting plant hydraulic conductivity under two
 water deficit treatments. Full gas exchange, specific leaf area, vessel
 diameter, theoretical hydraulic conductance, and ΦPSII were collected, and
 water use efficiencies calculated for each taxon at each location. Impacts
 of site, treatment, and taxa were analyzed on this suite of traits.
 Results show differences in taxa performance by climatic location (p
 &lt; 0.001) and between closely related species and cultivars.
 However, the irrigation treatments had limited significant impacts on
 physiological performance. These findings highlight the merits of
 common-taxa trials over multiple geographic locations to evaluate and
 identify climate suitability of plants. Our results provide evidence that
 landscape irrigation can be reduced substantially and utilize a
 unique research framework for filling plant-water knowledge gaps critical
 to address in the face of anthropogenic climate change.
description: <strong>Leaf physiology</strong>
 End of season measurements of stomatal conductance to water vapor
 (<em>g</em><sub>sw</sub>, mol m<sup>-2
 <sup>s</sup>-1</sup>) and
 <em>Φ<sub>PSII</sub></em> were taken with a LI-600
 Porometer/Fluorometer (LI-COR Biosciences, Lincoln, NE, USA) during midday
 (11:30-1:30pm, to reduce risk of variable weather influence) at the three
 sites. The LI-600 configuration was set to automode with fast
 g<sub>s</sub>, fluorescence and flowrate, with matching to
 ambient conditions set to every 10 minutes. Midday instantaneous gas
 exchange survey measurements were taken with a portable photosynthesis
 system (LI-6400XT at OSU and LI6800 at UW and USU; LI-COR Biosciences,
 Lincoln, NE, USA) with a 2 cm<sup>2</sup> chamber head and
 parameters set to 420 mmol mol <sup>-1</sup>
 CO<sub>2</sub>; flow rate 500 mmol s<sup>-1</sup>,
 PAR at 2000 mmol m<sup>-2 <sup>s</sup>-1</sup>.
 Full gas exchange survey measurements were used to calculate instantaneous
 water use efficiency (WUE; mmol mol<sup>-1</sup>) as
 photosynthetic rate over transpiration rate
 (<em>A</em>/<em>E</em>) and intrinsic water use
 efficiency (iWUE; mmol mol<sup>-1</sup>) calculated as
 photosynthetic rate over stomatal conductance
 (<em>A</em>/<em>g</em><sub>s</sub>).
 All leaf physiology measurements were conducted on full sun, undamaged,
 new but fully expanded leaves, with one representative leaf per plant
 selected for full gas exchange measurements, and four leaves measured for
 LI-600 measurements, of which the lowest value of
 <em>g</em><sub>sw</sub> was excluded and data were
 averaged to act as a per plant measurement. Gas exchange measurements were
 timed to occur prior to irrigation treatments to capture the effects of
 the deficit treatment. <strong>Specific leaf
 area</strong> Leaf punches of known areas were
 collected at the end of the growing season at all three sites from new,
 fully expanded leaves at each time. Samples were dried in an oven
 overnight and weighed to calculate specific leaf area (SLA,
 cm<sup>2</sup>/g). <strong>Xylem
 anatomy</strong> Stem segments from the top 5 cm
 of actively growing branches were collected from target taxa and stored
 frozen at -20 °C prior to being hand sectioned with a double-edge razor
 blade, stained with a 0.1% safranin solution for 40 seconds, cleared with
 DI water, and imaged under a microscope (E200 Eclipse, Nikon Instruments
 Inc., Melville, New York, USA) with a camera attachment (MU-1803 HS,
 AMScope, Irvine, California, USA). Image analysis was conducted using
 ImageJ-Fiji version: 2.14.0/1.54f (Schindelin, 2012).  For images with
 good contrast, vessel area was measured with an autothresholding function,
 and for the rest, vessels were manually traced, totaling a minimum of 50
 vessels per individual. Since vessels were not circular, diameter was
 estimated as the mean diameter of an ellipse: <em>D = (D<sub>1
 + D</sub>2)/2, with D<sub>1</sub> as the maximum vessel
 diameter and D<sub>2</sub> as the minimum vessel diameter.
 Vessel density (VD, n µ</em>m<sup>-2</sup>) was
 calculated as number of vessels per set area from which mean vessel
 hydraulic diameter (D<sub>mh</sub>;* µ*m) was calculated as:
 D<sub>mh</sub> = (/
 <em>n</em>)<sup>1/4</sup> (Fontes et al., 2022).
 The theoretical specific conductivity (K<sub>p</sub>; kg m
 MPa<sup>-1</sup>s<sup>-1</sup>) was calculated
 using the Hagen-Poiseuille equation:  where  is the density of water
 (998.23 kg/m<sup>3</sup>) and  is the viscosity of water
 (1.002 x10<sup>-9</sup> MPa/s), both at 20°C (Santiago et al.,
 2004; Tyree & Ewers, 1991).
description: # Data from: Plasticity in plant hydraulic traits: An evaluation of a
 common-taxa experiment across a climatic gradient in the Western U.S.
 [https://doi.org/10.5061/dryad.sf7m0cggx](https://doi.org/10.5061/dryad.sf7m0cggx) ## Description of the data and file structure Data (CRLP_2023_endcore.csv) includes physiological and morphological data collected at 3 sites in the Climate Ready Landscape Plants project in 2023: University of Washington (UW) Center for Urban Horticulture, Oregon State University (OSU) North Willamette Research and Extension Center and Utah State University (USU) Logan Research Farm. Four target taxa were selected, being grown at all 3 sites: *Cercis canadensis,* *Cercis occidentalis*, *Physocarpus*  'Little Devil' and *Physocarpus* 'Diabolo'. Replicates of each taxa were randomly assigned to receive an irrigation deficit treatment calculated as percent evapotranspiration with the high treatment (H) at 80% EtO and the low treatment (L) at 20% EtO. All data were collected after ~3 months of deficit treatment. NA in the dataset indicates that a measurement was not taken. The following traits are included: | **Abbreviation** | **Trait** | **Unit** | | :--------------- | :--------------------------------------------------------- | :-------------------- | | gsw\_MD or gsw | Midday stomatal conductance (measured by LI600) | mol m-2 s-1 | | *ΦPSII* | Midday chlorophyll fluorescence - photosystem 2 efficiency | unitless | | SLA | Specific leaf area | cm2/g | | Photo (*A*) | Photosynthetic assimilation rate | umol m-2 s-1 | | Cond (*g*s) | Stomatal conductance (measured by LI6400 or LI6800) | mol m-2 s-1 | | Trmmol (*E*) | Transpiration rate | mmol m-2 s-1 | | WUE (*A*/*E*) | Instantaneous water use efficiency | umol CO2 × mmol-1 H2O | | iWUE (*A*/*g*s) | Intrinsic water use efficiency | umol CO2 × mol-1 H2O | | Dmh | Mean vessel hydraulic diameter | mm | | Kp | Theoretical specific conductivity | kg m-1 MPa-1 s-1 | ### Files and variables #### File: Statistical_analyses.R **Description:** R code for running RRPP ANOVAs, PCAs and calculating RDPI. #### File: CRLP_2023_endcore.csv **Description:** Dataset containing one line per plant individual with associated physiological and morphological data. ##### Variables * Site: UW, USU, OSU * Season: end, indicating measurements taken at the end of growing season * Position: unique code for each plant at each site * Trt: either H for high (80% EtO) or L for low (20% EtO) * Species: one of 4: *Cercis occidentalis, Cercis canadensis, Physocarpus* 'Diabolo' or *Physocarpus* 'Little Devil' * Species_Code: 4 digit code for each species: CEOC: *Cercis occidentalis*, CECA: *Cercis canadensis*, PHDI: *Physocarpus* 'Diabolo', PHLD: *Physocarpus* 'Little Devil' * Genus: *Cercis* or *Physocarpus* * gsw_MD: midday stomatal conductance * PhiPS2_MD: midday PhiPS2 efficiency * SLA: specific leaf area * Photo: photosynthetic assimilation * Cond: stomatal conductance * Trmmol: transpiration rate * WUE: instantaneous water use efficiency (Photo/Trmmol) * iWUE: intrinsic water use efficiency (Photo/Cond) * Dmh: mean weighted vessel diameter * Kp: theoretical hydraulic conductance ## Code/software Code was run using R studio verson 2023.09.0+463. The following packages are required: tidyverse, vegan, ggh4x, ggplot2, ggbiplot, ggpubr.  ## Access information Other publicly accessible locations of the data: * N/A Data was derived from the following sources: * N/A