DOI: 10.5281/zenodo.13368278
title: Data from: The thermal limits of native plant species in California Coastal Sage Scrub

description: Field and laboratory data for Goldsmith et al. (In Review) entitled, "The thermal limits of native plant species in California Coastal Sage Scrub." Four data files are included: 

Goldsmithetal_PlantFunctionalTraitMetaData-18July24.xlsx -Provides metadata (header, description, units, measurement type, and expample) for each column of the file entitled "Goldsmithetal_PlantFunctionalTraitData-18July24.csv." 

Goldsmithetal_PlantFunctionalTraitData-18July24.csv - Provides raw data for field and lab observations of plant functional traits as described in the methods section of this data record. 

Goldsmithetal_PlantFvFmLabData-29March24.csv - Provides raw data for experimental lab observations of leaf fv/fm following experimental heat treatments as described in the methods section of this data record. 

Goldsmithetal_PlantFvFmLabMetaData-2Aug23.xlsx - Provides metadata (header, description, units, measurement type, and expample) for each column of the file entitled "Goldsmithetal_PlantFvFmLabData-29March24.csv." 

 

Contact Greg Goldsmith (goldsmith at chapman dot edu) for additional information. 
description: Study Site

Field observations were carried out between 14:00-16:30 on clear sky days at Hicks Haul Road (33.7362, -117.7128; 220 m asl) on 14 March 2024 and Saddleback Wilderness (33.7781, -117.7369; 293 m asl) on 11 April 2024. 

At Hicks Haul Road, observations were made on Artemisia californica Less., Encelia farinosa A.Gray ex Torr., Isocoma menziesii (Hook. & Arn.) G.L.Nesom, Malosma laurina (Nutt.) Nutt. ex Abrams, Malacothamnus fasciculatus (Nutt. ex Torr. & A.Gray) Greene, Rhus integrifolia (Nutt.) Benth. & Hook.f. ex Rothr., and Salvia mellifera Greene. At Saddleback Wilderness, observations were made on Baccharis pilularis DC., Baccharis salicifolia (Ruiz & Pav.) Pers., Diplacus sp. Nutt., Encelia californica Nutt., and Rhamnus crocea subsp. ilicifolia. Unless otherwise noted, observations were made on fully mature, healthy, and sunlit leaves of six individuals of each species.

Field Observations

Temperature: To determine leaf temperatures in situ, we placed thermocouples (0.1 °C accuracy; Physitemp RET-4, Clifton, NJ, USA) at the base and apex of the abaxial side on three leaves of each individual, taking care to avoid major veins and the edge of the leaf where possible. Stable leaf temperatures and a paired air temperature adjacent to the plant canopy were recorded simultaneously.

Leaf Functional Traits: We measured Fv/Fm on three leaves of every individual in the field following 20 min of dark adaptation using a chlorophyll fluorescence meter (OS30p; Opti-Sciences, Hudson, NH, USA). We measured leaf angle using a manual clinometer held against the midrib of one leaf of every individual, recording 90° as horizontal. We determined ab- and ad-axial leaf pubescence on three leaves of every individual by using a magnifying glass and rating leaves between (1) Smooth/Waxy; (3) Slightly Hairy/Patchy; (5) Moderately Hairy; (7) Very Hairy; and (9) Pilose, following (Bourland et al., 2003). We measured leaf thickness on three leaves of every individual using a micrometer (Mitutoyo IP65, Global Industrial, Port Washington, NY, USA), taking care to avoid midveins and leaf edges where possible. We measured leaf stomatal conductance (gs) on one leaf of every individual using a steady-state porometer (Meter SC-1 Leaf Porometer, Pullman, WA, USA). Finally, we measured relative leaf chlorophyll concentration on three leaves of every individual using a digital chlorophyll meter (SPAD 502, Konica Minolta Sensing Inc., Japan).

Laboratory Observations

Leaf Functional Traits: We measured leaf size by scanning five leaves of every individual of each species and determining area via ImageJ (Schneider et al., 2012). Leaves were then dried at 60 °C for at least 72 hrs and the dry weights used to calculate specific leaf area (leaf area per unit mass). We measured leaf cuticular conductance (gmin) on one leaf of every individual using a bench dry down following the protocol of Sack and Scoffoni (2010). We measured d13C on a sample of one dried and finely ground leaf of every individual via continuous flow elemental analysis coupled to isotope ratio mass spectrometry (EA IsoLink IRMS, Thermo Fisher Scientific Inc., USA), with results presented ‰ relative to the VPDB standard. The long-term standard deviation of a quality control standard was 0.07 ‰.

Leaf Thermal Tolerance: We measured the temperature at which a species experiences a 50% decrease in photosystem II efficiency based on Fv/Fm measurements (T50). Following the general protocol of (Slot et al., 2021), five leaves from each species were placed into opaque aluminum bags and submerged into a water bath with a water-circulating heating wand (Precision-Cooker Nano, Anova,) for 15 min at each of the following temperatures: 25, 35, 40, 45, 47, 49, 51, 53, 55, 57, 59, and 61°C (n = 60 total leaves per species). The leaves were then stored in a dark refrigerator for 24 hours, and Fv/Fm values measured using a chlorophyll fluorescence meter (OS30p, Opti-Sciences).