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Results for “Leaf Water Potential”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Leaf water potential by leaf age, Feb2017, PA-SLZ: Panama

Leaf water potential of sunlit canopy leaves of APEIME, GUATDU, MICOBO, TERMAM, VIROSP and VOCHFE species from PA-SLZ, February 2017. Leaf water potential measured on young, mature and old leaves collected before dawn and around midday on 21 Feb and 22 Feb. This data was collected as part of the 2017 BNL–STRI leaf traits by age campaign. See related datasets (existing and future) for further sample details, leaf spectra, sap flow, LMA, gas exchange and leaf chemistry.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Effect of Leaf Water Potential on Internal Humidity and CO 2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2 , thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Here, our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. Lastly, the omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf water potential measurements using the pressure chamber: Synthetic testing of assumptions towards best practices for precision and accuracy

Leaf water potential (ψ leaf ), typically measured using the pressure chamber, is the most important metric of plant water status, providing high theoretical value and information content for multiple applications in quantifying critical physiological processes including drought responses. Pressure chamber measurements of ψ leaf (ψ leafPC ) are most typical, yet, the practical complexity of the technique and of the underlying theory has led to ambiguous understanding of the conditions to optimize measurements. Consequently, specific techniques and precautions diversified across the global research community, raising questions of reliability and repeatability. Here, we surveyed specific methods of ψ leafPC from multiple laboratories, and synthesized experiments testing common assumptions and practices in ψ leafPC for diverse species: (i) the need for equilibration of previously transpiring leaves; (ii) leaf storage before measurement; (iii) the equilibration of ψ leaf for leaves on bagged branches of a range of dehydration; (iv) the equilibration of ψ leaf across the lamina for bagged leaves, and the accuracy of measuring leaves with artificially ‘elongated petioles’; (v) the need in ψ leaf measurements for bagging leaves and high humidity within the chamber; (vi) the need to avoid liquid water on leaf surfaces; (vii) the use of ‘pulse’ pressurization versus gradual pressurization; and (viii) variation among experimenters in ψ leafPC determination. Based on our findings we provide a best practice protocol to maximise accuracy, and provide recommendations for ongoing species-specific tests of important assumptions in future studies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Panama leaf water potential census 2015-2019

This dataset contains values of leaf water potential from a monthly census of predawn and midday measurements conducted on nine trees in each of two sites in Panama from December 2015 to July 2019. The dataset includes individual measurements that were made with a pressure chamber. The measurements were made on the focal trees to complement concurrent measurements of sap flow. The trees were also intensively measured for leaf-level physiological condition during the 2016 ENSO campaign conducted by NGEE-tropics. A subset of measurements was made on leaves that were sealed in plastic bags and protected from solar radiation before they were collected, such that the measurements assessed branch water potential. The dataset contains a csv file that has columns for the time, location, and value of each measurement. The dataset also contains a metadata file, column description file, and an E-Field log file in the recommended NGEE-Tropic formats.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Pre-dawn leaf water potential, San Lorenzo, Panama, 2020

This data package contains predawn leaf water potential (LWP) data for leaves sampled in the San Lorenzo forest canopy crane site in Panama (PA-SLZ) from January to March 2020. Data were collected from 31 species, from top of canopy and vertical profiles within the canopy. All data and metadata are presented in .csv files. The protocol details are provided as *.pdf. See related data packages from the BNL 2020 field campaign for leaf optical properties and gas exchange measurements. Sample information including canopy elevation and leaf area index (LAI) can be found in the related “Leaf and canopy traits” data package.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Diurnal leaf water potential on four tree species, San Lorenzo, Panama, 2020

This data package contains pre-dawn and diurnal leaf water potential (LWP) measured on four trees at the STRI San Lorenzo crane site between January and March 2020. These data were collected from four of the core trees instrumented for sap flux (Guatteria dumetorum, Miconia minutiflora, Terminalia amazonia,Vochysia ferruginea), with measurements made on a single tree on each day. For each tree, leaf samples were harvested from fully sunlit, top of canopy positions pre-dawn (06:00 local time), and then hourly for the subsequent 12 hours. Leaf water potential was measured on 6 - 10 leaves from each time point. Harvested leaves were stored in a cool humid bag in the dark for no more than 40 minutes before LWP was measured. These data were collected as part of a 2020 dry season campaign led by Brookhaven National Laboratory (BNL). Refer to related datasets for further sample details, and paired leaf mass area (LMA), survey gas exchange, and leaf chemistry data. The files included in this data package are in .csv format, and include one data file and three metadata files.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf water potential, Feb2016-May2016, PA-SLZ, PA-PNM, PA-BCI: Panama

This data package contains leaf water potential data from the Barro Colorado Island (BCI), Parque Natural Metropolitano (PNM), and Bosque Protector San Lorenzo (SLZ) NGEE Tropics field sites in Panama. Pre-dawn and diurnal leaf water potential were measured on a monthly basis from February to May 2016 at SLZ and PNM. Data from BCI are only available for the month of March. This data was collected as part of the 2016 El Niño-Southern Oscillation (ENSO) campaign. Included in the attached zip file are data and metadata folders. The single data file "2016ENSO_Panama_LWP" has been provided in both Excel and CSV formats for usability purposes. The metadata file "Metadata_description_2016_ENSO_Panama" provides protocols, site descriptions, equipment information, and more, and has been provided in .docx and PDF file formats. See related datasets (existing and future) for further sample details, leaf spectra, leaf mass area (LMA), gas exchange and leaf chemistry data. VERSION 2 update. The identification of a species from the PNM site has been corrected as follows: the identification of the tree initially identified as Pseudosamanea guachapele (ALBIED) has been revised to Albizia adinocephala (ALBIAD). The updated data package includes revised data, metadata and protocol documents updated to reflect this change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Leaf gas exchange, leaf water potential and spectral reflectance, BIONTE, Brazil, 2023

Leaf traits measured at the top of the canopy on 30 tree species in the BIONTE experimental forest, near Manaus, Brazil, at three time points during August to November, 2023. The aim of this study was to test the relationship between leaf water use efficiency and wood density. Leaf gas exchange was measured on top-of-canopy leaves accessed by an articulated boom lift. Response curves (A-Ci and A-Q), and dark adapted respiration were measured on cut branches. Survey gas exchange measurements were performed on attached leaves at various times during the day. Following gas exchange, leaves were harvested, and measured for leaf water potential and spectral reflectance. Data in this data package is presented in csv files, with metadata in csv and descriptive experimental protocols as pdf. Gas exchange data and metadata meets the requirements of the ESS-DIVE reporting format for leaf-level gas exchange data and metadata.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Leaf water potential, Feb2016-May2016, PA-SLZ, PA-PNM, PA-BCI: Panama

Pre-dawn and diurnal leaf water potential measured on a monthly basis from Feb to May 2016 at SLZ and PNM. Data from BCI only available for March. This data was collected as part of the 2016 ENSO campaign. See related datasets (existing and future) for further sample details, leaf spectra, LMA, gas exchange and leaf chemistry.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Interacting Effects of Leaf Water Potential and Biomass on Vegetation Optical Depth

Remotely sensed microwave observations of vegetation optical depth (VOD) have been widely used for examining vegetation responses to climate. Nevertheless, the relative impacts of phenological changes in leaf biomass and water stress on VOD have not been explicitly disentangled. In particular, determining whether leaf water potential ( ψ L ) affects VOD may allow these data sets as a constraint for plant hydraulic models. Here, in this work, we test the sensitivity of VOD to variations in ψ L and present a conceptual framework that relates VOD to ψ L and total biomass including leaves, whose dynamics are measured through leaf area index, and woody components. We used measurements of ψ L from three sites across the US—a mixed deciduous forests in Indiana and Missouri and a piñon-juniper woodland in New Mexico—to validate the conceptual model. The temporal dynamics of X-band VOD were similar to those of the VOD signal estimated from the new conceptual model with observed ψ L ( R 2 = 0.6–0.8). At the global scale, accounting for a combination of biomass and estimated ψ L (based on satellite surface soil moisture data) increased correlations with VOD by ~ 15% and 30% compared to biomass and water potential, respectively. In wetter regions with denser and taller canopy heights, VOD has a higher correlation with leaf area index than with water stress and vice versa in drier regions. Our results demonstrate that variations in both phenology and ψ L must be considered to accurately interpret the dynamics of VOD observations for ecological applications.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2000

BOREAS TE-6 Predawn Leaf Water Potentials and Foliage Moisture Contents

The BOREAS TE-6 team collected several data sets to examine the influence of vegetation, climate, and their interactions on the major carbon fluxes for boreal forest species. This data set contains summaries of predawn leaf water potentials and foliage moisture contents collected at the TF and CEV sites that had canopy access towers. The data were collected on a nearly weekly basis from early June to late August 1994 by TE-06, members of the BOREAS staff, and employees of Environment Canada. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

Hall, Forrest G.↗
DOE OSTI2018

SUMO Leaf Water Potential

The Los Alamos Survival–Mortality experiment (SUMO) is located on Frijoles Mesa near Los Alamos, New Mexico, USA, at an elevation of 2150 m. This was a tree manipulation study that investigated the relative impacts of drought and warming on plant function and reveals how trees adapt to drought and heat in semi-arid regions. The study factored the role of tree hydraulic acclimation to both precipitation and temperature and separated their effects.The experiment is located in a pinon-juniper woodland near the ponderosa pine (Pinus ponderosa) forest ecotone. Monthly pre-dawn and midday shoot water potentials for each target tree. See SUMO Target Tree Information data package (doi:10.15485/1440544) for additional information. Data released by Los Alamos National Lab for public use under LA-UR-18-23656.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Light response (AQ) gas exchange by leaf age, Feb2017, PA-SLZ: Panama

Light response (AQ curves) gas exchange of sunlit canopy leaves of Terminalia amazonia (TERMAM), Vochysia ferruginea (VOCHFE), Miconia borealis (MICOBO) and Guatteria dumetorum (GUATDU) species from the Smithsonian Tropical Research Institute (STRI) canopy crane site in the San Lorenzo National Park, Republic of Panama, during February 2017. Light response was measured on young, mature and old leaves collected before dawn on 3 days. The data package comprises a single data spreadsheet (*.xlsx), two metadata spreadsheets, and data collection protocols and workflow (*.pdf). This data was collected as part of the 2017 Brookhaven National Lab – Smithsonian Tropical Research Institute leaf traits by age campaign. See related datasets for further sample details, leaf water potential, leaf spectra, diurnal gas exchange, sap flow, leaf mass area (LMA) and leaf chemistry.n National Lab - Smithsonian Tropical Research Institute (BNL–STRI) leaf traits by age campaign. See related datasets for further sample details, leaf water potential, leaf spectra, diurnal gas exchange, sap flow, leaf mass area (LMA) and leaf chemistry.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2000

BOREAS TE-12 SSA Leaf Water Potential Data

The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-12 (Terrestrial Ecology) team collected water potential data in 1993 and 1994 from aspen, jack pine, and black spruce leaves/needles. Collections were made at the Southern Study Area Nipawin Fen Site (SSA FEN), Young Jack Pine (YJP), Young Aspen (YA), Old Aspen (OA), and Old Black Spruce (OBS) sites. Measurements were made using a pressure chamber on a platform in the field. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Hall, Forrest G.↗
DOE OSTI2017

Leaf Pressure Volume Data in Caxiuana and Tapajos National Forest, Para, Brazil (2011)

Pressure volume curve measurements on leaves of canopy trees from the from the Caxiuana and Tapajos National Forests, Para, Brazil. Tapajos samples were harvested from the km 67 forested area, which is adjacent to the decommissioned throughfall exclusion drought experimental plot. Caxiuana samples were harvested from trees growing in the throughfall exclusion plots. Data were collected in 2011. Dataset includes: date of measurement, site ID, plot ID, tree ID (species, tree tag #), leaf area, fresh weight, relative weight, leaf water potential, and leaf water loss. P-V curve parameters (turgor loss point, osmotic potential, and bulk modulus of elasticity) can be found in Powell et al. (2017) Differences in xylem cavitation resistance and leaf hydraulic traits explain differences in drought tolerance among mature Amazon rainforest trees. Global Change Biology.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Leaf gas exchange survey by leaf age, Feb2017, PA-SLZ: Panama

Leaf gas exchange survey measurements on in situ sunlit canopy leaves of four tree species from the San Lorenzo Canopy Crane Site in Panama in February 2017. Multiple measurements were taken on young, mature and old leaves at 3 or 4 time points for each species (early morning, mid-morning, solar noon, afternoon) over 4 days. This data was collected as part of the 2017 BNL–STRI leaf traits by age campaign. See related datasets for other measurements made as part of this campaign including leaf water potential, leaf spectra, sap flow, leaf mass per area, other gas exchange measurements and leaf chemistry. Note: A corrected version of the data file was posted on October 9, 2018.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf sample detail, Feb2016-May2016, PA-SLZ, PA-PNM, PA-BCI: Panama

This data package contains details of the date, location, species and photographs of leaf samples collected on a monthly basis from Feb to May 2016 from Parque Natural Metropolitano (PA-PNM), Barro Colorado Island (PA-BCI) and Bosque Protector San Lorenzo (PA-SLZ) in Panama. Data from BCI only available for March. This data was collected as part of the 2016 El Niño-Southern Oscillation (ENSO) campaign. Included in this data package are an Excel file with data (2016ENSO_Panama_LeafSamples) and two Excel files with associated metadata. Sample photos are included in five zip files, organized by month and site. Also included is a Word document (Metadata_description_2016_ENSO_Panama) with details such as data collection methods, equipment used, and site information. Data to be used as a reference to linking related datasets including leaf water potential, leaf spectra, LMA, gas exchange and leaf chemistry (CHN, NSC). Most leaves were sampled from sunlit canopy trees. VERSION 2 update. The identification of a species from the PNM site has been corrected as follows: the identification of the tree initially identified as Pseudosamanea guachapele (ALBIED) has been revised to Albizia adinocephala (ALBIAD). The updated data package includes revised data, metadata and protocol documents updated to reflect this change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf mass area, Feb2016-May2016, PA-SLZ, PA-PNM, PA-BCI: Panama

This data package contains leaf mass data per unit area measured on a monthly basis from February to April, 2016, at the Bosque Protector San Lorenzo (PA-SLZ) and Parque Natural Metropolitano (PA-PNM) sites in Panama. Data from the Barro Colorado Island (PA-BCI) site are only available for March. This data was collected as part of the 2016 El Niño-Southern Oscillation (ENSO) campaign. Included in this data package are an Excel file with data (2016ENSO_Panama_LMA1) and two Excel files with associated metadata. Also included is a Word document (Metadata_description_2016_ENSO_Panama) with details such as data collection methods, equipment used, and site information. See related datasets for further sample details, leaf water potential, leaf spectra, gas exchange and leaf chemistry. VERSION 2 update. The identification of a species from the PNM site has been corrected as follows: the identification of the tree initially identified as Pseudosamanea guachapele (ALBIED) has been revised to Albizia adinocephala (ALBIAD). The updated data package includes revised data, metadata and protocol documents updated to reflect this change.

54 ENVIRONMENTAL SCIENCES↗