Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Ring‐specific vulnerability to embolism reveals accumulation of damage in the xylem
Summary Human‐caused climate change is predicted to bring more frequent droughts and higher temperatures in the western United States, which threaten ecologically important trembling aspen forests.We used ring‐specific vulnerability curves of aspen branches along two climate gradients to determine whether damages to pit membranes accumulate as the xylem ages.We found that rings older than 3 yr have a significant decline in hydraulic conductivity, especially at average summer water potentials for the species. These differences were not due to differences in the diameter of the vessels, but a difference in how much xylem was active between rings older than 3 yr and 1 yr, suggesting the presence of accumulated damage to pit membranes impairing water transport.Vulnerability to embolism differs across ring age and between wetter and drier populations, underscoring that damages due to drought may accumulate to lethal levels if the xylem does not acclimate to climate change in newer growth.  more » « less
Award ID(s):
2003017 2044937 2325700
PAR ID:
10652202
Author(s) / Creator(s):
 ;  ;  
Publisher / Repository:
New Phytologist
Date Published:
Journal Name:
New Phytologist
Volume:
246
Issue:
5
ISSN:
0028-646X
Page Range / eLocation ID:
2046 to 2058
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, Functional Ecology)
    Abstract Climate change has increased the frequency and severity of drought and large wildfire events across western North America. Despite the increasing concurrence of drought and wildfire events and the importance of forests as a global carbon sink, the impacts of fire on tree drought and carbon acquisition traits are not well understood, particularly on multi‐year time‐scales.In 2022–2024, we leveraged a natural experiment at a large 2018 wildfire in southwestern Colorado, comparing leaf and xylem functional traits related to drought resistance and carbon acquisition in burned and unburned ponderosa pine, quaking aspen, subalpine fir, and Engelmann spruce trees.Relative to unburned trees of the same species, we found reduced xylem vulnerability to embolism (P50) in burned ponderosa pine and subalpine fir; decreased leaf heat tolerance (T50) in burned quaking aspen and ponderosa pine; and increased investment in leaf structural over photosynthetic components (leaf C:N isotopic ratio) in burned quaking aspen, subalpine fir, and Engelmann spruce.In contrast to previous studies, our results suggest that wildfire positively impacts functional traits related to drought resistance and water movement in surviving burned trees. However, generally negative impacts of wildfire were found with respect to leaf physiological and photosynthetic traits, suggesting divergent water and carbon responses to fire. Read the freePlain Language Summaryfor this article on the Journal blog. 
    more » « less
  2. ; ; ; ; ; ; (, Plant Biology)
    Abstract Drought events may increase the likelihood that the plant water transport system becomes interrupted by embolism. Yet our knowledge about the temporal frequency of xylem embolism in the field is frequently lacking, as it requires detailed, long‐term measurements.We measured xylem embolism resistance and midday xylem water potentials during the consecutive summers of 2019 and 2020 to estimate maximum levels of embolism in leaf and stem xylem of ten temperate angiosperm tree species. We also studied vessel and pit membrane characteristics based on light and electron microscopy to corroborate potential differences in embolism resistance between leaves and stems.Apart fromA.pseudoplatanusandQ.petraea, eight species experienced minimum xylem water potentials that were close to or below those required to initiate embolism. Water potentials corresponding to ca. 12% loss of hydraulic conductivity (PLC) could occur in six species, while considerable levels of embolism around 50% PLC were limited toB.pendulaandC.avellana. There was a general agreement in embolism resistance between stems and leaves, with leaves being equally or more resistant than stems. Also, xylem embolism resistance was significantly correlated to intervessel pit membrane thickness (TPM) for stems, but not to vessel diameter and total intervessel pit membrane surface area of a vessel.Our data indicate that low amounts of embolism occur in most species during moderate summer drought, and that considerable levels of embolism are uncommon. Moreover, our experimental andTPMdata show that leaf xylem is generally no more vulnerable than stem xylem. 
    more » « less
  3. ; ; ; (, New Phytologist)
    Summary Trees harbor large stores of nonstructural carbohydrates, some of which are quite old (> 10 yr), yet we know little of how these older stores may be used for woody growth. Crucially, the use of old carbohydrates during cellulose biosynthesis could confound climate reconstructions that rely on tree ring stable isotope ratios.We analyzed tree‐ring cellulose Δ14C and δ13C in earlywood of two pine species from montane forests in western North America using tree rings produced during the radiocarbon bomb pulse (1966–1980).Comparison of the Δ14C from ponderosa pine in Utah with estimates of atmospheric14CO2showed that the cellulose Δ14C values can be explained using only carbon fixed in the same growing season as ring construction. In the more arid Arizona pine, the cellulose Δ14C values indicate that up to 50% of the carbon used in tree‐ring construction can be from photosynthate assimilated the year before ring construction. Correlations between cellulose δ13C time series and aridity indices validated the results obtained from Δ14C values.The results reveal that in some semiarid coniferous forests, tree‐ring isotope composition could partially reflect the climate from at least one previous growing season, but that carbon sources older than 2 yr are likely seldom used. 
    more » « less
  4. ; ; ; ; ; ; ; (, New Phytologist)
    Summary Our ability to explain and predict the spatial patterns of forest mortality remains limited. We tested the predictability of water stress across populations and explored how water availability and plant allocation mediate spatial variation in tree growth in a widespread oak species (Quercus douglasiiHook & Arn.).We conducted a range‐wide survey of drought stress, xylem water isotopes, growth, and allocation traits across 15 sites spanning almost 1000 m difference in annual precipitation.We found little relationship between end‐of‐season water availability (predawn leaf water potentials) or maximum stress (midday water potentials) and climate or soils. Instead, stem water stable isotopes indicated that water availability was predicted by access to deep water resources derived from large winter storms. We also found a three‐way decoupling of water stress, prior growth, and allocation to leaf tissue, such that simulated hydraulic risk from a mechanistic model was uncorrelated with observed performance.Our results reveal that deeply rooted trees can be hydrologically decoupled from aboveground climate, and that the seasonality of growth, trait development, and hydraulic risk are phenologically disconnected. The complicated relationship between carbon gain and hydraulic risk in seasonal environments and limited data on critical zone hydrology are key challenges to predicting drought vulnerability. 
    more » « less
  5. ; ; ; ; ; ; ; (, WIREs Water)
    Abstract As a key ingredient of batteries for electric vehicles (EVs), lithium plays a significant role in climate change mitigation, but lithium has considerable impacts on water and society across its life cycle. Upstream extraction methods—including open‐pit mining, brine evaporation, and novel direct lithium extraction (DLE)—and downstream processes present different impacts on both the quantity and quality of water resources, leading to water depletion and contamination. Regarding upstream extraction, it is critical for a comprehensive assessment of lithium's life cycle to include cumulative impacts related not only to freshwater, but also mineralized or saline groundwater, also known as brine. Legal frameworks have obscured social and ecological impacts by treating brine as a mineral rather than water in regulation of lithium extraction through brine evaporation. Analysis of cumulative impacts across the lifespan of lithium reveals not only water impacts in conventional open‐pit mining and brine evaporation, but also significant freshwater needs for DLE technologies, as well as burdens on fenceline communities related to wastewater in processing, chemical contaminants in battery manufacturing, water use for cooling in energy storage, and water quality hazards in recycling. Water analysis in lithium life cycle assessments (LCAs) tends to exclude brine and lack hydrosocial context on the environmental justice implications of water use by life cycle stage. New research directions might benefit from taking a more community‐engaged and cradle‐to‐cradle approach to lithium LCAs, including regionalized impact analysis of freshwater use in DLE, as well as wastewater pollution, cooling water, and recycling hazards from downstream processes. This article is categorized under:Human Water > Human WaterHuman Water > Water GovernanceHuman Water > Water as Imagined and RepresentedScience of Water > Water and Environmental Change 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email