Uncoupling of stomatal conductance and photosynthesis at high temperatures: mechanistic insights from online stable isotope techniques

New Phytologist, Journal Year: 2024, Volume and Issue: 241(6), P. 2366 - 2378

Published: Feb. 1, 2024

Summary The strong covariation of temperature and vapour pressure deficit (VPD) in nature limits our understanding the direct effects on leaf gas exchange. Stable isotopes CO 2 H O provide mechanistic insight into physiological biochemical processes during We conducted combined exchange online isotope discrimination measurements four common European tree species across a range 5–40°C, while maintaining constant leaf‐to‐air VPD (0.8 kPa) without soil water limitation. Above optimum for photosynthesis (30°C) under controlled environmental conditions, stomatal conductance ( g s ) net rate A n decoupled all tested species, with increasing but decreasing. During this decoupling, mesophyll (cell wall, plasma membrane chloroplast conductance) consistently significantly decreased among species; however, reduction did not lead to reductions concentration at surface stroma. question conventional that diffusional limitations contribute high temperatures. suggest stomata membranes could work strategically facilitate transpiration cooling supply, thus alleviating heat stress photosynthetic function, albeit cost reduced water‐use efficiency.

Language: Английский

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Comparative Foliar Atmospheric Mercury Accumulation across Functional Types in Temperate Trees

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 22, 2025

Vegetation assimilation of atmospheric gaseous elemental mercury (GEM) represents the largest dry deposition pathway in global terrestrial ecosystems. This study investigated Hg accumulation mechanisms deciduous broadleaves and evergreen needles, focusing on how ecophysiological strategies─reflected by δ13C, δ18O, leaf mass per area, matter content-mediated accumulation. Results showed that leaves exhibited higher total (THg) concentrations rates (THgrate), which were 85.3 ± 17.7 110.0 0.3% than those needles. The two tree types distinct strategies: broadleaves, with stomatal conductance photosynthetic rates, rapidly adjust stomata to changes meteorological pollutant factors, playing a key role controlling THgrate. In contrast, needles featured stable control, highlighting direct positive effect GEM their Precipitation wind speed negatively influenced foliar Correlations between PM2.5, NO2, THgrate suggested synergistic patterns pollutants. underscores across functional emphasizes importance species-specific strategies. An empirical model linking ecophysiological, meteorological, pollution factors was provided, contributing refinement models.

Language: Английский

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Thawing permafrost can mitigate warming-induced drought stress in boreal forest trees

The Science of The Total Environment, Journal Year: 2023, Volume and Issue: 912, P. 168858 - 168858

Published: Nov. 27, 2023

Perennially frozen soil, also known as permafrost, is important for the functioning and productivity of most boreal forest, world's largest terrestrial biome. A better understanding complex vegetation-permafrost interrelationships needed to predict changes in local- large-scale carbon, nutrient, water cycle dynamics under future global warming. Here, we analyze tree-ring width stable isotope (C O) measurements Gmelin larch (Larix gmelinii (Rupr.) Rupr.) from six permafrost sites northern taiga central Siberia. Our multi-parameter approach shows that tree growth were predominantly controlled by temperature moisture content active soil upper layers. The observed patterns range strong limitations early summer temperatures at higher elevations significant controls precipitation warmer well-drained lower-elevation sites. Enhanced radial mainly found with fast thawing mineral layers, comparison isotopes over five-year periods different amounts indicates trees can prevent drought stress accessing melted snow seasonally soil. Identifying layers resources during dry summers demonstrates complexity ecosystem responses climatic changes.

Language: Английский

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Multi-decadal tree-ring stable isotope records of apple and pear trees indicate coherent ecophysiological responses to environmental changes in alpine valleys

Frontiers in Plant Science, Journal Year: 2025, Volume and Issue: 15

Published: Jan. 10, 2025

The ecophysiological and ecohydrological impacts of climate change progressively increasing atmospheric carbon dioxide (CO2) concentration on agroecosystems are not well understood compared to the forest ecosystems. In this study, we utilized presence old apple pear trees in alpine valleys Northern Italy (maintained for cultural heritage purposes) investigate climate-scale physiological responses. We developed long-term tree-ring stable isotopic records (δ13C δ18O) from (1976-2021) (1943-2021). This allowed reconstruction key processes like variations intrinsic water use efficiency (iWUE), investigated how these responded CO2 changes over decades. Results showed a slight declining trend discrimination (Δ 13C) while intercellular (Ci) both species has been since late 1980s. Concurrently exhibited rising iWUE, with demonstrating higher efficiency, which appears be primarily driven by CO2-fertilization effect. concomitant trends δ18O suggested relatively local hydroclimate during study period some species-specific Analyses further revealed that minimum growing season temperature, precipitation was most significant factor influencing rise iWUE alongside fertilization species' δ13C coupled their respective confirmed due increased assimilation rather than decline evapotranspiration. Moreover, δ13C-δ18O analyses assimilation, showing inter-decadal variations. These provide unique opportunity test calibrate systems respond recent anticipated change.

Language: Английский

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Stable Isotopes Reveal the Drivers of Post‐Wildfire Natural Regeneration of Interior Douglas‐Fir Seedlings in British Columbia

Ecology and Evolution, Journal Year: 2025, Volume and Issue: 15(3)

Published: March 1, 2025

ABSTRACT Wildfires are increasing in frequency and severity due to climate change, posing challenges forest ecosystems, including the southern interior of British Columbia, Canada. Interior Douglas‐fir ( Pseudotsuga menziesii var. glauca ) is a species great cultural, ecological, economic importance, necessitating investigation post‐wildfire regeneration amidst this changing wildfire regime. This study examines seedling across three burn levels (low, moderate, high) 5 years at site Columbia. Natural traits were measured 2022 paired with stable isotope analyses (δ 13 C, δ 15 N, 18 O) foliar nutrient assessments. We employed linear mixed‐effects models assess impact light, water, factors on biomass. Results indicate higher density low sites but larger individual biomass moderate high sites. Light availability was primary factor limiting biomass, greater C sites, suggesting that reduced canopy cover enhances photosynthesis water use efficiency. Despite solar exposure, seedlings did not show increased drought stress according leaf O stem contents, likely interception competition for soil by overstory trees. Biomass growth linked status, indicating availability, particularly limit While light current growth‐limiting regenerating study, intensity heat waves droughts associated change may increase stress, emphasizing need long‐term monitoring adaptive management support Douglas‐fir.

Language: Английский

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Growth and Assemblage Dynamics of Temperate Forest Tree Species Match Physiological Resilience to Changes in Atmospheric Chemistry

Global Change Biology, Journal Year: 2025, Volume and Issue: 31(3)

Published: March 1, 2025

Human-induced environmental changes are altering forest productivity and species composition, significantly impacting tree physiology, growth, water uptake, nutrient acquisition. Investigating the intricate interplay between plant physiology shifts, we analyzed tree-ring isotopes (δ13C, δ18O, δ15N) to track long-term trends in intrinsic water-use efficiency (iWUE) nitrogen availability for European beech, Norway spruce, silver fir a unique old-growth temperate mountain since 1501 ce. Our findings reveal that dominant species, exhibited iWUE saturation, exacerbated by acidic precipitation, resulting growth declines during periods of high air pollution increased drought frequency. In contrast, deep-rooted, deciduous beech demonstrated physiological resilience acid deposition, benefiting from lower dry deposition precipitation acidity thriving under conditions elevated temperatures, thereby sustaining stem regardless potential climatic limitations. Silver showed most dynamic response pollution, with contemporary adaptations leaf gas exchange allowing accelerated cleaner conditions. These different responses underscore shifts competition, gaining dominance as spruce decline. Furthermore, influence ontogeny is evident, tree-rings initial values higher δ15N, reflecting uptake dynamics ecological role age. study integrates tree-growth trends, revealing pivotal atmospheric chemistry shaping competitive trajectories forests.

Language: Английский

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Tree‐Ring Stable Isotopes Reveal a Hydroclimate Shift in Eastern England Around 4.2 ka Ago

Geophysical Research Letters, Journal Year: 2025, Volume and Issue: 52(7)

Published: April 1, 2025

Abstract Tree ring‐based climate reconstructions are fundamental for high‐resolution paleoclimatology, but only a few of them extend back into the mid‐Holocene (8,200–4,200 years BP). Here, we present annually‐resolved tree‐ring stable carbon and oxygen isotopes (δ 13 C δ 18 O) from subfossil yew ( Taxus baccata ) wood excavated in Fenland region eastern England. We develop an eco‐physiological model to reconstruct hydroclimate variability 5,224 4,813 ± 4 4,612–4,195 6 cal. BP. Our findings suggest that relative sea‐level rise North Sea, riverine flooding, prolonged negative phase Atlantic Oscillation caused unusually wet conditions around 4,200 ago when woodlands England disappeared. expect our study stimulate isotope measurements relict encourage integration terrestrial marine proxy archives causes consequences large‐scale variations still debated 4.2 ka event.

Language: Английский

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Preservation of stable isotopic composition in charred grains: Implications for paleoenvironmental and archeological research

Journal of Quaternary Science, Journal Year: 2025, Volume and Issue: unknown

Published: April 1, 2025

ABSTRACT The charring process can preserve archaeobotanical remains, providing valuable insights into past climates, agricultural practices, and plant growth conditions. However, the impact of on stable isotopes, especially at temperatures above 300°C, remains poorly understood. To investigate this, wheat (einkorn, emmer) millet grains were experimentally charred 450°C, 550°C for 15 min to 48 h under aerobic anaerobic Consequently, isotopic ratios carbon ( 13 C/ 12 C; δ C), nitrogen N/ 14 N; N), oxygen 18 O/ 16 O; O) determined in fully with a blackened pericarp, visually comparable archeological remains. Our results indicate that C values are well preserved grains, showing minimal shifts (<0.55‰ <0.2‰ millet), while N retained species‐specific differences, moderate variations (<1.31‰ <0.68‰ millet) influenced by In contrast, O showed high variability limiting their reliability interpretative use. These findings underscore potential and, lesser extent, isotopes reconstructing ancient conditions improving understanding formation processes research.

Language: Английский

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Understanding physiological mechanisms of European beech dieback responses to climate using a triple isotope approach in northern Switzerland

Dendrochronologia, Journal Year: 2025, Volume and Issue: unknown, P. 126335 - 126335

Published: April 1, 2025

Language: Английский

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Key role of ambient temperature in modulating leaf water isotopic enrichment seasonality in a humid subtropical climate

Agricultural and Forest Meteorology, Journal Year: 2025, Volume and Issue: 368, P. 110561 - 110561

Published: April 14, 2025

Language: Английский

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