Stem water cryogenic extraction biases estimation in deuterium isotope composition of plant source water

Proceedings of the National Academy of Sciences, Journal Year: 2020, Volume and Issue: 117(52), P. 33345 - 33350

Published: Dec. 14, 2020

The hydrogen isotope ratio of water cryogenically extracted from plant stem samples (δ2Hstem_CVD) is routinely used to aid applications that span hydrological, ecological, and paleoclimatological research. However, an increasing number studies have shown a key assumption these applications-that δ2Hstem_CVD equal the δ2H source (δ2Hsource)-is not necessarily met in plants various habitats. To examine this assumption, we purposedly designed experimental system allow independent measurements δ2Hstem_CVD, δ2Hsource, transported xylem conduits (δ2Hxylem) under controlled conditions. Our performed on nine woody species diverse habitats revealed consistent significant depletion compared with both δ2Hsource δ2Hxylem Meanwhile, no discrepancy was observed between any investigated. These results cast doubt long-standing view deuterium fractionation occurs during root uptake and, alternatively, suggest measurement bias inherent cryogenic extraction method cause depletion. We rehydration experiment show error could originate dynamic exchange organically bound liquid extraction. In light our finding, caution when partitioning sources reconstructing past climates using isotopes, carefully propose paradigm-shifting phenomenon ecohydrological separation ("two worlds") underpinned by artifact.

Language: Английский

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Evidence for distinct isotopic compositions of sap and tissue water in tree stems: consequences for plant water source identification

New Phytologist, Journal Year: 2021, Volume and Issue: 233(3), P. 1121 - 1132

Published: Nov. 12, 2021

Summary The long‐standing hypothesis that the isotopic composition of plant stem water reflects source is being challenged by studies reporting bulk from woody stems with an cannot be attributed to any potential source. mechanism behind such source–stem offsets still poorly understood. Using a novel technique extract selectively sap xylem conduits, we show that, in cut and potted plants, irrigation water, demonstrating unambiguously no fractionation occurs during root uptake or extraction. By contrast, nonconductive tissues always depleted deuterium compared irrespective wood anatomy. Previous have shown heterogeneity also exists soils at pore scale which adsorbed onto soil particles more than unbound water. Data collected riparian forest indicated matches best depth below −70 cm, while differ markedly. We conclude can explained micrometre‐scale isotope ratios within micro‐pores.

Language: Английский

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Plant and root‐zone water isotopes are difficult to measure, explain, and predict: Some practical recommendations for determining plant water sources

Methods in Ecology and Evolution, Journal Year: 2020, Volume and Issue: 11(11), P. 1352 - 1367

Published: Aug. 2, 2020

Abstract Stable isotope ratios of water (δ 18 O, δ 2 H) have long been used to study a core question in plant ecology and ecohydrology: ‘From where do plants take up water?’ Indeed, decades research has involved sampling potential sources the subsurface, classifying those as distinct endmembers (e.g. deep vs. shallow soil waters) then evaluating their contributions xylem sample through mixing‐model analysis identify depths root uptake. However, more detailed interrogations subsurface domains revealed under‐considered transport isotopic fractionation phenomena. These now apparent complexities raise new questions challenge many past assumptions inherent endmember‐mixing models that seem overly simple. Here, we introduce discussions these recent insights provide an overview effects occur naturally zone plant, well artificially during handling. Better accounting for associated uncertainties can lead accurate robust designs, analytical frameworks and, ultimately, inferences. Finally, robustly characterize using O H, some practical recommendations aim at maximizing contrast between and/or minimizing uncertainties.

Language: Английский

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Vertical decoupling of soil nutrients and water under climate warming reduces plant cumulative nutrient uptake, water‐use efficiency and productivity

New Phytologist, Journal Year: 2021, Volume and Issue: 230(4), P. 1378 - 1393

Published: Feb. 7, 2021

Warming-induced desiccation of the fertile topsoil layer could lead to decreased nutrient diffusion, mobility, mineralization and uptake by roots. Increased vertical decoupling between nutrients in water availability subsoil/bedrock layers under warming thereby reduce cumulative over growing season. We used a Mediterranean semiarid shrubland as model system assess impacts warming-induced on plant water- nutrient-use patterns. A 6 yr manipulative field experiment examined effects (2.5°C), rainfall reduction (30%) their combination soil resource utilization Helianthemum squamatum shrubs. drier ('growth pool') led greater proportional from deeper, wetter, but less ('maintenance plants. This was linked uptake, increased nonstomatal (nutritional) limitation photosynthesis reduced water-use efficiency, above-ground biomass growth drought survival. Whereas shift stored deep may buffer negative impact transpiration, this plastic response cannot compensate for associated carbon assimilation, which compromise capacity plants adjust warmer climate.

Language: Английский

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Stable isotopes of water reveal differences in plant – soil water relationships across northern environments

Hydrological Processes, Journal Year: 2020, Volume and Issue: 35(1)

Published: Dec. 24, 2020

Abstract We compared stable isotopes of water in plant stem (xylem) and soil collected over a complete growing season from five well‐known long‐term study sites northern/cold regions. These spanned decreasing temperature gradient Bruntland Burn (Scotland), Dorset (Canadian Shield), Dry Creek (USA), Krycklan (Sweden), to Wolf (northern Canada). Xylem was isotopically depleted waters, most notably for deuterium. The degree which potential sources could explain the isotopic composition xylem assessed quantitatively using overlapping polygons enclose respective data sets when plotted dual isotope space. At angiosperms showed strong overlap with water; this not case gymnosperms. In cases, on given sampling day be better explained if considered longer antecedent periods spanning many months. at usually dissimilar drier summer months, although differed sequence change. Open questions remain why significant proportion cannot by sources, particularly It is recommended that future research focuses fractionation affect uptake soil‐root interface, both through effects exchange between vapour liquid phases mycorrhizal interactions. Additionally, cold regions, evaporation diffusion winter may an important process.

Language: Английский

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In situ measurements of soil and plant water isotopes: a review of approaches, practical considerations and a vision for the future

Hydrology and earth system sciences, Journal Year: 2020, Volume and Issue: 24(9), P. 4413 - 4440

Published: Sept. 11, 2020

Abstract. The number of ecohydrological studies involving water stable isotope measurements has been increasing steadily due to technological (e.g., field-deployable laser spectroscopy and cheaper instruments) methodological (i.e., tracer approaches or improvements in root uptake models) advances recent years. This enables researchers from a broad scientific background incorporate water-isotope-based methods into their studies. Several effects are currently not fully understood but might be essential when investigating depths vegetation separating processes the soil–vegetation–atmosphere continuum. Different viewpoints exist on (i) extraction for soil plant artifacts potentially introduced by them, (ii) pools (mobile vs. immobile) measured with those methods, (iii) spatial variability temporal dynamics composition different compartments terrestrial ecosystems. In situ have proposed as an innovative necessary way address these issues required order disentangle take them account studying plants soil–plant–atmosphere interaction based isotopes. Herein, we review current status isotopes soils plants, point out highlight potential future research. Moreover, put strong focus practical aspects this provide guideline limited previous experience methods. We also include section opportunities incorporating data obtained described existing isotope-enabled models examples illustrating benefits doing so. Finally, propose integrated methodology measuring both carrying at authors shown that reliable can generated field using composition. For transpiration, common effort. Little attention paid xylem measurements. Research needs improving further developing There is need consistent combined (soils plants) Such systems should designed adapted environment studied. conclude many rely extensively because technical difficulty uncertainties. Future research aim simplified approach provides reasonable trade-off between practicability precision accuracy.

Language: Английский

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Tree water deficit and dynamic source water partitioning

Hydrological Processes, Journal Year: 2020, Volume and Issue: 35(1)

Published: Dec. 10, 2020

Abstract The stable isotopes of hydrogen and oxygen (δ 2 H δ 18 O, respectively) have been widely used to investigate tree water source partitioning. These tracers shed new light on patterns use in time space. However, there are several limiting factors this methodology (e.g., the difficult assessment isotope fractionation trees, labor‐intensity associated with collection significant sample sizes) alone has not enough provide a mechanistic understanding Here, we combine data xylem soil measurements tree's physiological information including deficit (TWD), fine root distribution, matric potential, mechanism driving We m 3 lysimeter willow trees ( Salix viminalis ) planted within, conduct high spatial–temporal resolution experiment. TWD provided an integrated response plant status supply demand. combined isotopic measurement showed that short‐term variation (within days) partitioning is determined mainly by hydraulic changes potential. observed relationship between potential matched shifts Our results show dynamic process scale days. findings demonstrate plasticity over days can be identified high‐resolution status. further support distribution indicator uptake dynamics. Overall, combining traditional tracing reveal insights into responses changing environmental conditions.

Language: Английский

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Potential effects of cryogenic extraction biases on plant water source partitioning inferred from xylem‐water isotope ratios

Hydrological Processes, Journal Year: 2022, Volume and Issue: 36(2)

Published: Jan. 21, 2022

Language: Английский

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Technical note: On uncertainties in plant water isotopic composition following extraction by cryogenic vacuum distillation

Hydrology and earth system sciences, Journal Year: 2022, Volume and Issue: 26(22), P. 5835 - 5847

Published: Nov. 17, 2022

Abstract. Recent studies have challenged the interpretation of plant water isotopes obtained through cryogenic vacuum distillation (CVD) based on observations a large 2H fractionation. These hypothesized existence an H-atom exchange between and organic tissue during CVD extraction with magnitude H related to relative content sample; however, clear evidence is lacking. Here, we systematically tested uncertainties in isotopic composition CVD-extracted by conducting series incubation rehydration experiments using isotopically depleted water, at natural isotope abundance, woody materials exchangeable H, without (cellulose triacetate caffeine). We show that offsets hydrogen oxygen ratios expected reference values (Δ2H Δ18O) inversely proportional relationships absolute amount being extracted, i.e. lower amount, higher Δ2H Δ18O. However, neither nor Δ18O values, were sample content. The pattern was more pronounced for atoms than non-exchangeable atoms. This caused combined effect enrichments evaporation sublimation depend amount. itself negligible. Despite these technical issues, observed amount-dependent patterns much less samples abundance particularly low when sufficiently high amounts extracted (>600 µL). Our study provides new insights into mechanisms causing fractionation water. methodological can be controlled if are used ecohydrological studies.

Language: Английский

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Updating the dual C and O isotope—Gas‐exchange model: A concept to understand plant responses to the environment and its implications for tree rings

Plant Cell & Environment, Journal Year: 2023, Volume and Issue: 46(9), P. 2606 - 2627

Published: June 7, 2023

Abstract The combined study of carbon (C) and oxygen (O) isotopes in plant organic matter has emerged as a powerful tool for understanding functional responses to environmental change. approach relies on established relationships between leaf gas exchange isotopic fractionation derive series model scenarios that can be used infer changes photosynthetic assimilation stomatal conductance driven by parameters (CO 2 , water availability, air humidity, temperature, nutrients). We review the mechanistic basis conceptual model, light recently published research, discuss where observations do not match our current physiological response environment. demonstrate (1) was applied successfully many, but all studies; (2) although originally conceived isotopes, been extensively tree‐ring context tree physiology dendrochronology. Where deviate from physiologically plausible conclusions, this mismatch isotope provides valuable insights into underlying processes. Overall, we found grouped situations increasing resource limitation versus higher availability. dual‐isotope helps interpret multitude factors.

Language: Английский

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