Deep roots mitigate drought impacts on tropical trees despite limited quantitative contribution to transpiration

The Science of The Total Environment, Год журнала: 2023, Номер 893, С. 164763 - 164763

Опубликована: Июнь 10, 2023

Deep rooting is considered a central drought-mitigation trait with vast impact on ecosystem water cycling. Despite its importance, little known about the overall quantitative use via deep roots and dynamic shifts of uptake depths changing ambient conditions. Knowledge especially sparse for tropical trees. Therefore, we conducted drought, soil labeling re-wetting experiment at Biosphere 2 Tropical Rainforest. We used in situ methods to determine stable isotope values tree high temporal resolution. Complemented by stem content sap flow measurements determined percentages quantities deep-water total root dynamics different species. All canopy trees had access (max. depth 3.3 m), contributions transpiration ranging between 21 % 90 during when surface availability was limited. Our results suggest that an essential source delays potentially detrimental drops plant potentials limited could hence mitigate impacts increasing drought occurrence intensity as consequence climate change. Quantitatively, however, amount low due trees' reduction drought. Total largely followed switched back their dynamically, from shallow soils, following rainfall. fluxes were driven precipitation input.

Язык: Английский

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Toward a common methodological framework for the sampling, extraction, and isotopic analysis of water in the Critical Zone to study vegetation water use

Wiley Interdisciplinary Reviews Water, Год журнала: 2024, Номер 11(4)

Опубликована: Март 5, 2024

Abstract The analysis of the stable isotopic composition hydrogen and oxygen in water samples from soils plants can help to identify sources vegetation uptake. This approach requires that heterogeneous nature plant soil matrices is carefully accounted for during experimental design, sample collection, extraction analyses. comparability shortcomings different methods extracting analyzing have been discussed specialized literature. Yet, despite insightful comparisons benchmarking methodologies laboratories worldwide, community still lacks a roadmap guide extraction, analyses, many practical issues potential users remain unresolved: example, which (soil or plant) pool(s) does extracted represent? These constitute hurdle implementation by newcomers. Here, we summarize discussions led framework COST Action WATSON (“WATer isotopeS critical zONe: groundwater recharge transpiration”—CA19120). We provide guidelines (1) sampling material analysis, (2) laboratory situ (3) measurements composition. highlight importance considering process chain as whole, design minimize biased estimates relative contribution conclude acknowledging some limitations this methodology advice on collection key environmental parameters prior article categorized under: Science Water > Hydrological Processes Environmental Change Extremes

Язык: Английский

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UAV‐Based Land Surface Temperatures and Vegetation Indices Explain and Predict Spatial Patterns of Soil Water Isotopes in a Tropical Dry Forest

Water Resources Research, Год журнала: 2025, Номер 61(2)

Опубликована: Фев. 1, 2025

Abstract The spatial variation of soil water isotopes (SWI)—representing the baseline for investigating root uptake (RWU) depths with stable isotope techniques—has rarely been investigated. Here, we use SWI depth profile sampling in combination unmanned aerial vehicle (UAV) based land surface temperature estimates and vegetation indices (VI) order to improving process understanding relationships between variability content patterns canopy status, represented form VI. We carried out a 10 profiles tropical dry forest. UAV data were collected analyzed obtain detailed characterization status. then performed statistical analysis VI temperatures values at different resolutions (3 cm–5 m). Best used generating isoscapes entire study area. Results suggest that are strongly mediated by parameters (VI). Various correlate across all depths. depend on ( R 2 0.66 δ 18 O 0.64 H). Strongest overall correlations found resolution 0.5 m. speculate this might be ideal spatially characterizing investigate RWU forest environments. Supporting analyses UAV‐based approaches future avenue representation credibility such studies.

Язык: Английский

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Continuous in situ measurements of water stable isotopes in soils, tree trunk and root xylem: Field approval

Rapid Communications in Mass Spectrometry, Год журнала: 2021, Номер 36(5)

Опубликована: Дек. 4, 2021

New methods to measure stable isotopes of soil and tree water directly in the field enable us increase temporal resolution obtained data advance our knowledge on dynamics plant fluxes. Only few applications exist. However, these are needed further improve novel hence exploit their full potential.We tested borehole equilibration method collected situ destructive samples soil, trunk root xylem over a 2.5-month experiment tropical dry forest under natural abundance conditions following labelled irrigation. Water from was extracted using cryogenic vacuum extraction. Isotope ratios were determined with IRIS instruments cavity ring-down spectroscopy both laboratory.In general, timelines agreed well for samples. Irrigation heavy hydrogen clearly impacted isotope composition one two studied species. Inter-method deviations increased consequence labelling, which revealed different capabilities cover spatial heterogeneities.We applied remote location. Our reinforced potential this measuring trunks roots confirmed reliability gas permeable probes. measurements should be developed reduce uncertainty within range potential.

Язык: Английский

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A comparative study of plant water extraction methods for isotopic analyses: Scholander-type pressure chamber vs. cryogenic vacuum distillation

Hydrology and earth system sciences, Год журнала: 2022, Номер 26(13), С. 3673 - 3689

Опубликована: Июль 14, 2022

Abstract. Recent tracer-based studies using stable isotopes of hydrogen and oxygen showed that different methods for extracting water from plant tissues can return isotopic compositions due to the presence organic compounds because they extract domains. One most used is cryogenic vacuum distillation (CVD), which tends total water. Conversely, Scholander-type pressure chamber (SPC), commonly by tree physiologists measure potential in determine stress, expected only more mobile (i.e., xylem inter-cellular water). However, few reported application SPC analyses, therefore, inter-method comparisons between CVD are great value. In this work, we analyzed variability composition extracted CVD, also considering signature various leaves, twig without bark, with close trunk tree, wood core) species alder, apple, chestnut, beech). The extraction simple, be carried out field, it does not require specific laboratory work as case CVD. main limitation very small volume lignified twigs under stress conditions compared Our results indicated were significantly different. difference obtained two was smaller beech samples chestnut samples. enriched δ2H δ18O, respectively, than We conclude an alternative mostly extracts water, whereas retrieve all stored sampled tissue both living dead cells. aiming quantify relative contribution soil sources transpiration should rely on (which theoretically SPC) (sampled CVD), contains a fraction could longer time.

Язык: Английский

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Water sources used by artificial Salix psammophila in stands of different ages based on stable isotope analysis in northeastern Mu Us Sandy Land

CATENA, Год журнала: 2023, Номер 226, С. 107087 - 107087

Опубликована: Март 27, 2023

Язык: Английский

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Transpiration patterns and water use strategies of beech and oak trees along a hillslope

Ecohydrology, Год журнала: 2021, Номер 15(2)

Опубликована: Ноя. 13, 2021

Abstract The role of landscape topography in mediating subsurface water availability and ultimately tree transpiration is still poorly understood. To assess how hillslope position affects use, we coupled sap velocity with xylem isotope measurements a temperate beech‐oak forest along transect Luxembourg. We generally observed greater velocities at the upslope locations trees from average‐sized trees, suggesting presence more suited growing conditions. found lower difference among positions for larger likely due to exploitation deeper persistent sources canopy light interception. Beech exploited shallower seasonally less source than oak root system trees. different strategy could also explain stronger stomatal sensitivity beech vapour pressure deficit compared Xylem isotopic composition was variable all locations, mainly reflecting contribution soil that groundwater did not contribute, or only marginally contributed, transpiration. Overall, our results suggest rely on stored unsaturated zone shallow table may necessarily subsidize uptake species do tolerate anoxic Contrary previous studies, site, find higher downslope as structure promotes vertical flux over lateral redistribution vadose zone.

Язык: Английский

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Sapwood and heartwood are not isolated compartments: Consequences for isotope ecohydrology

Ecohydrology, Год журнала: 2022, Номер 15(8)

Опубликована: Сен. 7, 2022

Abstract In most tree species, xylem consists of two different functional parts: sapwood and heartwood. While sapwood, as the flowpath for sap, has received more attention in isotope studies assessing water sources accessed by trees (e.g. soil from depths, groundwater, stream or a mixture these), much remains unknown about heartwood possible exchange between parts. We investigated four species ( Fagus sylvatica , Quercus petraea Pseudotsuga menziesii Picea abies ) characterised anatomy timing physiological activity to evaluate degree differentiation isotopic composition on biweekly time scale. found that all displayed concurrent variation their throughout growing season day‐night scale suggesting are not isolated compartments. parts display consistent difference conifers, they similar values broadleaved higher exchange. Furthermore, we have also observed progressive change with sampling depth rather than xylem. Our study highlights value accounting radial variation, which might potentially lead uncertainties concerning origin extracted uptake studies.

Язык: Английский

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Water uptake dynamics in apple trees assessed by an isotope labeling approach

Agricultural Water Management, Год журнала: 2022, Номер 266, С. 107572 - 107572

Опубликована: Март 5, 2022

Improving our knowledge on the relative contribution of irrigation water, precipitation, and groundwater to tree transpiration is necessary for an efficient sustainable use water resources in agriculture. For this purpose, we applied deuterium (2H) enriched trace uptake by apple trees under field pot conditions. 2H-enriched was supplied Alpine valley mimicking sprinkler irrigation. Labeled infiltration soil presence shoots measured over a week. An ancillary experiment using potted performed elucidate role after saturation with water. Under conditions, infiltrated maximum depth 0.6 m, where most fine roots were present, mixed pre-irrigation Sprinkler taken up 2–4 h its supply shoot content increased first 24 h, then it leveled off. Tree absorbed from layer represented average 48 ± 3% 26 2% total axes leaves, respectively. The results confirmed allowed us speculate that conditions (ca. 0.9 m deep, capillary rise expected depth) did not significantly contribute uptake. Results indicate large fraction (52–74%) derive recent uptake, suggesting rather limited mixing within organs.

Язык: Английский

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Dry season plant water sourcing in contrasting tropical ecosystems of Costa Rica

Ecohydrology, Год журнала: 2023, Номер 16(5)

Опубликована: Март 7, 2023

Abstract Tracer‐aided studies to understand plant water uptake sources and dynamics in tropical ecosystems are limited. Here, we report the analysis of dry season source patterns five unique Costa Rica across altitudinal (<150–3,400 m asl) latitudinal (Caribbean Pacific slopes) gradients: evergreen seasonal rainforests, cloud forest, Páramo forest. Soil samples were collected during 2021. Plant soil extractions conducted using centrifugation. Stem extracted volume stem total content calculated via gravimetric analysis. Water contributions estimated a Bayesian mixing model. Isotope ratios stems exhibited strong meteoric origin. Enrichment trends only detected cactus within forest ecosystem. profiles revealed nearly uniform isotopic profiles; however, depletion trend was observed ecosystem below 25 cm. More enriched compositions reported for volumes above ~20% ( adj. r 2 = 0.34, p < 0.01). The most prominent rainforest (74.0%), (86.4%) (66.0%) corresponded well‐mixed water. In ecosystem, recent rainfall produced by trade wind incursions resulted significant (61.9%), whereas mean annual precipitation (38.6%) baseflow (33.1%) dominant sources. latter highlights prevalence distinct between cold front (near‐surface storage) more moisture season, revealing ecohydrological processing previously unknown this region.

Язык: Английский

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