Contrasting drought legacy effects on gross primary productivity in a mixed versus pure beech forest

Biogeosciences, Journal Year: 2022, Volume and Issue: 19(17), P. 4315 - 4329

Published: Sept. 12, 2022

Abstract. Droughts affect terrestrial ecosystems directly and concurrently can additionally induce lagged effects in subsequent seasons years. Such legacy of drought on vegetation growth state have been widely studied tree ring records satellite-based greenness, while legacies ecosystem carbon fluxes are still poorly quantified understood. Here, we focus two monitoring sites central Germany with a similar climate but characterised by different species age structures. Using eddy covariance measurements, detect gross primary productivity (GPP) calculating the difference between random forest model estimates potential GPP observed GPP. Our results showed that, at both sites, droughts caused significant seasonal annual timescales, which were partly explained reduced leaf development. The reduction due to is comparable magnitude concurrent differed neighbouring forests divergent methodology proposed here allows quantification temporal dynamics sub-seasonal scale separation from uncertainties. application larger range will help us quantify whether identified lag general factors they may depend.

Language: Английский

---

Xylem water in riparian willow trees (<i>Salix alba</i>) reveals shallow sources of root water uptake by in situ monitoring of stable water isotopes

Hydrology and earth system sciences, Journal Year: 2022, Volume and Issue: 26(8), P. 2073 - 2092

Published: April 27, 2022

Abstract. Root water uptake (RWU) is an important critical zone process, as plants can tap various sources and transpire these back into the atmosphere. However, knowledge about spatial temporal dynamics of RWU associated at both high resolution (e.g. daily) over longer time periods seasonal) still limited. We used cavity ring-down spectroscopy (CRDS) for continuous in situ monitoring stable isotopes soil xylem two riparian willow (Salix alba) trees growing season (May to October) 2020. This was complemented by isotopic sampling local precipitation, groundwater, stream order help constrain potential RWU. A eddy flux tower, together with sap flow monitoring, moisture measurements, dendrometry, also provide hydroclimatic ecohydrological contexts isotope monitoring. In addition, respective bulk twig samples were collected corroborate data. The period characterised frequent inputs interspersed warm dry periods, which resulted variable storage upper 20 cm profile dynamic signatures. variability greatly damped 40 cm, composition subsoil groundwater relatively stable. very similar those soil, analysis using a Bayesian mixing model inferred that overall ∼90 % derived from profile. while signatures, direct equilibrium method showed good comparability results, water, cryogenic extractions signatures only moderately or not all comparable. Sap dendrometry data indicated availability did seriously limit transpiration during study period, though it seemed deeper (>40 cm) provided higher proportion (∼30 %) drier late summer. demonstrates utility prolonged real-time natural abundance soil–vegetation systems, has great further understanding partitioning under changing conditions.

Language: Английский

---

The natural abundance of stable water isotopes method may overestimate deep-layer soil water use by trees

Hydrology and earth system sciences, Journal Year: 2023, Volume and Issue: 27(1), P. 123 - 137

Published: Jan. 4, 2023

Abstract. Stable water isotopes have been used extensively to study the use strategy of plants in various ecosystems. In deep vadose zone (DVZ) regions, rooting depth trees can reach several meters tens meters. However, existence roots soils does not necessarily mean occurrence root uptake, which usually occurs at a particular time during growing season. Therefore, quantifying contribution deep-layer soil (DLSW) DVZ regions using natural abundance stable may be accurate because this method assumes that always extract shallow- and water. We propose multi-step for addressing issue. First, isotopic labeling layers identifies whether absorb DLSW determines layer depths from derive their source. Next, we calculate sources based on determined above quantify trees. also compared results with method. The 11- 17-year-old apple were taken as examples analyses China's Loess Plateau. Isotopic showed uptake 11-year-old reached 300 cm blossom young fruit (BYF) stage only 100 swelling (FSW) stage, whereas consumed 0–320 layer. Overall, absorbed most (>140 cm) BYF more these than throughout addition, overestimated DLSW, especially 320–500 Our findings highlight determining helps regions.

Language: Английский

---

Tree‐ and stand‐scale variability of xylem water stable isotope signatures in mature beech, oak and spruce

Ecohydrology, Journal Year: 2024, Volume and Issue: 17(2)

Published: Jan. 17, 2024

Abstract In ecohydrology, water isotopologues are used to assess potential sources of root uptake by comparing xylem signatures with source signatures. Such comparisons affected the variability and uncertainty isotope plant sources. The tree‐scale stand‐scale variabilities in stem often unknown but important for sampling design estimation assessing tree uptake. Here, we quantified beech, oak spruce trees a mature forest on Swiss plateau. For water, sub‐daily replicates different cardinal directions showed no systematic differences, found differences height. observed at heights along suggests that residence times within need be considered, their effects compartments (stem, branches, leaves). Further, concerning hydrogen signatures, height‐ species‐specific offsets (SW‐excess δ 2 H). Stem water's was similar magnitude its smaller than branch bulk soil around each tree. Xylem from cores close ground, therefore, can give more precise estimate isotopic signal most recent facilitate accurate attribution.

Language: Английский

---

On the use of leaf water to determine plant water source: A proof of concept

Hydrological Processes, Journal Year: 2021, Volume and Issue: 35(3)

Published: Feb. 6, 2021

Abstract Source water apportionment studies using the dual isotopes of oxygen and hydrogen have revolutionized our understanding ecohydrology. But despite these developments—mostly over past decade—many technical problems still exist in terms linking xylem to its soil groundwater sources. This is mainly due sampling issues possible fractionation water. Here we explore whether or not leaf alone can be used quantify blend rainfall event inputs from which originates. Leaf has historically been avoided plant uptake extreme processes at surface. In proof concept work embrace those use well‐known Craig Gordon model map back individual precipitation We also employ a Bayesian uncertainty estimation approach source uncertainties. show this controlled, vegetated lysimeter experiment where were able correctly identify mean seasonal that was taken up by plant, with an typically within ± 1‰ for δ 18 O. While appropriate all studies, shows isotope composition may provide new, relatively un‐intrusive method addressing questions about source.

Language: Английский

---

Do Various Conifers Respond Differently to Water Stress? A Comparative Study of White Pine, Concolor and Balsam Fir

Kastamonu University Journal of Forestry Faculty, Journal Year: 2022, Volume and Issue: unknown, P. 1 - 16

Published: March 30, 2022

Aim of study: Two-year-old containerized balsam and concolor fir one-year-old Eastern white pine transplants were grown under variable watering regimes with the goal identifying plant morphological some physiological traits water stress. Area This experiment was conducted in a greenhouse at Tree Research Center on Michigan State University campus, East Lansing, Michigan. Material methods: Relative root collar diameter (RRCD), height growth (RHG), length (RRL) measured as parameters. Stem potential (Ψ), stomatal conductance (gs), net photosynthetic rate (Anet), intrinsic use efficiency (iWUE=Anet/gs), foliar potassium (K+), calcium (Ca+2) concentration traits. Main results: Well-watered had significantly higher RRCD, RHG, RRL species. Balsam Ψ than severe Fir species Anet, gs, lower iWUE pine. White K+ concentration, while highest Ca+2 concentration. stress due to their ability maintain uptake despite reduced soil content. Highlights: It is concluded that has better drought tolerance because withstand through mechanism activities growth, minimize loss, increase uptake.

Language: Английский

---

Ecohydrological decoupling under changing disturbances and climate

One Earth, Journal Year: 2023, Volume and Issue: 6(3), P. 251 - 266

Published: March 1, 2023

Terrestrial disturbances are increasing in frequency and severity, perturbing the hydrologic cycle by altering vegetation-mediated water use microclimate. Here, we synthesize literature on post-disturbance ecohydrological coupling, including mechanistic relationship between vegetation streamflow, under changing disturbance regimes, atmospheric CO2, climate. Disturbance can cause decoupling transpiration streamflow connectivity, size, availability, spatial distribution of their source pools. Successional trajectories influence dynamics partitioning. Changing climate regimes alter succession prolong decoupling. Increasing rates, spread along with warming could promote greater globally. From this review emerges a framework testable hypotheses that identify critical processes regulating coupling provide roadmap for future research. Accurate prediction requires understanding degree hydraulic connectivity pools response to regimes.

Language: Английский

---

A Fully Coupled Numerical Solution of Water, Vapor, Heat, and Water Stable Isotope Transport in Soil

Water Resources Research, Journal Year: 2025, Volume and Issue: 61(1)

Published: Jan. 1, 2025

Abstract Modeling water stable isotope transport in soil is crucial to sharpen our understanding of cycles terrestrial ecosystems. Although several models for have been developed, many rely on a semi‐coupled numerical approach, solving only after obtaining solutions from and heat equations. However, this approach may increase instability errors model. Here, we developed an algorithm that solves one‐dimensional water, heat, equations with fully coupled method (MOIST). Our results showed MOIST more under various spatial temporal discretization than has good agreement semi‐analytical transport. We also validated long‐term measurements lysimeter study three scenarios hydraulic parameters calibrated by HYDRUS‐1D the first two last scenario. In scenario 1, overall NSE , KGE MAE simulated δ 18 O 0.47, 0.58, 0.92‰, respectively, compared 0.31, 0.60, 1.00‰ HYDRUS‐1D; 2, these indices were 0.33, 0.52, 1.04‰, 0.19, 1.15‰ 3, exhibited highest (0.48) (0.76), smallest (0.90) among all scenarios. These findings indicate better performance simulating flow simplified ecosystems HYDRUS‐1D, suggesting great potential furthering understandings ecohydrological processes

Language: Английский

---

Bark water affects the isotopic composition of xylem water in tropical rainforest trees

Frontiers in Forests and Global Change, Journal Year: 2025, Volume and Issue: 7

Published: Jan. 28, 2025

The movement of water between xylem and inner bark (phloem associated tissues), mostly driven by potential differences, forms a key part the diel transpiration cycle. It is not known how use stored in at cycle may influence isotopic composition water. Understanding these possible effects major challenge for identification tree sources interpretation patterns using isotopes. Here, we examined variation scale assessed this varied relation to traits strategies on nine species tropical rainforest end dry season. We measured δ 2 H 18 O two shallow depths: ‘outer xylem’ ‘inner (up ~0.5 cm ~ 1 from bark, respectively) collected predawn, morning midday. Considering all together, average outer was similar predawn midday, suggesting exchange tissues reflected times, but differed significantly during increased transpiration. Results suggest that bark-xylem throughout affects trees. Furthermore, variations were more pronounced deep-rooted, isohydric with dense wood than shallow-rooted, anisohydric low density. This differences related hydraulic reliance bark-stored across buffer changes potential. discuss implications interpreting strategies.

Language: Английский

---

Mitigating drought stress in European beech and pedunculate oak: The role of competition reduction

Forest Ecosystems, Journal Year: 2025, Volume and Issue: unknown, P. 100303 - 100303

Published: Feb. 1, 2025

Language: Английский

---