Magali F. Nehemy

Magali F. Nehemy
Trent University

PhD

About

21
Publications
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86
Citations

Publications

Publications (21)
Article
Ecohydrological investigations commonly use the stable isotopes of water (hydrogen and oxygen) as conservative ecosystem tracers. This approach requires accessing and analyzing water from plant and soil matrices. Generally, there are six steps involved to retrieve hydrogen and oxygen isotope values from these matrices: (1) sampling, (2) sample stor...
Article
Full-text available
Studies of tree water source partitioning have primarily focused on the growing season. However, little is yet known about the source of transpiration before, during, and after snowmelt when trees rehydrate and recommence transpiration in the spring. This study investigates tree water use during spring snowmelt following tree's winter stem shrinkag...
Preprint
Ecohydrological investigations commonly use the stable isotopes of water (hydrogen and oxygen) as a conservative ecosystem tracer. This approach requires accessing and analyzing water constrained within plant and soil matrices. Generally, there are six steps that researchers must pass through to retrieve hydrogen and oxygen isotope values from thes...
Article
Full-text available
A comprehensive assessment of the tree growth/climate relationship was undertaken to better understand the potential impacts of climate change on the growth dynamics of four widespread and common boreal tree species, namely jack pine (Pinus banksiana), black spruce (Picea mariana), eastern larch (Larix laricina), and trembling aspen (Populus tremul...
Article
Full-text available
Plant transpiration plays a significant role in the terrestrial cycles, but the spatiotemporal origins of water used by plant remains highly uncertain. Therefore, the missing link to fully characterize the water mass balance, for any control volume including significant vegetated surfaces, is identifying and quantifying the key factors that control...
Article
Full-text available
The interspecific and temporal dynamics of tree water use are poorly understood. We investigated in high-temporal resolution patterns of water use of two tree species, Platycladus orientalis and Quercus variabilis, in a temperate mountainous monsoon forest in northern China. We leverage a unique sampling design where we systematically traced tree w...
Article
Full-text available
The stable isotopes of hydrogen and oxygen in xylem water are often used to investigate tree water sources. But this traditional approach does not acknowledge the contribution of water stored in the phloem to transpiration, and how this may affect xylem water and source water interpretations. Additionally, there is a prevailing assumption that ther...
Article
Full-text available
The boreal forest is a major contributor to the global climate system, therefore, reducing uncertainties in how the forest will respond to a changing climate is critical. One source of uncertainty is the timing and drivers of the spring transition. Remote sensing can provide important information on this transition, but persistent foliage greenness...
Article
Rationale: Hydrogen and oxygen stable isotope ratios (δ2 H, δ17 O, and δ18 O values) are commonly used tracers of water. These ratios can be measured by isotope ratio infrared spectroscopy (IRIS). However, IRIS approaches are prone to errors induced by organic compounds present in plant, soil, and natural water samples. A novel approach using 17 O...
Article
Full-text available
Closure of the soil water balance is fundamental to ecohydrology. But closing the soil water balance with hydrometric information offers no insight into the age distribution of water transiting the soil column via deep drainage or the combination of soil evaporation and transpiration. This is a major challenge in our discipline currently; tracing t...
Article
Source water apportionment studies using the dual isotopes of oxygen and hydrogen have revolutionized our understanding of ecohydrology. But despite these developments—mostly over 26 the past decade—many technical problems still exist in terms of linking xylem water to its soil water and groundwater sources. This is mainly due to sampling issues an...
Presentation
Our understanding of the source of transpiration and how phenological and hydrological processes affect tree water use are based mainly on temperate and tropical zones. In cold regions, as trees emerge from winter dormancy, tree water storage refilling sinks large volume of water. Understanding the timing of snowmelt, tree water storage refilling,...
Poster
Accurate travel time estimation by hydrological models is of significant importance as it is key to understand biogeochemical processes in the subsurface. In particular, our understanding of how plants rely on water from previous precipitation events remains poor and mainly based on streamflow and soil water data. In this study, we quantify the age...
Article
Full-text available
The stable isotopes of hydrogen and oxygen (δ2H and δ18O, respectively) have been widely used to investigate tree water source partitioning. These tracers have shed new light on patterns of tree water use in time and space. However, there are several limiting factors to this methodology (e.g. the difficult assessment of isotope fractionation in tre...
Data
This repository holds data collected during the “SPIKE II” tracer experiment. The experiment was carried out on a large vegetated lysimeter (2.5 m3) planted with two willow trees (clones) (Salix viminalis) within the EPFL campus (CH), in Switzerland. SPIKE II took place from May 10 to June 29 in 2018. This composite dataset contain stable isotopic...
Preprint
Full-text available
Abstract. The stable isotopes of oxygen and hydrogen (δ<sup>2</sup>H and δ<sup>18</sup>O) have been widely used to investigate plant water source partitioning. These tracers have shed new light on patterns of plant water use in time and space. However, this black box approach has limited our source water interpretations and mechanistic understandin...
Poster
We present a new controlled experiment using a 2 m3 lysimeter planted with a small willow tree (Salix viminalis) to explore how plant water status affects water source partitioning and uptake. We combine high resolution sampling of tree and soil water isotopic composition with measurements of tree hydrodynamics, soil matric potential and climate da...
Article
Rationale The stable isotope compositions of hydrogen and oxygen in water (δ²H and δ¹⁸O values) have been widely used to investigate plant water sources, but traditional isotopic measurements of plant waters are expensive and labor intensive. Recent work with direct vapor equilibration (DVE) on laser spectroscopy has shown potential to sidestep lim...
Article
Insect defoliation events are a major forest disturbance in the boreal forest in Canada. Reconstructing previous events are crucial to understanding natural factors that lead to insect defoliation periods, improving our ability to predict future infestations and increasing the reliability of forest management plans and pest control programs. Resear...

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