ORCID Profile
0000-0003-0090-7537
Current Organisation
University of Idaho
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Publisher: Wiley
Date: 06-10-2016
Publisher: Wiley
Date: 13-06-2013
DOI: 10.1111/NPH.12359
Abstract: The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant–climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water‐soluble OM and further to phloem‐transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady‐state conditions. While leaf water‐soluble OM showed the expected 18 O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine ( Pinus sylvestris ), European larch ( Larix decidua ) and Alpine ash ( Eucalyptus delegatensis ). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem 18 O enrichment patterns. Our results indicate species‐specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.PHYTOCHEM.2017.11.004
Abstract: Compartmentation of C
Publisher: Cold Spring Harbor Laboratory
Date: 06-06-2017
DOI: 10.1101/121368
Abstract: Optimal stomatal theory is an evolutionary model proposing that leaves trade-off Carbon (C) for water to maximise C assimilation ( A ) and minimise transpiration ( E ), thereby generating a marginal water cost of carbon gain (λ) that remains constant over short temporal scales. The circadian clock is a molecular timer of metabolism that controls A and stomatal conductance ( g s ), amongst other processes, in a broad array of plant species. Here, we test whether circadian regulation contributes towards achieving optimal stomatal behaviour. We subjected bean ( Phaseolus vulgaris ) and cotton ( Gossypium hirsutum ) canopies to fixed, continuous environmental conditions of photosynthetically active radiation, temperature and vapour pressure deficit over 48 hours. We observed a significant and self-sustained circadian oscillation in A and in stomatal conductance ( g s ) which also led to a circadian oscillation in λ . The lack of constant marginal water cost indicates that circadian regulation does not directly lead to optimal stomatal behaviour. However, the temporal pattern in gas exchange, indicative of either maximizing A or of minimizing E , depending upon time of day, indicates that circadian regulation could contribute towards optimizing stomatal responses. More broadly, our results add to the emerging field of plant circadian ecology and show that molecular controls may partially explain leaf-level patterns observed in the field.
Publisher: Copernicus GmbH
Date: 28-11-2011
Abstract: Abstract. The terrestrial carbon (C) cycle has received increasing interest over the past few decades, however, there is still a lack of understanding of the fate of newly assimilated C allocated within plants and to the soil, stored within ecosystems and lost to the atmosphere. Stable carbon isotope studies can give novel insights into these issues. In this review we provide an overview of an emerging picture of plant-soil-atmosphere C fluxes, as based on C isotope studies, and identify processes determining related C isotope signatures. The first part of the review focuses on isotopic fractionation processes within plants during and after photosynthesis. The second major part elaborates on plant-internal and plant-rhizosphere C allocation patterns at different time scales (diel, seasonal, interannual), including the speed of C transfer and time lags in the coupling of assimilation and respiration, as well as the magnitude and controls of plant-soil C allocation and respiratory fluxes. Plant responses to changing environmental conditions, the functional relationship between the physiological and phenological status of plants and C transfer, and interactions between C, water and nutrient dynamics are discussed. The role of the C counterflow from the rhizosphere to the aboveground parts of the plants, e.g. via CO2 dissolved in the xylem water or as xylem-transported sugars, is highlighted. The third part is centered around belowground C turnover, focusing especially on above- and belowground litter inputs, soil organic matter formation and turnover, production and loss of dissolved organic C, soil respiration and CO2 fixation by soil microbes. Furthermore, plant controls on microbial communities and activity via exudates and litter production as well as microbial community effects on C mineralization are reviewed. A further part of the paper is dedicated to physical interactions between soil CO2 and the soil matrix, such as CO2 diffusion and dissolution processes within the soil profile. Finally, we highlight state-of-the-art stable isotope methodologies and their latest developments. From the presented evidence we conclude that there exists a tight coupling of physical, chemical and biological processes involved in C cycling and C isotope fluxes in the plant-soil-atmosphere system. Generally, research using information from C isotopes allows an integrated view of the different processes involved. However, complex interactions among the range of processes complicate or currently impede the interpretation of isotopic signals in CO2 or organic compounds at the plant and ecosystem level. This review tries to identify present knowledge gaps in correctly interpreting carbon stable isotope signals in the plant-soil-atmosphere system and how future research approaches could contribute to closing these gaps.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Copernicus GmbH
Date: 13-08-2012
Abstract: Abstract. Stable isotope analysis is a powerful tool for assessing plant carbon and water relations and their impact on biogeochemical processes at different scales. Our process-based understanding of stable isotope signals, as well as technological developments, has progressed significantly, opening new frontiers in ecological and interdisciplinary research. This has promoted the broad utilisation of carbon, oxygen and hydrogen isotope applications to gain insight into plant carbon and water cycling and their interaction with the atmosphere and pedosphere. Here, we highlight specific areas of recent progress and new research challenges in plant carbon and water relations, using selected ex les covering scales from the leaf to the regional scale. Further, we discuss strengths and limitations of recent technological developments and approaches and highlight new opportunities arising from unprecedented temporal and spatial resolution of stable isotope measurements.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Oxford University Press (OUP)
Date: 20-10-2016
Location: United States of America
Location: United States of America
Location: United States of America
No related grants have been discovered for Zachary Kayler.