Year-end Sale % OFF 
Abstract
The oxygen isotope composition (δ18O) of plant cellulose has been widely used to study ecohydrological processes of ecosystems as well as to reconstruct past climate conditions in terrestrial climate archives. These applications are grounded on a key assumption that the biochemical fractionation during cellulose synthesis is a constant around +27‰ and is not affected by environmental factors. Here we revisit the influence of temperature on biochemical fractionation factor during cellulose synthesis using a global compilation of Sphagnum cellulose δ18O data. Sphagnum (peat mosses) are known for inhabiting waterlogged peatlands and possessing unique physiological strategy in that their cellulose δ18O could closely reflect growing-season precipitation δ18O. Although within-site cellulose δ18O variability shows a median standard deviation of 0.7–0.8‰ resulting from different degree of evaporative enrichment of 18O in metabolic leaf water, this evaporative enrichment is a small quantity due to the external capillary “water buffer” in Sphagnum mosses. Using site-specific minimum cellulose δ18O data that most likely reflect the signal of unevaporated source water, we show that the apparent enrichment factor between cellulose and precipitation δ18O increases with decreasing air temperature. In particular, the apparent enrichment factor could reach as high as 32‰ when growth temperature is below 5 °C. This observational dataset extends the support for the temperature-dependent oxygen isotope fractionation in plant cellulose synthesis previously demonstrated in laboratory experiment, with implications for paleoclimate and plant physiology studies that employ cellulose δ18O measurements particularly in alpine regions.
Highlights
The oxygen isotope ratio (18O/16O, expressed as δ18O) of plant cellulose is a valuable tracer to characterize the environmental conditions during tissue growth (Barbour, 2007; Sternberg, 2009)
There is a pattern that more sites have a positive correlation between δ18Oc and water table depth (WTD) (Figure 3C) and that Sphagnum collected from hummock locations have higher δ18Oc than from hollow locations (Figure 3D), but few are statistically significant
Due to the presence of external water buffer for Sphagnum mosses, we propose that the evaporative enrichment of 18O in their metabolic leaf water, despite being difficult to be directly measured or modeled, is a fairly small quantity compared to εbio
Summary
The oxygen isotope ratio (18O/16O, expressed as δ18O) of plant cellulose (hereafter δ18Oc) is a valuable tracer to characterize the environmental conditions during tissue growth (Barbour, 2007; Sternberg, 2009). It has been used as a proxy to reconstruct past climate conditions in tree rings (Libby et al, 1976), lake sediments (Edwards and McAndrews, 1989), and peat deposits (Hong et al, 2000). Plant δ18Oc signal essentially reflects precipitation δ18O (hereafter δ18Op) with an offset governed by both physiological and biochemical processes (Richter et al, 2008; Sternberg, 2009)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
