Leaf wax n-alkanes and δ13C values of CAM plants from arid southwest Africa

Boom, Arnoud; Carr, Andrew S.; Chase, Brian M.; Grimes, Hannah L.; Meadows, Michael E.

doi:10.1016/j.orggeochem.2013.12.005

Cited by 36 publications

(33 citation statements)

References 18 publications

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“…This >50-μm subset of oaceae pollen is also positively correlated with the 401 abundance of Chenopodiaceae pollen, which in this region includes C 4 genera such as Salsola sp. 402 (13.6 ‰; Boom et al 2014). Despite potential differences in the age models (fewer radiocarbon ages 403 for KFN1996), trends in δ 13 C TOC from KFN2010 largely mirror DCA axis 1 from KFN1996, suggesting 404 that the abundance of Spartina/Sporobolus/Chenopodiaceae is indeed a major control on down-core 405 δ 13 C TOC variation (Fig.…”

Section: Baxter (2001) Argued That In the Verlorenvlei System (Meadowmentioning

confidence: 99%

Holocene sea level and environmental change on the west coast of South Africa: evidence from plant biomarkers, stable isotopes and pollen

et al. 2015

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Section: Baxter (2001) Argued That In the Verlorenvlei System (Meadowmentioning

confidence: 99%

Holocene sea level and environmental change on the west coast of South Africa: evidence from plant biomarkers, stable isotopes and pollen

et al. 2015

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“…For 343 example, pollen data suggest that increased wind strength caused an increase in delivery of material 344 from western South Africa during the last glacial period (Shi et al, 2000). However, in southern 345 Namibia and South Africa modern vegetation displays lower leaf--wax δ 13 C values due to the 346 dominance of C 3 and CAM vegetation (Boom, et al, 2014). Therefore, the glacial increase in C 4 347 cannot be explained by a southward shift of the source area.…”

Section: Potential Bias By Co2 and Source Area Shifts 336mentioning

confidence: 99%

Insolation and glacial–interglacial control on southwestern African hydroclimate over the past 140 000 years

Collins

Schefuß

Govin

et al. 2014

Earth and Planetary Science Letters

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11The past climate evolution of southwestern Africa is poorly understood and interpretations of past 12 hydrological changes are sometimes contradictory. Here we present a record of leaf--wax δD and δ 13 C 13 taken from a marine sediment core at 23°S off the coast of Namibia to reconstruct the hydrology and 14 C 3 versus C 4 vegetation of southwestern Africa over the last 140,000 years (140 ka). We find lower 15 leaf--wax δD and higher δ 13 C (more C 4 grasses), which we interpret to indicate wetter Southern 16Hemisphere (SH) summer conditions and increased seasonality, during SH insolation maxima relative 17 to minima and during the last glacial period relative to the Holocene and the last interglacial period. 18Nonetheless, the dominance of C 4 grasses throughout the record indicates that the wet season 19 remained brief and that this region has remained semi--arid. Our data suggest that past precipitation 20 increases were derived from the tropics rather than from the winter westerlies. Comparison with a 21 record from the Congo Basin indicates that hydroclimate in southwestern Africa has evolved in 22 antiphase with that of Central Africa over the last 140 ka. 23Keywords: Leaf--wax n--alkane, Hydrogen and carbon isotopes, African palaeoclimate, monsoonal 24 precipitation, Namibia 25 26

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“…Previous studies of CAM species suggest that shifts in carbon allocation among plants to mitigate water availability has the potential to explain variability of 0.5 to 12.8‰ in the depletion of lipids relative to the carbon isotope composition of bulk tissue (Boom et al, 2014). Although we did not analyse CAM species as part of this study, in principle similar mechanisms could operate in our C 3 and C 4 saltmarsh plants.…”

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confidence: 93%

Investigating the carbon isotope composition and leaf wax n-alkane concentration of C3 and C4 plants in Stiffkey saltmarsh, Norfolk, UK

Eley

Dawson

Pedentchouk

2016

Organic Geochemistry

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The carbon isotope composition of terrestrial plants records valuable ecophysiological and palaeoecological information. However, interspecies variability in 13C/12C, at both the bulk and compound-specific (CS) level, requires further exploration across a range of ecosystem types. Here, we present bulk and n-alkane δ13C values, and n-alkane concentrations, from seven plants (C3 and C4) growing in a temperate UK saltmarsh. Inter- and intra-species variation in n-alkane δ13C values among C3 plants ranged from 8‰ (n-C31) to 10‰ (n-C27) across the 2011 and 2012 growing seasons, exceeding variability in bulk tissue (7‰). In contrast, the C4 monocot showed < 2‰ seasonal shifts in bulk and CS values. As a result of the variability in our CS data, we calculate that n-alkane based C3/C4 reconstructions in temperate saltmarshes have a maximum uncertainty of ∼11%. For dicots and succulents, seasonal bulk and CS δ13C trends diverged, while for C3 and C4 monocots, bulk and CS values followed similar temporal patterns. Fractionation between bulk and n-alkane carbon isotope values varied from −4 to −10‰ for C3 plants, and reached −13‰ for the C4 monocot. We explain discrepancies between bulk and n-alkane δ13C values by referring to possible interspecies variation in salinity adaptation, which may influence the partitioning of pyruvate, shifting the isotopic composition of lipid biomarkers. These findings open new avenues for empirical studies to further understand the metabolic processes fractionating carbon during the synthesis of n-alkanes, enhancing interpretation of the biomarker signal from the geological record

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Leaf wax n-alkanes and δ13C values of CAM plants from arid southwest Africa

Cited by 36 publications

References 18 publications

Holocene sea level and environmental change on the west coast of South Africa: evidence from plant biomarkers, stable isotopes and pollen

Holocene sea level and environmental change on the west coast of South Africa: evidence from plant biomarkers, stable isotopes and pollen

Insolation and glacial–interglacial control on southwestern African hydroclimate over the past 140 000 years

Investigating the carbon isotope composition and leaf wax n-alkane concentration of C3 and C4 plants in Stiffkey saltmarsh, Norfolk, UK

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