Evolutionary differences in Δ13C detected between spore and seed bearing plants following exposure to a range of atmospheric O2:CO2 ratios; implications for paleoatmosphere reconstruction

Porter, Amanda S.; Yiotis, Charilaos; Montañez, Isabel P.; McElwain, Jennifer C.

doi:10.1016/j.gca.2017.07.007

Cited by 43 publications

(37 citation statements)

References 72 publications

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“…All measurements were made close to midday. Holtum and Winter (2001) n/a +50 0.10 Panama during wet and dry seasons Lloyd et al (1996) −3 +70 1 Brazil (Amazon Basin) Quay et al (1989) −3 +20 2 Brazil (Amazon Basin) Sternberg et al (1989) −2 +25 1 Panama during wet and dry seasons…”

Section: Leaves That Grow Close To the Forest Floormentioning

confidence: 99%

“…Because O 2 is directly responsible for photorespiration, f should scale with O 2 (or, more precisely, the O 2 : CO 2 molar ratio). Unfortunately, this effect is poorly constrained (Beerling et al, 2002;Berner et al, 2003;Porter et al, 2017). In contrast, the theoretical effect of O 2 on * is known: it is linear with an approximate slope of 2 ; see their Eq.…”

Section: Photorespirationmentioning

confidence: 99%

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Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO<sub>2</sub> concentration

et al. 2019

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Abstract. Leaf gas-exchange models show considerable promise as paleo-CO2 proxies. They are largely mechanistic in nature, provide well-constrained estimates even when CO2 is high, and can be applied to most subaerial, stomata-bearing fossil leaves from C3 taxa, regardless of age or taxonomy. Here we place additional observational and theoretical constraints on one of these models, the “Franks” model. In order to gauge the model's general accuracy in a way that is appropriate for fossil studies, we estimated CO2 from 40 species of extant angiosperms, conifers, and ferns based only on measurements that can be made directly from fossils (leaf δ13C and stomatal density and size) and on a limited sample size (one to three leaves per species). The mean error rate is 28 %, which is similar to or better than the accuracy of other leading paleo-CO2 proxies. We find that leaf temperature and photorespiration do not strongly affect estimated CO2, although more work is warranted on the possible influence of O2 concentration on photorespiration. Leaves from the lowermost 1–2 m of closed-canopy forests should not be used because the local air δ13C value is lower than the global well-mixed value. Such leaves are not common in the fossil record but can be identified by morphological and isotopic means.

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Section: Leaves That Grow Close To the Forest Floormentioning

confidence: 99%

Section: Photorespirationmentioning

confidence: 99%

Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO<sub>2</sub> concentration

et al. 2019

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“…This method relies on the concentration of CO 2 in seawater being the primary influence on the magnitude of carbon isotopic fractionation between dissolved inorganic carbon in the growth medium and the primary photosynthate of the algal cell (Rau et al, 1989). The fractionation factor, ε p , is also influenced by algal cell geometry (Popp et al, 1998) and physiology, including specific growth rates (Laws et al, 1995;Bidigare et al, 1997) and the type of carbon acquired and lost from the cells (Sharkey and Berry, 1985). The most widely applied proxy of this type is based on the δ 13 C composition of haptophyte algal alkenone biomarkers (Freeman and Pagani, 2014), which have been used to reconstruct atmospheric CO 2 from the middle Eocene to modern times Bijl et al, 2010;.…”

Section: Carbon Isotopic Composition Of Marine Phytoplanktonmentioning

confidence: 99%

Reply to Reviewer 2

Hollis¹

2019

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The early Eocene (56 to 48 million years ago) is inferred to have been the most recent time that Earth's atmospheric CO 2 concentrations exceeded 1000 ppm. Global mean temperatures were also substantially warmer than those of the present day. As such, the study of early Eocene climate provides insight into how a super-warm Earth system behaves and offers an opportunity to evaluate climate models under conditions of high greenhouse gas forcing. The Deep Time Model Intercomparison Project (DeepMIP) is a systematic model-model and model-data intercomparison of three early Paleogene time slices: latest Paleocene, Paleocene-Eocene thermal maximum (PETM) and early Eocene climatic optimum (EECO). A previous article outlined the model experimental design for climate model simulations.In this article, we outline the methodologies to be used for the compilation and analysis of climate proxy data, primarily proxies for temperature and CO 2 . This paper establishes the protocols for a concerted and coordinated effort to compile the climate proxy records across a wide geographic range. The resulting climate "atlas" will be used to constrain and evaluate climate models for the three selected time intervals and provide insights into the mechanisms that control these warm climate states. We provide version 0.

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“…Note that in the text to follow, p a will be used to denote ambient partial pressure of CO 2 (which may be an experimentally controlled value), and p CO2 to denote the partial pressure in the earth's atmosphere. Diefendorf et al (2010) (Lomax et al 2010;Schubert and Jahren, 2015;Porter et al, 2017).…”

Section: Influence Of Environmental Factorsmentioning

confidence: 99%

“…Almost all tree taxa use the C 3 photosynthetic pathway, in which water availability modulates isotope fractionating processes, leading to isotope data archives that can be interpreted in terms of environmental change under conditions of constant, or near-constant δ 13 C, in ambient air (see section 3.2). Much research has also been undertaken to evaluate the use of δ 13 C archives in fossil organic material produced by C 3 plants for interpreting δ 13 C and CO 2 content of past atmospheres, potentially over hundreds of millions of years (Porter et al, 2017, and references therein).…”

Section: Introductionmentioning

confidence: 99%

A multi-century δ13C record of the C4 grass Setaria macrostachya in the US Southwest: Identifying environmental causes of variability

Eastoe

Toolin

2018

Palaeogeography, Palaeoclimatology, Palaeoecology

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Evolutionary differences in Δ13C detected between spore and seed bearing plants following exposure to a range of atmospheric O2:CO2 ratios; implications for paleoatmosphere reconstruction

Cited by 43 publications

References 72 publications

Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO<sub>2</sub> concentration

Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO<sub>2</sub> concentration

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A multi-century δ13C record of the C4 grass Setaria macrostachya in the US Southwest: Identifying environmental causes of variability

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Evolutionary differences in Δ13C detected between spore and seed bearing plants following exposure to a range of atmospheric O2:CO2 ratios; implications for paleoatmosphere reconstruction

Cited by 43 publications

References 72 publications

Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentration

Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentration

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A multi-century δ13C record of the C4 grass Setaria macrostachya in the US Southwest: Identifying environmental causes of variability

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Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO<sub>2</sub> concentration

Sensitivity of a leaf gas-exchange model for estimating paleoatmospheric CO<sub>2</sub> concentration