BRYOCARB: A process-based model of thallose liverwort carbon isotope fractionation in response to CO2, O2, light and temperature

Fletcher, Benjamin J.; Brentnall, Stuart J.; Quick, W. Paul; Beerling, David J.

doi:10.1016/j.gca.2006.01.031

Cited by 45 publications

(51 citation statements)

References 49 publications

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“…Meanwhile, the increasing development of soil organic carbon reserves would have led to the efflux of CO 2 from soils tending to provide a respiratory bonus to the thalloid bryophytes appressed to their substrate, and shifted to a (probably) more 13 C-depleted source CO 2 to which they would have been predominantly exposed (see discussion above). At any event, these factors complicate the simple interpretation of bryophyte organic residues as markers of atmospheric CO 2 concentration (Fletcher et al 2006).…”

Section: Discussionmentioning

confidence: 99%

To concentrate or ventilate? Carbon acquisition, isotope discrimination and physiological ecology of early land plant life forms

Meyer

Seibt

Griffiths

2008

Phil. Trans. R. Soc. B

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A comparative study has been made of the photosynthetic physiological ecology and carbon isotope discrimination characteristics for modern-day bryophytes and closely related algal groups. Firstly, the extent of bryophyte distribution and diversification as compared with more advanced land plant groups is considered. Secondly, measurements of instantaneous carbon isotope discrimination (D), photosynthetic CO 2 assimilation and electron transport rates were compared during the drying cycles. The extent of surface diffusion limitation (when wetted), internal conductance and water use efficiency (WUE) at optimal tissue water content (TWC) were derived for liverworts and a hornwort from contrasting habitats and with differing degrees of thallus ventilation (as intra-thalline cavities and internal airspaces). We also explore how the operation of a biophysical carbon-concentrating mechanism (CCM) tempers isotope discrimination characteristics in two other hornworts, as well as the green algae Coleochaete orbicularis and Chlamydomonas reinhardtii. The magnitude of D was compared for each life form over a drying curve and used to derive the surface liquid-phase conductance (when wetted) and internal conductance (at optimal TWC). The magnitude of external and internal conductances, and WUE, was higher for ventilated, compared with non-ventilated, liverworts and hornworts, but the values were similar within each group, suggesting that both factors have been optimized for each life form. For the hornworts, leakiness of the CCM was highest for Megaceros vincentianus and C. orbicularis (approx. 30%) and, at 5%, lowest in C. reinhardtii grown under ambient CO 2 concentrations. Finally, evidence for the operation of a CCM in algae and hornworts is considered in terms of the probable role of the chloroplast pyrenoid, as the origins, structure and function of this enigmatic organelle are explored during the evolution of land plants.

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Section: Discussionmentioning

confidence: 99%

To concentrate or ventilate? Carbon acquisition, isotope discrimination and physiological ecology of early land plant life forms

Meyer

Seibt

Griffiths

2008

Phil. Trans. R. Soc. B

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“…4A) during which isotopic fractionation indicates that pO 2 returned to near pre-SPICE levels, whereas C and S isotope mass balance indicates that pO 2 remained at peak levels. This return to lower Δ 13 C likely indicates the role that fluctuations in atmospheric pCO 2 may also play in photosynthetic carbon isotope fractionation (20,21,23,(26)(27)(28)(29). Indeed, the enhanced isotopic fractionation by phytoplankton that we interpret as a response to the SPICE O 2 pulse occurred in spite of a decrease in atmospheric CO 2 brought about by the organic carbon burial that promoted the rise in O 2 (i.e., a decrease in CO 2 acting alone should lead to a decrease in fractionation) (26).…”

Section: Resultsmentioning

confidence: 96%

“…The dependence of biological carbon isotope fractionation on the partial pressure of atmospheric oxygen (pO 2 ) has been demonstrated in laboratory experiments using vascular land plants, bryophytes, and marine phytoplankton (20,21,27). Increased isotopic discrimination for 12 C is observed at increasing O 2 levels because CO 2 levels rise within the plant or plankton cell as photorespiration begins to outpace photosynthesis (O 2 competes with CO 2 for sites on the photosynthetic enzyme Rubisco).…”

Section: Resultsmentioning

confidence: 99%

Pulse of atmospheric oxygen during the late Cambrian

Saltzman

Young

Kump

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

156

105

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A rise in atmospheric O 2 has been linked to the Cambrian explosion of life. For the plankton and animal radiation that began some 40 million yr later and continued through much of the Ordovician (Great Ordovician Biodiversification Event), the search for an environmental trigger(s) has remained elusive. Here we present a carbon and sulfur isotope mass balance model for the latest Cambrian time interval spanning the globally recognized Steptoean Positive Carbon Isotope Excursion (SPICE) that indicates a major increase in atmospheric O 2 . We estimate that this organic carbon and pyrite burial event added approximately 19 × 10 18 moles of O 2 to the atmosphere (i.e., equal to change from an initial starting point for O 2 between 10–18% to a peak of 20–28% O 2 ) beginning at approximately 500 million years. We further report on new paired carbon isotope results from carbonate and organic matter through the SPICE in North America, Australia, and China that reveal an approximately 2‰ increase in biological fractionation, also consistent with a major increase in atmospheric O 2 . The SPICE is followed by an increase in plankton diversity that may relate to changes in macro- and micronutrient abundances in increasingly oxic marine environments, representing a critical initial step in the trophic chain. Ecologically diverse plankton groups could provide new food sources for an animal biota expanding into progressively more ventilated marine habitats during the Ordovician, ultimately establishing complex ecosystems that are a hallmark of the Great Ordovician Biodiversification Event.

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“…Four of these cores were inserted into each pot (n = 4 per species per [CO 2 ] a treatment) to surround the roots or rhizoids. A further mesh-core filled with glass wool was inserted into each pot to enable below-ground gas sampling throughout the 14 39,40 . Plants were acclimated to growth chamber conditions for 12 weeks to allow mycorrhizal fungi networks to establish between roots/rhizoids and the mesh-walled soil cores.…”

Section: Methodsmentioning

confidence: 99%

Contrasting arbuscular mycorrhizal responses of vascular and non-vascular plants to a simulated Palaeozoic CO2 decline

et al. 2012

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The arbuscular mycorrhizal (Am) fungal symbiosis is widely hypothesized to have promoted the evolution of land plants from rootless gametophytes to rooted sporophytes during the mid-Palaeozoic (480-360 myr, ago), at a time coincident with a 90% fall in the atmospheric Co 2 concentration ([Co 2 ] a ). Here we show using standardized dual isotopic tracers ( 14 C and 33 P) that Am symbiosis efficiency (defined as plant P gain per unit of C invested into fungi) of liverwort gametophytes declines, but increases in the sporophytes of vascular plants (ferns and angiosperms), at 440 p.p.m. compared with 1,500 p.p.m. [Co 2 ] a . These contrasting responses are associated with larger Am hyphal networks, and structural advances in vascular plant waterconducting systems, promoting P transport that enhances Am efficiency at 440 p.p.m. [Co 2 ] a . our results suggest that non-vascular land plants not only faced intense competition for light, as vascular land floras grew taller in the Palaeozoic, but also markedly reduced efficiency and total capture of P as [Co 2 ] a fell.

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BRYOCARB: A process-based model of thallose liverwort carbon isotope fractionation in response to CO2, O2, light and temperature

Cited by 45 publications

References 49 publications

To concentrate or ventilate? Carbon acquisition, isotope discrimination and physiological ecology of early land plant life forms

To concentrate or ventilate? Carbon acquisition, isotope discrimination and physiological ecology of early land plant life forms

Pulse of atmospheric oxygen during the late Cambrian

Contrasting arbuscular mycorrhizal responses of vascular and non-vascular plants to a simulated Palaeozoic CO2 decline

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