Microcosm studies of the role of land plants in elevating soil carbon dioxide and chemical weathering

Baars, Christian; Jones, T. Hefin; Edwards, Dianne

doi:10.1029/2008gb003228

Cited by 16 publications

(8 citation statements)

References 80 publications

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“…Terrestrial plants take up CO 2 primarily by diffusion, and increasing atmospheric CO 2 generally has a positive effect on photosynthesis, productivity and growth [ Ainsworth and Long , 2005]. CO 2 fertilized bioproductivity and plant weathering has been observed in many experimental studies [ Andrews and Schlesinger , 2001; Baars et al , 2008]. Previous carbon cycle models have also included terms implicating that the efficiency of CO 2 fertilization of terrestrial plants is a key factor controlling the long‐term evolution of silicate weathering and p CO 2 [e.g., Berner and Kothavala , 2001].…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO₂ fertilization

Kemp

2009

Global Biogeochemical Cycles

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[1] Cenozoic carbon fluxes associated with rock weathering, sediment burial, and volcanic degassing are calculated from the mass balance equations coupling marine isotopic records of carbon (both organic and inorganic), strontium, and osmium. The result is confirmed by the good match between modeled carbonate sedimentation rates and carbonate sedimentation rates previously integrated from ocean basins worldwide. The coevolution between weathering and burial of carbonate suggests that marine carbonate accumulation was regulated mainly by the recycling of carbonate rocks, which mediated the bicarbonate ion concentration of the oceans. A reduction in CO 2 effusion to the atmosphere caused by reduced volcanic degassing from 52 to 15 Ma and tectonically enhanced organic rock exhumation since 15 Ma is also observed. These changes in CO 2 effusion are balanced by concomitant changes in CO 2 sequestration by silicate weathering and organic carbon burial. Importantly, we demonstrate a clear decoupling of modeled silicate weathering rates from global climate over the last $15 Ma. This observation is inconsistent with temperature-mediated mineral dissolution acting as the key mechanism facilitating the CO 2 silicate weathering feedback process. However, we instead observe a clear coupling (positive correlation) between modeled silicate weathering, organic carbon burial, and atmospheric CO 2 concentration. We suggest that CO 2 fertilization effects on terrestrial biomass productivity and plant weathering could have represented a major negative feedback process helping to balance atmospheric CO 2 , at least during the Cenozoic ice house periods.

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Section: Discussionmentioning

confidence: 99%

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO₂ fertilization

Kemp

2009

Global Biogeochemical Cycles

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“…Baars et al . () used the latter ( Conocephalum conicum ) in less well controlled (as regards temperature and light regimes) microcosm experiments in which trays containing algae/Bacteria, bryophytes, Psilotum (a non‐rooted tracheophyte) and Equisetum (a rooted tracheophyte) were grown on trays in cabinets approaching ambient (360 ppm) and c . 10 PAL (3500 ppm), and the leachate containing inorganic carbon species and organic acids (negligible amounts) was collected and analysed.…”

Section: Vegetation and Rock Weathering Before Eutracheophytesmentioning

confidence: 99%

Could land‐based early photosynthesizing ecosystems have bioengineered the planet in mid‐Palaeozoic times?

2015

Self Cite

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The Ordovician and Silurian periods were times of major geological activity as regards palaeogeography, volcanism and climate change, the last of these evidenced by a series of cooling episodes and glaciations that climaxed in the Hirnantian (Late Ordovician). The presence of cryptospores in the Darriwilian (Middle Ordovician) marked the advent of higher plants on land. A critical survey of direct (mega-and microfossils) and some indirect evidence in succeeding rocks indicates the presence of algae, Bacteria, Cyanobacteria, Fungi, probable lichens, cryptophytes and basal tracheophytes. Similar associations of photosynthesizers and decomposers occur today in cryptogamic covers (CCs), for example biological crusts, except that bryophytes replace cryptophytes (basal embryophytes) and tracheophytes are absent. Thus, extant CCs, which make significant contributions today to global carbon and nitrogen fixation and prevention of erosion, provide an excellent analogue for the impacts of early land vegetation on both lithosphere and atmosphere. As a prerequisite to assessing impacts in Ordovician-Silurian times, with particular consideration of parameters used by climate modellers, the effects of a number of abiotic factors on the growth and survival of extant cryptogamic ground covers and their environmental impacts are reviewed. Factors include photosynthetically active radiation, ultraviolet radiation, temperature, water, oxygen, carbon dioxide, nitrogen, phosphorus, iron, surface roughness and albedo. A survey of the nature and extent of weathering facilitated by such vegetation concludes that it was limited based on depth of weathering when compared with that from rooted tracheophytes today, with minor effects on carbon dioxide drawdown. As global net productivity from Ordovician-Silurian CCs was very probably lower than today, and while the small fraction of intractable material in their organic carbon would have resulted in a more rapid turnover of terrestrial biomass, we conclude that there was decreased possibility of long-term organic carbon burial. Hence, there would have been very limited increase in atmospheric oxygen and decrease in carbon dioxide resulting from carbon burial.

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“…This effect may be related to K being more likely to remain in mineral phases without the chemical weathering effects of vegetation (Basu, 1981;Ranganathan, 1983). The lack of well-developed palaeosols in the floodplain assemblage may also be related to the diminished effects of chemical weathering commonly associated with land vegetation (Fuller, 1985;Baars et al, 2008) and the resultant dominance of immature soil profiles (Retallack, 1985;Algeo & Scheckler, 1998), such as the poorly developed protosols described here in the upper portions of crevasse splays (classification of Mack et al, 1993). The loss of Mn, but not Fe, from the protosols indicates that the Eh in the sediment near the surface was commonly between 225 mV, the redox potential for MnO 2 , and +100 to )100 mV, the redox potential for ferric iron.…”

Section: The Floodplain Depositional Systemmentioning

confidence: 99%

Sedimentology of a wet, pre‐vegetation floodplain assemblage

Fralick¹,

Zaniewski²

2011

Sedimentology

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Descriptions of fluvial systems operating prior to significant terrestrial macrophyte vegetation have concentrated on assessing the impact of plant evolution on channel style; this is probably in part due to the scarcity of well‐developed floodplain successions in fluvial assemblages of these ages. This study describes wet, pre‐vegetation floodplain deposits and processes observed and inferred from a continuous succession of drill core through an extensive, 1·4 Ga, delta‐top channel–floodplain assemblage forming a portion of the Sibley Group, Ontario, Canada. Sub‐aerial deposits are dominated by flaser, wavy and lenticular bedded, fine‐grained sandstones, siltstones and mudstones, with abundant small mudstone rip‐up clasts. Soft‐sediment deformation of these units is ubiquitous, with loading and injection features being the most prominent. Thicker medium‐grained sandstone beds, representing crevasse splays, commonly have poorly developed protosols in their upper portions. Well‐laminated sediments with wave ripples, and only rarely containing rip‐up clasts and soft‐sediment deformation, were deposited in floodplain ponds. These deposits differ from post‐vegetation floodplain sediments in having: (i) better preservation of layering without rootlet bioturbation; (ii) dominance of rippled sand on the floodplain, probably due to lack of vegetation‐induced baffling; (iii) large‐scale generation of small, intraformational clasts; (iv) desiccation crack fills consisting of peds and locally derived intraclasts, probably delivered during Horton overland flow during rainfall events; (v) ubiquitous soft‐sediment deformation features in sub‐aerial deposits; and (vi) well‐laminated, commonly oxidized sediment that accumulated in floodplain ponds. These attributes are the direct result of the lack of macrophyte vegetation, and produce floodplain assemblages that are distinctly different from those presently forming in similar climatic settings.

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Microcosm studies of the role of land plants in elevating soil carbon dioxide and chemical weathering

Cited by 16 publications

References 80 publications

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO₂ fertilization

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO₂ fertilization

Could land‐based early photosynthesizing ecosystems have bioengineered the planet in mid‐Palaeozoic times?

Sedimentology of a wet, pre‐vegetation floodplain assemblage

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Microcosm studies of the role of land plants in elevating soil carbon dioxide and chemical weathering

Cited by 16 publications

References 80 publications

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO2 fertilization

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO2 fertilization

Could land‐based early photosynthesizing ecosystems have bioengineered the planet in mid‐Palaeozoic times?

Sedimentology of a wet, pre‐vegetation floodplain assemblage

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Product

Resources

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Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO₂ fertilization

Evolution of the Cenozoic carbon cycle: The roles of tectonics and CO₂ fertilization