Stomatal frequency-based palaeo-CO2 reconstructions

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Bennettitalean leaf cuticle fragments (here Anomozamites and Pterophyllum) can be used interchangeably in stomatal frequency-based palaeo-CO2 reconstructions

by Steinthorsdottir M., Bacon K. L., Popa M. E., Bochner L., McElwain J. C. (2011)

MARGRET STEINTHORSDOTTIR1, KAREN L. BACON2, MIHAI E. POPA3, LAURA BOCHNER4 and JENNIFER C. MCELWAIN2

1 Department of Geological Sciences, Stockholm University, SE-10691 Stockholm, Sweden;

2 School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland

3 Faculty of Geology and Geophysics, University of Bucharest, 1, N. Balcescu Ave., 010041, Bucharest, Romania

4 Department of Geology and Environmental Geosciences, Lafayette College, Easton, PA, USA

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in Palaeontology 54: 867–882 –

Bennettitalean_leaf_cuticle_fragments_he.pdf

Abstract:

Bennettites are an abundant and frequently well- preserved component of many Mesozoic fossil floras, often playing an important ecological role in flood plain vegetation communities.

During a recent study focusing on stomatal indices of Triassic–Jurassic fossil plants, it became evident that the leaf fragments of two bennettite genera Anomozamites Schimper (1870) emend. Harris (1969) and Pterophyllum Brongniart (1825) display a significant overlap of leaf shape as well as cuticular characters.

Owing to the preference of recognition of single taxa (ideally species) for the stomatal method, we use a database of 70 leaf fragments of Anomozamites and Pterophyllum compressions from five isotaphonomic Late Triassic sedimentary beds of Astartekløft in East Greenland to test whether leaf and cuticle fragments of the two genera can be separated using a range of quantitative and qualitative morphological and statistical analyses.

None of the observed characters – including stomatal frequencies – could be applied to separate the fragments of the two genera into well-defined groups. Our results therefore indicate that fragmented material and dispersed cuticles cannot be utilized to distinguish between Anomozamites or Pterophyllum at the genus level, but that instead these cuticle fragments may be used interchangeably as stomatal proxies.

Classification of fossil leaves into either of these genera is thus only possible given adequate preservation of macro-morphology and is not possible based solely on cuticle morphology.

We suggest that this large inter- and intra-generic morphological variation in both leaf and cuticle traits within Anomozamites and Pterophyllum may be related to the bennettites’ role as understory plants, experiencing a range of micro-environmental conditions, perhaps depending mainly on sun exposure.

Based on the results obtained in this study, we conclude that Anomozamites and Pterophyllum cuticle fragments can be employed interchangeably in palaeo [CO2] reconstructions based on the stomatal method, thus potentially annexing a plethora of bennettitalean fossil plant material as CO2 proxies, including dispersed cuticles.

 

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Variations in stomatal density and index

 

 

Variations in stomatal density and index: implications for palaeoclimatic reconstructions. 

by Poole I., Weyers J. D. B., Lawson T., Raven J. A. (1996)

Tracy_Lawson
Tracy Lawson, University of Essex, School of Biological Sciences, UK
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in Plant, Cell and Environment 19, 705712 – DOI: 10.1111/j.1365-3040.1996.tb00405.x –

Wiley Online LibraryCrossRef

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.1996.tb00405.x/abstract

ABSTRACT

The variation in stomatal characters in leaves from one Alnus glutinosa (L.) Gaertn. tree is analysed. Measurements were taken from over 70 sites on the abaxial surfaces of representative ‘sun’ and ‘shade’ leaves having the same insertion point.

The mean values of stomatal density and index in the shade leaf were significantly lower (71 and 93%, respectively) than those for the sun leaf. Within leaves, up to 2.5-fold differences in stomatal density values were observed.

Contour maps derived from the data reveal non-random trends over the leaf surface. Correlations between stomatal density, epidermal cell density and stomatal index indicate that the variation in stomatal density within leaves arose primarily from local differences in stomatal differentiation, rather than from local differences in leaf expansion.

This research demonstrates that a high level of variation in stomatal characters occurs both within and between leaves. We conclude that a well-defined sampling strategy should be used when estimating stomatal characters for (tree) leaves.

Furthermore, the leaf’s insertion point and situation within the tree crown should be taken into account. We discuss the implications of these findings for palaeoclimatic interpretations and emphasize the need for great caution when drawing conclusions based solely on stomatal characters.

Stomatal density and index: the practice.

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Stomatal density and index: the practice.

by Poole I., Kurschner M. (1999)

in In: Jones, T.P., Rowe, N.P. (Eds.), Fossil Plants and Spores: Modern Techniques. – The Geological Society, London, 257–260 –

https://www.researchgate.net/publication/46596820_Stomatal_density_and_index_The_practice

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How plants learned to breathe.

 

 

How plants learned to breathe.

by Pennisi E. (2017)

Elizabeth Pennisi,

in Science 335(6330): 1110-1111 – DOI: 10.1126/science.355.6330.1110 –

http://science.sciencemag.org/content/355/6330/1110

Summary

Anyone awed by towering redwoods should offer thanks to stomata, the tiny pores on the leaves of all trees and other vascular plants.

These microscopic mouths allow plants to grow tall and to regulate carbon dioxide intake and water loss. Stomata, in short, helped plants colonize the landscape and transform the planet.

Now, molecular studies are giving scientists glimpses of the early days of stomata and how they have changed since then. They suggest complex stomata evolved to help early plants control moisture in their spore capsules and that other plants later exploited these pores to breathe in carbon dioxide and exhale water vapor.

And hundreds of millions of years later, more sophisticated stomata evolved in grasses, enabling them to tightly control water loss—a feature that helped them dominate dry landscapes around the world.

 

The story in the stomata.

One hundred eighty million year old fossilized leaf of a conifer tree magnified 100 times. Each stoma is sunken and concealed by three to five finger-like projections.

 

The story in the stomata.

by Murphy J., McElwain J., Weinstein J. (n.d.)

in Understanding Evolution.

berkeley.edu. -Fossils & climate change – page 3 of 8 –

http://evolution.berkeley.edu/evolibrary/article/mcelwain_03

Jennifer studies stomata that are preserved on the surfaces of fossil leaves. But what do stomata have to do with climate change? As an undergraduate in Ireland, Jennifer discovered that the number of stomata per square inch of leaf surface can reveal different aspects of the atmosphere in which that plant lived. Since then, she has continued in this vein of research. As Jennifer puts it, “Plants are wonderfully in tune with their environments, so there are many proxies or signals that we can obtain from fossil plants. We can work out the temperature they lived in, the atmospheric environment, and the carbon dioxide concentration.”
It works like this. Stomata control a tradeoff for the plant: they allow carbon dioxide in, but they also let precious water escape. A plant that could get enough carbon dioxide with fewer stomata would have an advantage since it would be better able to conserve its water. Levels of carbon dioxide in Earth’s atmosphere change over time — so at times when the atmosphere is carbon-dioxide-rich, plants can get away with having fewer stomata since each individual stoma will be able to bring in more carbon dioxide. During those high-carbon-dioxide times, plants with fewer stomata will have an advantage and will be common. On the other hand, when carbon dioxide levels are low, plants need many stomata in order to scrape together enough carbon dioxide to survive. During low-carbon-dioxide times, plants with more stomata will have an advantage and will be common.

11884_evo_resources_resource_image_370_original
Levels of carbon dioxide in Earth’s atmosphere change over time — so at times when the atmosphere is carbon-dioxide-rich, plants can get away with having fewer stomata since each individual stoma will be able to bring in more carbon dioxide. During those high-carbon-dioxide times, plants with fewer stomata will have an advantage and will be common. On the other hand, when carbon dioxide levels are low, plants need many stomata in order to scrape together enough carbon dioxide to survive. During low-carbon-dioxide times, plants with more stomata will have an advantage and will be common.

Jennifer uses stomata as indicators of carbon dioxide levels at different points in Earth’s history. Experiments help her figure out the exact relationship between stomata and carbon dioxide. Using growth chambers, she can simulate the temperature, light level, and atmospheric conditions common at different times in the deep past and at different places on Earth. So even when it’s subzero in Chicago, her seedlings might feel as though they are growing in sunny California or in the humid swamps of the Jurassic. Studying how modern plants respond to these environments helps Jennifer understand how the characteristics of long extinct plants were affected by their environments.

Estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size

 

 

Stomatal size in fossil plants: evidence for polyploidy in majority of angiosperms

by Masterson J. (1994)

Jane Masterson, Committee on Evolutionary Biology, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA

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in Science 264: 421–424 – DOI: 10.1126/science.264.5157.421 –

http://science.sciencemag.org/content/264/5157/421

Abstract

Three published estimates of the frequency of polyploidy in angiosperms (30 to 35 percent, 47 percent, and 70 to 80 percent) were tested by estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size as a proxy for cellular DNA content.

The inferred chromosome numbers of these extinct species suggest that seven to nine is the primitive haploid chromosome number of angiosperms and that most angiosperms (approximately 70 percent) have polyploidy in their history.

 

pCO2 estimates of the late Eocene based on stomatal densities

 

 

The pCO2 estimates of the late Eocene in South China based on stomatal densities of Nageia Gaertner leaves

by Liu X.-Y., Gao Q., Han M., Jin J.-H., (2015)

AA(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China),

AB(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China),

AC(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China),

AD(State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China

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in Climate of the Past Discussions, 11, 2615–2647 – doi:10.5194/cpd-11-2615-2015 –

http://adsabs.harvard.edu/abs/2015CliPD..11.2615L,

Abstract

The late Eocene pCO2 concentration is estimated based on the species of Nageia maomingensis Jin et Liu from the late Eocene of Maoming Basin, Guangdong Province.

This is the first paleoatmospheric estimates for the late Eocene of South China using stomatal data. Studies of stomatal density (SD) and stomatal index (SI) with N. motleyi (Parl.) De Laub., the nearest living equivalent species of the fossil, indicate that the SD inversely responds to atmospheric CO2 concentration, while SI has almost no relationships with atmospheric CO2 concentration.

Therefore, the pCO2 concentration is reconstructed based on the SD of the fossil leaves in comparison with N. motleyi.

Results suggest that the mean CO2 concentration was 391.0 ± 41.1 ppmv or 386.5 ± 27.8 ppmv during the late Eocene, which is significantly higher than the CO2 concentrations documented from 1968 to 1955 but similar to the values for current atmosphere indicating that the Carbon Dioxide levels during that the late Eocene at that time may have been similar to today.