Degradation of carbohydrates and lignins in buried woods

Hedges, John I.; Cowie, Gregory L.; Ertel, John R.; Barbour, R. James; Hatcher, Patrick G.

doi:10.1016/0016-7037(85)90165-6

Cited by 334 publications

(152 citation statements)

References 31 publications

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“…The main difference between Quaternary and pre-Quaternary wood samples relates (to a greater extent) to the changes in chemical composition during fossilization which in turn will affect the stable isotopic composition Poole et al 2004). During the fossilization process the holocellulose fraction is preferentially degraded relative to the lignin fraction (Hedges et al 1985). Even within the holocellulose fraction the hemicelluloses are normally degraded faster than the cellulose.…”

Section: Palaeoclimate Signals From Stable Isotopes In Woodmentioning

confidence: 99%

Physiognomic and chemical characters in wood as palaeoclimate proxies

Poole

Bergen

2006

Plants and Climate Change

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Fossil wood is both abundant and ubiquitous through geological time and space. During growth the parent plant was directly influenced by the biotic and abiotic (including climatic-) factors in the surrounding environment. The climate affects wood production in a number of ways and it is the resulting physiognomic and chemical characters that can help retrodict palaeoclimate. Physiognomic characters include those morphological and anatomical characters that in turn have enabled the use of wood characters, tree ring characters and statistical parameters (Mean Sensitivity) to determine seasonality, length and favourability of growing season, growth rates and forest productivity. Potential chemical characters discussed include (i) the preservation of wood-derived compounds (e.g. guaiacyl, syringyl p-hydroxyphenyl and resins); (ii) degree of lignin degradation to determine climate induced environmental changes; and (iii) stable isotopes (dD, d 13 C and d 18 O) to help determine aspects of past climates as derived from environmental changes. The feasibility and methodology of these characters, in both angiosperm and conifer wood, are reviewed in order to establish certain safe guards, or prerequisites, such that interpretations of palaeoclimate can be as unbiased, and thus as reliable, as possible.

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Section: Palaeoclimate Signals From Stable Isotopes In Woodmentioning

confidence: 99%

Physiognomic and chemical characters in wood as palaeoclimate proxies

Poole

Bergen

2006

Plants and Climate Change

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“…Decay was anaerobic, with little or no activity of metazoan scavengers. The preservation of periderm may indicate that the periderm protein, like lignin (Hedges et al, 1985), was comparatively resistant to anaerobic decay.…”

Section: Scavenging and Recyclingmentioning

confidence: 99%

The position of graptolites within Lower Palaeozoic planktic ecosystems

Underwood

1993

LET

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An integrated approach has been used to assess the palaeoecology of graptolites both as a discrete group and also as a part of the biota present within Ordovician and Silurian planktic realms. Study of the functional morphology of graptolites and comparisons with recent ecological analogues demonstrates that graptolites most probably filled a variety of niches as primary consumers, with modes of life related to the colony morphotype. Graptolite coloniality was extremely ordered, lacking any close morphological analogues in Recent faunas. To obtain maximum functional efficiency, graptolites would have needed varying degrees of coordinated automobility. A change in lifestyle related to ontogenetic changes was prevalent within many graptolite groups. Differing lifestyle was reflected by differing reproductive strategies, with synrhabdosomes most likely being a method for rapid asexual reproduction. Direct evidence in the form of graptolithophage 'coprolitic' bodies, as well as indirect evidence in the form of probable defensive adaptations, indicate that graptolites comprised a food item for a variety of predators. Graptolites were also hosts to a variety of parasitic organisms and provided an important nutrient source for scavenging organisms.

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“…Upon burial and subsequent diagenesis the di¡erent organic constituents of wood undergo varying degrees of degradation. It is well known that under natural anaerobic conditions the polysaccharides in wood are preferentially degraded compared with lignin and within the polysaccharide fraction hemicellulose degrades faster than cellulose (e.g., Hedges et al, 1985;Benner et al, 1987). This phenomenon can have a dramatic e¡ect on the bulk stable carbon isotope composition of fossil wood as the removal of polysaccharides results in the material becoming more depleted in 13 C (Fig.…”

Section: Introductionmentioning

confidence: 99%

Stable carbon isotopes of wood: a clue to palaeoclimate?

Bergen

Poole

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

102

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Detailed stable carbon isotope and molecular investigations were undertaken on a number of archaeological and fossil wood specimens to provide insights into their use as rigorous independent palaeoclimatic and palaeoenvironmental parameters. The isotope data revealed large differences amongst the material with the oldest specimens being least depleted in 13 C. Although natural variation could account for some of the observed differences, the isotope values of the archaeological and Tertiary specimens are most probably related to the absolute abundance of polysaccharides present and the degree of lignin alteration. The molecular data, based on pyrolysis, of the Antarctic Cretaceous conifer specimens revealed only transformed lignin, with virtually no intact lignin building blocks (2-methoxyphenols) preserved, and no evidence of polysaccharides. This degree of chemical alteration is suggested here to be one of the main causes for the 13 C enriched values of these conifer specimens. These results show the importance of combining detailed molecular information on individual wood components with stable carbon isotope data for palaeoclimatic and palaeoenvironmental studies. ß

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Degradation of carbohydrates and lignins in buried woods

Cited by 334 publications

References 31 publications

Physiognomic and chemical characters in wood as palaeoclimate proxies

Physiognomic and chemical characters in wood as palaeoclimate proxies

The position of graptolites within Lower Palaeozoic planktic ecosystems

Stable carbon isotopes of wood: a clue to palaeoclimate?

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