Experimental production and analysis of microscopic charcoal from wood,                 leaves and grasses

Umbanhowar, Charles E.; Mcgrath, Molly J.

doi:10.1191/095968398666496051

Cited by 160 publications

(148 citation statements)

References 20 publications

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“…The elongation degree is preserved even when the particle is broken (24). Experimental analysis conducted on burned grasses and wood from North America showed that charcoal from grasses has a greater elongation ratio than charcoal derived from wood (24). We thus infer that the increase in the mean elongation of microcharcoal particles is an indicator of low-intensity fires spreading in grass-dominated fueled environments.…”

Section: Resultsmentioning

confidence: 86%

“…During a fire, charcoal fragmentation occurs along axes derived from the anatomical structure of plant species. The elongation degree is preserved even when the particle is broken (24). Experimental analysis conducted on burned grasses and wood from North America showed that charcoal from grasses has a greater elongation ratio than charcoal derived from wood (24).…”

Section: Resultsmentioning

confidence: 99%

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Orbital-scale climate forcing of grassland burning in southern Africa

Daniau

Goñi

Martinez

et al. 2013

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

137

106

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Although grassland and savanna occupy only a quarter of the world's vegetation, burning in these ecosystems accounts for roughly half the global carbon emissions from fire. However, the processes that govern changes in grassland burning are poorly understood, particularly on time scales beyond satellite records. We analyzed microcharcoal, sediments, and geochemistry in a high-resolution marine sediment core off Namibia to identify the processes that have controlled biomass burning in southern African grassland ecosystems under large, multimillennial-scale climate changes. Six fire cycles occurred during the past 170,000 y in southern Africa that correspond both in timing and magnitude to the precessional forcing of north-south shifts in the Intertropical Convergence Zone. Contrary to the conventional expectation that fire increases with higher temperatures and increased drought, we found that wetter and cooler climates cause increased burning in the study region, owing to a shift in rainfall amount and seasonality (and thus vegetation flammability). We also show that charcoal morphology (i.e., the particle's length-to-width ratio) can be used to reconstruct changes in fire activity as well as biome shifts over time. Our results provide essential context for understanding current and future grassland-fire dynamics and their associated carbon emissions.

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Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Orbital-scale climate forcing of grassland burning in southern Africa

Daniau

Goñi

Martinez

et al. 2013

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

137

106

View full text Add to dashboard Cite

show abstract

“…Dans les sols minéraux secs, les reliques paléobotaniques correspondent à des pièces carbonisées résultant de feux récurrents sur de longues périodes (Carcaillet, 1998 ;Talon, et al, 1998). Bien que les feuilles, les stomates, les cônes ou leurs écailles et les rameaux soient d'excellents éléments pour la détermination des assemblages d'espèces de conifères (Dunwiddie, 1987 ;Umbanhowar et McGrath, 1998) (Payette et Filion, 1975 ;Payette, 1983), les facteurs historiques demeurent méconnus. La distinction des restes de mélèze serait aussi essentielle pour établir sa limite passée en Hudsonie (Gagnon et Payette, 1981) et pour suivre dans le temps son patron de migration dans la péninsule du Qué-bec-Labrador.…”

Section: Introductionunclassified

Distinction anatomique du bois du mélèze (Larix laricina [Du Roi] K. Koch), de l'épinette blanche (Picea glauca [Moench.] Voss), et de l'épinette noire (Picea mariana [Mill.] B.S.P.), en vue de l'analyse des macrorestes

Marguerie¹,

Bégin²,

Cournoyer³

2002

gpq

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Eighty-four specimens of wood collected in northeastern North America from pre-identified conifers were used to define new anatomical criteria to distinguish woody macroremains of Picea mariana, Picea glauca and Larix laricina. In addition to characters already described in the literature, the torus surface of bordered pits along the longitudinal tracheids were demonstrated to be a very good distinction criterion. The distinction between Picea glauca and P. mariana is based on the seriation of bordered pits on the tracheids of the rays. As a method of species distinction, we suggest a dichotomous classification based on the dominance of uniseriate or biseriate pits. In the wood collection studied, 69 % of radial tracheids were predominantly biseriated in Picea mariana, compared with only 28 % in Picea glauca. These simple distinction methods are only applicable in cases where no other Picea species could cause confusion in batches of woody and charred sub-fossils. They add a practical tool for further paleoecological reconstructions in northeastern North America.Quatre-vingt-quatre spécimens de bois de conifères récoltés sur un vaste territoire dans le nord-est de l'Amérique du Nord ont servi à définir de nouveaux critères de distinction anatomique entre Picea mariana, Picea glauca et Larix laricina. En plus des critères habituellement décrits dans la littérature, l'état de surface du torus des ponctuations aréolées des trachéides longitudinales chez Larix laricina est présenté comme un excellent élément de détermination, facilement accessible. La distinction entre Picea glauca et P. mariana peut être faite par l'examen de la sériation des ponctuations des trachéides des rayons ligneux. Une classification dichotomique des croisements des cellules dans les rayons sur la base de la dominance de l'unisériation ou de la bisériation des ponctuations des trachéides de rayon est proposée comme méthode de distinction des espèces en plus d'autres caractères reconnus dans la littérature. Ainsi, chez Picea mariana, plus de 69 % des trachéides radiales sont à dominante bisériée et seulement 28 % chez Picea glauca. En présence de lots de macrorestes ligneux subfossiles gorgés d'eau ou carbonisés où seule la présence de ces deux espèces d'épinettes est possible, ces méthodes simples d'identification ouvrent de nouvelles perspectives dans le domaine de la recherche paléoécologique des milieux boréaux nord-américains.Vierundachtzig Holzproben von Tannenholz wurden auf einem ausgedehnten Gebiet im Nordosten Nordamerikas gesam- melt und dienten dazu, neue Kriterien zur anatomischen Unterscheidung zwischen Picea mariana, Picea glauca und Larix laricina zu definieren. Zusätzlich zu den gewöhnlich in der Literatur beschriebenen Kriterien wird die Torus-Oberfläche des Rands der gepunkteten Vertiefungen der Längs-Tracheen bei Larix laricina als ausgezeichnetes, leicht zugängliches Bestimmungselement beschrieben. Zwischen Picea glauca/Picea mariana kann durch die Untersuchung der Serienfolge der gepunkteten Tracheen auf den Holzringen u...

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“…A further question arising from such morphometric studies is the extent to which particle morphology is infl uenced by the method by which larger charcoal pieces have been broken down. Charcoal crushed in a mortar and then sieved, as in Umbanhowar and McGrath (1998) , may display different morphological features compared to that broken down by natural processes. simulated the effects of bedload transport by placing charcoal produced from Pinus sylvestris L. twigs, sieved to between 3.3 and 9.5 mm, with sand and water http://www.bioone.org/loi/apps Particles of less than 315 μ m 2 or greater than 1,000,000 μ m 2 were excluded from the analysis.…”

Section: Methodsmentioning

confidence: 99%

“…We have subjected charcoal particles derived from a range of plant materials to a realistic method of breakdown, with the aim of establishing whether different fuel types undergo distinctive changes in morphology under increasing degrees of breakdown. We also further test the hypothesis of Umbanhowar and McGrath (1998) that the aspect ratio of charcoal particles can reveal whether they originate in grassland or woodland fi re.…”

mentioning

confidence: 99%