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Abstract: Charcoal, predominantly the product of wildfires, is abundant in many sedimentary rocks deposited in a wide range of environments, from terrestrial to marine. It also occurs in some volcanic rocks. This paper outlines aspects of charcoal formation (both natural and experimental) and briefly considers the taphonomic processes leading to a final assemblage. This is done using examples from recent fires and through experimentation. The ways in which charcoal assemblages are recognized in the field and extraction in the laboratory are also considered. Methods of charcoal identification are presented. The range of charcoalified plant organs that can be found is discussed and a wide range of study methods outlined (including light microscopy, dark field light microscopy, reflectance microscopy, scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy). Emphasis in this paper is on the study of macro- and meso-charcoal (above180µm). Finally there is a consideration of the broad use of charcoal from plant evolution studies, fire history studies, vegetation studies, anatomical studies, climate and atmospheric studies and the wider importance of charcoal for the Earth and Biological Sciences. Charcoal is information rich but yet is an under-utilized resource. [Copyright &y& Elsevier]

Understanding human impact on the vegetation of the Tibetan Plateau through the Holocene is important for developing strategies for sustainable ecosystem management in the region. In this paper, 53 pairs of surface-soil samples from inside and outside livestock enclosures were obtained from across the Tibetan Plateau to investigate the differences in pollen assemblages between grazed and ungrazed sites. This modern dataset was then applied to palynological records from four lakes in the northeast Tibetan Plateau region to investigate middle to late Holocene grazing history. Results show that modern grazing activities have a limited impact on the vegetation, although grazing activity leads to an increase in the pollen proportion of Cyperaceae, Artemisia , Ranunculaceae, Brassicaceae, Taraxacum -type, Fabaceae, and Saxifrageceae while representatives of Poaceae, Chenopodiaceae, and Aster -type pollen decrease. Application of these grazing indicators to the pollen spectra obtained from the four lake sites, together with other proxies, reveals that grazing activity only commenced during the last few hundred years in the northeast marginal areas of the Tibetan Plateau at c. 3000 m a.s.l, while there is no grazing signal in pollen records from above 4000 m a.s.l. Our study emphasises the importance of using multi-proxy methods in estimating signals of past human activity. • Pollen assemblage should be insensitive to grazing activities on the Tibetan Plateau. • Human impacts on vegetation at ∼3400 m a.s.l are limited to within a few centuries. • No significant pollen signal of grazing is revealed for the high-elevation areas. [ABSTRACT FROM AUTHOR]

Grapevine and wine have deeply shaped the landscapes, economy and cultures of Europe and the Mediterranean. In France, it is considered that viticulture started in the south via contacts with Mediterranean populations (Greeks, Etruscans, Phoenicians), during the second half of the 1st millennium BCE, and spread further with the Romans. Wild grapevines were nevertheless present in various areas of the country all through the Holocene. No archaeological or historical source allows us to follow the history of grapevine and viticulture over the entire Holocene period and over the whole territory. In this paper we investigate the potential of archaeological plant macroremains (seed/fruits and wood) to trace the history of the vine on a large scale. We have assembled the largest possible database of published and unpublished archaeobotanical data, comprising 4449 site-phases for seed and fruits and 1356 site-phases for wood remains. In spite of taphonomic discrepancies and imbalances in the datasets, the different types of macroremains and modes of preservation produce consistent patterns. They provide the first comprehensive picture of the spread of grapevine, fluctuations in the economic role of viticulture and grape uses over time, although some periods and regions are less documented. Grapevine remains are regularly recorded from the Mesolithic to the Iron Age in most regions showing that human societies were already familiar with the wild plant and its fruits, especially in the Mediterranean. In this region, Vitis remains become considerably more frequent and numerous during the Iron Age, from around 500 BCE onwards, testifying to the rapid and strong implantation of viticulture. Grapevine macroremains confirm that the spread of viticulture outside the Mediterranean area occurred mainly during the Roman period. However, this expansion was limited and mainly focused on the South. The main expansion into the temperate zone took place during the Middle Ages. However, the more detailed fluctuations of viticulture, particularly in relation to climate oscillations are still difficult to follow. Pip remains are mainly associated with urban sites. This is a consequence of the actual consumption of grapes and may be evidence of a viticulture centered around urban areas. • Macroremains data to retrace the Holocene history of Vitis. • Unique database of 4449 site-phases for seeds and 1356 site-phases for wood remains. • First comprehensive picture of the spread of Vitis and viticulture in France. • Significant and consistent involvement of cities in viticultural activities. [ABSTRACT FROM AUTHOR]

Marine Isotope Stage 5 (MIS 5) is well represented in palynological studies of North Atlantic marine cores but in only a handful of archeological sequences from the adjacent Iberian landmass. In this paper, we undertake a multi-proxy analysis of small mammal assemblages (insectivores, bats, and rodents) from a 6 m-thick succession, dated to MIS 5a-5b (Layers 7–22), situated in the southeastern edge of the Central Limestone massif of Estremadura at Gruta da Oliveira, near Torres Novas, Portugal. Application of quantitative (Habitat Weighting, Simpson's Diversity Index) and qualitative (Mutual Ecogeographic Range, Bioclimatic Model, Quantified Ecology) methods suggest that open woodland habitats were dominant through the time of accumulation with reconstructed mean annual temperatures (MAT) tracking the 18O curve from the NorthGRIP ice core, from the end of MIS 5c to the beginning of MIS 4. Our findings are consistent with the general trends derived from other Gruta da Oliveira proxies (wood charcoal, coprolite pollen, large mammal associations), limited evidence from other MIS 5 terrestrial sites in Iberia, and offshore marine palynological records. • Combined quantitative and qualitative methods to reconstruct MIS 5 at Gruta da Oliveira. • Small-mammal assemblage used as a proxy to apply these methods. • A landscape dominated by open woodlands habitats has been identified. • Findings are consistent with the trends reported from other Gruta da Oliveira proxies. • Results accord with data from marine core pollen and other MIS 5 Iberian sites. [ABSTRACT FROM AUTHOR]

Many regions worldwide have experienced increasing wildfire activity in recent years and climate changes are predicted to result in more frequent and severe fires. Reconstruction of past fire activity offers paleoenvironmental context for modern and future burning. Pyrogenic polycyclic aromatic hydrocarbons (PAHs) have been increasingly used as a molecular biomarker for fire occurrence in the paleorecord and offer opportunity for nuanced reconstructions of fire characteristics. A suite of PAHs is produced during combustion, and the emission amount and assemblage is influenced by many variables including fuel type, fire temperature, and oxygen availability. Despite recent advances in understanding the controls and taphonomy of these biomass burning markers, the spatial scale of this proxy is unknown. In this paper, measurements of PAH fluxes preserved in a lake sediment archive from the Sierra Nevada, California were compared with a historical geographic information system (GIS) dataset of area burned up to 150 km distance from the lake to determine the spatial scales for which these biomarkers are reliable proxies of biomass burning. The PAH fluxes in the Swamp Lake sediments record a change in the relative anthropogenic and pyrogenic sourcing of PAHs. Anthropogenic pollution sources could explain why some PAHs (fluoranthene (Fl), pyrene (Py), benz[ a ]anthracene (BaA), retene (Ret), benzo[ a ]pyrene (BaP), dibenzo[ a , h ]anthracene (DA) and ideno[1,2,3- cd ]pyrene (IP)) did not correlate with area burned within 150 km. This indicates that individual PAHs may have different efficacies in recording area burned and be more susceptible to masking of fire signals by pollution sources. Despite these complications, we find that the PAHs naphthalene (Na), acenaphthene (Ace), fluorene (F), and anthracene (An) are reliable local proxies of area burned (within 40 km), whereas the PAHs phenanthrene (Phe), chrysene (Ch), benzo[ b ]fluoranthene (BbF), benzo[ k ]fluoranthene (BkF), and benzo[ g , h , i ]perylene (Bghi) are both reliable local (within 36 km) as well as more regional (as much as 75 km for phenanthrene (Phe), chrysene (Ch), and benzo[ g , h , i ]perylene (Bghi) or 150 km for benzo[ b ]fluoranthene (BbF) and benzo[ k ]fluoranthene (BkF)) area burned proxies. Comparisons of PAH fluxes with charcoal accumulation rates in the same sediments suggest that pyrogenic particulate transport modulates low to mid-molecular weight PAHs via adsorption. Overall, the results show that PAH records integrate a combination of spatial signals of area burned and measurement of individual PAHs may enable cross-scale paleofire reconstructions. • The spatial scales of PAHs as paleofire proxies are poorly understood. • We use fire data to determine PAHs' reliability in recording area burned. • The spatial fidelity of PAHs varies due to their variable chemical properties. • We provide the first source area constraints for PAHs as paleofire proxies. [ABSTRACT FROM AUTHOR]

The Changbaishan volcano, located in northeast China, produced a large amount of charcoal during the "Millennium Eruption" (c. 946 CE). In this paper, we report a high-resolution date for the eruption using multiple methods applied to the fossil charcoal and living trees, including wood anatomy, radiocarbon dating and tree-ring cross-dating. In addition, we develop a new floating annual-resolution tree-ring chronology spanning nearly 200 years that provides information about paleoclimate conditions. In our study, we identified 60 samples of charcoal as Larix olgensis based on anatomical characteristics and geographical location. Using these materials, we dated the eruption to the winter of 946 CE based on a combination of radiocarbon dating, traditional dendrochronological cross-dating and cambial cell growth status. This allowed us to develop an L. olgensis tree-ring width chronology covering 764–946 CE and 1715–2016 CE, with significant sensitivities to April–September temperature (p < 0.05). The tree-ring data have great potential to indicate extreme climate events; for example, we identify an extremely cold year in 903 CE. Such marker years can improve the reliability and accuracy of tree-ring data. Our study provides direct and precise tree-ring evidence for volcanic eruptions and anomalous climate years in the Middle Ages. [Display omitted] • Cambial activity enables us to date the Millennium Eruption to winter 946 CE. • The first chronology reaching the Middle Ages so far developed in northeastern China. • The chronology was assembled from volcanic charcoal and living larch. • This chronology is sensitive to temperature. [ABSTRACT FROM AUTHOR]

Abstract: This paper shows a Holocene paleoecological reconstruction based on a peat bog sequence (El Paují, 4°28′N–61°35′W, 865m elevation) located in the transition zone between the Gran Sabana (SE Venezuela) savannas and the Amazon rainforests. Paleoecological trends are based on the analysis of pollen and pteridophyte spores, algal and animal remains, fungal spores, and charcoal particles. The whole record embraces the last ca. 8000calyr BP, and was subdivided into five pollen zones, representing the following vegetation succession: savanna/rainforest mosaic (8250–7715yr BP), dense rainforests (7715–5040yr BP), savanna/rainforest mosaic (5040–2690yr BP), secondary dry forests (2690–1440yr BP), and peat bog in an open savanna landscape (1440yr BP–present). These vegetation changes have been attributed to the action of climate and/or land use changes, as well as the corresponding synergies between them. Fire has been determinant in the landscape evolution. Based on the reconstructed fire and vegetation shifts, a changing land use pattern could have been recognized. Between the early and the mid Holocene (ca. 8.3–5.0kyr BP), land use practices seem to have been more linked to shifting agriculture in a rainforest landscape – as is usual in Amazon cultures – with medium fire incidence affecting only local forest spots or surrounding savannas. More extensive forest burning was recorded between ca. 5.0 and 2.7kyr BP, followed by land abandonment and the dominance of drier climates between 2.7 and 1.4yr BP. The modern indigenous culture, which prefers open environments and makes extensive use of fire thus preventing forest re-expansion, seem to have established during the last 1500yr. Therefore, a significant cultural replacement has been proposed for the region, leading to the present-day situation. Changing human activities have been instrumental for ecological evolution in this savanna–rainforest transitional region, as well as for the shaping of modern landscapes. [Copyright &y& Elsevier]

Abstract: High-resolution macroscopic charcoal and pollen analyses were used to reconstruct the fire and vegetation history of the Willamette Valley for the last 1200years. Presented in this paper are three new paleoecological reconstructions from Lake Oswego, Porter Lake, and Warner Lake, Oregon, and portions of previous reconstructions from Battle Ground Lake, Washington, and Beaver Lake, Oregon. The reconstructions show that prior to Euro-American settlement vegetation and fire regimes were influenced by a combination of natural and anthropogenic factors. Battle Ground Lake shows a stronger influence from climate, while Lake Oswego, Beaver Lake, Porter Lake, and Warner Lake were more controlled by human activity. However, human-set fires were also modulated by regional climate variability during the Medieval Climate Anomaly and the Little Ice Age. Fire reconstructions from Battle Ground Lake, Lake Oswego, Beaver Lake, and Porter Lake imply that fires were infrequent in the Willamette Valley 200–300years prior to Euro-American settlement. The decline of Native American populations due to introduced disease may have led to this reduction in fire activity. The prehistoric record from Warner Lake, however, indicates that fires in the foothills of the Cascade Range were more frequent than on the valley floor, at least until ca. AD 1800. The historic portions of the reconstructions indicate that Euro-American land clearance for agriculture and logging produced the most dramatic shifts in vegetation and fire regimes. All five records indicate that few fires in the Willamette Valley have occurred since ca. AD 1930, and fires today are predominantly grass fires. [ABSTRACT FROM AUTHOR]

Abstract: A discussion on the representativeness of charcoal from archaeological contexts and their potential for palaeoecological reconstruction is presented. The charcoal deposits studied are the result of human activities and natural processes, difficult to separate on the basis of their effects only. This is why “taphonomy” should not be limited to the study of charcoal, after the extinction of fire. As a result our questioning has been widened to include the entire succession of processes, from past vegetation to the anthracological diagram. We propose a review of the taphonomic processes affecting anthracological assemblages in archaeological contexts, from wood gathering to the analysis of charcoal results. Human practices appear clearly as the first filter determining or conditioning the assemblage. The combustion process can induce a double filter by limiting the taxonomic information and by falsifying the initial quantity of burned wood. Post-depositional agents represent a third level of filters between the vegetation and the anthracological assemblage. Finally, sampling and quantification methods can also induce a distortion of the assemblage. The aim of this paper is to present the state of the discipline today, the problems already solved, and the questions that remain to be studied. [Copyright &y& Elsevier]

Abstract: The present paper concerns long Upper Pleistocene loess sequences from Eastern Europe with multiple Upper Palaeolithic occupations, rich in charcoal, as well as loess sequences from Central Siberia with abundant wood remains. These complementary records have allowed establishing a high-resolution climatic sequence integrating 24 interstadial episodes between ca 42.5 and 10kyr BP. Here, we discuss the methodology of dating used to fix the chronological framework of this climatic sequence, based on a set of 240 available radiocarbon dates, mainly produced on charcoal and wood remains. Special attention is paid to the strategy of sampling charcoal and wood material in strict accordance with stratigraphy, as well as to the preparation process in the laboratory for extraction, cleaning, identification and selection of the best fragments to date. Careful stratigraphic drawing and detailed positioning of the samples for each geological layer are also considered in order to clarify the relationship of the obtained dates with respect to any sedimentary, pedological or archaeological event to be dated. The reliability and accuracy of the dates obtained from loess sequences are further controlled by the internal consistency with regard to stratigraphy. Palaeoenvironmental implications are also discussed. [Copyright &y& Elsevier]

Disentangling fire and its controls over thousands of years ago is a major challenge in the study of paleofires. In this paper, we synthesize sedimentary charcoal and black carbon from the coastal plain of Laizhou Bay, China to improve our ability to reconstruct fire history in the past 5000 years, and to assess the controls of fire using principal component analysis and multiple regression approach. The results show that there were three distinct fire episodes at the intervals of 5300–5100 yr BP., 1190–1060 yr BP., and 300–0 yr BP., based on the Changyi (CY) profile. A large-scale fire episode was synchronous with a rapid climate variability that occurred 5300 yr BP., which had frequent drought and cold epoch. High fluxes of black carbon and charcoal were closely related to mass migration and the use of fire for land reclamation from 1190 to 1060 yr BP. Subsequently, anthropogenic biomass burning for cereal cultivation has reached a higher level over the past 300 years. However, between 4600 and 4000 yr BP. the shifts in the frequency of high-magnitude floods and climate aridity consequently resulted in the decline of fire-episode frequency and the abandonment of the late Neolithic settlements in the study region. Therefore, climate is still a prerequisite factor for fire occurrence on the southern coast of Laizhou Bay in the past 5000 years. A rapid climate variability was not only responsible for various fire patterns, but also could affect human settlements and the mode of production during middle-late Holocene. In the past 1000 years, human land use has been a more important control of fire. However, temperature has become one of the evidently identified controls of fire across the study area in recent decades. To synthesize the methods of Principal Component Analysis and Multiple Regression Analysis with multi-proxy evidence is necessary for us to better understand fire and its controls on coastal plain of Laizhou Bay at the region. • Charcoal and BC have recorded fire mid-Holocene at the Laizhou Bay of China. • Climate was still a prerequisite control of fire at the Laizhou Bay mid-Holocene. • In the past 1000 years, human land use has been an important control of fire. • Temperature has become one of the identified controls of fire across the study area. • Principal component analysis will contribute to disentangling fire and its controls. [ABSTRACT FROM AUTHOR]

Fire has been an important Earth System phenomenon for millions of years and our ability to understand its role in geologic history relies upon robust and unequivocal paleofire archives. Charcoal particles preserved in sedimentary deposits form the primary basis of our understanding of fire's variability on geologic timescales as well as its role in the emergence of plant physiology, ecosystems, and biogeographic configurations. An intriguing aspect of global Cenozoic fire history is the surge in fire activity that is thought to have occurred in the late Neogene (beginning ca. 7 Ma) and indicates that modern biogeography, ecology, and plant physiology was born out of the ashes of an extremely fiery period in Earth's history. The late Neogene fire surge is primarily inferred from charcoal fluxes to sediment records in the North Pacific. In this paper, we revisit these data and show that they are unlikely to reflect an increase in fire activity alone. Rather, these charcoal fluxes likely also reflect an anomalous late Neogene increase in the amount of terrigenous material (and charcoal) supplied to marine sediment records and/or an inflation of late Neogene charcoal flux measurements (and sedimentation rates) resulting from the incompleteness of older stratigraphic sections. These results highlight the importance of accounting for sediment preservation biases when interpreting long term paleoenvironmental records and suggest charcoal fluxes in the North Pacific do not provide conclusive evidence that fire activity increased in the late Neogene. • Late Neogene (~7 Ma) surge in marine charcoal fluxes is unlikely to reflect fire alone. • Preservation biases likely inflate the charcoal fluxes, exaggerating fire activity. • The Sadler effect is present in the marine charcoal dataset. • Marine charcoal fluxes are inconclusive evidence for a late Neogene fire surge. [ABSTRACT FROM AUTHOR]

The sedimentary charcoal proxy is plagued by the source area problem: estimates of the spatial scales for which charcoal serves as a reliable recorder of fire history span several orders of magnitude, thereby precluding higher-order fire-climate and fire-vegetation analyses requiring spatially explicit reconstructions. This problem is tackled using a meta-analytical approach: (1) published estimates of charcoal source area are compiled to assess all available data and constraints, (2) the limitations and implications of these source area estimates are discussed, and (3) the parameter space of the relationship between charcoal size and dispersal distance is modelled using the published estimates as constraints and with the goal of estimating the functional charcoal source area (FCSA), or the globally applicable source area necessary to facilitate spatially-explicit fire history reconstructions and data-model comparisons. Source area estimates exist in numerous forms and flavors including direct assessments of source area (both relevant (RSAC) and potential charcoal source area (PCSA)) as well as indirect and/or opportunistic observations of dispersal distance. These estimates span several orders of magnitude and do not exhibit size dependent dispersal which may be due to differences in the flavor of source area constrained by each study, limitations of the inferences by the observed fire history at each site in time and space, the physical inability of size class differences examined in paleofire research (e.g. micron scale), to result in observable size-dependence of dispersal, or the effects of other unconstrained influences affecting dispersal and source area. The model results show the FCSA of all size fractions is limited to 50 km. This estimate of the FCSA enables spatially explicit paleofire reconstructions and climate model comparisons. However, the meta-analysis results and broad strokes approach of the model in this paper highlight the need for further research characterizing the parameters affecting charcoal dispersal as well as the limitations of fire history in delineating charcoal source area. • The charcoal source area problem plagues paleofire research. • Source area estimates are inferences limited by the observed fire history at a site. • Functional charcoal source area (FCSA) is likely limited to 50 km. • FCSA facilitates spatially explicit global and regional paleofire records. • FCSA enables comparison of paleofire data with model simulations. [ABSTRACT FROM AUTHOR]