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This study was funded by the LATESICE-CGL2016-78380-P, FINICES-PID2020-117685 GB-I00 and MED-REFUGIA-RTI2018-101714-BI00 (Plan Nacional I + D + I, Spanish Ministry of Science, Innovation and Universities) projects. This study was also funded by the OROMEDREFUGIA project (P18-RT-4963) from the Andalusian Office of Economy and Knowledge. Luelmo Lautenschlaeger was funded by the Spanish Ministry of Education, Culture, and Sports (FPU16/00676). We sincerely thank Dr. Guy Jalut for the constructive and helpful comments that improved our original draft. We would also like to sincerely thank Professor Eneko Iriarte, University of Burgos, Spain, for his help and advice in interpreting the geochemical records. We also thank the editor and the anonymous reviewers for their helpful comments and constructive suggestions that have significantly improved this manuscript., The Iberian Central System (ICS) is a clue region to reveal Mediterranean/Atlantic inferences over Iberia. We present a multidisciplinary study from western Spain conducted in the Navamuño depression (ND), covering the last 16.8 ka (cal BP). A reconstruction of the palaeotemperature from the resulting geochemical data highlights four cold and dry intervals, namely, the Oldest Dryas, Older Dryas, Intra-Allerød Cold Period (IACP), and the Younger Dryas, along with warmer intervals: the Bølling (14.7–14 ka) and the Allerød (12.9–12.6 ka); however, the Greenland Interstadial GI-1c (13.4–13.1 ka) is barely distinguishable in the ND. Despite the shortage of biomass to sustain fire, the earliest charcoals are from ~14.4–13.8 ka. Evidence of ash/dust events overprinting the geochemical background starts at ~13.8–12.8 ka. Significant fire activity in the Early Holocene at ~11.7–10.6 ka affected the ND, matching the westernmost ICS data. This period includes short oceanic spells inferred from Cl peaks at ~10.9–10.2 ka and three cold intervals at 11.4, 9.3, and 8.2 ka disrupted the progressive temperature increase. The Mid-Holocene showed a continuously increasing trend towards an arid climate, peaking at 4.2 ka under a pervasive dust influx from North Africa, which has prevailed since almost ~7.9 ka. A prominent volcanic event at ~6.8–5.8 ka is in Navamuño and Roñanzas (Asturias, N Spain; Gallego et al., 2013) identified from heavy metal-rich layer, synchronous with the last known eruption of the Calatrava volcanic field (South-Central Spain; Poblete-Piedrabuena et al., 2019). This volcanic eruption could affect many other regions half north of Iberia. The pervasive presence of oceanic aerosols in the last three millennia (2.8 ka ~ ) allowed the formation of a Cl-rich peat layer during the Ibero-Roman humid period ~2.1 ka, before a changing around ~0.4 ka toward colder and drier conditions at the Little Ice Age (LIA) period., Plan Nacional I + D + I, Spanish Ministry of Science, Innovation and Universities LATESICE-CGL2016-78380-P FINICES-PID2020-117685 GB-I00 MED-REFUGIA-RTI2018-101714-BI00, Andalusian Office of Economy and Knowledge P18-RT-4963, Spanish Ministry of Education, Culture, and Sports FPU16/00676

Pinus pinaster (maritime pine), a conifer native to the western Mediterranean, has a broad distribution, occupying a wide variety of habitats. On certain substrata such as ultramafic (ultrabasic) rock, the indigenous nature of this conifer has traditionally been questioned by the scientific community, which has regarded it as an introduction. In Sierra Bermeja, mountains forming the largest ultramafic outcrop in western Europe, the dominant woodland formations on serpentine soils are P. pinaster and Abies pinsapo. However the variable presence, albeit isolated, of various species of arboreal Quercus and the frequent forestry plantation of P. pinaster in recent centuries have led to broad-leaved woods being generally considered as the dominant natural communities in this mountain range, so marginalizing the role of these conifers. In an attempt to settle this scientific controversy, we have carried out soil charcoal analyses from seven localities in Sierra Bermeja. The palaeoecological data we have gathered show that P. pinaster has a natural status and has been present in this mountain range during a large part of the Holocene before the changes to its natural landscape by human activities. These results are of great importance for the management and conservation of rare serpentine ecosystems.

International audience; This paper focuses on past woodland changes and land uses in an ancient mining area of the Eastern Pyrenees (Ari ege, France). The area discussed is located at the western entrance of the Vicdessos, a valley with significant steel production, and it is crossed by the road used from the 14th c. to the end of the 18th c. for the iron-charcoal exchange with the forest Province of Couserans. The introduction of this singular exchange and the silver ore mining history of this border area raise the question of their impact on forest cover changes and changes in human practices and their link with anthropisation processes. To deal with this issue, we put in place an interdisciplinary approach involving archaeology, charcoal analysis, ecological history and geochemistry. The archaeological investigations and fourteen radiocarbon ages allowed characterising and dating of mining and charcoal-making remains. They situate the emergence of metal ore mining during the Second Iron Age and charcoal making activity between the 15th and 17th c. The geochemical analysis of 9 galena samples showed some different isotopic signatures between ores extracted in ancient times and those mined during the modern period. The charcoal analysis of (i) 2442 charcoals from 31 charcoal kilns (ii) 500 from one pedoarchaeological pit excavated in a waste heap related to firesetting, and (iii) 250 from two pedoanthracological sampling points carried out in the charcoal burning forest, permits a detailed reconstruction of the woodland cover changes from the Second Iron Age to the 19th c. Furthermore, the combination of data from different disciplines allows for a long-term reconstruction of human practices history and woodland management for different uses. In particular, the results show the transformation of the fir-beech forest, still dominated by fir around the turn of the Roman era, into pure beech wood managed on northern slopes for human daily needs, occasionally mining, lumber and mainly charcoal production until the 19th c. The elimination of fir dates back to the 17th c. This assumes the end of lumber activities in that period. Pedoanthracological and palynological data suggest that southern slopes, progressively deforested since the Bronze Age, were entirely devoted to permanent agropastoral activities probably at least since the end of the medieval period.

International audience; Human activities have profoundly transformed mountain woodland landscapes, particularly in the Pyrenees where they have intensified and diversified since the Bronze Age. Quantification of the role played by past practices with regard to woodland cover is critical for accurate assessment of how ongoing global environmental change may affect its dynamics in the future. A local study was made of charcoal remains from an ancient charcoal-making woodland (ca. 30 ha), the forêt de Bernadouze, located on a north-facing slope in the Vicdessos valley in the French central Pyrenees. This valley is well known as having had a long history of human influence related to pastoralism, iron ore mining and smelting. A total of 1,695 charcoal pieces from soils in three sampling pits was extracted, identified, quantified and dated in order to identify tree canopy openings and patterns of change in the woodland driven by past human uses. The results provide new and original insights regarding 1, the past higher biodiversity and the ancient character of the forêt de Bernadouze, 2, the dynamics and history of the main trees and 3, successive phases of human activity. We show that the current woodland has resulted from several millennia of human activities such as pasturing and use of the wood for making charcoal. From the Bronze Age, humans have progressively transformed a natural fir-dominated wood into a managed beech-dominated one, and caused the elimination of Taxus baccata L. (yew).

International audience; This poster presents the results of the dendro-anthracological analysis of charcoals collected in 16 charcoal kilns (CKs) located between 1300 and 1500 m ASL in the Bernadouze forest (Suc-et-Sentenac valley, French Pyrenees) (Fig. 1 and 3) and dated from the 11th to the 20th century. This study aims to restitute the minimum initial diameter of wood collected by charcoal burners in order to provide new insights into wood harvesting strategies, charcoal manufacturing and sylvicultural practices for charcoal products on intended to iron industry. This activity had been on a strong upward trend between the 14th to the 19th centuries.

Se analizan las formaciones vegetales con presencia de Taxus baccata situadas en la Sierra del Aramo, la composición florística de dichas comunidades, su distribución y estado. La investigación se ha fundamentado en el trabajo de campo y las herborizaciones fitosociológicas que han desvelado la relevancia de este taxón en el paisaje vegetal y la singularidad de algunos ejemplares y poblaciones. El estado de los tejos que forman parte del matorral petrano y la falta de brinzales en varias comunidades hace necesario plantear medidas para revertir su dinámica negativa. Asimismo, se ensaya el análisis pedoantracológico en dos ubicaciones por encima del límite superior del bosque, en zonas actualmente deforestadas. Los resultados demuestran la presencia de tejos en el Aramo desde la Edad del Bronce y ponen de manifiesto un cambio en el paisaje en consonancia cronológica con los hallazgos arqueológicos sobre la ocupación humana de las montañas del Macizo Asturiano The plant formations with presence of Taxus baccata located in the Sierra del Aramo are analyzed, in particular, the floristic composition of these communities, as well as their distribution and status. The research has been carried out through field work and phytosociological inventories. The relevance of this taxon in the vegetal landscape is revealed, as well as the singularity of some specimens and populations, while at the same time considering the necessary measures to reverse the negative dynamics of some communities in which it participates. On the other hand, the pedoanthracological analysis is tested from two pits made above the upper limit of the forest, in areas that are currently deforested. The results demonstrate the presence of yews in the Aramo since the Bronze Age and corroborate the archaeological findings about the human occupation of the mountains of the Asturian Massif.

International audience; Fir (Abies alba Mill.) occupies an important place in the Pyrenean context, where the species finds its optimal conditions in this mountain zone (800e1800 m a.s.l.). In the Pyrenees, the fir woods of Volvestre (Ari ege, France) are of particular interest because of two peculiarities of its location: its northern latitude with respect to the usual location of fir in the Pyrenean axis, and its lower altitude (330e440 m a.s.l.). This has given rise to various theories, some considering the silver fir forests as a glacial relic and others pointing to anthropogenic interference and possible plantings during the Middle Ages. Pedoanthraco-logical and palynological studies have been performed to establish the origin and history of this ancient forest, and both approaches show an ancient anthropized landscape with a continuous presence of Abies alba throughout the mid-and late-Holocene. The fir woodlands of Volvestre are testimonies to the ancient and significant presence of fir on the northeast slope of the Pyrenees and the current suitability of this species for lowland areas. Pedoanthracological sampling inside the forest has shown differences in vegetation dynamics at different valley points (north slope, south slope, and valley bottom).

Fire has been one of the main causes of disturbance of vegetation over time, and since the Neolithic has become an irreplaceable tool for the opening of forest spaces and maintenance of pastures. Previous studies showed that the intensity and effects of wildfires are related to the biomass and controlled by climate factors. However, in regions such as Cantabria, where agriculture and livestock have spread throughout the territory since prehistory, fires should also be closely related to human land uses. The aim of this paper was to investigate the history of fires and vegetation since the Neolithic in the Cantabrian Mountains, using sedimentary charcoal and pollen data to study the role of human activities in the processes that have shaped ecosystems throughout the Holocene. The asynchrony and quantitative differences in the results obtained at different sites indicate significant variations in fire patterns at regional scale since the Neolithic, although the type and size of each basin also had a strong influence on charcoal accumulation. Maximum values for charcoal accumulation rate at La Molina were observed between the Neolithic and the Bronze Age but occurred after about 3500 cal years BP at El Cueto de la Avellanosa. At El Sertal, low charcoal accumulation rate values were observed, probably because the sequence begins in a space that already had been cleared; the maximum values occurred during the most recent millennium. These data provide evidence that fire has been a key factor in forest retreat and in maintaining open landscapes since the Neolithic. This article was made possible by two Coordinated Project grants from Spain's Ministry of Economics and Competitiveness (MEC), “El uso del fuego y la conformación de los paisajes en la Montaña cantábrica y el Pirineo oriental: estudio comparado de su evolución histórica y tendencias actuales” (CSO2012-39680-C02-01) awarded to the Department of Geography, Urban studies and Land Planning, Universidad de Cantabria and “Geohistoria ambiental del fuego en el Holoceno. Patrones culturales y gestión territorial desde el inicio de la ganadería y la agricultura en la montaña Cantábrica y Pirineo “awarded to the Department of Geography, Universitat Autónoma de Barcelona (CSO2012-39680-C02-02). In addition, the project was funded by the Catalan government's Applied Geography program, “Grup de Geografia Aplicada” (AGAUR, Generalitat de Catalunya, 2014 SGR 1090).

Is presented the recent discovery and characterization of a endorheic basin at the summit of the Sierra Palmitera, an abrupt foothill of the peridotite massif of Sierra Bermeja (SW of Spain) that reaches 1,473 meters above sea level. Given the nature of this littoral ultramafic mountain, this basin is considered a geomorphological exceptionality for the whole of the known peridotite outcrops. Fieldwork and interpretation of photographs, main methodological procedures of the research, and the use of GIS have allowed a first geographical reconnaissance and the mapping of the main physical features to detail scale (1: 5.000). The obtained results are: (1) a topographic map (equidistance of 5 meters) as basis of the thematic mapping; (2) the identification, characterization and mapping of the major geomorphological and edaphic units to the mentioned scale; (3) the characterization of the vegetation and flora of the basin through the phytosociological analysis, and the development of a vegetation map to scale detail. These results provide knowledge about the origin of the basin, its operation and its ecological role. As outstanding feature, the accumulation of sediment at the bottom of the basin allows the paleo-ecological study of vegetation from the charcoals deposited on the soil, highlighting the finding of charcoal of Abies pinsapo, species of spruce threatened currently absent in the location., Se presenta el reciente hallazgo y caracterización preliminar de una cuenca endorreica en la cumbre de la Sierra Palmitera, una abrupta estribación del macizo peridotítico de Sierra Bermeja (SW de España) que alcanza 1.473 m.s.n.m. Dada la naturaleza ultramáfica de esta montaña litoral, dicha cuenca se considera una excepcionalidad geomorfológica para el conjunto de los afloramientos peridotíticos conocidos. El trabajo de campo y la interpretación de fotografías, principales procedimientos metodológicos de la investigación, así como el uso de un SIG, han permitido un reconocimiento geográfico inicial y el cartografiado de los principales rasgos físicos a escala de detalle (1: 5.000). Los resultados obtenidos son: (1) un mapa topográfico (equidistancia de curvas de nivel 5 m) como base de la cartografía temática; (2) la identificación, caracterización y cartografiado a la escala señalada de las principales unidades geomorfo-edáficas; (3) la caracterización de la vegetación y la flora de la cuenca mediante el análisis fitosociológico, y el levantamiento de un mapa de vegetación a escala de detalle. Estos resultados arrojan luz a una serie de interrogantes en cuanto al origen de la cuenca, su funcionamiento y papel ecológico. Como rasgo sobresaliente, la acumulación de sedimentos en el fondo de la cuenca ha posibilitado el estudio paleo-ecológico de la vegetación a partir de los carbones depositados en el suelo, destacando el hallazgo de carbón de Abies pinsapo, especie de abeto amenazada ausente actualmente en la localidad.

Using an interdisciplinary methodology based on pedoanthracology, palynology and sedimentary charcoals, landscape transformation in the Pyrenees mountains during the Holocene is analyzed, with special attention to altitudinal variation in the treeline. The data sources were eight soil profiles on a transect at 2000–2600 m a.s.l. and a sedimentary record extracted from a very nearby peat bog at 2247 m a.s.l. The combination of three different proxies permits a more viable and qualitatively complementary data set, making it possible to better interpret the vegetation dynamic in this space through the Holocene. Analysis of the data showed that the Pyrenees landscape has undergone important changes during this period. The changing treeline is a good example. There is evidence of the decisive role of fire in the configuration of this landscape. Finally, this study shows that herding and agricultural uses over thousands of years in the study area have had a determining influence on the current configuration of the territory, equal to or more important than climatic factors.

This chapter was made possible by two coordinated project grants from Spain’s Ministry of Economics and Competitiveness (MEC), “El uso del fuego y la conformación de los paisajes en la Montaña cantábrica y el Pirineo oriental: estudio comparado de su evolución historica y tendencias actuales” (CSO2012-39680-C02-01), awarded to the Department of Geography, Urban Studies and Land Planning, Universidad de Cantabria and “Geohistoria ambiental del fuego en el Holoceno. Patrones culturales y gestión territorial desde el inicio de la ganadería y la agricultura en la montañana Cantábrica y Pirineo,” awarded to the Department of Geography, Universitat Autònoma de Barcelona (CSO2012-39680-C02-02). In addition, the project was funded by the Catalan government’s applied geography program, ‘Grup de Geografia Aplicada’ (AGAUR, Generalitat de Catalunya, 2014 SGR 1090). Raquel Cunill gratefully acknowledges the Government of the Principality of Andorra, for the research grant on Andorran Issues, APTA007-AND/2014.

Estanilles peat bog, located in the northeastern Iberian peninsula, was studied to determine the anthropogenic changes in the landscape over the past seven millennia. The pollen diagram and sedimentary charcoal analyses from this site permit us to reconstruct the landscape changes in an area of both Mediterranean and Atlantic influence. In addition, Montarenyo ombrotrophic peat bog was studied to strengthen the analysis of data from more recent centuries. This paper attempts a reconstruction of historical cultural landscapes using two complementary palaeobotanical proxies (pollen and charcoal) in high mountain environments. The macroscopic charcoal record shows a fire signal since 7500 cal. b.p. However, the relationship between fire frequency and human impact is not always linear. This divergence is linked to fuel availability and fire activity. Fire has been used repeatedly to clear ground and to maintain open areas, and has been a key tool for the management of these high mountain areas. The intensity of use of the landscape implies the expansion of agricultural areas into higher altitudes, including cereal cultivation above 2,200 m a.s.l., during the Middle Ages. The first clear human influence detected in the pollen percentage data is recorded between 6000 and 7000 cal. b.p. and, until present times, the greatest changes in vegetation and landscape history occurred during periods of particular specialization in socioeconomic activities during the Middle Ages.

The principal objective of this research is to determine the maximum elevation reached by the treeline, as well as its altitudinal variations and composition throughout the Holocene, in a high mountain zone of the Pyrenean range. The temporal intervals of pedoanthracological data begin in 11000 cal. b.p. with the oldest dated charcoal, permitting a study of the entire Holocene period with the capacity to analyze climatic and anthropic situations. This is the first study to apply analysis of soil charcoals to the meridional slope of the Pyrenees for this purpose, and also its first use in research on the Iberian Peninsula. Eight pedoanthracological sites were sampled in a transect from 2,000 to 2,600 m altitude, with an altitudinal resolution of 100 m. The spatial precision provided by this proxy allows us to show that the maximum extension of the upper forest line was 400 m above the current line. This suggests a complete change in the landscape of a zone that is now covered with pasture from 2,000 m to the peak (2,593 m). Although pre-Neolithic fires appear to have a primarily climatic component, the fire origins during and after this period are more complex and far from being explained by a single, unequivocal cause.

This research is based on the discovery of a large number of charcoal kiln sites and abandoned iron mines in Vallferrera (Axial Pyrenees, northeastern Spain). The study reveals that this region has been affected by the metal mining and smelting industry for at least 2,000 years, with maximum intensity in the eighteenth and nineteenth centuries, followed by abandonment of the activity. The region’s woodland dendrochronology and historical records indicate that exploitation of wood charcoal for metalworking affected the past vegetation in the area and impeded the development of mature woodland. Our findings suggest that the greatest changes in vegetation and landscape history occurred at times of particular specialization in socioeconomic activities.

International audience; Estanilles peat bog, located in the northeasternIberian peninsula,was studied to determine the anthropogenicchanges in the landscape over the past seven millennia. Thepollen diagram and sedimentary charcoal analyses from thissite permit us to reconstruct the landscape changes in an areaof both Mediterranean and Atlantic influence. In addition,Montarenyo ombrotrophic peat bog was studied to strengthenthe analysis of data from more recent centuries. This paperattempts a reconstruction of historical cultural landscapesusing two complementary palaeobotanical proxies (pollen andcharcoal) in high mountain environments. The macroscopiccharcoal record shows a fire signal since 7500 cal. B.P. However,the relationship between fire frequency and humanimpact is not always linear. This divergence is linked to fuelavailability and fire activity. Fire has been used repeatedly toclear ground and to maintain open areas, and has been a keytool for the management of these high mountain areas. Theintensity of use of the landscape implies the expansion ofagricultural areas into higher altitudes, including cereal cultivationabove 2,200 m a.s.l., during the Middle Ages. Thefirst clear human influence detected in the pollen percentagedata is recorded between 6000 and 7000 cal. B.P. and, untilpresent times, the greatest changes in vegetation and landscapehistory occurred during periods of particular specializationin socioeconomic activities during the Middle Ages.

International audience; Using an interdisciplinary methodology based on pedoanthracology, palynology and sedimentary charcoals,landscape transformation in the Pyrenees mountains during the Holocene is analyzed, with specialattention to altitudinal variation in the treeline. The data sources were eight soil profiles on a transect at2000e2600 m a.s.l. and a sedimentary record extracted from a very nearby peat bog at 2247 m a.s.l.The combination of three different proxies permits a more viable and qualitatively complementarydata set, making it possible to better interpret the vegetation dynamic in this space through theHolocene.Analysis of the data showed that the Pyrenees landscape has undergone important changes during thisperiod. The changing treeline is a good example. There is evidence of the decisive role of fire in theconfiguration of this landscape.Finally, this study shows that herding and agricultural uses over thousands of years in the study areahave had a determining influence on the current configuration of the territory, equal to or moreimportant than climatic factors.

International audience; The study of macroscopic charcoal particles from peat bogs has led to a better understanding of climate,vegetation and fire history, and human impacts. To determine the relationship between human activities andthe role of fire events in vegetation change during the last 3300 cal yr BP, we present the results of a multiproxyapproach based on the analysis of sediment characteristics, sedimentary charcoal, organic matter andpollen, as well as historical sources. This multi-proxy research permits high resolution palaeoenvironmentaland fire history reconstruction of a mountain area located in the southern central Pyrenees (Spain). In thePyrenees, fire is typically attributed to human activities since the beginning of the Bronze Age and may becorrelated with slash-and-burn cultivation, metallurgy and pasturing activities.The data indicate a good linkage between high fire signals and Poaceae and Cerealia pollen, which reveals theimpact of agro-pastoral practices. This study also shows two periods, 2900–2650 cal yr BP and 1850–1550 calyr BP, for which higher frequencies of fire occurred, suggested by high arboreal pollen (AP) concentrations,and confirming the need for arboreal biomass to sustain fires. From the beginning of the Middle Ages, it seemsthat a change occurred in the anthropogenic use of fire, from a tool for agro-pastoral forest clearance to ameans of maintaining open spaces.

10 páginas., Superimposed on the long-term climate variability attributed to orbital forcing, there are other modes of variability covering timescales from interannual to millennial throughout the Holocene. Their signatures in climate proxy archives can differ substantially because of their lower magnitude and regional diversity. However, if identified they can yield better understanding of the physical mechanisms regionally linking causes and effects. Here we describe a high-resolution record of organic matter accumulation in the sediments of Burg lake (Pyrenees, NE Iberian Peninsula), as assessed using loss on ignition (LOI), and compare it with the ice rafted debris (IRD) indexes from the North Atlantic. The LOI record indicates two main phases in the water body, a lacustrine phase as a shallow lake and a palustrine phase as a fen. The latter covers the period 2600—7200 cal. yr BP and within it there is a high coherence between LOI and IRD, which indicates submillennial climate fluctuations in the Pyrenees that can be related to the North Atlantic influence. The Burg’s LOI record suggests wetter (and occasionally colder) situations in the Pyrenees during high IRD in the Atlantic (Bond oscillations). These fluctuations would likely affect the snow covered period in the mountains (winter and spring seasons) the most, the period in which Atlantic westerlies currently have higher influence on precipitation over the Pyrenees. These climatic oscillations could have favoured Abies penetration during the mid Holocene, as evidenced by increased pollen percentages of this taxon during low IRD values (drier conditions). The pollen record also suggests potential relationships between climate and human activity as early as at mid Holocene, as human-related cereals increase during all the low IRD periods. The human signature (charcoal, cereals) becomes particularly evident at around 2800 cal. yr BP; in this oscillation Pinus overtake Abies in the conifer response to low IRD.

The study of macroscopic charcoal particles from peat bogs has led to a better understanding of climate, vegetation and fire history, and human impacts. To determine the relationship between human activities and the role of fire events in vegetation change during the last 3300. cal yr BP, we present the results of a multi-proxy approach based on the analysis of sediment characteristics, sedimentary charcoal, organic matter and pollen, as well as historical sources. This multi-proxy research permits high resolution palaeoenvironmental and fire history reconstruction of a mountain area located in the southern central Pyrenees (Spain). In the Pyrenees, fire is typically attributed to human activities since the beginning of the Bronze Age and may be correlated with slash-and-burn cultivation, metallurgy and pasturing activities. The data indicate a good linkage between high fire signals and Poaceae and Cerealia pollen, which reveals the impact of agro-pastoral practices. This study also shows two periods, 2900-2650. cal yr BP and 1850-1550. cal yr BP, for which higher frequencies of fire occurred, suggested by high arboreal pollen (AP) concentrations, and confirming the need for arboreal biomass to sustain fires. From the beginning of the Middle Ages, it seems that a change occurred in the anthropogenic use of fire, from a tool for agro-pastoral forest clearance to a means of maintaining open spaces. © 2011 Elsevier B.V., This work was supported by 1) a research grant from the Comunitat de Treball dels Pirineus (2007ITT 00001): Environmental dynamic of the Pyrenees over the past 20,000 years: A study of the impact of changes in climate and land use on forest ecosystems for the development of possible scenarios (Dinàmica ambiental pirinenca dels darrers 20.000 anys: estudi de l'impacte dels canvis climàtics i dels usos del sòl sobre els ecosistemes forestals per a l'elaboració d'escenaris prospectius) and 2) a project of the Catalan government (Generalitat de Catalunya — 2006EXCAVA00022): Archaeology of the high Pyrenees mountains.

International audience; Superimposed on the long-term climate variability attributed to orbital forcing, there are other modes of variability covering timescales from interannualto millennial throughout the Holocene. Their signatures in climate proxy archives can differ substantially because of their lower magnitude and regionaldiversity. However, if identified they can yield better understanding of the physical mechanisms regionally linking causes and effects. Here we describe ahigh-resolution record of organic matter accumulation in the sediments of Burg lake (Pyrenees, NE Iberian Peninsula), as assessed using loss on ignition(LOI), and compare it with the ice rafted debris (IRD) indexes from the North Atlantic. The LOI record indicates two main phases in the water body, alacustrine phase as a shallow lake and a palustrine phase as a fen. The latter covers the period 2600–7200 cal. yr BP and within it there is a high coherencebetween LOI and IRD, which indicates submillennial climate fluctuations in the Pyrenees that can be related to the North Atlantic influence. The Burg’s LOIrecord suggests wetter (and occasionally colder) situations in the Pyrenees during high IRD in the Atlantic (Bond oscillations). These fluctuations wouldlikely affect the snow covered period in the mountains (winter and spring seasons) the most, the period in which Atlantic westerlies currently have higherinfluence on precipitation over the Pyrenees. These climatic oscillations could have favoured Abies penetration during the mid Holocene, as evidencedby increased pollen percentages of this taxon during low IRD values (drier conditions). The pollen record also suggests potential relationships betweenclimate and human activity as early as at mid Holocene, as human-related cereals increase during all the low IRD periods. The human signature (charcoal,cereals) becomes particularly evident at around 2800 cal. yr BP; in this oscillation Pinus overtake Abies in the conifer response to low IRD.

En este trabajo se presentan los primeros resultados paleoecologicos del estudio de los carbones del suelo en el macizo ultramafico de Sierra Bermeja (Cordillera Betica, sur de la Peninsula Iberica). Mediante el analisis pedoantracologico se ha obtenido un registro fosil de carbon de Abies sp. -con gran certeza perteneciente a Abies pinsapo- en una pequena cuenca endorreica en la cumbre de Sierra Palmitera, un apendice montanoso litoral de Sierra Bermeja en el que los abetales se encuentran actualmente extintos. Los resultados del analisis confirman la existencia, en el pasado, de un area de distribucion de Abies sp. mas extensa que la actual en el marco geografico de la Serrania de Ronda (extremo occidental de la Cordillera Betica). Las dataciones de Abies sp. y de otras especies halladas en la localidad de estudio, como Pinus pinaster y Quercus sp., permiten teorizar sobre la dinamica paleobotanica local entre 8.100 y 5.600 AP, resolviendo en gran parte la enquistada controversia dinamica y sucesional-ecologica entre latifolias-coniferas como vegetacion potencial sobre sustratos ultramaficos bajo clima mediterraneo que existia hasta ahora. Esta informacion debe ser considerada como esencial para la adecuada gestion de Abies pinsapo de cara a conseguir su preservacion en el futuro dada su catalogacion de especie relicta en peligro de extincion. Los datos obtenidos avalan, asimismo, la posible regeneracion de los abetales en aquellos enclaves considerados nichos ecologicos potenciales para estos bosques en Sierra Bermeja y, en general, en el conjunto de la Cordillera Betica.

International audience