Search

A new record from a long sediment core (S3) in Navamuño (1505 m asl, western Iberian Central System) provides the reconstruction of the vegetation history and environmental changes in the region between 15.6 and 10.6 ka cal BP, namely during the Late Glacial and the early Holocene, using a multiproxy analysis (pollen-based vegetation and climate reconstruction, sedimentary macrocharcoals, loss-on-ignition, magnetic susceptibility and X-ray fluorescence (XRF) measurements). The results are then compared with other sequences from the Iberian Central System and the whole Iberian Peninsula in order to better understand the past dynamics of the main forest constituents. The pollen record shows a shift from open pine forests ∼15.6–14.7 ka cal BP (Oldest Dryas) to mixed open pine-birch woodlands ∼14.7–14.0 ka cal BP (Bølling). Woodlands were succeeded by a steppe-like landscape until ∼13.4 ka cal BP (Older Dryas), which was replaced again by high-mountain pine forests and riparian woodlands ∼13.4–12.6 ka cal BP (Allerød). A great development of cold steppe grasslands linked to the decline of birch woodlands is documented ∼12.6–11.7 ka cal BP (Younger Dryas). The early Holocene (11.7–10.6 ka cal BP) was characterized by a progressive reforestation of the study area by pine and birch forests in the highlands and oak woods in the lowlands. Temperate tree taxa (Carpinus betulus, Castanea sativa, Corylus avellana, Fraxinus, Juglans, Tilia, and Ulmus) were also common but likely at lower elevations. Pollen of Fagus sylvatica was already recorded during the Late Glacial and the early Holocene. The marked increasing local fire activity during the warmer and wetter Allerød oscillation could be related to a rise in tree cover, supporting the climatically driven character of these fires. Nevertheless, the strong increase in fire activity during the Younger Dryas would probably be related to growing tree and shrub mortality, as well as to the wet/dry biphasic structure of this stadial. The standard “Modern Analogue Technique” has been also applied to the Navamuño sequence to provide quantitative climate estimations for the Late Glacial and the early Holocene periods. This record is one of the few continental archives that show the climatic trend between the Late Glacial and the early Holocene in central Iberia, agreeing with many other regional records from the Western Mediterranean.

Pollen analyses supported byfifteen AMS14C dates from Fuente de la Leche (1382 m) and Fuente del PinoBlanco (1343 m) peat sequences, in the Gredos range (central Spain), are used to reconstruct the lateHolocene vegetation history in this mountain region. These results are compared with other sequencesfrom the Spanish Central System in order to better understand the past dynamics of the main forestconstituents and to provide a critical view of the dialectic between conifers and deciduous forests. Thevegetation record at Fuente de la Leche starts at 3000 cal yr BP, with the occurrence of rather closedforests composed ofPinus sylvestrisandBetula.Pinus sylvestriswas the dominant pollen taxa for almostthe entire period. However, during the last 850 years,Pinus sylvestrisforests were progressively replacedbyQuercus pyrenaicawoodlands and grasslands, as a result of a high pastoral pressure, until formingmixed woodlands ~400 years ago. The interpretation of Fuente del Pino Blanco record is that dramaticchanges started about 265 years ago. Prior to this date, an open canopy woodland included species (Alnusglutinosa,Quercus pyrenaica) whose distributions no longer exist in the studied area. We suggest that theincrease in agricultural (rye and other cereals) and livestock activities forced a change in the role offire inthe supramediterranean belt of the Gredos range, thus Pyrenean oak canopy was consumed byfires,providing openings forPinus pinasterand broom communities better adapted tofire.

This paper describes the patterns and processes of vegetation change and fire history in the Late Holocene (c. 3,140 cal BP) palaeoecological sequence of El Tiemblo, in a mountainous area in central Spain (Gredos range, Spanish Central System), and provides the first Iberian pollen sequence undertaken within a Castanea sativadominated woodland. These new data reassess not only the autochthonous nature of the species in the region and in the Iberian Peninsula, but also the naturalness of well-developed sweet chestnut forests. The study focuses on anthropogenic dynamics linked both to the effects of livestock husbandry and the use of fire for forest clearance. With this aim, non-pollen palynomorphs (coprophilous fungi ascospores) and charcoal accumulation rate are useful indicators for assessing the increasing role of human influence on vegetation, We sincerely thank three anonymous reviewers and the editor for their constructive suggestions and comments. This work was funded by the project HAR2013-43701-P (Spanish Economy and Competitiveness Ministry) “Dinámicas socio-ecológicas, resiliencia y vulnerabilidad en un paisaje de montaña: el Sistema Central (9,000 cal BC-1850 cal AD) (DESIRÈ)”. J.A. López-Sáez is currently supported by a research Grant (Spanish Ministry of Education, Culture and Sport) at Caen Basse-Normandie University. We are grateful to A. López Andreu (RIP) and P. Sáez Navas for their collaboration and assistance during the field work.

[EN] Salt exploitation in the Villafáfila lagoon complex (Tierra de Campos, Zamora) is one of the most important events since Prehistory in the northern plateau of the Iberian Peninsula. Salt production is documented from the Bell Beaker (ca. 2450 cal BC). In 2013, a core drilling was performed in the salty swamp of the Laguna de las Salinas. The analysis of pollen and non-pollen palynomorphs of this record suggests the origin of the lagoon eight thousand years ago linked to the 8,2 ky cal BP climatic event, a very anthropized environment from the beginning of the Chalcolithic period ca. 3300 cal BC and the subsequent exploitation of salt, the gradual and definitive degradation of the holm oak forest from the Bronze Age onwards, and, in general, a wide climatic variability, with alternate humid and arid phases throughout the palaeoenvironmental sequence, [ES] La explotación de la sal en el complejo lagunar de Villafáfila (Tierra de Campos, Zamora) es uno de los eventos más importantes de la meseta norte de la península ibérica desde la Prehistoria. La producción de sal se documenta a partir del periodo Campaniforme (ca. 2450 cal BC). En 2013, se efectuó un sondeo mecánico en los pastizales húmedos anexos a la Laguna de las Salinas. El análisis de polen y microfósiles no polínicos de este registro sugiere el origen de la laguna hace al menos ocho mil años vinculado al evento climático 8,2 ka cal BP, un ambiente muy antropizado desde los inicios del Calcolítico ca. 3300 cal BC y la posterior explotación de la sal, la degradación paulatina y definitiva del bosque de encinas a partir de la Edad del Bronce, y, en general, una amplia variabilidad climática alternando fases húmedas y áridas a lo largo de toda la secuencia paleoambiental., Los autores agradecen al organismo gestor de la Reserva Natural Lagunas de Villafáfila, dependiente de la Fundación Patrimonio Natural de la Junta de Castilla y León, las facilidades ofrecidas para el desarrollo de este trabajo. Éste ha sido financiado por una ayuda de investigación concedida al primer autor por la Consejería de Cultura y Turismo de la Junta de Castilla y León en 2013 para el Estudio arqueobotánico y paleoambiental del entorno de las lagunas de Villafáfila; y parcialmente por el Proyecto HAR2013-43701-P del Plan Nacional I+D+I del Ministerio de Economía y Competitividad

Aim of study. The diachronic study of vegetation change through palynological analysis of sedimentary deposits is an essential tool both to design sound strategies on landscape management and to understand its anthropogenic dynamics., Area of study. La Meseguera mire (Ladrillar, Cáceres, Spain) is located in the Hurdes region in the western part of Iberian Central System and started to develop at the beginning of the Islamic period (ca. 770 cal AD), in an area widely dominated by heathland., Material and methods. Pollen, non-pollen palynomorphs and charcoal accumulation rate (CHAR) combined with historical data are useful indicators to assess the increasing role of human influence on vegetation., Main results. The use of fire and livestock husbandry represents the main drivers of landscape change in the course of the history. The establishment of forest afforestation plans, from the middle of 20th century, changed substantially the regional features. The sporadic presence of beech pollen is detected until 16th century, which implies the most western location in the Iberian Central Mountain System., Research highlights. The integration of pollen analysis and historical data is an essential tool when studying the changes in Holocene vegetation. These changes have been mainly driven by anthropogenic disturbances, more specifically by fire and livestock husbandry.

In this paper we present a review of the available Holocene pollen records from the Spanish Central System (113 sites and 150 14C dates). Palynological data obtained from pollen analyses of peat-bogs, lakes and archaeological sites, as well as radiocarbon dating, were used to infer the human impact on vegetation and landscape during the last 9 millennia. The Neolithic contribution to the configuration of landscape is scarce, limited to the valleys, while Chalcolithic settlements and their related activities (agriculture and grazing) represent the first evidence of significant human impact on the high-mountains. The pollen record has allowed us to relate two cultural periods of changing, the Copper Age–Early Bronze Age and Late Bronze Age–Early Iron Age transitions, to abrupt climate disruptions, the so-called 4.2 and 2.8 ka cal BP events respectively. From the Iron Age to the Early Middle Ages, anthropic activities were still sporadic, mainly located in the lowlands, but from the Feudal Period onwards, when La Mesta transhumance system takes place, high-mountain landscapes changed dramatically. Late Modern Period brings a further intensification of human pressure, especially related to forestry, with widespread pinewood afforestation., We are indebted to the CONSOLIDER-INGENIO 2010 Program (CSD2007-00058), EXCELENCIA 2011 Program (RNM-7033) and AGRIWESTMED (ERC-Advanced Grants, proposal n° 230561)

Persistence of relict tree species in Mediterranean environments is becoming increasingly unlikely in view of ongoing and future global change. The variability in the Holocene climate and more recent anthropogenic impacts have driven many populations to fragmentation and isolation, and even to extinction. However, some have persisted to the present day. The understanding of their evolution requires long-term studies, in which pollen analysis is a key approach both for formulating hypotheses and supporting results from other disciplines. Mountain ranges have played and still play an essential role as both glacial and interglacial refugia during the Quaternary. The Spanish Central System harbors an exceptional diversity due to its geographical location and complex topography. Some cold-adapted species have survived here with significant proportions of their southernmost populations, often displaying striking adaptations to their changing environments. This work contains a comprehensive review of the palynological investigations conducted in the Spanish Central System, and reveals the distribution of genera such as Taxus, Betula, Fagus, Carpinus and Tilia throughout the Holocene. We also highlight the scarcity of well-dated and high-resolution works, which may contribute to a better understanding of their recent and future evolution.

[EN] Palaeobotanical studies are a very interesting tool for evaluating past vegetation, climatic variability and human pressure on the landscape. In this paper we offer an overview of Holocene evolution of the yew (Taxus baccata L.) in the Basque Mountains (Northern Iberian Peninsula). For this purpose, we have collected all macro- and micro-remain evidence of the presence of yew within its chronological framework. The results suggest the existence of a period of expansion of yew populations during the Middle Holocene and a regression phase in the Late Holocene., [ES] Los estudios paleobotánicos son una herramienta de gran interés para conocer la evolución de la cubierta vegetal del pasado, además de las condiciones climáticas y la dinámica antrópica. Pero también resulta muy útil a la hora de evaluar la historia de particular de algunas especies. En este trabajo ofrecemos una visión sintética de la evolución holocena del tejo (Taxus baccata L.) en las montañas vascas (Norte de la Península Ibérica). Para ello hemos recogido todos los depósitos con macrorestos o microrrestos botánicos de tejo, así como su adscripción cronológica. Los resultados sugieren la existencia de un período de expansión de los tejos durante el Holoceno medio, así como una fase de regresión durante el Holoceno final.

15 páginas, 4 figuras, 1 tabla., This article describes the patterns and processes of vegetation change and fire history in the Late Holocene (c. 2400 calendar year BP) palaeoecological sequence of Lanzahíta, Sierra de Gredos in central Spain, and provides the first Iberian pollen sequence undertaken within a monospecific Pinus pinaster woodland. These new data reassess not only the autochthonous nature of this pine species in the region and the Iberian Peninsula, but also the naturalness of well-developed cluster pine forests. Conflicts of palaeoecological evidence with phytosociological models of vegetation dynamics in the study region, and the relationships of P. pinaster with fire occurrence in Mediterranean-type ecosystems, are discussed., This study was funded by the projects HAR2008-06477-C03-03/HIST, CGL-2006-2956-BOS (Plan Nacional I + D + i, Ministry of Education and Science, Spain), CSD2007-00058 (Consolider Program, Consejo Superior de Investigaciones Científicas, Spain) and Paleodiversitas Network (Fundación Séneca, Murcia).