Suchergebnisse

Peer reviewed ; The paucity of modern pollen-rain data from the Iberian Peninsula is a significant barrier to understanding the Late Quaternary vegetation history of this globally important southwestern mediterranean region. The relationships between current vegetation, the available environmental data and modern pollen are examined in Central Spain for both natural and human-induced vegetation types, as an aid for palaeoenvironmental reconstructions. A set of 60 surface moss polsters was sampled from different vegetation and land-use types in the Madrid autonomous region, and analysed to obtain modern pollen analogues of ancient cultural landscapes. Hierarchical cluster analysis (HCA) was used to divide the main pollen taxa into two major groups and ten subgroups representing the anthropic and natural vegetation types and the main communities within them. Statistically distinctive taxa were identified using principal components analysis (PCA). The results indicate that human-influenced communities have pollen assemblages that are different from those of natural vegetation types. When modern pollen assemblages are compared, the three Holm oak (Quercus rotundifolia) communities of Madrid, representing two phytogeographical provinces and three subprovinces, are easily distinguishable by their pollen spectra. This research was funded by the Technology Research 'Consolider' Program (TCP-CSD2007 – 00058), by the R&D National Plan of the Spanish Government (HAR2008 – 06477-C03 – 03/HIST project), and by the CSICCAM Consolidation project (CCG07-CSIC/HUM-1924). ; 16 páginas, 5 figuras, 1 tabla.

16 páginas, 5 figuras, 1 tabla. ; The paucity of modern pollen-rain data from the Iberian Peninsula is a significant barrier to understanding the Late Quaternary vegetation history of this globally important southwestern mediterranean region. The relationships between current vegetation, the available environmental data and modern pollen are examined in Central Spain for both natural and human-induced vegetation types, as an aid for palaeoenvironmental reconstructions. A set of 60 surface moss polsters was sampled from different vegetation and land-use types in the Madrid autonomous region, and analysed to obtain modern pollen analogues of ancient cultural landscapes. Hierarchical cluster analysis (HCA) was used to divide the main pollen taxa into two major groups and ten subgroups representing the anthropic and natural vegetation types and the main communities within them. Statistically distinctive taxa were identified using principal components analysis (PCA). The results indicate that human-influenced communities have pollen assemblages that are different from those of natural vegetation types. When modern pollen assemblages are compared, the three Holm oak (Quercus rotundifolia) communities of Madrid, representing two phytogeographical provinces and three subprovinces, are easily distinguishable by their pollen spectra. ; This research was funded by the Technology Research 'Consolider' Program (TCP-CSD2007 – 00058), by the R&D National Plan of the Spanish Government (HAR2008 – 06477-C03 – 03/HIST project), and by the CSICCAM Consolidation project (CCG07-CSIC/HUM-1924). ; Peer reviewed

This work presents the palinological analysis undertaken at Castro Ventosa's Roman deposit (El Bierzo, León). Reading the pollen diagram makes it possible to perceive the different stages of occupation of the site in Roman times and possibly also medieval. The change in the paleo-economic bases related to the cultivation of cereals and chestnut trees between the two periods and the impact of pastoral pressure are discussed. This work has been carried out within the framework of the Joint Research Programme in Technologies for the valuation and conservation of cultural heritage — TCP-CSD2007-00058, and has also been funded by the CSIC Intramural Border Project 'Cultural and natural landscapes of the Bierzo: Geoarqueology, Paleoambio and Paleobiology (BierzoRVN)' (PIF 06-055) and under the cooperation agreement between the Government of Castile-Leon and the CSIC on ancient mining areas of Castile-Leon (CyLIA-24.044.0006.07). ; Peer reviewed ; This work presents the palinological analysis undertaken at Castro Ventosa's Roman deposit (El Bierzo, León). Reading the pollen diagram makes it possible to perceive the different stages of occupation of the site in Roman times and possibly also medieval. The change in the paleo-economic bases related to the cultivation of cereals and chestnut trees between the two periods and the impact of pastoral pressure are discussed. This work has been carried out within the framework of the Joint Research Programme in Technologies for the valuation and conservation of cultural heritage — TCP-CSD2007-00058, and has also been funded by the CSIC Intramural Border Project 'Cultural and natural landscapes of the Bierzo: Geoarqueology, Paleoambio and Paleobiology (BierzoRVN)' (PIF 06-055) and under the cooperation agreement between the Government of Castile-Leon and the CSIC on ancient mining areas of Castile-Leon (CyLIA-24.044.0006.07). ; Este trabajo presenta el análisis palinológico emprendido en el yacimiento romano de Castro Ventosa (El Bierzo, León). La lectura del diagrama polínico ...

The Mediterranean seagrass Posidonia oceanica maintains a biodiverse ecosystem and it is a world-wide important carbon sink. It grows for millennia, accumulating organic-rich soils (mats) beneath the meadows. This marine habitat is protected by the European Union; however, it is declining rapidly due to coastal development. Understanding its response to disturbances could inform habitat restoration, but many environmental impacts predate monitoring programs (<50 years). This research explores the palaeoecological potential of Posidonia mats to reconstruct six thousand years of environmental change that could have affected Posidonia meadows and, in turn, left an imprint on the mats. Palynological, microcharcoal, magnetic susceptibility and glomalin-related soil protein (GRSP) analyses on Posidonia mats enabled us to detect climate- and human-induced environmental processes impacting on the seagrass during the Late Holocene. The pollen and microcharcoal records reconstructed anthropogenic disturbances attributed to agriculture. The record of GRSP shows that agrarian activities affected continental soil quality. Changes in magnetic susceptibility reveal that enhanced soil erosion was caused by both climate (major flooding events in the NW Mediterranean) and humans (cultivation) which impacted on the Posidonia mat. Finally, increased human impact is linked to eutrophication of coastal waters since Roman-Medieval times. Synthesis. This study shows that climate and land-use changes in the western Mediterranean resulted in enhanced loadings of terrigenous material to the coastal zone since the Late Holocene, likely disturbing the Posidonia meadows and their mat carbon accumulation dynamics. Under the current global change scenario in which CO2 emissions are projected to increase, restoring carbon sinks is a priority. Seagrass habitat restoration should consider not only the coastal perturbations, but also the continental ones at a catchment scale to preserve the socio-economic ecosystem services provided by ...

Understanding long-term fire ecology is essential for current day interpretation of ecosystem fire responses. However palaeoecology of fire is still poorly understood, especially at high-altitude mountain environments, despite the fact that these are fire-sensitive ecosystems and their resilience might be affected by changing fire regimes. We reconstruct wildfire occurrence since the Lateglacial (14.7. cal. ka BP) to the Mid-Holocene (6. cal. ka BP) and investigate the climate-fuel-fire relationships in a sedimentary sequence located at the treeline in the Central Spanish Pyrenees. Pollen, macro- and micro-charcoal were analysed for the identification of fire events (FE) in order to detect vegetation post-fire response and to define biomass-fire interactions. mean fire intervals (mfi) reduced since the Lateglacial, peaking at 9-7.7. cal. ka BP while from 7.7 to 6. cal. ka BP no fire is recorded. We hypothesise that Early Holocene maximum summer insolation, as climate forcing, and mesophyte forest expansion, as a fuel-creating factor, were responsible for accelerating fire occurrence in the Central Pyrenees treeline. We also found that fire had long-lasting negative effects on most of the treeline plant communities and that forest contraction from 7.7. cal. ka BP is likely linked to the ecosystem's threshold response to high fire frequencies. © 2014 Elsevier B.V. ; This research has been funded by the projects DINAMO (CGL2009-07992) (funding EGPF — grant ref. BES-2010-038593 and MSC), DINAMO2 (CGL2012-33063), ARAFIRE (2012 GA LC 064), GRACCIE-CONSOLIDER (CSD2007-00067). GGR was funded by the Juan de la Cierva Program (grant ref. JCI2009-04345) and JAE-Doc CSIC Program, LLM was supported by a postdoctoral MINT fellowship funded by the Institute for the Environment (Brunel University), AMC is a Ramón y Cajal fellow (ref: RYC-2008-02431), APS holds a grant funded by the Aragon Government (ref. 17030G/5423/480072/14003) and JAE holds a grant funded by the Basque Country Government (BFI-2010-5). We are indebted to Beatriz Bueno and Aida Adsuar for sampling processing and laboratory analyses and to César Morales del Molino for productive discussions on the ideas of this paper. We are grateful to Steven M. Holland for providing the free software to calculate rarefaction (Analytic Rarefaction), which is available at http://strata.uga.edu/software/. ; Peer Reviewed