Variations in modern pollen distribution in sediments from nearby upland lakes: implications for the interpretation of paleoecological data

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGTo determine whether modern pollen content in sediments from upland lake systems reflects the factual regional and extra-local vegetation composition, we analysed twenty-five samples focusing on aspects such as pond size and morphology, relative position in the catchment, local vegetation, canopy configuration and seasonality of the water table. The average pollen percentages of all sediment samples studied allows a fairly good reconstruction of the main vegetation units in the area, but major differences between the average samples obtained in each sedimentary system, and also between some samples taken from the same system are found. The main factors explaining those differences are the size of the pond, its tree canopy and the seasonality of the water table, which strongly determines the Ericaceae and Pinus percentages. A high-resolution multiproxy palaeoecological record from a small upland lake is re-evaluated in light of the new experimental evidence, and it is concluded that the interpretation of the importance of heathland and pinewoods in the Late Glacial landscape using pollen data may be magnified by the transport of both pollen types through water flows and their accumulation in the basin. Furthermore, anomalous Pinus pollen peaks occur in dry periods when the water table remains low. The sediment can also be depleted of some high-buoyancy pollen types (tetrads and saccate) when the water level is high and effluents are active. These effects may also be important in fluvio-marine systems in which Ericaceae and Pinus pollen are often overrepresented.Ministerio de Educación y Ciencia | Ref. CGL2012-33584Xunta de Galicia | Ref. ED431C 2019/28Xunta de Galicia | Ref. GRC 2015/02

Post-disturbance vegetation dynamics during the Late Pleistocene and the Holocene: An example from NW Iberia

This is the post-print version of the final paper published in Global and Planetary Change. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.There is a wealth of studies dealing with the reconstruction of past environmental changes and their effects on vegetation composition in NW Iberia, but none of them have focused specifically on the post-disturbance dynamics (i.e. the type of response) of the vegetation at different space and time scales. To fill this gap, we analysed the record of pollen and non-pollen palynomorphs (NPP) of a 235-cm thick colluvial sequence spanning the last ~ 13,900 years. The aims were to detect the changes in vegetation, identify the responsible drivers and determine the type of responses to disturbance. To extract this information we applied multivariate statistical techniques (constrained cluster analysis and principal components analysis on transposed matrices, PCAtr) to the local (hydro-hygrophytes and NPP) and regional (land pollen) datasets separately. In both cases the cluster analysis resulted in eight local and regional assemblage zones, while five (local types) and four (regional types) principal components were obtained by PCAtr to explain 94.1% and 96.6% of the total variance, respectively. The main drivers identified were climate change, grazing pressure, fire events and cultivation. The vegetation showed gradual, threshold and elastic responses to these drivers, at different space (local vs. regional) and time scales, revealing a complex ecological history. Regional responses to perturbations were sometimes delayed with respect to the local response. The results also showed an ecosystem resilience, such as the persistence of open Betula-dominated vegetation community for ~ 1700 years after the onset of the Holocene, and elastic responses, such as the oak woodland to the 8200 cal yr BP dry/cold event. Our results support the notion that palaeoecological research is a valuable tool to investigate ecosystem history, their responses to perturbations and their ability to buffer them. This knowledge is critical for modelling the impact of future environmental change and to help to manage the landscape more sustainably.The Spanish Governmen

Modificaciones de la vegetación y del paisaje litoral del NW Ibérico en relación con los cambios climáticos ocurridos en la transición entre los estadios isotópicos 3 y 2. El depósito pleistoceno de Caamaño

XV lnternational A.P.L.E. Symposium of Palynolog

The late Holocene extinction of Pinus sylvestris in the West of the Cantabrian Range

Aim To reconstruct the historical biogeography of Pinus sylvestris in the Cantabrian Range (Iberian Peninsula) during the Holocene, and to consider the interactions between vegetation dynamics, climate change and the role of man in the present-day distribution of the species. Location The study site is a mire (1300 m a.s.l.) at Vega de Viejos, on a south-facing slope of the western Cantabrian Range, Spain. The region’s present-day landscape is almost treeless, with the exception of some patches of Quercus pyrenaica and a few copses of Salix and Betula along stream banks. Methods Tree macrofossils from Vega de Viejos were studied by transmitted light and dark-field reflection microscopy; strobili were subjected to comparative morphological analyses. Two Pinus macrofossils were dated by conventional 14C methods. Results The taxonomic accuracy achieved in the identification of the macrofossils provided new information regarding the Holocene history of Pinus sylvestris in this territory. Ninety-five cones of this species were identified; in fact, more than 80% of the 36 identified wood remains were of Pinus gr. sylvestris. Radiocarbon dating revealed that the forest to which the fossils belonged was present until at least 2170 ± 50 yr bp – its disappearance was therefore relatively recent. Main conclusions Pinus sylvestris suffered long-term isolation, and after the Wu¨rm glacial period tended to migrate towards the east. In western Iberia, a temperate climate and autogenic succession favoured broadleaved taxa at the expense of Pinus. Late Holocene human disturbances may have further accelerated the decline of P. sylvestris; in the Cantabrian Range, only a few stands on southern slopes have persisted until the present day. The history of the capercaillie (Tetrao urogallus), a bird characteristic of pure or mixed Palaeartic coniferous forests, was almost certainly affected by the demise of these forests in this area. Cantabrian capercaillies are the only members of this species that live in purely deciduous forests, perhaps a recent adaptation to the regional extinction of pines. Today’s P. sylvestris and capercaillie populations are now highly fragmented and their future, given the predictions of global climate change, is uncertain

Cambios en la representación polínica de los ecosistemas fluvio-marinos de transición del entorno de la Ría de Vigo durante los últimos 1500 años

XV lnternational A.P.L.E. Symposium of Palynolog

Reconstrucción de la dinámica del sistema barrera-lagoon del Parque Nacional de las Islas Cíes a partir de su registro sedimentario

XV lnternational A.P.L.E. Symposium of Palynolog

First high-resolution multi-proxy palaeoenvironmental record of the Late Glacial to Early Holocene transition in the Ría de Arousa (Atlantic margin of NW Iberia)

A 322-cm-long sedimentary sequence obtained in the shallow marine basin of the Ría de Arousa—a submerged unglaciated river valley on the Atlantic margin of northwestern Iberia—was analysed using a multi-proxy approach to study how climatic and sea level changes affected the coastal ecosystems during the Last Glacial–Interglacial Transition. Past sedimentation, vegetation and marine productivities were inferred from palynological, radiocarbon, seismic and lithological data. A substantial reduction in the pollen and dinoflagellate cyst accumulation rates is observed at ∼12,700 to 11,700 cal a BP, suggesting lower marine and vegetation productivities likely as a response to the Younger Dryas cooling event. Overall, the regional vegetation changed from cold-tolerant open woodlands (Pinus sylvestris/P. nigra and Betula) dominating before ∼10,200 cal a BP to coastal wetlands and the regional spread of Quercus-dominated forests after ∼9800 cal a BP. Cluster analysis and principal component analysis allowed the identification of several small environmental oscillations, such as the 11.4 ka and 10.5 ka cooling events. After that, a conspicuous heath expansion was likely favoured by the palaeotopography, the increased precipitation and the relative sea level rise, which might have caused a profound change in the coastal configuration. Concurrently, both the dinoflagellate cyst and non-pollen palynomorph records reveal variations in the marine productivity and coastal hydrodynamics that also agree with a period of marked marine transgression, warming and increasing river flow. New sedimentary data highlight the high sensitivity of the ria's ecosystems to environmental oscillations and show a close temporal correspondence between terrestrial and marine responses to climate change

Influència del bloqueig directe i l’un contra un en l’èxit del llançament en basquetbol

El present estudi té com a objectiu analitzar l’impacte de l’un contra un i el bloqueig directe sobre l’eficàcia en els llançaments. Es va desenvolupar un instrument ad hoc denominat sistema d’observació de conceptes fonamentals en basquetbol (SOCFB) per estudiar les accions ofensives del Futbol Club Barcelona Regal a la Copa del Rei en la temporada 2013-2014. Es van analitzar un total de 643 accions ofensives on es destaquen les troballes següents: a) el 34 % de les accions del jugador amb pilota van acabar en llançament mentre que el 66 % van acabar en passades; b) la principal conseqüència de l’un contra un interior van ser els llançaments (z = 6,2, p

Influencia del bloqueo directo y el uno contra uno en el éxito del lanzamiento en baloncesto

El presente estudio tiene como objetivo analizar el impacto del uno contra uno y el bloqueo directo sobre la eficacia en los lanzamientos. Se desarrolló un instrumento ad hoc denominado sistema de observación de conceptos fundamentales en baloncesto (SOCFB) para estudiar las acciones ofensivas del Fútbol Club Barcelona Regal en la Copa del Rey en la temporada 2013-2014. Se analizaron un total de 643 acciones ofensivas donde se destacan los siguientes hallazgos: a) el 34 % de las acciones del jugador con balón finalizaron en lanzamiento mientras que el 66 % terminaron en pases; b) la principal consecuencia del uno contra uno interior fueron los lanzamientos (z = 6,2, p