Lourdes López-Merino

Peatlands in north-west Iberia are globally important carbon reservoirs, yet their fen communities remain less well understood than those of bogs. Here, we present a multiproxy study of a ~11,100 cal. yr BP peat sequence cored at the Toxiza fen (TOX, Xistral Mountains, Galicia). Our analyses of palynology, rarefaction, charcoal, elemental composition and CIELab colour identify three main ecological phases. First, early Holocene mire initiation through terrestrialisation: wet meadows progressively replaced by a transitional fen at ~10,350 cal. yr BP, and subsequently by a Sphagnum -rich fen. Second, the mire experienced a prolonged phase of hydrological stability during the Holocene Climatic Optimum, characterised by Sphagnum -rich vegetation, high organic-matter content and sustained peat accumulation. Third, late Holocene increasing disturbance, including catchment erosion (~4900-4200 cal. yr BP) and fire-intense phases leading to an Ericaceae-rich fen; with Sphagnum partially recovered in reduced-burning intervals. Phases of ecological transition (i.e., early Holocene terrestrialisation and late Holocene disturbance) showed higher pollen richness, whereas comparatively stable values were found during the mid-Holocene, reflecting long-term ecosystem stability. Comparisons with nearby ombrotrophic mires highlight the importance of hydrological setting (minerotrophy vs. ombrotrophy) in shaping peatland vegetation trajectories under similar climatic forcing. Today the fen shows clear signs of degradation, including fire activity, sediment inputs and afforestation pressure, with no clear Sphagnum recovery. The TOX record, therefore, provides a process-based reference baseline for conservation where the mid-Holocene Sphagnum -rich phase represents a benchmark of hydrological stability and minimal disturbance, offering a framework for understanding biodiversity change and for guiding restoration of minerotrophic peatlands under ongoing environmental change.

Se ha realizado el estudio polínico de 6 muestras tomadas en un corte del Sector 1 del yacimiento Cerro del Tesoro (Zalamea de La Serena, Badajoz). Este análisis ha permitido reconstruir el paisaje y las actividades agropecuarias de este asentamiento ubicado cronológicamente en el cambio de era. Este paisaje se caracterizó por su apertura y alto grado de antropización, en donde las dehesas compartirían espacio con formaciones abiertas dedicadas al cultivo (cereal, guisante y olivo) y a la actividad ganadera. Estos datos han permitido dar respuesta a interrogantes sobre el tipo de asentamiento que representa este yacimiento surgido del debate científico durante las distintas excavaciones del mismo.

En estas actas se recopilan las aportaciones de diferentes especialistas en el estudio de la romanización en la Península Ibérica. Los participantes de la reunión científica organizada por Victorino Mayoral y Sebastián Celestino tratan un amplio abanico de aspectos relacionados con las fortificaciones de este período y su incidencia en hábitat, paisaje y territorio, ya sea desde un acercamiento puntual, a través del estudio de un único yacimiento o de una reflexión más general.

The NW Iberian city of Vigo contains buried structures of a Roman salinae that follow the ancient coastline. To investigate its environmental legacy, we studied two pedo-sedimentary profiles at the O Areal saltworks to reconstruct human activities during and after the salinae use, as well as framing them within the last two millennia of climate variability. The bottom layer consists of organic-rich sands, with marine palynomorphs, confined within the saltworks’ structures that operated during the Early Roman Empire, when the demand in fish-salted products increased and the salting industry fluorished on the Atlantic coast of Iberia. During the Late Roman Empire, salt production at the O Areal may have ended, coeval with the development of a marsh with hydro-hygrophyte vegetation and the salting industry demise. The Roman environment also experienced intense agropastoralism that triggered water eutrophication. After Roman times, a dune phase sealed the archaeologicl structures. The overall trend points to a shift from a marine to a terrestrial setting coeval to known periods of climate variability. Therefore, humans and climate impacted the coast during the last two millennia, including the very intense Roman-period saltworks, agriculture and livestock. Roman times climate would have also influenced the saltworks’ establishment and abandonment.

An 8500-year record of high-resolution pollen, non-pollen palynomorph, microscopic charcoal and selected geochemical data (Ti, Zr and Pb) is presented from an ombrotrophic mire from the Xistral Mountains, Galicia, North-West Iberia. The results suggest that vegetation changes over the last eight millennia are primarily the result of human disturbance, fire and climate change. Climate and fire were the main factors influencing vegetation development during the early to mid-Holocene, including a short-lived decline in forest cover c. 8.2 cal. ka BP. Changes associated with the 4.2 and 2.8 cal. Ka BP events are less well defined. Human impact on vegetation became more pronounced by the late Holocene with major periods of forest disturbance from c. 3.1 cal. ka BP onwards: during the end of Metal Ages, Roman period and culminating in the permanent decline of deciduous forests in the post-Roman period, as agriculture and metallurgy intensified, leading to the creation of a cultural landscape. Climate change appears to become less influential as human activity dominates during the Late Holocene.

The mineral content of peat has received little attention until the last few decades, when peat cores have been increasingly used to study past dust deposition. Paleodust deposition is commonly reconstructed through elemental datasets, which are used to infer deposition rates, storminess patterns, mineral composition, source identification, and fertilization effects. To date, only a few studies have directly analyzed the mineralogy (by XRD and SEM) and particle size of peat mineral matter, and the conducted studies have usually been constrained by the need to remove a large amount of organic matter, which risks altering the mineral component. One alternative is to use quick, nondestructive techniques, such as FTIR-ATR, that require little sample preparation. In this study, we analyzed by FTIR-ATR both the bulk peat and ash fractions of a sequence taken in a minerogenic mire that covered a wide inorganic matter content range (6%–57%). Aided by principal component analysis on transposed IR spectral data, we were able to identify the main minerals in bulk peat and ash, quartz, mica (likely muscovite), K feldspar (likely microcline), and plagioclase (likely anorthite), which are consistent with the local geology of the mire catchment. Changes in mineral composition during the last ca. 2800 years were coeval with previously reconstructed environmental changes using the same core. Our results suggest that FTIR-ATR has great potential to investigate peat mineral matter and the processes that drive its compositional change.