A new Late-glacial and Holocene record of vegetation and fire history from Lago del Greppo, northern Apennines, Italy

Detailed Late-glacial and Holocene palaeoenvironmental records from the northern Apennines with a robust chronology are still rare, though the region has been regarded as a main area of potential refugia of important trees such as Picea abies and Abies alba. We present a new high-resolution pollen and stomata record from Lago del Greppo (1,442m a.s.l., Pistoia, northern Apennines) that has been dated relying on 12 terrestrial plant macrofossils. Late-glacial woodlands became established before 13000cal b.p. and were dominated by Pinus and Betula, although more thermophilous taxa such as Quercus, Tilia and Ulmus were already present in the Greppo area, probably at lower altitudes. Abies and Picea expanded locally at the onset of the Holocene at ca. 11500cal b.p. Fagus sylvatica was the last important tree to expand at ca. 6500cal b.p., following the decline of Abies. Human impact was generally low throughout the Holocene, and the local woods remained rather closed until the most recent time, ca. a.d. 1700-1800. The vegetational history of Lago del Greppo appears consistent with that of previous investigations in the study region. Late-glacial and Holocene vegetation dynamics in the northern Apennines are very similar to those in the Insubrian southern Alps bordering Switzerland and Italy, across the Po Plain. Similarities between the two areas include the Late-glacial presence of Abies alba, its strong dominance during the Holocene across different vegetation belts from the lowlands to high elevations, as well as its final fire and human-triggered reduction during the mid Holocene. Our new data suggest that isolated and minor Picea abies populations survived the Late-glacial in the foothills of the northern Apennines and that at the onset of the Holocene they moved upwards, reaching the site of Lago del Greppo. Today stands of Picea abies occur only in two small areas in the highest part of the northern Apennines, and they have become extinct elsewhere. Given the forecast global warming, these relict Picea abies stands of the northern Apennines, which have a history of at least 13,000years, appear severely endangere

CONIFEROUS WOODS IN THE EARLY PLEISTOCENE BROWN COALS OF THE LEFFE BASIN (LOMBARDY, ITALY). Ecological and biostratigraphic inferences

49 autochthonous wood samples collected in brown coal from the Leffe palustrine deposits (Early Pleistocene, Lombardy, N-Italy) have been identified and their stratigraphical position has been discussed in comparison with pollen spectra. A peat level in the lower part of the succession contains Piceoxylon wood. Pollen spectra point to a conifer forest of dry and cool climate. Glyptostroboxylon  tenerum,  Chamaecyparis, Pinus aff. tabulaeformis, Carya, Pterocarya, Alnus, Fraxinus and Celtis woods have been identified from the "Main" brown coal layer in the middle (biogenic) unit of the Leffe Formation. The coniferous woods are described and some inferences about their ecological requirements are presented. These trees formed part of the swamp vegetation during interglacial phases. Pinus occurred, only during meso/oligotrophic phases. The biostratigraphic interest of these finds and climate dynamics are discussed, in order to interpret the discontinuous record of the "Tertiary plants" in Northern Italy during lowermost Pleistocene

Drilling Overdeepened Alpine Valleys (ICDP-DOVE): Quantifying the age, extent, and environmental impact of Alpine glaciations

The sedimentary infill of glacially overdeepened valleys (i.e., structures eroded below the fluvial base level) is an excellent but yet underexplored archive with regard to the age, extent, and nature of past glaciations. The ICDP project DOVE (Drilling Overdeepened Alpine Valleys) Phase 1 investigates a series of drill cores from glacially overdeepened troughs at several locations along the northern front of the Alps. All sites will be investigated with regard to several aspects of environmental dynamics during the Quaternary, with focus on the glaciation, vegetation, and landscape history. Geophysical methods (e.g., seismic surveys), for example, will explore the geometry of overdeepened structures to better understand the process of overdeepening. Sedimentological analyses combined with downhole logging, analysis of biological remains, and state-of-the-art geochronological methods, will enable us to reconstruct the erosion and sedimentation history of the overdeepened troughs. This approach is expected to yield significant novel data quantifying the extent and timing of Middle and Late Pleistocene glaciations of the Alps. In a first phase, two sites were drilled in late 2021 into filled overdeepenings below the paleolobe of the Rhine Glacier, and both recovered a trough filling composed of multiphase glacial sequences. Fully cored Hole 5068_1_C reached a depth of 165m and recovered 10m molasse bedrock at the base. This hole will be used together with two flush holes (5068_1_A, 5068_1_B) for further geophysical cross-well experiments. Site 5068_2 reached a depth of 255m and bottomed out near the soft rock-bedrock contact. These two sites are complemented by three legacy drill sites that previously recovered filled overdeepenings below the more eastern Alpine Isar-Loisach, Salzach, and Traun paleoglacier lobes (5068_3, 5068_4, 5068_5). All analysis and interpretations of this DOVE Phase 1 will eventually lay the ground for an upcoming Phase 2 that will complete the pan-Alpine approach. This follow-up phase will investigate overdeepenings formerly occupied by paleoglacier lobes from the western and southern Alpine margins through drilling sites in France, Italy, and Slovenia. Available geological information and infrastructure make the Alps an ideal area to study overdeepened structures; however, the expected results of this study will not be restricted to the Alps. Such features are also known from other formerly glaciated mountain ranges, which are less studied than the Alps and more problematic with regards to drilling logistics. The results of this study will serve as textbook concepts to understand a full range of geological processes relevant to formerly glaciated areas all over our planet

Altitudinal training sets of pollen rain – vegetation cover and modelled climate as a tool for the interpretation of paleoecological records

To improve our ability to reconstruct past environments and climate from fossil pollen records, modern proxy calibration studies along climatic and ecological gradients are needed. Here we present the first training set of modern pollen rain, vegetation, climate and terrain parameters developed along a 1700m-high transect in the western Italian Alps. The accurate knowledge on the relationships between these factors is essential for robust and sound reconstructions of past ecosystems based on microscopic plant remains

Antiguos bosques de las Islas Canarias: métodos y técnicas para la reconstrucción de la vegetación

La Paleoecología es el estudio de las relaciones entre los organismos del pasado y los ambientes en los que vivían, mediante el análisis de fósiles y de los sedimentos en los que dichos fósiles se han preservado (Birks y Birks, 1980). Los fósiles son restos de organismos del pasado o indicadores de su actividad que se preservan con el paso del tiempo. Los fósiles de origen vegetal, en particular, se utilizan para reconstruir la vegetación del pasado y para determinarla influencia que los factores geológicos, climáticos, bióticos o antrópicos han tenido sobre las comunidades vegetales a lo largo del tiempo. Existen numerosos tipos de restos vegetales que pueden encontrarse en secuencias sedimentarias y que sirven para identificar las especies vegetales que habitaban en una determinada zona en el pasado. De acuerdo con su tamaño podemos diferenciar los macrofósiles vegetales, es decir aquellos que pueden ser identificados bajo la lupa (hojas, flores, frutos, semillas, maderas, carbones, etc.) y los microfósiles vegetales (granos de polen, esporas de helechos y briófitos, fitolitos, diatomeas, etc.), cuyo tamaño es tan pequeño que necesitan ser observados al microscopio. Otros fósiles de origen vegetal se pueden utilizar como indicadores de incendios ocurridos en el pasado (carbones, esporas de hongos asociadas a materiales quemados), o indicadores que proliferan como resultado de las actividades humanas,por ejemplo con la eutrofización de lagos (algas), la presencia de herbívoros domésticos (esporas fúngicas), o el incremento de incendios (carbones), además de indicadores de cambios en las propiedades físico-químicas de los lagos como resultado de cambios climáticos (diatomeas, algas)(Smol et al., 2001). Junto con los indicadores fósiles se suelen utilizar otros indicadores paleoambientales que implican el estudio de la propiedades físicas y químicas de los sedimentos. Los análisis geoquímicos indican procesos de erosión, alternancia de periodos húmedos y secos, o variaciones en los niveles de ciertos elementos químicos que a su vez pueden relacionarse con la contaminación antrópica. Las medidas de la susceptibilidad magnética detectan variabilidad en los procesos erosivos, y pueden asociarse a modificaciones de la cobertura vegetal o a determinados fenómenos climáticos. Otra propiedad de los sedimentos es la proporción de isótopos estables, que puede usarse como indicador de la temperatura del pasado, la aridez, y la concentración de CO2 atmosférico (Anderson et al., 2007). Por último, es esencial proveer de un marco temporal a las secuencias que contienen los fósiles para poder interpretar los procesos ambientales de forma ordenada en el tiempo. Para ello se aplican diferentes métodos de datación (datación radiométrica, paleomagnetismo, termoluminiscencia, o bioestratigrafía), dependiendo del material y del periodo de edad aproximado que se pretenda datar. La técnica más utilizada para el Holoceno (los últimos 11500 años de historia de La Tierra) es la datación por radiocarbono, basada en la tasa de descomposición radiactiva del carbono-14 (14C)que se encuentra en todos los organismos vivos (Roberts, 1998), y que se puede aplicar sobre materiales diversos (madera, carbones, semillas, huesos, dientes, conchas, fibras vegetales, etc.