Modern vegetation and its pollen spectra in the Cantabrian mountains, northern Iberian Peninsula, compared with fossil pollen records

Vegetation History and Archaeobotany https://doi.org/10.1007/s00334-024-01001-y ORIGINAL ARTICLE Modern vegetation and its pollen spectra in the Cantabrian mountains, northern Iberian Peninsula, compared with fossil pollen records Marc Sánchez‑Morales1 Albert Pèlachs1 · Ramon Pérez‑Obiol2 · Virginia Carracedo3 · Jordi Nadal1 · Ana Ejarque4 · Received: 21 October 2023 / Accepted: 9 March 2024 © The Author(s) 2024 Abstract The study of the pollen rain from modern vegetation has greatly improved the interpretation of pollen diagrams and our understanding of ancient plant communities. In this study, 76 pollen samples were studied from various vegetation types in Cantabria, northern Iberian Peninsula. The pollen signals of the main taxa were compared to their estimated spatial coverage at various scales (100 m, 1 km and 5 km from the sampling point) using vegetation maps. Additionally, we investigated whether there were similar modern vegetation types to past ones interpreted from the pollen record from La Molina peatland, Cantabria. Our results revealed that the pollen rain from the laurel-evergreen oak community (Lauro nobilis-Quercetum ilicis) was mainly evergreen Quercus pollen (59–77%), with Laurus nobilis being very under-represented. The representation of Fagus sylvatica pollen varied according to its local presence. In the modern vegetation, two sample sites with over 95% cover of Fagus within a 100 m radius had a pollen content below 3%. Pine demonstrated high dispersal capability, with pollen values exceeding 20% even in samples with little or no pine cover within 1 and 5 km. Poaceae had limited representation, with up to 60% even in samples lacking tree cover within a 5 km radius. Mixed deciduous woodlands were dominated by deciduous Quercus and Corylus, and their resemblance to woods in the northern Iberian Peninsula during the mid Holocene is discussed. While a principal component analysis linked modern vegetation to the most recent part of the pollen diagram from La Molina, no clear parallels emerged between present-day and ancient vegetation. Finally, it was found that there were no differences in pollen concentrations trapped by acrocarpous and pleurocarpous mosses. Keywords Pollen rain measurement · Mosses · Fossil pollen record · Landscape · Northern Iberian Peninsula Introduction Communicated by W. Tinner. * Marc Sánchez‑Morales 1 Department of Geography, Edifici B, Facultat de Filosofia Lletres, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193 Bellaterra, Spain 2 Department of Animal Biology, Plant Biology, and Ecology, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193 Bellaterra, Spain 3 Department of Geography, Urban Studies and Land Planning, Avenida de Los Castros s/n, Universidad de Cantabria, 39005 Santander, Spain 4 ISEM, CNRS, IRD, University of Montpellier, Montpellier, France The analysis of pollen records has become the main technique for studying the changes in vegetation and landscapes through time. The results are often presented in the form of pollen diagrams, in which the pollen percentages of each taxon vary through the sequences studied. However, interpreting these percentages can sometimes be complex because the amount of pollen that accumulates in sedimentary deposits and is reflected in the pollen diagrams depends on various factors, and if these are not considered, it can lead to the over- or under-representation of certain taxa. For example, pollen production varies significantly between taxa (Piotrowska 2008). Anemophilous plants that disperse pollen by wind such as Pinus and Abies produce the most pollen and are generally the best represented in pollen spectra (Bresinsky et al. 2013). On the other hand, Vol.:(0123456789) Vegetation History and Archaeobotany animals, particularly insects, disperse the pollen of many plants (zoophily). The pollen is produced in smaller quantities and it is not adapted for airborne transport, but rather for attachment to animals. Therefore, this group is much less represented in pollen records, for example Fabaceae, Rosaceae, Liliaceae, Salix, Eucalyptus and Laurus (Bresinsky et al. 2013; Lara-Ruiz 2019). Finally, a small number of angiosperms disperse pollen via water (hydrophily). These are mostly aquatic plants such as Potamogeton and may be represented in the pollen spectra if they are present in the bodies of water where the sedimentary deposits are found. However, they are generally not indicative of the vegetation of the regional landscape (Bresinsky et al. 2013). In addition, pollen transport is also influenced by physical barriers, such as plant community structure and the geomorphology of the region. Some authors have observed that in dense woodlands, it is difficult for pollen to penetrate from surrounding plant communities. In contrast, open and less wooded areas allow for easier pollen dispersion (for example, Pérez-Obiol and Roure 1985; Sugita et al. 1999). Additionally, there are distinctions between coniferous or evergreen woods and deciduous ones. Deciduous woods have less canopy area for pollen interception during springtime before the leaves grow large, potentially leading to an increased contribution of pollen from vegetation growing elsewhere (Jackson and Lyford 1999). All these factors therefore imply complex relationships between vegetation and its pollen rain. To introduce objective weightings into the interpretation of pollen records, the study of modern vegetation and its pollen output has proven to be a very valuable tool in Europe since the 1930s (for example, Pohl 1933, 1937; Heim 1963, 1970). This type of study is based on the fact that modern pollen deposition can be recorded in a similar way in modern surface samples of mosses as it is for ancient pollen in lakes and bogs (Wilmshurst and McGlone 2005). It allows for the determination of the output of pollen by different plant communities and an assessment of which taxa may be over- or under-represented. In the Iberian Peninsula, there is a considerable body of literature on the modern pollen rain, especially for mountainous areas such as the Pyrenees (Pérez-Obiol and Roure 1985; Mazier 2001; Mazier et al. 2006, 2009; Cañellas-Boltà et al. 2009; Cugny et al. 2010; Ejarque et al. 2011; López-Vila et al. 2014; Leunda Esnaola 2019; Pérez-Obiol et al. 2019, 2021), in the Iberian and central mountain systems (Vazquez-Gomez and PeinadoLorca 1993; Sánchez-Goñi and Hannon 1999; López-Sáez et al. 2010, 2013; Aranbarri 2016; Broothaerts et al. 2018; Morales-Molino et al. 2020), in the Sierra Morena (DíazFernández 1994) and in mountain ranges of the northwestern Iberian Peninsula (Catrufo-Ferreño and Aira-Rodríguez 1990; González-Porto et al. 1993). The modern pollen rain has also been studied in some coastal environments, such as the southeastern Iberian Peninsula (Carrión 2002), Galicia (García-Moreiras et al. 2015; Castro-Parada and MuñozSobrino 2022) and the Balearic Island (...truncated)