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The lipid content of a high mountain lake (Lake Isoba) allowed the reconstruction of the paleoenvironmental changes and anthropic influence in Northern Spain during the last 550 years. Fatty acids (FAs) and n-alkan-2-ones indicate little degradation of OM. Three units were delimited. During Unit A (ca. 1460–1780 CE) high carbon preference index values, predominance of high-molecular-weight saturated FAs, and good correspondence between the predominant n-alkane and saturated FA chains indicate higher OM input and evidence of minimal degradation, linked to the cold and dry Little Ice Age, that favoured the OM input derived mainly from land plants, and the reduced bacterial activity. In Unit B (ca. 1780–2006 CE) the n-alkane and saturated FA profiles showed a remarkable mismatch suggestive of preferential microbial synthesis of long chain saturated FAs from primary OM and/or bacterial activity (predominance of low-molecular-weight saturated FAs but with a bimodal distribution), in coincidence with a decrease in OM input, which could be linked to the global warming that started in the second half of the 19th century. Although OM continued deriving mainly from terrigenous plants, aquatic macrophytes increased their contribution to the OM indicating the amelioration of environmental conditions. Evidence of considerable phytoplankton productivity and microbial activity was significant in Unit C (ca. 2006–2018 CE) coinciding with the highest concentrations of n-alkanes and saturated FAs, linked to warmer and drier conditions, and to greater anthropogenic influence. In addition, organic sulfur and gammacerane indicates loss of oligotrophy, and the record of faecal stanols, particularly that of 24-ethylcoprostanol, strongly evidences notable and rising water pollution associated with increasing cattle ranching in the lake catchment during the past 10–15 years., AEI/FEDER, UE, Agencia Estatal de Investigación, University of Bern, Ministerio de Universidades/Universidad de Alcalá/European Union, Gobierno del País Vasco, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

[Background] The global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300., [Results] Respondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios., [Conclusion] The influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.

Acknowledgements This work was performed as part of the Spanish research projects CGL-200602956/BOS (Paleodiversitas I) and CGL-200806005/BOS., The native or allochthonous nature of certain extant species of the Iberian Peninsula is a matter of some controversy given our lack of knowledge regarding the survival and extinction processes to which they have been subject. The aim of the present work is to provide a review of the current knowledge regarding these processes during the Quaternary. The Middle Pleistocene Transition was a period of noticeable disappearance of Arctotertiary taxa in the Iberian Peninsula, related to the alteration in glacial cyclicity and climate change, including an increase in the severity of glaciations, a reduction in the length of the interglacial periods, and increased dryness during the coldest times. It is difficult to maintain that human activities played any important part in the complete or near-complete disappearance of some taxa during the Quaternary. In the Late Pleistocene and Holocene, however, the extinction of Cedrus, Picea and Carpinus might be related to climate change, competition with other taxa, and anthropogenic disturbances. In contrast, the extreme reduction or even complete disappearance of Platanus or Syringa seems to be due to natural causes alone. The available geological, molecular and palaeobotanical data suggest that some Arctotertiary taxa persisted over long periods of time during the Quaternary in the Iberian Peninsula. Indeed, the fossil record of one important group of taxa, including Castanea, Ceratonia, Carpinus and Juglans, shows its continued presence throughout the Quaternary., Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub

Funding C. Morales-Molino holds a Universidad Politécnica de Madrid pre-doctoral grant. This study was funded by the research projects CGL2008-06005 BOS – SensCom (Ministerio de Ciencia e Innovación, Spain) and ‘Estudio de turberas en la Cuenca del Duero’ (code 43711816057, Junta de Castilla y León, Spain), In the southern Duero Basin of central Spain, there are vast areas of aeolian sand sheets and dune fields. A comprehensive survey of the sand quarries in this area identified a number of palaeosols in sedimentary sequences. The identification and AMS radiocarbon dating of soil charcoal fragments collected in these palaeosols indicate the persistence of Pinus pinaster in this area throughout most of the Holocene. Although potential natural vegetation models have usually considered the Pinus pinaster forests in this inland area of artificial origin, soil charcoal analysis provides firm evidence of a natural origin. Our data fit perfectly with the pattern of Holocene vegetation development for inland areas of Iberia, which are characterised by stability of pine forests throughout the Holocene. Finally, the growing body of palaeobotanical evidence from Iberia (macrofossils and pollen) is contributing to improve our knowledge of P. pinaster ecology, showing that this species has been present in most Iberian regions during the Holocene, where it has inhabited areas characterised by a very diverse set of climatic and soil conditions., Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub

Understanding ecosystem resilience requires long data series provided by palaeoecological studies, the best tool for reconstructing vegetation dynamics. Here, we analyzed a continuous and well-dated record of pollen, non-pollen palynomorphs, macrocharcoal remains, loss-on-ignition and magnetic susceptibility from one of the most singular peatlands in the Toledo Mountains (central Spain), in order to delineate the anthropogenic and/or climate impact on the peatland and the ecosystem’s response. La Ventilla mire is an isolated site of birch woodland dominated by Betula pubescens subsp. celtiberica (Rothm. & Vasc.) Rivas Mart. This mire, acting as a refugium for this species, is located in Cabañeros National Park and is recognized as ‘Special Area of Conservation’ according to Habitats Directive of the Natura 2000 network. We describe major patterns and trends in the development of this palaeorefugium since the mid-Holocene (∼ 6145 cal BP) and provide historical context for some natural and/or human-induced dynamics. Around 1500 cal BP, the lotic depositional environment with slow moving backwaters developed into a minerotrophic mire. Until the Middle Ages, macroclimate and autogenic succession appear to have been the main drivers of both local and regional development of vegetation. Between 1500 and 500 cal BP, an abrupt decline in birch cover started, coincident with the Visigothic period. The pronounced peaks in the coprophilous fungi record ca. 1000 and 150 cal BP reflect extensive pastoral activities in the area. This study shows how palaeoecological knowledge helps to explain present patterns in the composition of a valuable protected site, which may be used in prioritizing conservation.

The multi-proxy study of sediment cores from Lake Isoba (43° 02′ N, 5° 18′ W; 1400 m a.s.l.) allows a detailed assessment of the past hydrological and environmental dynamics in north-western Iberia resulting from the interplay between climate variability and anthropogenic impact. The combination of diatom stratigraphy, sedimentology and high-resolution elemental geochemistry along with a robust chronological framework (established by 210Pb, 137Cs and 14C dating) provides a detailed environmental reconstruction for the past ~ 500 years. Abrupt changes in the fossil diatom assemblages indicate a high sensitivity of this small lake to past environmental change and allow identifying four major stages related to the main climate fluctuations of the Little Ice Age (LIA) and recent warming. High lake levels, enhanced runoff and higher productivity characterised the middle phase of the LIA (~ 1550 to 1630 CE), indicating an overall wet climate. Conversely, shallow lake levels, decreased runoff and relatively low productivity prevailed during the last phase of the LIA and the onset of the Industrial Era (~ 1630 to 1925 CE), likely due to colder and drier conditions. High lake levels and higher carbonate input occurred after ~ 1925 CE until the 1980s CE, when our data show an abrupt drop in lake levels probably caused by a regional negative rainfall anomaly related to climate warming during the past decades. Finally, since ~ 1997 CE a remarkable and abrupt increase in the lake nutrient load and turbidity is detected, probably associated with the replacement of transhumant sheep flocks with staying cattle. The main environmental changes reconstructed at Lake Isoba mostly agree with other palaeoclimatic records from northern Spain. However, the hydrological patterns reconstructed are opposed to those observed on the northern slopes of the Cantabrian Mountains. The recent and strong impact of land-use changes on the lake, causing more ecological disruptions than previous climate

Aim: Knowing a species' response to historical climate shifts helps understanding its perspectives under global warming. We infer the hitherto unresolved postglacial history of Pinus cembra. Using independent evidence from genetic structure and demographic inference of extant populations, and from palaeoecological findings, we derive putative refugia and re‐colonisation routes. Location: European Alps and Carpathians. Taxa: Pinus cembra. Methods: We genotyped nuclear and chloroplast microsatellite markers in nearly 3000 individuals from 147 locations across the entire natural range of P. cembra. Spatial genetic structure (Bayesian modelling) and demographic history (approximate Bayesian computation) were combined with palaeobotanical records (pollen, macrofossils) to infer putative refugial areas during the Last Glacial Maximum (LGM) and re‐colonisation of the current range. Results: We found distinct spatial genetic structure, despite low genetic differentiation even between the two disjunct mountain ranges. Nuclear markers revealed five genetic clusters aligned East–West across the range, while chloroplast haplotype distribution suggested nine clusters. Spatially congruent separation at both marker types highlighted two main genetic lineages in the East and West of the range. Demographic inference supported early separation of these lineages dating back to a previous interstadial or interglacial c. 210,000 years ago. Differentiation into five biologically meaningful genetic clusters likely established during postglacial re‐colonisation. Main Conclusions: Combining genetic and palaeoecological evidence suggests that P. cembra primarily survived the LGM in ‘cold period’ refugia south of the Central European Alps and near the Carpathians, from where it expanded during the Late Glacial into its current Holocene ‘warm period’ refugia. This colonisation history has led to the distinct East–West structure of five genetic clusters. The two main genetic lineages likely der

The multi-proxy study of sediment cores from Lake Isoba (43° 02′ N, 5° 18′ W; 1400 m a.s.l.) allows a detailed assessment of the past hydrological and environmental dynamics in north-western Iberia resulting from the interplay between climate variability and anthropogenic impact. The combination of diatom stratigraphy, sedimentology and high-resolution elemental geochemistry along with a robust chronological framework (established by 210Pb, 137Cs and 14C dating) provides a detailed environmental reconstruction for the past ~ 500 years. Abrupt changes in the fossil diatom assemblages indicate a high sensitivity of this small lake to past environmental change and allow identifying four major stages related to the main climate fluctuations of the Little Ice Age (LIA) and recent warming. High lake levels, enhanced runoff and higher productivity characterised the middle phase of the LIA (~ 1550 to 1630 CE), indicating an overall wet climate. Conversely, shallow lake levels, decreased runoff and relatively low productivity prevailed during the last phase of the LIA and the onset of the Industrial Era (~ 1630 to 1925 CE), likely due to colder and drier conditions. High lake levels and higher carbonate input occurred after ~ 1925 CE until the 1980s CE, when our data show an abrupt drop in lake levels probably caused by a regional negative rainfall anomaly related to climate warming during the past decades. Finally, since ~ 1997 CE a remarkable and abrupt increase in the lake nutrient load and turbidity is detected, probably associated with the replacement of transhumant sheep flocks with staying cattle. The main environmental changes reconstructed at Lake Isoba mostly agree with other palaeoclimatic records from northern Spain. However, the hydrological patterns reconstructed are opposed to those observed on the northern slopes of the Cantabrian Mountains. The recent and strong impact of land-use changes on the lake, causing more ecological disruptions than previous climate, Ministerio de Ciencia e Innovación (MICINN)/FEDER, Universidad del País Vasco, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The Toledo Mountains are a mid-elevation mountain range that separates the Tagus and Guadiana basins in the central area of the Iberian Peninsula. The location of these mountains allows the development of typical Mediterranean vegetation with some Atlantic influence. Consequently, typical broadleaved evergreen Mediterranean vegetation currently dominates the regional landscape, with the remarkable presence of more mesophilous species in sheltered and more humid microsites such as gorges (e.g., Prunus lusitanica, Taxus baccata, Ilex aquifolium) and mires/bogs (e.g., Betula pendula susbp. fontqueri, Erica tetralix, Myrica gale). Palaeoecological studies in these mountains are essential to understand the long-term ecology and original distribution of these valuable communities and are key to assess their resilience. Understanding the hazards and opportunities faced in the past by the plant communities of the Toledo Mountains is necessary to enhance the management and protection of those species currently threatened. This study focuses on El Perro mire, a peatland on the southern Toledo Mountains (central Spain) where climatic variability has played a major role in landscape dynamics at multi-decadal to millennial timescales. Climatic events such as the 4.2 ka cal. Before Present (BP) or the Little Ice Age triggered relevant landscape changes such as the spread and latter decline of birch and hazel forests. Human communities also seemed to be affected by these events, as their resilience was apparently jeopardized by the new climatic conditions and they were forced to find new strategies to cope with the new scenarios.