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H3N2 viruses continuously acquire mutations in the hemagglutinin (HA) glycoprotein that abrogate binding of human antibodies. During the 2014–2015 influenza season, clade 3C.2a H3N2 viruses possessing a new predicted glycosylation site in antigenic site B of HA emerged, and these viruses remain prevalent today. The 2016–2017 seasonal influenza vaccine was updated to include a clade 3C.2a H3N2 strain; however, the egg-adapted version of this viral strain lacks the new putative glycosylation site. Here, we biochemically demonstrate that the HA antigenic site B of circulating clade 3C.2a viruses is glycosylated. We show that antibodies elicited in ferrets and humans exposed to the egg-adapted 2016–2017 H3N2 vaccine strain poorly neutralize a glycosylated clade 3C.2a H3N2 virus. Importantly, antibodies elicited in ferrets infected with the current circulating H3N2 viral strain (that possesses the glycosylation site) and humans vaccinated with baculovirus-expressed H3 antigens (that possess the glycosylation site motif) were able to efficiently recognize a glycosylated clade 3C.2a H3N2 virus. We propose that differences in glycosylation between H3N2 egg-adapted vaccines and circulating strains likely contributed to reduced vaccine effectiveness during the 2016–2017 influenza season. Furthermore, our data suggest that influenza virus antigens prepared via systems not reliant on egg adaptations are more likely to elicit protective antibody responses that are not affected by glycosylation of antigenic site B of H3N2 HA.

Post-fire forest resilience must be quantified in a long-term perspective considering changes in land-use related to fire dynamics. Historical land-use changes leading to increased wildfire severity may produce no analogue regime shifts including a loss in post-fire growth recovery. Here we reconstruct the historical fire dynamics by combining paleoecological proxies, historical fire records and tree-ring width data of relict Pinus nigra subsp. salzmannii forests in the Sierra de Gredos (central Spain). A high incidence of historical fires was recorded in the 1890s, coinciding with a peak in charcoal accumulation rates and a sharp decrease in pollen of P. nigra/Pinus sylvestris with a rapid increase of pollen of more flammable Pinus pinaster and shrubs. The shift observed in pollen assemblages, coupled with a peak in charcoal influx, support the occurrence of high-severity fires during the 1890s, when abrupt growth suppressions were observed. Trees took 2 years to recover to their pre-fire growth rates. Lasting growth-recovery periods or no growth suppression were observed in the 1920s and 1980s, when fire frequency was also high but the study sites were fragmented or protected. We documented an abrupt regime shift in the fire record during the 1890s affecting pine forests, which rapidly recovered pre-fire growth rates.

Charcoal accumulated in lake, bog or other anoxic sediments through time has been used to document the geographical patterns in changes in fire regimes. Such reconstructions are useful to explore the impact of climate and vegetation changes on fire during periods when human influence was less prevalent than today. However, charcoal records only provide semi-quantitative estimates of change in biomass burning. Here we derive quantitative estimates of burnt area from vegetation data in two stages. First, we relate the modern charcoal abundance to burnt area using a conversion factor derived from a generalised linear model of burnt area probability based on eight environmental predictors. Then, we establish the relationship between fossil pollen assemblages and burnt area using tolerance-weighted weighted averaging partial least-squares regression with a sampling frequency correction (fxTWA-PLS). We test this approach using the Iberian Peninsula as a case study because it is a fire-prone region with abundant pollen and charcoal records covering the Holocene. We derive the vegetation–burnt area relationship using the 31 records that have both modern and fossil charcoal and pollen data and then reconstruct palaeoburnt area for the 113 records with Holocene pollen records. The pollen data predict charcoal-derived burnt area relatively well (R2 = 0.44), and the changes in reconstructed burnt area are synchronous with known climate changes through the Holocene. This new method opens up the possibility of reconstructing changes in fire regimes quantitatively from pollen records, after regional calibration of the vegetation–burnt area relationship, in regions where pollen records are more abundant than charcoal records.

This paper describes the patterns and processes of vegetation change and fire history in the Late Holocene (c. 3,140 cal BP) palaeoecological sequence of El Tiemblo, in a mountainous area in central Spain (Gredos range, Spanish Central System), and provides the first Iberian pollen sequence undertaken within a Castanea sativa-dominated woodland. These new data reassess not only the autochthonous nature of the species in the region and in the Iberian Peninsula, but also the naturalness of well-developed sweet chestnut forests. The study focuses on anthropogenic dynamics linked both to the effects of livestock husbandry and the use of fire for forest clearance. With this aim, non-pollen palynomorphs (coprophilous fungi ascospores) and charcoal accumulation rate are useful indicators for assessing the increasing role of human influence on vegetation.

This article describes the patterns and processes of vegetation change and fire history in the Late Holocene (c. 2400 calendar year BP) palaeoecological sequence of Lanzahíta, Sierra de Gredos in central Spain, and provides the first Iberian pollen sequence undertaken within a monospecific Pinus pinaster woodland. These new data reassess not only the autochthonous nature of this pine species in the region and the Iberian Peninsula, but also the naturalness of well-developed cluster pine forests. Conflicts of palaeoecological evidence with phytosociological models of vegetation dynamics in the study region, and the relationships of P. pinaster with fire occurrence in Mediterranean-type ecosystems, are discussed.

Atlas cedar (Cedrus atlantica (Endl.) Manetti ex Carrière) is an endemic and relict conifer species from northwestern Africa, relatively drought-tolerant but also highly sensitive to recurrent summer heat stress. Cedar forests have undergone a dramatic range contraction in recent decades. The development of effective conservation strategies requires long-term perspectives to understand how forests have responded to past disturbances. We present a multi-proxy, high-resolution analysis of a 122 cm-deep fossil record (Merj Lkhil; LKH) located at 1213 m a.s.l. in Jbel Bou Hachem (Moroccan Rif), providing insights into the fragmentation of cedar stands. Cedrus likely formed extensive lowland populations during the final stages of the Late Glacial and began migrating upslope during the Greenlandian. It reached its maximum extent in the Rif around 7000 cal yr BP. Thereafter, increasing aridity, enhanced seasonality, and growing anthropogenic pressure triggered its long-term decline. This trajectory involved a vertical reorganization of montane ecosystems, with Cedrus progressively retreating within mid- and low-elevation forests, while deciduous oaks maintained a long-term co-dominance and Q. ilex L. gradually expanded, especially at lower elevations. Today, Cedrus is confined to isolated high-elevation stands in Jbel Bou Hachem. These relic populations should be prioritized for conservation under ongoing climate and land-use change.

A high-altitude peat sequence from the heart of the Spanish Central System（Gredos range） was analysed through a multi-proxy approach to determine the sensitivity of high-mountain habitats to climate, fire and land use changes during the last seven hundred years, providing valuable insight into our understanding of the vegetation history and environmental changes in a mountain pass close to a traditional route of transhumance. The pollen data indicate that the vegetation was dominated by shrublands and grasslands with scattered pines in high-mountain areas, while in the valleys cereals, chestnut and olive trees were cultivated. Strong declines of high-mountain pines percentages are recorded at 1540, 1675, 1765, 1835 and 1925 cal AD, which may be related to increasing grazing activities and/or the occurrence of anthropogenic fires. The practice of mountain summer farming and transhumance deeply changed and redesigned the landscape of the high altitudes in central Spain（Gredos range） since the Middle Ages, although its dynamics was influenced in some way by climate variability of the past seven centuries.

A strategic aim of research into climate change in the distant past is to respond to the contemporary challenges of global warming at the present. Determining the processes of adaptation by ecosystems to these challenges, evaluating the effects of environmental change on human communities and finding which regions are more or less sensitive to climate change are among the key topics of environmental research today. Throughout the past millennia, some of the most abrupt environmental upheavals were the successive phases of the Late Pleistocene to Early Holocene transition, ranging from cold and dry to mild and damp climates. These phases differed in intensity and effects across all regions of the planet. In this paper, the long-term changes to both vegetation cover and human settlements within the upper Ebro river basin (northern Iberia, western Mediterranean) are shown by new palaeoenvironmental sequences from two archaeological sites dated between ca. 14,000 and 8,000 cal bp , which serve as proxy evidence for past vegetation cover. Summed radiocarbon probability distributions of other nearby archaeological sites were also used to study the dynamics of land occupation throughout the period. The main findings point to vegetation changes changing from the dominance of open landscapes with pines and deciduous woods during the late Pleistocene to the dominance of deciduous forest cover with few areas with open landscapes and far fewer pinewoods during the early Holocene.

Knowledge of the current status of Fagus sylvatica in the Western Pyrenean Region (Northern Iberian Peninsula) is based on its widespread presence in mountain areas. However, the past evolution of this taxon and its links to natural and anthropogenic activities is not well defined. We have compiled all the published palaeobotanical data (macro and micro remains) on this region, including both natural and archaeological deposits and with particular emphasis on available radiocarbon dates. To support our analysis of the evolution of F. sylvatica, we present the palynological study of a new sequence (Gesaleta, Navarre), covering the last 11,400 cal yr bp. The main results of this paper suggest the ancient presence of F. sylvatica in the Western Pyrenean Region from at least the Late Pleistocene and Early and Middle Holocene, with a clear expansion from ca 4,500–3,500 cal yr bp, although with some regional differences. This was the point when European beech became one of the main actors in mountain forests, where it has been exploited for a variety of anthropogenic activities.

Mid-mountain ecosystems provide a broad diversity of resources, heterogeneous relief, and a mild climate, which are all very useful for human necessities. These features enable different strategies such as the terracing of the slopes as well as wide crop diversification. Their relations lead to a parallel co-evolution between the environment and human societies, where fire and grazing become the most effective landscape management tools. This paper presents the results obtained from a multi-proxy study of the Bermú paleoenvironmental record, which is a minerotrophic mire located in the Quintos de Mora National Hunting Reserve (Toledo Mountains, central Spain). The bottom of this core has been dated in the Islamic period (ca. 711–1100 cal AD), and the study shows how the landscape that was built over time in the Toledo Mountains up to the present day is narrowly linked to human development. This study shows the increasing human pressure on the landscape, as well as the subsequent strategies followed by the plant and human communities as they faced diverse environmental changes. Thus, it is possible to attest the main role played by the humans in the Toledo Mountains, not only as a simple user, but also as a builder of their own reflexion in the environment.