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Aim: The Expansion‐Contraction model has been used to explain the responses of species to climatic changes. During periods of unfavourable climatic conditions, species retreat to refugia from where they may later expand. This paper focuses on the palaeoecology of red deer over the past 54 ka across Europe and the Urals, to reveal patterns of change in their range and explore the role of environmental conditions in determining their distribution. Location: Europe and western Asia to 63°E. Taxon: Red deer (Cervus elaphus). Methods: We collected 984 records of radiocarbon‐dated red deer subfossils from the Late Pleistocene and the Holocene, including 93 original dates. For each deer sample we compiled climatic and biome type data for the corresponding time intervals. Results: During the last 54 ka changes in red deer range in Europe and the Urals were asynchronous and differed between western and eastern Europe and western Asia due to different environmental conditions in those regions. The range of suitable areas for deer during the Last Glacial Maximum (LGM) was larger than previously thought and covered vast regions not only in southern but also in western and eastern Europe. Throughout the period investigated the majority of specimens inhabited forests in the temperate climatic zone. The contribution of forests in deer localities significantly decreased during the last 4 ka, due to deforestation of Europe caused by humans. Mean January temperature was the main limiting factor for species distribution. Over 90% of the samples were found in areas where mean January temperature was above −10°C. Main conclusions: Red deer response to climatic oscillations are in agreement with the Expansion‐Contraction model but in contradiction to the statement of only the southernmost LGM refugia of the species. During the last 54 ka red deer occurred mostly in forests of the temperate climatic zone. [ABSTRACT FROM AUTHOR]

Aim This paper examines eight fossil pollen datasets from Romania with the aim of exploring regional and elevational patterns in site similarity throughout the Holocene. In particular, we aim to determine whether there are clear intervals of homogenization/differentiation and to ascertain the potential driving factors. Location Romania. Methods Qualitative (pollen diagrams) and numerical methods including principal components analysis and Bray-Curtis similarity analyses were used. Results We found strong variability in the past vegetation dynamics during the Holocene. Bray-Curtis similarity analyses show large fluctuations in vegetation similarity and distinct periods of homogenization and differentiation throughout the Holocene. The magnitude and length of these periods appear quite variable in time, but the significant ones can be delimited as follows: (1) differentiation between 11,250 and 11,000 cal. yr bp, 10,000 and 9750 cal. yr bp, 6000 and 5750 cal. yr bp, 2500 and 2250 cal. yr bp, and especially over the last 200 years; and (2) homogenization between 9750 and 9500 cal. yr bp, and 2750 and 2500 cal. yr bp, with more stable periods between 9000 and 7750 cal. yr bp, 4750 and 3500 cal. yr bp, and 2000 and 1000 cal. yr bp. Main conclusions First, periods of biotic homogenization that occurred before significant anthropogenic impact on vegetation demonstrate that not all homogenization is a product of anthropogenic change: it can also be driven by natural causes. In fact, recent human impact (over the last 200 years) appears to have resulted in increased regional differentiation and not in homogenization - a result that contradicts most studies based on more modern, short-term records. Second, both abiotic (climate and disturbance) and biotic factors are likely drivers of intervals of differentiation and homogenization. We suggest that differentiation may be triggered primarily by climate changes and disturbances (mostly natural pre-2500 cal. yr bp and human-induced thereafter), whereas homogenization may be driven predominantly by biotic interactions (e.g. immigration and interspecific competition). Third, this long-term study raises awareness that assessments of pattern in vegetation homogenization/differentiation may depend on the specific time period and length of investigation. Long-term investigations through multiple generations are likely to yield particularly useful information on the mechanisms and effects of biotic homogenization. [ABSTRACT FROM AUTHOR]

Aim The assumedly anomalous occurrence of savannas and forest–savanna mosaics in the Gran Sabana – a neotropical region under a climate more suitable for tropical rain forests – has been attributed to a variety of historical, climatic, and anthropogenic factors. This paper describes a previously undocumented shift in vegetation and climate that occurred during the early Holocene, and evaluates its significance for the understanding of the origin of the Gran Sabana vegetation. Location A treeless savanna locality of the Gran Sabana (4°30′–6°45′ N and 60°34′–62°50′ W), in the Venezuelan Guayana of northern South America, at the headwaters of the Caroní river, one of the major tributaries of the Orinoco river. Methods Pollen and charcoal analysis of a previously dated peat section spanning from about the Pleistocene/Holocene boundary until the present. Results Mesothermic cloud forests dominated by Catostemma (Bombacaceae) occupied the site around the Pleistocene/Holocene boundary. During the early Holocene, a progressive but relatively rapid trend towards savanna vegetation occurred, and eventually the former cloud forests were replaced by a treeless savanna. Some time after the establishment of savannas, a marked increase in charcoal particles indicates the occurrence of the first local fires. Main conclusions The occurrence of cloud forests at the Pleistocene/Holocene boundary contradicts the historical hypothesis according to which the Gran Sabana is a relict of the hypothetical widespread savannas that have been assumed to have dominated the region during the last glaciation. The first local fires recorded in the Holocene were on savanna vegetation, which is against the hypothesis of fire as the triggering factor for the establishment of these savannas. Climate change, in the form of global warming and a persistently drier climate, emerges as the most probable cause for the forest–savanna turnover. [ABSTRACT FROM AUTHOR]

The Holocene spread of Picea abies in Fennoscandia is well established from many sites and thus provides an opportunity for detailed study of the dynamics of tree spread and population expansion. Early- and mid-Holocene macrofossil evidence for presence of P. abies in Fennoscandia has questioned traditional interpretations of the timing and direction of its spread. This paper aims to determine when, from where and by which pathways P. abies spread into Fennoscandia. Understanding the character and dynamics of this spread may give insight into the general understanding of Holocene tree spread. The north-western distribution of P. abies in Europe, including Norway, Sweden, Finland, Estonia, Latvia, Lithuania, north-western Russia, parts of Byelorussia and Poland. Holocene pollen diagrams with independent dating control were collected from this region. The timing of the onset of the continuous curve, the timing of the rise of the curve, the first appearance of frequencies of 1%, 3%, 5%, and 10%, as well as timing and the maximum amount of P. abies pollen, was obtained from these pollen diagrams. A GIS analysis was used to display the data and interpolate ages over the area under investigation. Maps are presented showing a clear ESE to WNW trend in the spread of P. abies for all characters interpolated. The timing of the rise of the curve was difficult to use as sites east of the Baltic have slowly rising P. abies frequencies while the western sites often show a rapid rise. The spread of P. abies in Fennoscandia and adjacent areas can be separated into two phases: (i) A rapid early Holocene spread out of Byelorussia and northern Russia at low population density giving rise to small outpost populations, possibly as far west as the Scandes Mountains. (ii) A mid- to late Holocene front-like spread at high population densities moving from east to west into the Baltic Republics and Finland, into northern Scandinavia and then moving south and west towards its present-day distributional limits. [ABSTRACT FROM AUTHOR]

Aim This paper seeks to elucidate the first post-glacial arrival of tree species to high elevations in the Scandes. This enables testing of general theories concerning glacial refugia, immigration routes and palaeoclimate. Location The study site, 1360 m a.s.l., was close to the summit of Mt Åreskutan in the alpine region of the southern Swedish Scandes, 400–500 m above modern tree-limits. Methods Tree megafossils (trunks, roots, cones) were retrieved (and radiocarbon-dated) from the ground surface in the forefields of receding `perennial' snow-patches. This approach allows elevational range-margin reconstructions to be made with an accuracy not possible with any other method. Results and conclusions Megafossils were recovered substantially higher and earlier than previously recorded or inferred for tree growth in this part of Europe. The species were Betula pubescens Ehrh. ssp. tortuosa (Ledeb.) Nyman, Picea abies (L.) Karst. and Pinus sylvestris (L.). The oldest dates obtained are c . 14,000, 11,000 and 11,700 BP for these species, respectively. For the first time, explicit evidence of tree growth in the Late-Glacial (including the Younger Dryas stadial) is demonstrated for central/northern Scandinavia. The swift appearance of boreal tree species at high northern latitudes and altitudes on the western fringe of Scandinavia and near the most extended margin of the Weichselian ice sheet hypothetically suggests that the first immigration of the trees considered here was from the west. Glacial refugia for these species (other plants and animals as well) on the exposed continental shelf areas west and southwest of Norway is hypothesized. By extension, the results fit into a more general pattern, suggesting the presence of boreal and temperate trees quite close to the full glacial (Weichselian) ice margins in central Europe. Thus, the Quaternary forest and landscape history of Europe seems more complex than previously believed. [ABSTRACT FROM AUTHOR]

Summary Aim The aim of this paper is to describe and interpret early Holocene floras and faunas. Location The floras and faunas come from various localities in North-east Greenland. Methods Sediment samples were wet sieved, and macrofossils picked out and dated by the AMS radiocarbon-dating method. Results Sediments, dated to the first centuries after the last glacial stage came to an abrupt end, contain a macroflora of bryophytes and a few herbs, and we suggest that these plant remains represent a pioneer vegetation entirely without woody plants. The named species of herbs are either confined to the northern parts of Greenland at present, or they become increasingly more important towards the north. Crowberry is the oldest woody plant recovered; it was present at 10.4 cal. ka BP, and it appears to have been common during the early Holocene in East Greenland. Main conclusions We suggest that the majority of the extant flora of vascular plants of East Greenland arrived by long distance dispersal during the Holocene. Some species may also have arrived during the late-glacial, and a few hardy species that are adapted to low summer temperatures may have survived the last glacial stage in nonglaciated areas. Some hardy animals may also have survived, but the majority of the fauna are considered Holocene immigrants. We suggest that migrating birds and storms, perhaps in combination, are under-appreciated dispersal vectors. [ABSTRACT FROM AUTHOR]

SummaryThe concept of biodiversity can operate at several different ecological levels from that of the Global ecosystem to the genetic diversity of a single species. This paper focuses on the beta-type diversity of vegetation communities at the intra and inter-regional scale, using five mid-Holocene (Neolithic) pollen diagrams from eastern Cumbria (c. 500 km2 centred on the Eden valley). The sites were selected in order to include the variation in both soil/rock type and altitude within the study area, ranging from the Eden valley and southern limestone plateau to the foothills and summits of the western edge of the Pennines. The local pollen component which is dominant in these small sites, is used to determine intra-regional vegetation diversity for a time-slice in the Neolithic. Simple statistical methods are used to compare sites and as a measure of intra-regional vegetation-type diversity. This is compared with estimates of the community diversity for the British Isles during the same period. The results suggest that the intra-regional vegetation diversity is comparable to that of Northern England, and it is related to variation in both altitude and soil type. There are some differences, for example the steepness of the western face of the Pennines is probably responsible for a lack of the pine dominated zone, and pedological constraints probably prevented the full development of woodland on the limestone plateau at the south of the study area. The open landscape of the limestone plateau acted as a refuge for late glacial herbaceous taxa prior to their re-expansion into the wider landscape after widespread deforestation and arable cultivation. The results have implications for both the mapping of past vegetation at the national scale and for landscape archaeology. [ABSTRACT FROM AUTHOR]

Aim: In recent decades, a surge in the number of significant and uncontrolled wildfires has occurred worldwide. Global warming may amplify this trend and threaten most ecosystems worldwide. Deciduous forests are characterized by high plant diversity, and understanding their long‐term dynamics is crucial to anticipate changes in these ecosystems during ongoing global warming. The aim of this study is to understand how European beech forests have colonized the inner Eastern Carpathians and how changes in fire regime and human activities have affected their biodiversity. Location: Inner Eastern Carpathian Mountains, Slovakia. Taxon: Plantae, gymnosperms, angiosperms. Methods: Peat core was extracted from the centre of Ďurova mláka mire in 2018. A multi‐proxy approach has been applied to investigate the development of beech forest. Charcoal analysis has been done each centimetre to reconstruct the fire signal. Pollen analysis has been done at 2 cm resolution to reconstruct the vegetation composition and dynamics, and the variation in palynological richness (PRI), evenness and turnover has been analysed. Macro‐remains analysis has been performed at 10 cm resolution to add more information about the local vegetation. Results: Low diversity spruce forest was dominant until 5200 cal. BP during a fire‐prone period due to specific climatic conditions (drier climate than the following period). The higher fire frequency and intensity following this period is simultaneous with the first expansion of Fagus which indicate that Fagus could occupy post‐fire habitats, at least at the local scale. However, its dominance coincided with major gaps in fire events from 3900 cal. BP. The PRI has increased during the transition from spruce to beech forest highlighting the importance of beech forests in maintaining plant biodiversity. However, the stronger increase in the richness is synchronous with the increase in human activities around 2000 cal. BP, and then 350 cal. BP. Main Conclusions: Climate‐driven fire frequency has been a natural driver of vegetation changes in the Carpathians by promoting the emergence of high diversified beech forest. These changes were significantly modified by later increase in human activities. [ABSTRACT FROM AUTHOR]

Aim: Understanding long‐term heathland development is key in mitigating their current attrition globally. However, such knowledge is limited in Australia and the wider Southern Hemisphere. We aim to identify potential climatic and environmental drivers of Holocene heathland development in temperate‐oceanic Australia (Bass Strait), and also assess the applicability of Iversen's conceptual model of interglacial vegetation development to the area. Location: Bass Strait, southeast Australia. Taxon: Monotoca, Epacris, Sprengelia and Restionaceae. Methods: We used multiple sedimentary pollen and charcoal records from truwana/Cape Barren Island (CBI) in Bass Strait to reconstruct vegetation and fire history. We also used rarefaction analysis on pollen records to estimate floristic richness for all sites, and magnetic susceptibility and organic content were derived for two of the four sites as proxies for local sedimentary changes. Reconstructed vegetation and fire histories were then compared to independent records of climate and sea‐level change in temperate Australia, using a Detrended Correspondence Analysis ordination, to identify major drivers of heathland development. Results: Major heathland expansion occurred on truwana/CBI between the early and mid‐Holocene in response to sea‐level rise, high effective precipitation, reduced seasonality and increased Indigenous burning. Increasing seasonality, low effective precipitation, El Niño‐Southern Oscillation intensification, stable sea level, and decreased fire activity drove the expansion of scrub and woodland at the expense of heathland in the late Holocene. The overall vegetation development on truwana/CBI fits poorly with the classic Iversen conceptual model of interglacial vegetation development in the Northern Hemisphere, due to the significant role of interglacial sea‐level rise on truwana/CBI. Therefore, a modified model, which takes into account the role of sea‐level change, is proposed for Southern Hemisphere‐temperate‐oceanic settings. Main conclusions: Heathland developments in both hemispheres reflect some level of homogeneity, considering the roles of increased Indigenous burning and reduced seasonality in both hemispheres. Frequent, controlled burning strategies are recommended to maintain heathland on truwana/CBI. [ABSTRACT FROM AUTHOR]

Abstract: Aim: We analysed a dataset composed of multiple palaeoclimate and lake‐sediment pollen records from New England to explore how postglacial changes in the composition and spatial patterns of vegetation were controlled by regional‐scale climate change, a subregional environmental gradient, and landscape‐scale variations in soil characteristics. Location: The 120,000‐km2 study area includes parts of Vermont and New Hampshire in the north, where sites are 150–200 km from the Atlantic Ocean, and spans the coastline from southeastern New York to Cape Cod and the adjacent islands, including Block Island, the Elizabeth Islands, Nantucket, and Martha's Vineyard. Methods: We analysed pollen records from 29 study sites, using multivariate cluster analysis to visualize changes in the composition and spatial patterns of vegetation during the last 14,000 years. The pollen data were compared with temperature and precipitation reconstructions. Results: Boreal forest featuring Picea and Pinus banksiana was present across the region when conditions were cool and dry 14,000–12,000 calibrated 14C years before present (ybp). Pinus strobus became regionally dominant as temperatures increased between 12,000 and 10,000 ybp. The composition of forests in inland and coastal areas diverged in response to further warming after 10,000 ybp, when Quercus and Pinus rigida expanded across southern New England, whereas conditions remained cool enough in inland areas to maintain Pinus strobus. Increasing precipitation allowed Tsuga canadensis, Fagus grandifolia, and Betula to replace Pinus strobus in inland areas during 9,000–8,000 ybp, and also led to the expansion of Carya across the coastal part of the region beginning at 7,000–6,000 ybp. Abrupt cooling at 5,500–5,000 ybp caused sharp declines in Tsuga in inland areas and Quercus at some coastal sites, and the populations of those taxa remained low until they recovered around 3,000 ybp in response to rising precipitation. Throughout most of the Holocene, sites underlain by sandy glacial deposits were occupied by Pinus rigida and Quercus. Main conclusions: Postglacial changes in the composition and spatial pattern of New England forests were controlled by long‐term trends and abrupt shifts in temperature and precipitation, as well as by the environmental gradient between coastal and inland parts of the region. Substrate and soil moisture shaped landscape‐scale variations in forest composition. [ABSTRACT FROM AUTHOR]

Abstract: Aim: The Mediterranean is characterized by diverse and spatially heterogeneous mosaic landscapes. Within this study, a cluster analysis‐based method is developed for the classification of Mediterranean vegetation types based on modern and fossil pollen datasets. The application of this approach to multiple pollen records spanning the Mediterranean region has allowed temporal variations in vegetation dynamics to be explored throughout the Holocene. We ask how far back stable baseline vegetation communities can be identified in the pollen record, and whether those types considered to be characteristic of the Mediterranean landscapes have been present in the past as well as at the present. Location: The research location includes the land areas surrounding the Mediterranean Sea. The pollen sites are principally located in mainland Spain, southern France, Greece and Turkey, Italy, North Africa, the Levant, and some Mediterranean islands. Methods: A total of 5,641 samples from 158 fossil pollen records (cores) and 1,799 modern pollen surface samples were harmonized taxonomically and pollen count data summed into 200‐year time windows on a common time‐scale from 11,000  bp to the present‐day. Cluster analysis and community classification were used to identify major vegetation types along with other approaches to explore patterns in ecological datasets, such as Simpson's diversity index and nonmetric multidimensional scaling. Results: The pollen datasets were classified into 11 closed forest/woodland and five open or scrubland vegetation types. Closed vegetation clusters declined from the mid‐Holocene with a marked increase in open or human‐modified vegetation types since 3,500  bp and with an increasing rate of vegetation change and habitat diversity through time. Main conclusions: The Mediterranean has been a dynamic landscape throughout the Holocene with frequent changes in land cover identified in the pollen datasets. The pollen‐inferred clusters reveal a wider range of Mediterranean vegetation types than identified in previous studies; for example, including both beech and alder woods. Evergreen Oleaceae‐dominated shrubland is much better represented in modern than in fossil samples while mesic forest was abundant in the past but is uncommon today. [ABSTRACT FROM AUTHOR]

Abstract: Aim: The Tasmanian devil (Sarcophilus harrisii), currently restricted to the island of Tasmania, was found over most of the Australian mainland prior to its extinction ~3,000 years ago. Recent debate has focused on the roles of humans, climate change and dingoes as drivers of the mainland extinction. Determining past genetic diversity and population dynamics of both populations is a fundamental component to understand why the species went extinct on mainland Australia, but survived in Tasmania. Here, we investigate the phylogeography and demographic history of the Tasmanian devil across southern Australia over the last ~30k years. Location: Australia. Taxon: Tasmanian devil (Sarcophilus harrisii). Methods: We used complete and partial mitochondrial DNA (mtDNA) genomes from 202 devils representing the extinct mainland (n = 17) and the extant Tasmanian (n = 185) populations to investigate the population dynamics of southern mainland and Tasmanian devils. The samples were sub‐fossil bones, historical museum specimens and modern tissue samples, dating from the present to 17k years before present. Using summary statistics, frequentist inference and Bayesian phylogenetic analysis we explored whether levels of genetic diversity were similar, and if the southern mainland experienced a gradual rather than an abrupt decline prior to its extinction. Results: MtDNA genomes from mainland devils suggest that this population was larger and had more genetic diversity than the Tasmanian population. Directly dated samples indicates that the southern mainland population expanded after the last glacial maximum and remained stable until its extinction. The Tasmanian population has much lower diversity and descends from a single mtDNA lineage ~3,000 years ago. The recent origin for all Tasmanian mtDNA diversity is concordant with a previously documented late‐Holocene population bottleneck and is broadly contemporaneous with the extinction of the southern mainland population. Main conclusions: This pattern shows striking similarity to the demographic history of thylacines, suggesting that a shared factor initiated population declines in both species on the southern mainland and in Tasmania. El Niño Southern Oscillation (ENSO)‐related climate change is the only factor common to both mainland Australia and Tasmania. Additional, direct or indirect, pressures from humans and/or dingoes on the mainland may have ultimately resulted in their extinction. [ABSTRACT FROM AUTHOR]

Aim We sought to determine if the present fragmentary distribution of the giant columnar cactus Echinopsis terscheckii in tropical drylands is a relict of a previously more widespread range during cold and dry phases of the Last Glacial Maximum (LGM). Location Tropical and subtropical dry ecotonal areas of northern and central Andes of Argentina. Methods We combined ecological niche models (ENM) with molecular polymorphisms of isozymes and DNA sequences. We collected samples from 30 individuals at 24 locations for genetic analysis covering a wide range of environmental conditions. We sequenced the nuclear ITS and three non-coding regions of the chloroplast DNA and we resolved 15 isozyme loci. Potential distribution was modelled using 88 E. terscheckii presence training records and a reduced set of 10 modern bioclimatic variables. LGM and the Mid-Holocene distributions were derived by projecting bioclimatic data under present to past environmental conditions according to CCSM4 and MIROC-ESM Global Climate Models. Results We detected high isozyme diversity towards the south. The multivariate cluster analysis yielded two groups of populations that were geographically concordant with the DNA haplotypes located north and south of a divide at 27°S. Distribution models show range expansion during the LGM in two north and south areas separated by a gap of low suitability at 27°S. Suitable areas in the south were close to current populations, while in the north, populations survived in more disjunct locations that probably suffered from founder effects. In contrast, Mid-Holocene bioclimatic conditions were relatively unsuitable in the south. Main conclusions Our results suggest that the divergence of north and south groups of E. terscheckii populations reflect long-lasting persistence through climatic cycles that were reinforced by the presence of an orogenic divide at mid-latitudes. Latitudinally divergent groups of populations should be treated as distinct evolutionary significant units that deserve independent conservation actions. Increased genetic diversity and inbreeding towards the south may guide setting up priorities for the long-term protection of a dominant element of drylands as E. terscheckii. [ABSTRACT FROM AUTHOR]

Aim We investigated the population genetic structure of a highly mobile marine species, the striped dolphin, Stenella coeruleoalba (Meyen, 1833), along a geographical range with habitat transitions and historical dynamics to identify the causes of genetic divergence, and to assess the effect of past climate change on demography and population connectivity. Location North-east Atlantic Ocean and Mediterranean Sea. Methods Twenty microsatellite loci were used in conjunction with coalescent methods to investigate the genetic structure and demographic history of striped dolphins ( Stenella coeruleoalba) in the Mediterranean Sea and eastern North Atlantic Ocean. Approximate Bayesian modelling was used to compare the support for alternative scenarios for the pattern of divergence over time in the context of known geographical transitions and environmental change over the course of the Quaternary. Results We describe a novel pattern of structure among the extant populations along north-south and east-west axes. Modern gene flow shows strong directionality from north-east to south and west in the North Atlantic, and from west to east in the Mediterranean. On a temporal scale we found evidence for a progression starting with a division between the North Atlantic and Mediterranean Sea populations during the middle Pleistocene, followed by a division within the Mediterranean between the east and west basins towards the end of the Pleistocene, and finally an east-west division in the eastern North Atlantic at the start of the Holocene. Main conclusions In the context of known population structure for other marine species along the same geographical range, our data facilitate inference of the more general processes that shaped patterns of biogeography across this region through the environmental transitions of the Quaternary. In particular, Pleistocene era divisions apparently reflect strong physical habitat boundaries, with later divisions associated with climate warming in the Holocene. [ABSTRACT FROM AUTHOR]

Aim To test competing hypotheses about the timing and extent of Holocene landscape opening using pollen-based quantitative land-cover estimates. Location Dove Lake, Tasmanian Wilderness World Heritage Area, Australia. Methods Fossil pollen data were incorporated into pollen dispersal models and corrected for differences in pollen productivity among key plant taxa. Mechanistic models ( REVEALS-Regional Estimates of VEgetation Abundance from Large Sites) employing different models for pollen dispersal (Gaussian plume and Lagrangian stochastic models) were evaluated and applied in the Southern Hemisphere for the first time. Results Validation of the REVEALS model with vegetation cover data suggests an overall better performance of the Lagrangian stochastic model. Regional land-cover estimates for forest and non-forest plant taxa show persistent landscape openness throughout the Holocene (average landscape openness ~50%). Gymnoschoenus sphaerocephalus, an indicator of moorland vegetation, shows higher values during the early Holocene (11.7-9 ka) and declines slightly through the mid-Holocene (9-4.5 ka) during a phase of partial landscape afforestation. Rain forest cover reduced (from ~40% to ~20%) during the period between 4.2-3.5 ka. Main conclusions Pollen percentages severely under-represent landscape openness in western Tasmania and this bias has fostered an over-estimation of Holocene forest cover from pollen data. Treeless vegetation dominated Holocene landscapes of the Dove Lake area, allowing us to reject models of landscape evolution that invoke late-Holocene replacement of a rain forest-dominated landscape by moorland. Instead, we confirm a model of Late Pleistocene inheritance of open vegetation. Rapid forest decline occurred after c. 4 ka, likely in response to regional moisture decline. [ABSTRACT FROM AUTHOR]

Aim The impacts of Holocene fires on the genetic architecture of fire-intolerant species have largely been overlooked. Here, we investigate the relative impacts of the last glacial climate versus Holocene fires on the genetic diversity of two co-occurring, fire-intolerant conifers using a comparative population genetic study. Location The palaeoendemic plant-rich montane rain forests and alpine coniferous heath of Tasmania, Australia. Methods The Tasmanian endemic conifers Athrotaxis cupressoides D. Don (461 samples from 20 populations) and Diselma archeri Hook.f. (576 samples from 23 populations, 16 of which were for sites sampled for A. cupressoides), were genotyped using eight and nine EST nuclear microsatellites respectively. Genetic diversity and structure was compared between the two species and the factors underlying genetic patterns in both species were investigated by examining isolation by distance, correlations with Last Glacial Maximum modelled distributions and the fossil record, and a fire history index of the sampled stands. Results The range-wide genetic structure of the two species was similar ( Fst = 0.09 and F'st = 0.21 for A. cupressoides versus D. archeri; Fst = 0.06 and F'st = 0.24), and there were significant correlations between species for population-based expected heterozygosity, allelic richness, private allelic richness and pairwise genetic divergences. Furthermore, genetic diversity metrics decreased significantly with an index of fire history. Given fossil evidence and modelling evidence that both species occurred near their current ranges during the last glaciation and a lack of evidence for isolation by distance in either species, the plausible explanation for the patterns of diversity is genetic decline resulting from repeated Holocene fires. Main conclusions Our study suggests that fire can have substantial impacts on genetic structure and diversity of plant species, particularly those without fire-tolerant traits, and that any increases in fire resulting from climate change may impose substantial threats to such species. In Tasmania, the observed increase in dry lightning in recent years, combined with periods of abnormally dry conditions, may therefore further degrade the range and genetic diversity of fire-intolerant palaeoendemic species. [ABSTRACT FROM AUTHOR]

Aim Predicting species responses to global change is one of the most pressing issues in conservation biogeography. A key part of the problem is understanding how organisms have reacted to climatic changes in the past. Here, we use species distribution modelling to infer the effects of climate changes since the Last Interglacial ( LIG, c. 130,000 yr bp) on patterns of genetic structure and diversity in the western spadefoot toad ( Pelobates cultripes) in combination with spatially explicit phylogeographical analyses. Location Iberian Peninsula and mainland France. Methods Five hundred and twenty-four individuals from 54 populations across the species range were sampled to document patterns of genetic diversity and infer their evolutionary history based on data from mt DNA and 14 polymorphic microsatellites. Generalized linear models based on distribution data were used to infer climatic favourability for the species in the present and in palaeoclimatic simulations for the LIG, the mid-Holocene and the Last Glacial Maximum (LGM). Results Estimates of genetic diversity show a decreasing trend from south to north, suggesting persistence of high historical population sizes in the southern Iberian Peninsula. Species distribution models show differences in climatic favourability through time, with significant correlations between historically stable favourable areas and current patterns of genetic diversity. These results are corroborated by Bayesian skyline plots and continuous diffusion phylogeographical analyses. Main conclusions The results indicate the presence of southern refugia, with moderate recent expansions at the northern end of the species' range. Toads at the northern range margin exhibit the lowest genetic diversity and occupy areas of high past climate variability, classified as marginal in terms of favourability, rendering these populations most vulnerable to climate-mediated changes in the long term. [ABSTRACT FROM AUTHOR]

Aim The aim of this study was to understand the origin of the forest flora currently found in the Dahomey Gap ( DG), a 200-km-wide forest-savanna mosaic separating the West African and Central African rain forest blocks. More specifically, using a widespread rain forest tree species, Distemonanthus benthamianus (Fabaceae), we will test the hypothesis that the DG populations are remnants of a population dating back from the African Humid Period of the Holocene, when West African and Central African rain forests were supposedly connected. Location Tropical forests of Upper Guinea (West Africa) and Lower Guinea (Atlantic Central Africa) and the forest-savanna mosaic of the DG extending from eastern Ghana to Benin. Methods Four hundred and twenty-nine D. benthamianus samples from West to Central Africa were genotyped with 11 nuclear microsatellite markers. After detecting geographically coherent gene pools, their genetic diversity and differentiation were estimated and their demographic histories were inferred using coalescent simulations and approximate Bayesian computation ( ABC) tests. Results Five parapatric gene pools were identified: three in Lower Guinea, one in Upper Guinea and one in the DG. ABC tests indicate that the DG gene pool probably originates from the admixture of adjacent Upper and Lower Guinean gene pools, with a higher contribution from Upper Guinea, at a timeframe consistent with the early Holocene (around 13-7 ka). The lower genetic diversity documented in the DG could result from a founder effect and/or from a demographic decline consistent with the Holocene climatic pejoration documented around 3 ka. Main conclusions This phylogeographical study inferring the history of the DG populations of D. benthamianus is consistent with palaeovegetation data that suggest that the forest flora of the DG might be essentially relicts of the early Holocene period when the Guineo-Congolian forest reached its maximum geographical distribution. [ABSTRACT FROM AUTHOR]

Aim The forest steppe of the Transylvanian Plain is a landscape of exceptionally diverse steppe-like and semi-natural grasslands. Is this vegetation a remnant of a once continuous temperate forest extensively cleared by humans, or has the area, since the last glacial, always been a forest steppe? Understanding the processes that drive temperate grassland formation is important because effective management of this biome is critical to the conservation of the European cultural landscape. Location Lake Stiucii, north-western Romania, central-eastern Europe. Methods We analysed multi-proxy variables (pollen, coprophilous fungi, plant macroremains, macrocharcoal) from a 55,000 year discontinuous sequence ( c. 55,000-35,000; 13,000-0 cal. yr bp), integrating models of pollen-based vegetation cover, biome reconstruction, global atmospheric simulations and archaeological records. Results Needleleaf woodland occurred during glacial Marine Isotope Stage ( MIS) 3, but contracted at the end of this period. Forest coverage of c. 55% (early Holocene) and 65% (mid-Holocene) prevailed through the Holocene, but Bronze Age humans extensively cleared forests after 3700 cal. yr bp. Forest coverage was most widespread between 8600 and 3700 cal. yr bp, whereas grasses, steppe and xerothermic forbs were most extensive between 11,700 and 8600 cal. yr bp and during the last 3700 cal. yr bp. Cerealia pollen indicate the presence of arable agriculture by c. 7000 cal. yr bp. Main conclusions We have provided the first unequivocal evidence for needleleaf woodland during glacial MIS 3 in this region. Extensive forests prevailed prior to 3700 cal. yr bp, challenging the hypothesis that the Transylvanian lowlands were never wooded following the last glaciation. However, these forests were never fully closed either, reflecting dry growing season conditions, recurrent fires and anthropogenic impacts, which have favoured grassland persistence throughout the Holocene. The longevity of natural and semi-natural grasslands in the region may explain their current exceptional biodiversity. This longer-term perspective implies that future climatic warming and associated fire will maintain these grasslands. [ABSTRACT FROM AUTHOR]

Aim Top-down (climatic) controls of fire occurrence are expected to homogenize fire regimes in a given area over long (millennial) temporal scales. Previous investigations in south-eastern British Columbia have shown that bottom-up (local site) factors can override long-term climate as a dominant control. Here, we examine the interactions between fire regime controls using five 5000-year-long lake sediment records. Location All lakes are located in separate watersheds within a 550-km2 region of Engelmann spruce-subalpine fir forest in the Columbia Mountains, British Columbia, Canada. Methods Sedimentary macroscopic (> 150 μm) charcoal analysis was used to produce local fire history records. Fire events were identified by decomposing the charcoal concentration series using the program CharAnalysis. We analysed the temporal coherence of the reconstructed fire events and the distributions of the fire return intervals at all sites and pooled sites by their north-facing or south-facing aspect. Results Since 5000 cal. yr bp, fire frequency was highest between 4250 and 2750 cal. yr bp and lowest from 750 cal. yr bp to the present. Median fire return intervals were shorter on the warmer and drier south-facing slopes (135-190 years) and longer on the cooler and moister north-facing slopes (226-241 years). Significant synchrony existed between sites with similar aspect, but no synchrony was found at sites with opposing aspect, providing evidence for the importance of bottom-up controls. Smoothed fire frequencies suggested that the influence of aspect varied throughout the period and that the importance of aspect could be overridden by other controls. The asynchrony between sites with opposite aspects suggests that local conditions for fire are important spatial controls on the fire regime. Main conclusions Aspect is an important bottom-up control of fire regimes in mid-elevation forests and its influence varies through time. The variability of climate-fire-vegetation interactions in the region needs to be investigated to understand the importance of top-down and bottom-up controls. [ABSTRACT FROM AUTHOR]

Aim Within the last several decades, Grévy's zebra ( Equus grevyi) has undergone a massive reduction in geographical range and population size, largely as the result of human impacts. To place its recent decline in a deeper prehistoric context, and to understand the factors mediating its range and abundance over geological time frames, this study examines the fossil history of Grévy's zebra in equatorial East Africa. Location Equatorial East Africa. Methods Presence/absence data for ungulates recovered from fossil sites spanning the last c. 400,000 years in Kenya and Ethiopia were compiled from the literature and from previously unreported palaeontological sites. Associations between Grévy's zebra and other taxa were examined using principal coordinates analysis and non-random species pairs were identified using a Bayesian approach. Changes in rainfall were reconstructed using the average hypsodonty index of ungulate species from fossil assemblages. Results Grévy's zebra was common during dry phases of the Pleistocene and was found to the south and west of its historical range, coinciding with an expansion of arid grasslands. At the onset of the Holocene, Grévy's zebra was extirpated from southern Kenya and almost completely disappeared from the fossil record. Grévy's zebra was associated with several specialized grazers that became extinct by the end of the Pleistocene. These extinctions and the decline of Grévy's zebra from the Pleistocene to the Holocene are explained by increased precipitation and the consequent loss of arid grasslands at the Pleistocene- Holocene transition. Grévy's zebra is never associated with domestic livestock, unlike the widespread plains zebra. Main conclusions Grévy's zebra thrived in equatorial East Africa during periods of the Pleistocene when environmental conditions favoured an expansion of arid grasslands. Environmental change across the Pleistocene- Holocene transition contributed to decreases in the range size and abundance of Grévy's zebra, setting the stage for the anthropogenic decline observed in recent decades. The spread of pastoralists in the middle Holocene may have additionally contributed to its prehistoric decline. Contemporary climate change warrants further consideration in planning for the long-term survival of Grévy's zebra. [ABSTRACT FROM AUTHOR]

For decades, subfossil shells of the bivalve Mytilus edulis Linnaeus, 1758 in Svalbard have been taken as evidence of higher surface temperatures during the early Holocene because the modern northern occurrence of this mollusc was, until recently, in the southern Barents Sea. Here, we elucidate and discuss the spatial and temporal Late Pleistocene and Holocene distribution of the species within the entire Barents Sea region. The Barents Sea region. Radiocarbon dates of Mytilus shells from the Barents Sea region and information about the present distribution of the species were compiled, including two new radiocarbon dates from north-eastern Spitsbergen. The dataset was divided into time slices, each covering 1000 years, and compared with Holocene temperature variations, ocean current systems and present-day temperature patterns. Maps show the Late Pleistocene and Holocene spatial and temporal distribution of Mytilus edulis in the Barents Sea region. M. edulis was already present in northern Norway about 14,000 cal. yr . It appeared at western Spitsbergen about 11,000 cal. yr , and slowly spread to the rest of the archipelago. The maximum distribution in the region was reached 10,000-7000 cal. yr , coinciding with the Holocene climatic optimum. The species gradually disappeared in the late Holocene and became absent from the northern and eastern parts of the region 3000-1000 cal. yr . Today, M. edulis lives in the southern part and has begun to recolonize the northern parts. The time slices illustrate strong connections between the ocean current regimes, the climate and the distribution of M. edulis. The species settled in the southern part of the Barents Sea region several thousand years before it spread to the northern part during the Holocene climatic optimum. It may even have been completely absent from the region for a short time during the late Holocene cold period. The Holocene distribution of Mytilus implies that the underlying pattern of coastal sea surface temperatures in the region was very stable. [ABSTRACT FROM AUTHOR]

Aim To reconstruct the Late Glacial and Holocene vegetation history of western Tasmania and to test the long-held notion of a replacement of forest by moorland during the mid to late Holocene in western Tasmania, Australia. Location Western Tasmania, Australia. Methods Fossil pollen data were screened with a modern pollen dataset using detrended correspondence analysis and charcoal data were analysed using significance tests. Results At the landscape scale, the distribution of vegetation types in western Tasmania has remained remarkably stable through the post-glacial period. Open moorland has dominated the landscape since the Late Glacial, while rain forest expanded at that time in to areas which it occupies today. Vegetation development in the Holocene is markedly different and charcoal values are significantly higher when compared with those in previous interglacial periods. Main conclusions The dominant paradigm of a replacement of rain forest by moorland across western Tasmania during the mid to late Holocene is not supported by this regional analysis. The arrival of humans in Tasmania during the Last Glacial Stage provided an ignition source that was independent of climate, and burning by humans through the Late Glacial period deflected vegetation development and facilitated the establishment of open moorland in regions occupied by rain forest during previous interglacial periods. It is concluded that the present dominance of the landscape of western Tasmania by open moorland is the direct result of human activity during the Late Glacial and that this region represents an ancient cultural landscape. [ABSTRACT FROM AUTHOR]

Aim To use pollen data, numerical analysis and modelling to reconstruct late Quaternary vegetation and climate in a complex, mountainous environment. Location Georgia (Caucasus region). Methods Pollen data were assembled from various sources and used to map: (1) changing frequencies of individual taxa; (2) vegetation changes; and (3) reconstructed climatic parameters for the past 14,000 years. Numerical analyses were performed using two-way indicator species analysis (twinspan), detrended correspondence analysis (DCA), the modern analogue technique (MAT) and weighted averaging (WA). Results Mapping of pollen taxa showed that Chenopodiaceae, Artemisia and Ephedra were most abundant in the study area during the late-glacial. Betula and Corylus expanded during the early Holocene, yielding to Abies, Carpinus, Fagus, Quercus and Castanea. Picea, Pinus, Juglans and Ostrya-type expanded during the late Holocene. Mixed forests grew in the moist, Black Sea refugium throughout the late Quaternary. Elsewhere in Georgia, the Pleistocene–Holocene transition is recorded as a shift from desert-steppes to oak-xerophyte communities and mixed forests. This kind of vegetation remained relatively stable until the mid–late Holocene, when coniferous forests and mountain grasslands advanced. DCA showed that rainfall was most strongly correlated with pollen composition in the study area ( r2 = 0.55). No temperature signal was detected. A weighted-averaging transfer function linking pollen percentages to annual precipitation was selected over a MAT model as it performed better when applied to a validation data set. Rainfall reconstructions indicate widespread aridity at the terminal Pleistocene, followed by a gradual increase in precipitation, peaking during the mid Holocene (7000–4000 cal. yrbp) and generally decreasing thereafter. Main conclusions On a regional scale, the results confirm those from previous studies of palaeovegetation and palaeoclimate in Western Asia. On a local scale, reconstructions from individual sites often diverge from the regional trend because of edaphic changes, ecological succession, human impacts and other disturbances. Some of these factors are probably responsible for the increasing heterogeneity of Georgia’s vegetation in the latter half of the Holocene. [ABSTRACT FROM AUTHOR]

Aim To reconstruct the historical biogeography of Pinus sylvestris in the Cantabrian Range (Iberian Peninsula) during the Holocene, and to consider the interactions between vegetation dynamics, climate change and the role of man in the present-day distribution of the species. Location The study site is a mire (1300 m a.s.l.) at Vega de Viejos, on a south-facing slope of the western Cantabrian Range, Spain. The region’s present-day landscape is almost treeless, with the exception of some patches of Quercus pyrenaica and a few copses of Salix and Betula along stream banks. Methods Tree macrofossils from Vega de Viejos were studied by transmitted light and dark-field reflection microscopy; strobili were subjected to comparative morphological analyses. Two Pinus macrofossils were dated by conventional 14C methods. Results The taxonomic accuracy achieved in the identification of the macrofossils provided new information regarding the Holocene history of Pinus sylvestris in this territory. Ninety-five cones of this species were identified; in fact, more than 80% of the 36 identified wood remains were of Pinus gr. sylvestris. Radiocarbon dating revealed that the forest to which the fossils belonged was present until at least 2170 ± 50 yr bp– its disappearance was therefore relatively recent. Main conclusions Pinus sylvestris suffered long-term isolation, and after the Würm glacial period tended to migrate towards the east. In western Iberia, a temperate climate and autogenic succession favoured broadleaved taxa at the expense of Pinus. Late Holocene human disturbances may have further accelerated the decline of P. sylvestris; in the Cantabrian Range, only a few stands on southern slopes have persisted until the present day. The history of the capercaillie ( Tetrao urogallus), a bird characteristic of pure or mixed Palaeartic coniferous forests, was almost certainly affected by the demise of these forests in this area. Cantabrian capercaillies are the only members of this species that live in purely deciduous forests, perhaps a recent adaptation to the regional extinction of pines. Today’s P. sylvestris and capercaillie populations are now highly fragmented and their future, given the predictions of global climate change, is uncertain. [ABSTRACT FROM AUTHOR]

Aim We aim to propose validated, spatially explicit hypotheses for the late Quaternary distribution of the Brazilian Atlantic forest, and thereby provide a framework for integrating analyses of species and genetic diversity in the region. Location The Atlantic forest, stretching along the Brazilian coast. Methods We model the spatial range of the forest under three climatic scenarios (current climate, 6000 and 21,000 years ago) with BIOCLIM and MAXENT. Historically stable areas or refugia are identified as the set of grid cells for which forest presence is inferred in all models and time projections. To validate inferred refugia, we test whether our models are matched by the current distribution of the forest and by fossil pollen data. We then investigate whether the location of inferred forest refugia is consistent with current patterns of species endemism and existing phylogeographical data. Results Forest models agree with pollen records and predict a large area of historical forest stability in the central corridor (Bahia), as well as a smaller refuge (Pernambuco) along the Brazilian coast, matching current centres of endemism in multiple taxa and mtDNA diversity patterns in a subset of the species examined. Less historical stability is predicted in coastal areas south of the Doce river, which agrees with most phylogeographical studies in that region. Yet some widely distributed taxa show high endemism in the southern Atlantic forest. This may be due to limitations of the modelling approach, differences in ecology and dispersal capability, historical processes not contemplated by the current study or inadequacy of the available test data sets. Main conclusions Palaeoclimatic models predict the presence of historical forest refugia in the Atlantic rain forest and suggest spatial variation in persistence of forests through the Pleistocene, predicting patterns of biodiversity in several local taxa. The results point to the need for further studies to document genetic and species endemism in the relatively poorly known and highly impacted areas of Atlantic rain forests of north-eastern Brazil. [ABSTRACT FROM AUTHOR]

Aim To assess the genetic and archaeological evidence for the migration of modern humans out of Africa to the circum-Pacific region and compare the migration patterns with Late Pleistocene and Holocene changes in sea level and climate. Location Southern and eastern Asia, Australia, and Oceania. Methods Review of the literature and detailed compilations of data on early human settlements, sea level, and climate change. Results The expansion of modern humans out of Africa, following a coastal route into southern Asia, was initially thwarted by a series of large and abrupt environmental changes. A period of relatively stable climate and sea level from c. 45,000 yrbp to 40,000 yrbp supported a rapid coastal expansion of modern humans throughout much of Southeast Asia, enabling them to reach the coasts of northeast Russia and Japan by 38,000–37,000 yrbp. Further northwards, migrations were delayed by cold northern climates, which began to deteriorate rapidly after 33,000 yrbp. Human migrations along the coast of the Bering Sea into the New World appear to have occurred much later, c. 14,000 yrbp, probably by people from central Asia who were better adapted to cold northern climates. Cold, dry climates and rapidly changing sea levels leading into and out of the Last Glacial Maximum inhibited coastal settlement, and many of the sites occupied prior to 33,000 yrbp were abandoned. After 16,000 yrbp, the sea-level rise slowed enough to permit coastal ecosystems to develop and coasts to be re-colonized, but abrupt changes in climate and sea level inhibited this development until after 12,000 yrbp. Between 12,000 yrbp and 7000 yrbp there was a dramatic increase in reef and estuary/lagoon ecosystems, concurrent with a major expansion of coastal settlements. This early Holocene increase in coastal environments and the concomitant expansion of human coastal-resource exploitation were followed by corresponding declines in both phenomena in the mid-Holocene, c. 6000–4000 yrbp. This decline in coastal resources is linked to the drop in sea level throughout the Pacific, which may have caused the widespread population dislocations that ultimately led to the human expansion throughout Oceania. Main conclusions Climate and sea-level changes played a central role in the peopling of the circum-Pacific region. [ABSTRACT FROM AUTHOR]

Aim This study aims to separate regional and local controls on Holocene vegetation development and examine how well pollen records reflect climate change in a semi-arid region. The relative importance of climate and human activity as agents of vegetation change in the Sahel during the late Holocene is also considered. Location Jikariya Lake, an inter-dune depression in the Manga Grasslands of north-eastern Nigeria. Methods Pollen and charcoal were used to provide a record of Holocene vegetation history. Palaeoclimate and hydrological changes were reconstructed from sedimentary and geochemical data. Regional and local influences were separated by comparing the evidence obtained from Jikariya Lake with previously published data from the Manga Grasslands. Results The Manga Grasslands experienced a prolonged wet period during the early and mid-Holocene, during which swamp forest vegetation with Guinean affinities ( Alchornea, Syzygium, Uapaca) occupied the inter-dune depressions. However, variation in the pollen records between sites suggests that their establishment was dependent on conditions being locally favourable, rather than being directly coupled to regional climate. The pollen records from the Manga Grasslands are more consistent in suggesting the colonization of the dunefields by trees associated with Sudanian savanna (Combretaceae, Detarium) c. 8700 cal. yrbp. The Jikariya Lake pollen data are in accordance with the sedimentological and geochemical data from the region in indicating that the onset of arid conditions occurred progressively during the late Holocene (from c. 4700 cal. yrbp). Abrupt changes in pollen stratigraphy, recorded at other Manga Grasslands sites 3500 cal. yrbp, appear to be the product of the local passing of ecological thresholds. The dunefield vegetation (Sahelian savanna) appears to have been resilient to (or at least palynologically silent regarding) to the climatic variability of the late Holocene. Main conclusions While climate appears to have been the primary control on vegetation development in the Manga Grasslands during the Holocene, local conditions (particularly depression size and sand influx) had a strong influence on the timing of pollen stratigraphic changes. Anthropogenic influences are difficult to detect, even during the late Holocene. [ABSTRACT FROM AUTHOR]

Aim To investigate the influence of Holocene climatic and human-induced changes on a region of high biodiversity in southern Peruvian Amazonia. Location Four palaeoecological records from separate lakes within a lake district close to the modern city of Puerto Maldonado, Peru. Results The lakes provide a palaeoecological record spanning the last 8200 years. A mid-Holocene dry event is documented in all of the records that extend back > 6000 years. The dry event appears to have lasted from c. 7200 yrbp until c. 3300 yrbp. The onset of wetter conditions coincides with the formation of the youngest of the four lakes. The earliest occupation of these sites is inferred from the presence of charcoal at 7200 yrbp, and the first crop pollen is found at 3630 yrbp. Lakes that were regularly occupied were colonized soon after they formed. A reduction in charcoal concentration and the absence of crop pollen after c. 500 bp in all lakes is consistent with site abandonment following conquest. Main conclusions The mid-Holocene dry event is suggested to be part of a time-transgressive drying that tracked from north to south in both the Andes and the Amazon lowlands. The last millennium may represent the period of highest sustained lake levels within the Holocene. The proximity of the four lakes allows a landscape-scale analysis of the spatial extent of human disturbance centred on a known site of human occupation and reveals the highly localized nature of pre-Columbian anthropogenic disturbance in Amazonian landscapes. Inferences regarding widespread pre-Columbian landscape modification by indigenous peoples must take into account key site attributes, such as seasonality and proximity to rivers. [ABSTRACT FROM AUTHOR]

Aim We analysed lake-sediment pollen records from eight sites in southern New England to address: (1) regional variation in ecological responses to post-glacial climatic changes, (2) landscape-scale vegetational heterogeneity at different times in the past, and (3) environmental and ecological controls on spatial patterns of vegetation. Location The eight study sites are located in southern New England in the states of Massachusetts and Connecticut. The sites span a climatic and vegetational gradient from the lowland areas of eastern Massachusetts and Connecticut to the uplands of north-central and western Massachusetts. Tsuga canadensis and Fagus grandifolia are abundant in the upland area, while Quercus, Carya and Pinus species have higher abundances in the lowlands. Methods We collected sediment cores from three lakes in eastern and north-central Massachusetts (Berry East, Blood and Little Royalston Ponds). Pollen records from those sites were compared with previously published pollen data from five other sites. Multivariate data analysis (non-metric multi-dimensional scaling) was used to compare the pollen spectra of these sites through time. Results Our analyses revealed a sequence of vegetational responses to climate changes occurring across southern New England during the past 14,000 calibrated radiocarbon years before present (cal yrbp). Pollen assemblages at all sites were dominated by Picea and Pinus banksiana between 14,000 and 11,500 cal yrbp; by Pinus strobus from 11,500 to 10,500 cal yrbp; and by P. strobus and Tsuga between 10,500 and 9500 cal yrbp. At 9500–8000 cal yrbp, however, vegetation composition began to differentiate between lowland and upland sites. Lowland sites had higher percentages of Quercus pollen, whereas Tsuga abundance was higher at the upland sites. This spatial heterogeneity strengthened between 8000 and 5500 cal yrbp, when Fagus became abundant in the uplands and Quercus pollen percentages increased further in the lowland records. The differentiation of upland and lowland vegetation zones remained strong during the mid-Holocene Tsuga decline (5500–3500 cal yrbp), but the pattern weakened during the late-Holocene (3500–300 cal yrbp) and European-settlement intervals. Within-group similarity declined in response to the uneven late-Holocene expansion of Castanea, while between-group similarity increased due to homogenization of the regional vegetation by forest clearance and ongoing disturbances. Main conclusions The regional gradient of vegetation composition across southern New England was first established between 9500 and 8000 cal yrbp. The spatial heterogeneity of the vegetation may have arisen at that time in response to the development or strengthening of the regional climatic gradient. Alternatively, the differentiation of upland and lowland vegetation types may have occurred as the climate ameliorated and an increasing number of species arrived in the region, arranging themselves in progressively more complex vegetation patterns across relatively stationary environmental gradients. The emergence of a regional vegetational gradient in southern New England may be a manifestation of the increasing number of species and more finely divided resource gradient. [ABSTRACT FROM AUTHOR]

Aim Previous studies have failed to reconstruct the regional post-glacial migration pattern of Abies alba in southern France. Based on the first exhaustive compilation of palaeoecological data in this region, we present the state-of-the-art and attempt to synthesize the available information concerning glacial refugia and post-glacial migration, and analyse the information with regard to climate and orography. Location South-western Alps and adjacent areas, southern France. Methods The work compiles the available palaeoecological data in the south-western Alps (52 sites, 290 radiocarbon dates). The post-glacial migration pattern of Abies alba is reconstructed based on 22 selected palynological analyses (11 well-dated reference sites and 11 supplementary ones). Results The geographical patterns of approaching area limit, immigration and expansion are reconstructed at the scale of the southern French Alps. Main conclusions Despite previous assertions, the evidence of refugia in southern France is non-existent. The late-glacial records of fir pollen, previously interpreted in French Mediterranean regions and on adjacent foot-hills as possibly reflecting regional refugia, most probably correspond to reworking phenomena or long-distance pollen transport. Fir migration, originating in the Apennine refugia and through the south-western extremity of the Alps, was extremely rapid in the southern French Alps, only spanning a few centuries between 10,100 and 9800 cal. yrbp. The subsequent spread of fir populations was controlled by local parameters, such as the aridity of the inner valleys, which resulted in a delayed expansion in comparison to other regions. Abies almost disappeared from the south-western Alps during the Roman era, around 2000 cal. yrbp. [ABSTRACT FROM AUTHOR]

Aim To use surface pollen and vegetation relationships to aid the interpretation of a Holocene pollen record. Location South-west Tasmania, Australia. Methods A survey was undertaken of surface-pollen samples from the major regional vegetation types: alpine, rain forest and moorland. Relationships between vegetation type and surface-pollen representation were analysed usingtwinspan classification and ordination. A core was retrieved from moorland vegetation, and interpretation of the fossil pollen sequence was aided using relationships detected in our surface-pollen analysis. Results Regional vegetation types are reflected in the pollen rain of south-west Tasmania, despite the over-representation of important rain forest tree species in samples from non-forest sites.twinspan classification of the surface-pollen samples identified the following indicator pollen taxa for each vegetation type: Astelia alpina (alpine); Lagarostrobos franklinii (rain forest); Leptospermum and Melaleuca (moorland). Detrended correspondence analysis of the surface-pollen samples clearly separates samples from each vegetation type. Correlation of the ordination axes with environmental data identified a dominant temperature/altitudinal gradient in the surface-pollen data ( R = 0.852/0.844). Application of the results of the surface-pollen analysis to the fossil sequence revealed that fire-promoted moorland has dominated the local environment around the core site for the entire Holocene. Changes in fossil pollen composition also suggest that temperatures increased through the Late Glacial to peak in the mid-Holocene and declined thereafter, a trend consistent with other sites in the region. Main conclusions Pollen spectra can successfully be used to predict local vegetation in south-west Tasmania. At least this part of inland south-west Tasmania has remained forest-free throughout the Holocene, conflicting with the dominant palaeoecological paradigm of a mid-Holocene dominated by rain forest. A comparison with pollen records from moorland vegetation across the region suggests that fire-promoted moorland has dominated the landscape since the Late Glacial. We suggest that burning by people through the Late Glacial (if not earlier) facilitated the spread of moorland throughout the region, greatly restricting the expansion of rain forest. The continued influence of fire throughout the Holocene in this perennially wet landscape argues for a revision of the dominant human-occupation model that depicts an abandonment of the interior of south-west Tasmania in the Late Glacial in response to the expansion of rain forest. [ABSTRACT FROM AUTHOR]

In this study, charcoal-based data for Pinus cembra L . (arolla pine) were gathered from soil and travertine sequences in order to reconstruct its historical biogeography at the landscape level in the inner western Alps during the Holocene. The study sites are located between 1700 and 2990 m a.s.l., in the southern (Queyras Massif and Ubaye Valley) and the northern (Maurienne Valley) parts of the inner French Alps. Charcoal fragments were extracted from sediments by water sieving, using meshes of 5, 2, 0.8 and 0.4 mm. The charcoal mass of P. cembra was determined in each charcoal assemblage. Accelerator mass spectrometry and conventional 14C measurements were used to date the fragments. Supported by 40 14C datings, the fragments show that, over 2000 m a.s.l., P. cembra accounts for around 40% (mean value) of identified fragments. Data reveal that arolla pine once extended between 260 and 375 m above the present-day local tree lines. It was established in the southern and the northern French Alps from at least c. 9000 and 6000 cal yr bp, respectively. While present-day populations of P. cembra are very fragmented in the inner French Alps, charcoal records indicate large past occurrences of this tree since the early Holocene. Human disturbance since the Neolithic seems to be the main reason for the regression of the arolla pine woodlands. On the south-facing slopes of the study sites, currently deforested, this species extended up to 2800 m a.s.l. In the northern areas, charcoal records of the P. cembra expansion are consistent with the regional pollen archives, but in the southern massifs charcoal records indicate its presence c. 2600 years earlier than other palaeobotanical studies suggest. This discrepancy highlights the necessity to crosscheck data using several different proxies in order to assess the validity of conclusions regarding tree development in space and time. [ABSTRACT FROM AUTHOR]

Our aim was to elucidate the postglacial migration of Viola rupestris F.W. Schmidt, with its two subspecies, rupestris and relicta Jalas, in Europe, using molecular methods. Norway, Sweden, Finland, England, the Netherlands, France and Switzerland. Isoenzymes were analysed from 49 populations of Viola rupestris s.lat. Based on former experience of variation in the taxon, the following were included: aspartate aminotransferase, leucine/aminopeptidase, and phosphoglucomutase, yielding a total of nine interpretable and six variable (putative) loci. Six multilocus phenotypes were revealed ( A–F). Phenotype A (only one individual) is restricted to northern Norway, B is shared by all populations in northern Norway and an isolated population on the west coast of southern Norway (Møre). Phenotype B comes close to C, co-occurring with D in England, the latter also occurring in southern France. Phenotypes E and F occur in the rest of Europe. Viola rupestris ssp. relicta Jalas, previously known only from northern Scandinavia (northern unicentric), was discovered on the west coast of southern Norway (Møre), making the taxon ‘bicentric’. Populations are connected through a putative migration route from the Grands Causses in southern France (Massif Central) via England and western Norway to northern Scandinavia. The Grands Causses might represent a glacial refugium. [ABSTRACT FROM AUTHOR]

The phylogeography of ‘southern’ species is relatively well studied in Europe. However, there are few data about ‘northern’ species, and so we studied the population genetic structure of the arctic-alpine distributed burnet moth Zygaena exulans as an exemplar. The allozymes of 209 individuals from seven populations (two from the Pyrenees, five from the Alps) were studied by electrophoresis. All 15 analysed loci were polymorphic. The mean genetic diversities were moderately high ( A: 1.99; He: 11.5; P: 65%). Mean genetic diversities were significantly higher in the Alps than in the Pyrenees in all cases. FST was 5.4% and FIS was 10%. Genetic distances were generally low with a mean of 0.022 between large populations. About 62% of the variance between populations was between the Alps and the Pyrenees. The two samples from the Pyrenees had no significant differentiation, whereas significant differentiation was detected between the populations from the Alps ( FST = 2.8%, P = 0.02). Zygaena exulans had a continuous distribution between the Alps and the Pyrenees during the last ice age. Most probably, the species was not present in Iberia, and the samples from the Pyrenees are derived from the southern edge of the glacial distribution area and thus became genetically impoverished. Post-glacial isolation in Alps and Pyrenees has resulted in a weak genetic differentiation between these two disjunct high mountain systems. [ABSTRACT FROM AUTHOR]

Abstract Long-distance plant dispersal explains the rapid northward migration of plant species during the Holocene but the mechanisms by which it occurred are poorly understood. Given that Native Americans spread numerous cultigens over thousands of kilometres during the late Holocene, I examined historical literature for evidence of non-cultigen dispersal or cultivation in North America's eastern woodlands. Cultivation references are included because a strong relationship between dispersal and indigenous flora husbandry is assumed. Sixty-seven texts describing Native American lifestyle, cultural activities, and land management reported some form of plant use. Most accounts, however, focus on cultigen production or the use of indigenous flora for medicine or food without mention of dispersal. Twenty-four of the texts described the trade, transport, or cultivation of plants indigenous to eastern North American woodlands. Most accounts focus on the informal production of food plants, especially trees and shrubs. Confounding these reports was clear evidence of observer bias, limited botanical knowledge, acculturation, and secrecy by Native American informants. Because of these shortcomings, the likelihood of widespread long-distance plant dispersal by Native Americans could not be determined using historical literature. This activity was either not widespread or was not observed by, or revealed to, Europeans. To adequately test the Native American plant dispersal hypothesis, direct evidence from other sources (e.g. archaeobotancial data) will be required. [ABSTRACT FROM AUTHOR]

Aim Aim Investigate: (1) the role of human impact in shaping the landscape and particularly the initiation of blanket bog; (2) the short-lived abrupt changes and their causation; (3) the phenomenon of large-scale upland peat erosion to answer the question of when and why erosion of upland blanket peat commenced in the Connemara uplands. Location Lough Maumeen in the Maumeen Gap, Connemara, Western Ireland. Methods Pollen, sedimentary analysis and 14 C dating on the lake sediment cores. Results Pollen diagrams, charcoal fragments, bulk and dry densities, mineral content (or loss-on-ignition), whole core magnetic susceptibility, specific magnetic susceptibility for the core profile. Main conclusions Pine-dominated woodland developed from 9250 BP. Human activities effected the deforestation between 5050–4000 BP. Peat bog initiated on the wet hollow ground in the gap during the elm decline. The major expansion of blanket bog landscape in the upland commenced at 4000 BP following immediately the Taxus decline. Human impact was the dynamic force responsible for the destruction of the woodland and the formation of blanket bog in the upland. Three episodes of short-lived erosion events were identified between 8650–8400 BP, 5450–5250 BP, and 600–200 cal. BP, respectively. They are very different from each other in their causation. Large-scale peat erosion is a recent phenomenon. It has been caused by intensive sheep grazing, which has been extended to the upland blanket bogs since the late eighteen century. [ABSTRACT FROM AUTHOR]

Aim Holocene plant migration rates appear to greatly exceed measured dispersal distances. This is a feature of species with all dispersal mechanisms and in all communities. The role of dispersal by large mammalian herbivores is explored as a mechanism that accounts for the observed dispersal rates. Methods A simple model was constructed that took into account herbivore dispersal and how migration rates might vary with herbivore territory size, gut survival and probability of consumption. Results Even at relatively low probabilities of consumption and gut survival, dispersal by animals within large territories could account for observed rates of dispersal in the palaeorecord. Animals with small territory sizes could not produce large enough rates of dispersal. Main conclusions As many modern day grassland plants appear to survive gut passage, endozoochory by large mammalian herbivores could be the main mechanism for long-distance dispersal of herbaceous species. [ABSTRACT FROM AUTHOR]

SummaryThe relationship between the diversity of higher plant macrofossils in surface sediments of lakes and the surrounding vegetation is examined in two mountain regions; Grødalen in central Norway and the south-east Cairngorms in Scotland. Two lake sediment cores from each area were also analysed to examine vegetation history and to estimate changes in biodiversity through the Holocene. The diversity of present day vegetation in each region was estimated using both quadrat data and classified satellite images of the study areas. The mean surface sample macrofossil representation of species recorded in quadrats collected within 250 m of the lakes was c. 17%. This figure drops to only c. 2% when the satellite imagery of the same area is used to provide a maximal species list. The macrofossil data from the Norwegian cores show that deglaciation in this region occurred earlier on the mountain summit than in the valley and that the maximum tree line elevation was during the interval 9100–4400 14C yr BP. In the Cairngorms the maximum tree line elevation was prior to c. 4500 14C yr BP. The changes in higher plant diversity recorded at these sites through the Holocene show that c. 4000 14C yr BP the reduction in the tree line resulted in decreased β-diversity at higher altitudes but an increase at the lower altitude as the forest cover opened up. Under conditions of climatic warming it is likely areas that come to lie below the tree line will experience reduced diversity and that a permanent loss of biodiversity would result from a severe reduction in the area above the tree line. [ABSTRACT FROM AUTHOR]