Late Glacial Holocene Research Articles

Deformation of terrace surfaces in the Bystrzyca River valley, central Sudetic Foreland, SW Poland

This article addresses the development of Pleistocene terraces in the Bystrzyca River catchment (Sudetic Foreland, Southwestern Poland) in the vicinity of the Sudetic Marginal Fault, within the Roztoka–Mokrzeszów Graben. Nineteen research sites located within the Świdnica Plain are documented in this paper, representative of terraces of the Bystrzyca and its Piława and Witoszówka tributaries, with reporting on analyses of structure, grain size, petrography, quartz-grain morphoscopy, and heavy minerals. The Bystrzyca River, flowing in the largest and deepest valley in the Sowie Mountains, crossing the fault zone and extending into the Sudetic Foreland, has been influenced by significant tectonic and glacial events. During the Middle Pleistocene a fluvial piedmont fan was formed and survives as traces of higher-level (pre-Saalian) terraces. The main fluvial terraces are recognized as follows: an Upper Terrace, from the Saalian, a Middle Terrace from the Upper Pleistocene Last Glacial (Weichselian) and, in the valley bottom, a Lateglacial–Holocene Lower Terrace and a Holocene Lowermost Terrace. The sediments forming these terraces document a complex history of tectonic uplift, glacio-isostatic rebound, and climatic changes. Notable features include a sequence of alluvial fans and terraces shaped by neotectonic activity, particularly during the Late Quaternary.

First experience on optically stimulated luminescence (OSL) dating of the crest relief deposits of the Tobol-Ishim interfluve

Using optically stimulated luminescence dating, the Late Pleistocene-Holocene deposits of the crest relief of the Tobol-Ishim interfluve (southwest of the Western Siberian Plain, Russian Federation), footslope colluvial deposits on the right-bank terrace of the Ishim River valley and dune sands in the Tobol River valley were studied for the first time. The first obtained luminescence ages provide older ages of crest deposits, than previously assumed, from 33.5±1.5 to 25.8±1.3 ka. The formation of the footslope colluvial cover on the right bank of the Ishim River valley began ~22 ka ago. Dune pinery sands in the Tobol River valley relate to a later stage of aeolian accumulation and were formed due to local wind reworking of the alluvial deposits of the youngest river terrace in the Late Glacial-Holocene.

The Neapolitan Yellow Tuff record in the Gaeta Gulf (Eastern Tyrrhenian margin, Southern Italy)

Abstract. The Neapolitan Yellow Tuff caldera-forming eruption (ca. 15 kyr) is a large event that occurred at Phlegrean Fields during the Late Glacial–Holocene time span. The eruptive products represent a widespread isochronous marker that links the marine and terrestrial stratigraphic record of the central Mediterranean and Northern Europe sequences. In this research, we describe the stratigraphic signature of the NYT deposits in the Late Glacial–Holocene shelf sequence of the Gulf of Gaeta (northern Campania region, southern Tyrrhenian Sea) throughout the seismo-stratigraphic interpretation of a grid of high and very high-resolution Chirp seismic profiles. The seismo-stratigraphic data allowed to individuate in the Upper Pleistocene–Holocene stratigraphic architecture a continental shelf characterized by an offlap prograding succession followed by a very thick transgressive onlapping unit, and by an upper highstand unit mainly characterized by undulations probably linked to gas-prone sediment. The NYT reflector observed was parallel and with a high amplitude. It was continuously detected from the shelf to the slope within transgressive deposits. On the inner shelf, its continuity was interrupted by shallow gas pockets. The NYT depths ranges from 2 m b.s.f. on the slope to 38 m b.s.f. on the continental shelf. The NYT event appeared to have played a key role in controlling the stratigraphic architecture of the studied area during the last transgression, acting as a trigger for the formation of the aggradational sedimentary successions fed by pyroclastic and volcaniclastic deposits.

NEW RADIOCARBON DATES FROM POLISH INLAND DUNES POINT TO PREVALENCE OF HUMAN IMPACT ON DUNE MOBILITY

ABSTRACTThe timeframes of Holocene anthropogenic dune remobilization in Central Europe remain less studied compared to those of Late Glacial climatically controlled dune formation. The present contribution aims to reinforce existing knowledge on the chronology of Late Glacial–Holocene dune activity and stability, as well as to reveal the scale of human impact on dune remobilization. Accelerator mass spectrometry radiocarbon (AMS 14C) dating and calibration of the results are reported from paleosol horizons buried in inland dune deposits that occur in Central and Eastern Poland. Twenty-three new dates are based on charcoal samples collected at 13 sites. From each of the investigated sites, at least one AD date is obtained, indicating that buried paleosols of such young age are far more widespread in Polish dunes than reflected in previous studies. The widespread preservation of these paleosols under cover of aeolian sand reflects the extent of the anthropogenic dune formation phase that peaked during the Medieval and Early Modern periods.

Environment and Plant Use at La Tourasse (South-West France) at the Late Glacial–Holocene Transition

Abstract The aim of this study is to present new data on vegetation dynamics and plant collecting practices during the Late Glacial and the Early Holocene in southwestern France. La Tourasse cave is located in the Pyrenean piedmont plain, where the Azilian cultural complex was initially defined. The last excavations of the site took place in the 1980s and 1990s and the recovered materials are currently being studied or revisited from a multidisciplinary perspective. We present here the results of the charcoal analysis performed on La Tourasse’s Azilian (ca. 13000–11500 cal. BP) and Mesolithic (ca. 10500–9000 cal. BP) levels, complemented by the study of a small seed assemblage. Our results document the shift from an open landscape towards a forested environment, with the gradual passage from open vegetation dominated by shrubs of the Rose family (Prunus spp.) to the mixed oak forest, which speaks in favor of the biochronological coherence of this sequence. However, marked differences in taxonomic richness and state of the wood from one level to another, unrelated to the prevailing environmental conditions, suggest variable behavior of humans toward wood that could be the result of differing mobility strategies, hearth functionalities, or taxonomic preferences.

Vegetation dynamics and land-use change at the Neolithic lakeshore settlement site of Ploča Mičov Grad, Lake Ohrid, North Macedonia

Detailed knowledge about the interactions between vegetation, climate and land use during the Mesolithic and Neolithic, at the transition from foraging to farming, is still scarce in the Balkans. Here we present a palaeoecological study combining pollen, spores and charcoal found in sedimentary cores from Lake Ohrid, Ploča Mičov Grad, North Macedonia, with a particular focus on the vegetation dynamics during the Late Glacial-Holocene and the Mesolithic-Neolithic transitions. Our record begins at ca. 13,500 cal bp (11,550 cal bc) when partially open vegetation, consisting mainly of Pinus, Abies and deciduous Quercus tree stands grew on the hilly flanks of the bay of Ploča. From 12,650 cal bp (cal 10,700 bc), herbs dominated the record until the onset of the Holocene (ca. 11,700 cal bp; 9750 cal bc), when increasing temperatures led to the establishment of pine-deciduous oak forests including Alnus, Fraxinus ornus, Tilia, Ulmus and Abies. These forests persisted until 7,500 cal bp (cal 5550 bc), when deforestation started due to Neolithic land use. This first phase of Neolithic activities in the Ploča Mičov Grad area precedes the earliest archaeological structures so far recorded by almost 1,000 years. Our data suggest two phases of human land use between 7,500 and 6,300 cal bp (5550–4350 cal bc), when high values of Cerealia type pollen and other cultural indicators indicate intense arable and pastoral farming activities. Once human activities decreased, forests were able to re-establish quickly (within 100–250 years), although the composition changed with disturbance-adapted Ostrya type (mostly Ostrya carpinifolia) and Fagus becoming more important. We conclude that forests were resilient to early human disturbance, despite intensive land use and logging activities gradually leading to forest composition changes. Many of these composition changes can still be seen today, suggesting the legacy of Neolithic farmers is still present in today’s landscape.

THE MAIN RESULTS OF THE SCIENTIFIC STUDIES OF THE INSTITUTE OF NATURE MANAGEMENT OF THE NATIONAL ACADEMY OF SCIENCES OF BELARUS IN THE AREA OF MODERN GEODYNAMICS AND PALEOGEOGRAPHY OF THE CENOZOIC

The main results of scientific studies in the area of modern geodynamics and paleogeography of the Cenozoic obtained for the recent fifteen years are given in the article. The schemes of their area distribution are created on the base of the indicates study of modern endogenic and technogenic processes, the
 influence of geological factors on population dwelling comfort is characterized, the geochemical background of the quaternary sediments and radon field on the territory of Belarus are characterized. The palynological data for the sediments of the Muravinsky Interglacial and the Late Glacial-Holocene are obtained in the frameworks of the study of the dynamics of the adjoined regions of Lithuania, Poland, Ukraine and Russia, the paleorelief and paleolandscape of the optimal phases of the named time intervals of the quarter are reconstructed, corresponding chronostratigraphic schemes are developed and approved, the interregional chronostratigraphic and paleoclimatic correlation of paleogeografic events of the Pleistocene and the Late Glacial-Holocene to the adjacent regions to Belarus is done.

Early Holocene presence of Norway spruce (Picea abies) on a high mountain nunatak in the Swedish Scandes: A further contribution to the biotic composition of the first deglaciated landscape and a link between past and present

A megafossil wood remnant of Norway spruce (Picea abies (L.) Karst.) was retrieved from a high-elevation nunatak in the southern Swedish Scandes. The site was nearly 600 m higher than the present-day treeline. These circumstances comply with analogous earlier recoveries, indicating presence of spruce at high elevations in the Scandes, several thousands of years prior to inferences made by pollen analysis. Radiocarbon-dating yielded a median age of 9300 cal a BP. This result adds firm detail and adheres to ongoing reappraisal of the structure and biodiversity of the late-glacial and early Holocene mountain landscape, in the light of growing megafossil and molecular genetic evidence.

Late glacial–Holocene record of Southern Hemisphere westerly wind dynamics from the Falkland Islands, South Atlantic Ocean

Abstract The Southern Hemisphere westerly wind belt (SHWW) is a major feature of Southern Hemisphere, midlatitude climate that is closely linked with the sequestration and release of CO2 in the Southern Ocean. Past changes in the strength and position of this wind belt are poorly resolved, particularly across the Pleistocene-Holocene transition, a time period associated with fluctuations in atmospheric temperatures and CO2 levels. We used dust geochemistry, particle size measurements, and paleoecological analyses from a peat sequence in the Falkland Islands, South Atlantic Ocean, to describe changes in the SHWW between 16.0 and 6.5 ka (thousands of years before CE 1950). Wind strength was low at ~51°S before and during the Antarctic Cold Reversal (ACR, 14.9–13.0 ka), intensified between 13.1 and 12.1 ka as atmospheric temperatures increased, and then weakened, reaching a minimum between 12.1 and 10.9 ka during the Early Holocene thermal maximum. Northwesterly air masses became more dominant from 12.0 to 10.2 ka, and wind strength remained low until our record was affected by a storm surge or tsunami ca. 7.8 ka. These data indicate a southward shift in the latitude of the SHWW, from north of 51°S prior to and during the ACR, at ~51°S before the onset of the Holocene, and south of 51°S during the early Holocene thermal maximum. This pattern suggests that the latitude of the SHWW was coupled with atmospheric temperatures through the Pleistocene-Holocene transition.

Environmental changes since 14 ka BP in the southernmost Kuril islands (North-Western Pacific) and regional correlation of events

• New data on climatic changes at the late Pleistocene-Holocene boundary for Kurils. • Climate fluctuations and volcanic ash-falls were mail drivers in lake-mire evolution. • The lake level was highest during warmer and humid climate of the Allerød. • Younger Dryas cooling in the Kuril Islands was less distinct than on the continent. • Pollen record vegetation changes on the land bridge at Late Glacial–early Holocene. Despite considerable progress in understanding Late Pleistocene and Holocene palaeoenvironmental changes worldwide, there are still very few such data for the Far East, and Kuril islands, in particular. Here, the sea level rise during the Late Glacial–Holocene transition was accompanied by a loss of the land connectivity culminating into the development of isolated islands. The ecosystems evolution and importance of isolation for vegetation dynamics on islands are still insufficiently understood. We investigated a unique natural record of environmental change since 14 ka has been recently discovered in lake–mire complex on Kunashir Island. The sediments include 12 tephra layers from Kunashir and Hokkaido volcanoes. The lake level was highest during warmer and humid climate of the Allerød. Diatom assemblages indicated the higher lake level between 12 730–12 160 cal yr BP. The first half of Younger Dryas was characterized by heavy snowfalls. Cooling attributed to the Younger Dryas in the Southern Kurils was less distinct than on the continent. The pollen assemblages recorded changes in vegetation on the land bridge. At the end of the Pleistocene large areas were occupied by birch forests and shrub pine. The broadleaf species first appeared at the end of Allerød. Starting from the Pleistocene-Holocene transition and during the early Holocene , the role of conifers sharply increased. In the middle Holocene the proportion of broadleaf trees in forests increased. Coniferous forests became abundant during the Little Ice Age. Short-tern climatic fluctuations correlate well with regional pattern, particularly with fluctuations of the moisture supply.

Bioaerosols as Evidence of Atmospheric Circulation Anomalies over the Okhotsk Sea and Shantar Islands in the Late Glacial–Holocene

Allochthonous biofossil distribution in the blanket peat bog of Bolshoy Shantar Island was used to analyze atmospheric circulation anomalies in the north-western Okhotsk Sea over the last 12.6 ka. The main aim of this study was to determine periods of intensification of deep cyclones and extreme storms. The composition of bioaerosols is significantly influenced by atmospheric zonal and meridional transport anomalies associated with anomalies of the monsoon system of Northeast Asia, atmospheric fronts and cyclone trajectories. Marine diatoms enter the peatland from the sea during extreme storms and record the passage of sea cyclones in the autumn-winter, whereas the distribution of allochthonous pollen indicates the intensity of continental cyclones. We used Pinus pumila pollen as an indicator of heavy snowfalls and winter cyclone activity. Fifteen phases of extreme storms were identified. Changes in ice coverage also played an important role in bioaerosol emission. During cold periods, emissions of bioaerosols mainly occurred in the open sea, whereas during warm periods, emissions occurred near the coast. The recurrence and intensity of cyclones during the cold seasons depends on displacement of the Siberian High and Aleutian Low. Periods of continental cyclones intensified in spring-summer and coincided with periods of active winter cyclogenesis.

Accuracy of the typological classifications of the Late Glacial and Early Holocene osseous projectile points according to the new AMS dates of selected artifacts from Poland

Late Glacial and Early Holocene bone and antler artifacts are recovered from all over the Polish Lowland. Elements of projectile weaponry, in the form of various points made of osseous raw materials, were an important part of hunter-gatherer equipment of that time. We present the results of AMS dating of a unique collection of thirteen artifacts that had previously been chrono-culturally attributed by means of relative dating using typological approaches only. The results obtained are considered alongside current knowledge and typological arrangements for these types of tools in Europe. We also attempt to determine the interpretative potential of the technological studies to which the discussed osseous points were subjected in terms of possibly identifying processing techniques that can be specific to the given periods of the Stone Age. Suggestions made in this respect are verified through the radiocarbon dating results.

Deep-seated gravitational slope deformation involving glacial evidence in the Rodoretto Valley (NW Alps)

ABSTRACT The Rodoretto Valley (about 25 km2) (Western Alps, NW Italy) shaped in the metamorphic bedrock, covered by Quaternary sediments, is involved in significant deep-seated gravitational slope deformation (DSGSD). A detailed field survey revealed several morpho-structures typically related to DSGSD phenomena (open fractures, doubled ridges, scarps, trenches, counterscarps and bulging reliefs) and other significant gravitational morphologies, here defined as gravitational valleys, not previously reported in geological literature.Fieldwork also allowed us to distinguish various types of glacial sediments, reconstructing the supply basins, relatively dating glacialism to LGM and Late Glacial-Holocene and evaluating their gravitational dislocation. The wide extension of the area characterized by DSGSD and incredibly big dimension of single morpho-structures are the most important recognized features. In particular, we observed that entire sectors of the study area were gravitatively conditioned not only by local slid along the Rodoretto slopes but also by movement towards the nearby and deeper Germanasca Valley.

Lateglacial–Holocene environments and human occupation in the Upper Lena region of Eastern Siberia derived from sedimentary and zooarchaeological data from Lake Ochaul

In the current study, different geochemical and biological proxies, including pollen, non-pollen palynomorphs, ostracods and molluscs, from an AMS radiocarbon-dated sediment core from Lake Ochaul (54°14′N, 106°28′E; 641 m a.s.l.) are presented and discussed. Ochaul is a fresh-water lake and an archaeological site situated ca. 100 km northwest of Lake Baikal in the upper reaches of the Lena River. The 260-cm-long sedimentary record presented here spans the Lateglacial–Holocene interval, between ca. 13,500 cal yr BP and the present. The reconstructions of the postglacial vegetation and lake system development are discussed along with the regional climate dynamics and the hemispheric-scale environmental changes. During the Allerød interstadial the region around Lake Ochaul was dominated by sparse taiga forests. Cooling during the Younger Dryas led to a more open tundra landscape where trees formed patchy forest stands in climatically favourable environments. This facilitated a rapid spread of forests at the onset of the Early Holocene during which the study region was probably characterized by seasonally dry climate controlled by the interplay of higher insolation, lower global sea levels and remaining ice sheets in the North Atlantic region. After thermal and moisture optimum conditions and a maximum spread of forests during the Middle Holocene, continuous cooling and a trend to more open forests landscapes marked the Late Holocene. These long-term trends were interrupted by several relatively short episodes of change in the vegetation and algal records, which coincide with short-term (centennial-scale) Northern Hemisphere cooling/drying phases. This shows that the regional vegetation reacted sensitively to these climate oscillations. Six AMS radiocarbon dates of bone material of large herbivorous animals from the Ochaul archaeological site located at the northern shore of the lake provide important information about prehistoric hunter-gatherers and indicate that activities at the site took place at ca. 27,780–27,160 cal yr BP (95% probability range) as well as during the Mesolithic (ca. 8850–8450 cal yr BP), Early, Middle and Late Neolithic (between ca. 6840 and 5490 cal yr BP) and the Iron Age (ca. 2120–1930 cal yr BP). Our results demonstrate that despite major environmental transformations following the Last Glacial Maximum, Lake Ochaul and the Malaya Anga River valley remained attractive for large herbivores and for prehistoric hunter-gatherers, even during the Middle Neolithic cultural “hiatus” (ca. 6660–6060 cal yr BP) in Cis-Baikal, as documented by the published archaeological records.

Food availability and temperature optima shaped functional composition of chironomid assemblages during the Late Glacial–Holocene transition in Northern Europe

Non-biting midges (Chironomidae) are the most diverse and abundant invertebrate group in boreal lakes and are strongly responsive to climate change, thus they are a valuable palaeoecological proxy for studying aquatic biodiversity response in the face of climate change. Here, we aim to decipher the influence of climate-induced changes on temporal patterns in chironomid assemblages. We apply a novel approach combining traditional taxon-based analysis and species-trait framework to subfossil chironomid assemblages in a sediment core covering the Late Glacial–Holocene transition in Northern Europe. We produce pollen-based July and January temperature reconstructions to characterize past climate fluctuations that show a distinct Early Holocene warming for continuous 1700 years with considerably greater warming in winter (ca. 10 °C) than summer (ca. 4 °C) temperature. Overall, chironomid taxonomic changes were mainly induced by the temperature tolerances and optima of species, as temporal dynamics showed agreement with temperature reconstructions. Our results suggest that vegetation dynamics could also play a role in structuring chironomid assemblages by selecting taxa with the highest ability to exploit available food resources, thus potentially confounding chironomid-based summer climate reconstructions. We demonstrate that the study of the hidden chironomid functional composition could help to identify secondary drivers and thus strengthen the reliability of climate reconstruction based on subfossil chironomids.

Lateglacial and Holocene changes in vegetation and human subsistence around Lake Zhizhitskoye, East European midlatitudes, derived from radiocarbon-dated pollen and archaeological records

The numerous lake and peat sedimentary archives of Central European Russia are ideal for studying the Lateglacial–Holocene climate and vegetation history of the region. However, robustly dated palaeoenvironmental records have only become available in the last decade and are still few and far between. Together with the continuously growing archaeological record and increasing focus on absolute dating of cultural assemblages, such records, where available, offer an excellent opportunity to study human-environment interactions in the region. For this study we selected one of the most detailed regional pollen records, from a 4.5-m-long sediment section from Zmeinoe Mire (56°16′53″ N, 31°15′36″ E) at Zhizhitskoye Lake (165 m a.s.l.). We performed quantitative pollen-based biome reconstruction and constructed a Bayesian age-depth model to ensure maximum chronological control of the sediment succession. To link the reconstructed vegetation changes to human activities, we gathered and summarized available archaeological data from the study area. Our results show that humid conditions and taiga-like patchy forests (spruce, pine, birch) dominated the study region during the Lateglacial. The Early Holocene (ca. 11,650–8000 cal yr BP) was marked by a warming and drying trend indicated by the spread of cool-temperate summergreen broad-leaved trees and shrubs (elm, lime, hazel) and the retreat of spruce. Warmest conditions, expressed by the maximum contribution of temperate deciduous woody taxa to the pollen assemblages, were recorded during the Middle Holocene (ca. 8000–4000 cal yr BP) when Mesolithic and Neolithic hunter-fisher-gatherer groups flourished in the region. The pollen record suggests that the regional climate became cooler and wetter after 4000 cal yr BP, which may explain the decline of the Neolithic pile dwelling settlement Naumovo at Zhizhitskoye Lake around 3800 cal yr BP. Evidence for human impact on natural forest vegetation becomes visible from 5000 cal yr BP, although it remains at modest levels until the end of the Neolithic (3500–3000 cal yr BP). Decline in arboreal pollen percentages intensified after ca. 2800 cal yr BP, indicating the onset of increased deforestation for pasture, farmland, construction material and fuel by Iron Age populations. This is in line with the foundation of the fortified Iron Age Anashkino settlement north of Zhizhitskoye Lake dated to around 2750 cal yr BP. Forest clearance further increased during the second half of the Iron Age (5th century BCE–5th century CE) and again from ca. 1200 cal yr BP after the onset of the Middle Ages.

The Stratigraphy of the Blanket Peatland and the Development of Environments on Bolshoi Shantar Island in the Late Glacial–Holocene

The Stratigraphy of the Blanket Peatland and the Development of Environments on Bolshoi Shantar Island in the Late Glacial–Holocene

A 14000 year multi-proxy alluvial record of ecotone changes in a Fynbos-Succulent Karoo transition in South Africa

To address long-standing questions concerning Southern Hemisphere climate dynamics and palaeoecological change in southern Africa, a Late Glacial-Holocene alluvial sediment sequence from the relatively dry interior year-round rainfall zone in South Africa was investigated. The study site borders the Fynbos biome and Succulent Karoo biome ecotone, and comprises a rare stratified sequence of sandy and organic-rich silt deposits, shown to span the last 14,000 years. A high resolution multi-proxy record of ecological change was derived using pollen, phytoliths and organic geochemical analyses. For the period 14–11 ka, significant valley aggradation occurred under relatively drier conditions, followed, during the early and middle Holocene, by alternating phases of humid and dry events with higher stream energy, slower accumulation or subtle seasonality changes. A transition from relatively humid to more arid conditions at 4–3 ka is identified and is consistent in timing with several interior year-round rainfall zone records. Results revealed alternations of fynbos and karroid elements and C3/C4 grasses throughout the last fourteen thousand years, but did not suggest large-scale biome shifts. The record joins a growing number of sites contributing to debate over the complex atmospheric-oceanic drivers of palaeoclimate in this region. These data broadly fit to the regional pattern for the southernmost interior of South Africa in showing alternating influences from the westerly winter rain systems in the early Holocene, with a greater contribution from subtropical summer rain system during the middle and later Holocene.

Postglacial Vegetation and Climate History of the Oka Plateau (East Sayan Mountains, South Siberia)

The first results of palynological analysis of the bottom deposits of Kaskadnoe Lake and a reconstruction of vegetation and climate on the Oka Plateau over the last 14.2 ky are reported. It is shown that approximately 1.2–12.9 cal ka BP (GI-1) the regional climate was sufficiently warm and humid to allow the development of a forb–shrub tundra with spruce and larch stands. Cooling at approximately 12.9–11.5 cal ka BP (GS-1) led to the predominance of the forb–shrub tundra in the lake basin. Siberian pine settled on the Oka Plateau in a moderate–cold and humid climate at approximately 11.5–9.0 cal ka BP. The warmer and drier climate, which prevailed in the Middle Holocene approximately 9.0–4.5 cal ka BP, resulted in the retreat of dark-coniferous forests from the Kaskadnoe Lake basin. The spreading of larch and Siberian pine coincided with the onset of Neoglacial conditions in the Late Holocene. It was established that the environmental conditions on the Oka Plateau in the Late Glacial Period and Holocene were generally controlled by the interaction of the western atmospheric transport and the East Asian summer monsoon, the temperature variations caused by the insolation level, and the specific features of regional atmospheric circulation.

Long-Term Responses of Mediterranean Mountain Forests to Climate Change, Fire and Human Activities in the Northern Apennines (Italy)

Fagus sylvatica (beech) dominates the montane forests of the Apennines and builds old-growth high-conservation value stands. However, recent severe drought-induced diebacks raise concern on the future persistence of these forests and of Southern European mesophilous woodlands overall, growing at their dry edge. To explore the history of Apennine beech-dominated forests, we draw on the multiproxy paleoecological record from Lago Verdarolo, which includes a robust vegetation-independent temperature reconstruction. Numerical techniques are used to investigate the drivers of long-term Mediterranean mountain forest dynamics. Specifically, we focus on disentangling the ecological factors that caused the shift from high-diversity mixed forests to beech-dominated stands and on assessing the occurrence of legacy effects on present-day forests. Abrupt climate change largely drove vegetation dynamics during the Late Glacial and Early Holocene. Species-rich mixed Abies alba (silver fir) forests dominated about 10,500—5500 years ago, under rather dry and warmer-than-today conditions (+ 1—2 °C) and limited fire occurrence. Cooler and moister summers and increasing fire activity caused declines in several fire-sensitive temperate deciduous trees (for example, Ulmus, Tilia, Fraxinus) and favored the establishment of fir-beech forests around 5500 years ago. Further enhancement of fire activity and farming around 2000 years ago led to local Abies alba extinction and forest impoverishment. We conclude that the currently widespread monospecific Apennine beech forests are the result of multi-millennial land-use intensification superimposed on Late Holocene cooling and moistening. Given their higher drought-tolerance compared to beech stands, reviving ancient species-rich mixed fir forests represents a feasible and ‘tested’ possibility to adapt forests to climate change.