High-resolution Pollen Analysis Research Articles

Unravelling vegetation and human dynamics during the first millennium ad in Brandenburg, north-eastern Germany: insights from lake sediments

AbstractDuring the first millennium ad, Germany, like other European regions, witnessed dynamic interactions between human populations and the environment, resulting in effects on landscapes and vegetation. Despite their significance, the detailed changes and links between vegetation and population dynamics in Germany during this period are not yet fully understood. This study addresses this gap in an interdisciplinary approach combining high resolution pollen analysis, varve counts and AMS radiocarbon dating on a partially annually laminated lake sediment core from Kleiner Tornowsee, in Brandenburg, north-eastern Germany. Archaeological evidence of the region and available pollen data from another lake, Sacrower See, also in Brandenburg, were used for comparison and allowed the identification of regional developments. The results suggest that the Germanic tribes living there during the Roman Iron Age (ca. ad 1–375) were adept at maintaining an economy based on crop growing and the keeping of livestock. During the Migration period (ad 375–600) there was a relatively slow but continuous expansion of woodland, coinciding with two phases of depopulation. A low but constant presence of indicators of human activity in the pollen profiles, however, suggests that these areas were not completely abandoned. Evidence for an early phase of human activities starting again in the late 6th or early 7th century ad at both sites is striking, because of a lack of archaeological evidence for any settlements in this period. During the High Middle Ages (ad 1000–1300), a further increase in farming activities resulted in intensified clearance of woodland for farmland and led to more crop growing than grazing in the 11th and 12th centuries.

Holocene Vegetation Dynamics Revealed by a High-Resolution Pollen Record from Lake Yangzonghai in Central Yunnan, SW China

Long-term regional vegetation dynamics is essential for the understanding of past land cover changes. High-resolution pollen analysis of a 1020 cm core from a large lake, Lake Yangzonghai (YZH), in central Yunnan, SW China, was conducted to reveal regional vegetation dynamics in the lake catchment over the past 13,400 years. Pollen record, principal component analysis (PCA) of pollen percentages of major arboreal taxa, and plant abundances estimated from the “Regional Estimates of VEgetation Abundance from Large Sites” (REVEALS) model show five successional stages of vegetation dynamics since 13,400 cal. a BP: regional vegetation with high coverages in the lateglacial (13,400–11,400 cal. a BP) was dominated by evergreen broadleaved forest (EBF) and deciduous broadleaved forest (DBF), together with some grass meadows and marshes; pine forest and alder forest expanded in the early Holocene (11,400–9000 cal. a BP) when vegetation coverages were still high; regional vegetation with low coverages was dominated by sweetgum forest, together with some pine forest during the mid-Holocene (9000–4200 cal. a BP); more pine forest, grass meadows and marshes occupied the lake catchment during the late Holocene (4200–800 cal. a BP), when vegetation coverages were higher than the average of the past 13,400 years; regional vegetation with low coverage was dominated by grass meadows and marshes, great deforestation happened in the last 800 years. Regional vegetation dynamics over the past 13,400 years in the Lake YZH catchment was the result of regional vegetation response to climate changes during the lateglacial and early–mid Holocene, and to human activities mainly during the late Holocene.

Late Quaternary Araucaria forest and Campos (grasslands) vegetation dynamics inferred from a high-resolution pollen record from Lagoa Dourada in southern Brazil

Forest-grassland mosaics are ecosystems with sharp contrasts. Factors controlling their heterogeneity have interested researchers worldwide. To date, only few natural remains of these ecosystems exist, such as the Araucaria and Campos region in southern Brazil. Different paleoecological studies elucidate the vegetation and climate history of the region, documenting shifts between forests and grasslands since the Middle Holocene. However, uncertainty remains about whether system shifts were sudden or gradual and on the importance of driving factors and triggers such as climate, change and disturbance. We reconstruct the paleoecological history of the Araucaria forest-grassland mosaics in Paraná state in decadal to sub-decadal resolution during the Holocene. High resolution pollen analysis documents that in this region the expansion of woodlands occurred gradually while sedimentological analyses reveal stepwise shifts of the precipitation regime of the region. During the Early Holocene (10300-8300 cal yr BP), the landscape was characterized by grassland-dominated Campos vegetation, with sporadic occurrences of arboreal taxa. Araucaria angustifolia was present initially in small abundances. In the Mid-Holocene (8300-4000 cal BP), a transition to more humid conditions fostered the development of woodlands. The establishment of Araucaria angustifolia near the lake occurred around 7300 cal yr BP, together with a general expansion of woodlands. In the Late Holocene (4000-150 cal yr BP), Araucaria angustifolia became dominant within forest patches with a second stepwise expansion around 3300 cal yr BP. The onset of Euro-American land use during the last two centuries intensified erosion and altered species composition, reflected in sediment and pollen data. In addition, Lagoa Dourada documents vegetational changes that seem to coincide with the 8.2 ka event and the Little Ice Age.

The Neolithic ceremonial centre at Nowe Objezierze (NW Poland) and its biography from the perspective of the palynological record

Rondels are the oldest monumental ceremonial objects in Europe. They appeared some 200 years after the demise of the Linear Pottery culture (c. 4800BCE). They have given a new shape to the resurgent 'Danubian Neolithic World'. However, despite intensive research, it is still unclear (1) how the transition process took place after the fall of the LBK; (2) how long rondels were function; and (3) under what circumstances they were abandoned. In this paper, we present a new approach to this problem based on an analysis of the biography of a single object based on the integration of archaeological and palaeoenvironmental data. We assume that the high-resolution pollen analysis of lake sediments provides critical data on the dynamics of population change (hiatuses, sharp declines and increases in population size) and how the environment is affected (felling of specific tree species, fires, cultivation of particular crops, grazing intensity). They provide a better understanding of the sequence of settlement and construction changes as well as alterations in material culture available in the archaeological record. The subject of the analysis is a site in the Lower Oder Valley (north-west Poland), at the furthest northern periphery of the 'Danubian World'.

Landscape Response to Dynamic Human Pressure in the Paliouras Lagoon, Halkidiki Peninsula, Macedonia, Greece

High-resolution pollen analysis of a sediment core recovered from Paliouras lagoon (Greece) allowed us to reconstruct the environmental dynamics of the Halkidiki peninsula during the last 4000 years. Palynological results have been interpreted and compared with detailed historical data, showing distinct phases of human-landscape interactions from the Bronze Age until recent times. Pollen spectra revealed an environment characterized by Mediterranean vegetation, mixed deciduous forest, and pine stands from the Late Bronze Age until the 11th century CE. The first signs of human impact were attested during the Archaic period with the cultivation of Olea, Castanea, and Vitis in the inland of the study area. An intensive land management was highlighted by arboriculture and cereal cultivation (Secale and Hordeum group) in Roman times. Late Antique-Early Medieval times coincided with less human pressure due to warfare-related crises, leading to the expansion of the forest and the abandonment of fields colonized by Amaranthaceae. A massive increase in pastoral activities, suggested by the high percentages of Cichorieae during the Ottoman period, is possibly linked to the significant demographic growth of the nearby city of Thessaloniki in the 16th century CE.

Quantitative reconstruction of the vegetation of the Qinhuangdao area, western coast of Bohai Sea, North China, during the Little Ice Age

It is widely recognized that the climate of the Little Ice Age (LIA) was generally cold. However, there are differences in the climate response of the vegetation in different regions during the LIA, and high-resolution quantitative research is lacking. Here, we present a high-resolution pollen analysis and the Landscape Reconstruction Algorithm (LRA) based on relative pollen productivity, combined with AMS 14C dating, to quantitatively reconstruct the vegetation response to climate and sea level change on the western coast of Bohai Sea. The main findings are as follows: (1) The coverage of the main plant taxa reconstructed using estimates of relative pollen productivity was closer to the actual vegetation conditions than that based on pollen percentages. (2) Since ∼1250 A.D., the study area was occupied by temperate deciduous broadleaved forest, dominated by Quercus, with a smaller proportion of Pinus forest. The regional vegetation types did not change significantly, but the forest cover decreased gradually from ∼60% in the Middle Warm Period (MWP, 1250–1310 A.D.) to ∼40% in the LIA (1310–1610 A.D.), due to the combined influences of climate and human activities. (3) The composition of herbaceous plants changed substantially during the LIA. In the early LIA (1310–1450 A.D.), the climate became cold and dry and the sea level began to fall, resulting in a substantial increase in the proportion of Poaceae (∼10%). In the middle of the LIA (1450–1610 A.D.), the climate became colder and drier, the sea level fell further, and the lagoon shrank. In response, there was an increase in drought and salt-tolerant Chenopodiaceae (∼10%) and Artemisia (∼5%), a substantial increase in Selaginella sinensis supplied by fluvial processes.

Managing wilderness? Holocene-scale, human-related disturbance dynamics as revealed in a remote, forested area in the Czech Republic

In the lowlands and uplands of Central Europe, which were inhabited continuously from the very start of the Holocene to the present times, it is difficult to find territories suitable for investigation of natural baselines. For this reason, we picked the complicated rocky terrain of one upland area in NE Bohemia called Adrspach because, based on the absence of archeological finds, it was supposed to have never been deforested or managed by people. The remote and inhospitable character of this particular area further encouraged this assumption. To our great surprise, however, high-resolution pollen analyses, supplemented by analyses of non-pollen palynomorphs and microscopic charcoals reveals that the local forest ecosystem had a dynamic development over entire Holocene. We were able to correlate this high-resolution understanding of vegetation successions with repeated fire disturbances. Was this fire disturbance dynamic natural? Subsequent archeological exploration and excavation in the area brought unexpected evidence, pointing to rather continuous human presence throughout most of the Holocene. From the Early Mesolithic to the Late Neolithic, available evidence suggests a hunter-gatherer mode of resource management. From the start of the Late-Holocene (ca 4 ka BP), the occurrence of coprophilous fungal spores and secondary anthropogenic pollen indicators suggest this area was impacted by recurrent domestic animal grazing. Testing this approach also in other remote forested areas of Central Europe, we argue, can have far-reaching implications for understanding long term human-environment agency by transforming our understanding of alternative subsistence and land use strategies during prehistory. At the same time, this can significantly alter existing concepts used in Central European nature conservation strategies, which tend to be based on an underlying assumption that our work challenges – the survival of little impacted wilderness at the Holocene scale.

The influence of climatic change, fire and species invasion on a Tasmanian temperate rainforest system over the past 18,000 years

We aim to understand how did cool temperate rainforest respond to changes in climate and fire activity over the past 18 kcal yrs, interrogating the role that flammable plant species (such as Eucalyptus) have in the long-term dynamics of rainforest vegetation. We used high-resolution pollen and charcoal analysis, radiometric dating (lead and carbon), modern pollen-vegetation relationships, detrended correspondence analysis, rarefaction (palynological richness), rate of change and granger causality to understand the patterns and drivers of change in cool temperate rainforest from the sediments of Lake Vera, southwest Tasmania through time. We record clear changes in key rainforest taxa in response to climatic change throughout the record. The spread of rainforest through the lake catchment in the early and mid-Holocene effectively negated disturbance from fire despite a region-wide peak in fire activity. An anomalously dry period in the late-Holocene resulted in a local fire that facilitated the establishment of Eucalyptus within the local catchment. Granger causality tests reveal a significant lead of Eucalyptus over fire activity in the Holocene, indicating that fires were enhanced by this pyrogenic taxon following establishment.

A high-resolution pollen and diatom record of mid-to late-Eemian at Kozłów (Central Poland) reveals no drastic climate changes in the hornbeam phase of this interglacial

In the region of 20 newly-found fossil lakes in the Garwolin Plain (Central Poland), formed during the Eemian interglacial (MIS 5e), the Kozłów site is considered one of the longest examples of sequences of palaeolake deposits. Pollen investigations have revealed an entire Eemian interglacial (MIS 5e) with a very long hornbeam phase. Repeated coring allowed for high-resolution pollen and diatom analysis to be used in tracing climate-driven palaeoenvironmental changes during the mid- and late-Eemian. The resulting thick series of organogenic deposits from Kozłów joins the collection of existing high-resolution long records of this interglacial in central-eastern Europe. It should be emphasized that a very good correlation was found between palynological and diatom data, which allows for drawing consistent conclusions. The warm and humid climate of the Corylus phase at the onset of the mid-Eemian was marked by a great abundance of planktonic Cyclotella sensu lato species, which indicate a rising water level, increased water temperatures, thermal stratification and a warm-wet climate. In the diatom zones correlated with the Carpinus phase, a distinct change was observed, from an assemblage dominated by planktonic species to one composed of benthic ones, including Fragilaria sensu lato taxa. The greater frequency of oceanic air masses must have affected the humidity and thermal conditions in lake and its surroundings in the first part of the interglacial optimum. Climate changes are very clearly visible at the transition between Carpinus and Picea-Abies zones, which were caused by increased influence of continental air masses. However, in the Middle Eemian no drastic changes were observed in both the pollen and diatom records.In the upper part of the core, represented by Pinus pollen, the presence of cold-loving diatom species, and an increase of green algae Pediastrum spp. point to a drop in temperatures at the close of the interglacial. The pollen results were compared to the well-recognized mid-to late-Eemian successions from Poland and West Europe.

Late Quaternary vegetation and climate of SE Europe–NW Asia according to pollen records in three offshore cores from the Black and Marmara seas

High-resolution pollen analyses were performed on two cores from the western Black Sea and one core from the Marmara Sea, covering the Late Glacial-Holocene transition using 14C chronology. Particular effort was invested in the botanical identification of pollen grains thereby significantly improving our knowledge of regional flora. When interpreted with respect to modern vegetation, pollen records revealed all the major changes caused by climatic fluctuations over the last 20,000 years. The results of this study provide evidence for the occurrence of relict thermophilous-hygrophilous trees (papillate Cupressaceae, Carya, Liquidambar, Zelkova) in certain refugia up to the Holocene. Vegetation dynamics is specified for some taxa (e.g. Cupressus–Juniperus, Fagus, Cedrus) and some ecosystems (e.g. mesophilous forests, Mediterranean sclerophyllous populations, steppes). Pollen data enabled palaeoclimatic reconstructions which were compared with available estimates in the region. The use of a powerful pollen ratio between ‘thermophilous and steppe taxa’ led to fruitful climatostratigraphic relationships with the oxygen isotope curve from the NGRIP core. The Younger Dryas and cooling at 8.2 ka are among the most obvious climatic phases identified in the three cores studied here.

From Climatic to Anthropogenic Drivers: A Multi-Proxy Reconstruction of Vegetation and Peatland Development in the French Jura Mountains

A 4 m core was extracted from the center of a peatland located in the Drugeon valley (France). Thirteen radiocarbon dates were used to build a robust age model. Testate amoebae were used for reconstructing mire surface wetness. High-resolution pollen analysis of the sequence reconstructed 9 millennia of development of the peatland and its surrounding vegetation. During the early/middle Holocene (9500 to 5800 cal BP), warm conditions led to high evapotranspiration and low water levels. The vegetation history is characterized by the development of a Pinus and a mixed Quercus forest. From 5800 cal BP, testate amoebae show wetter conditions, indicating the onset of the cooler Neoglacial period. The cooling is also evidenced by the development of Abies and Fagus trees, replacing the oak forest. The first indicators of human impact appear at about 4800 cal BP, and indicators of farming activity remains very rare until ca. 2600 cal BP, at the beginning of the Iron Age. The development of the peatland responded to climatic fluctuation until 2600 cal BP, after which human impact became the main driver. The last millennium has been characterized by sudden drying and the spread of pine on the peatland.

High-resolution (sub-decadal) pollen analysis of varved sediments from Lake Montcortès (southern Pyrenean flank): A fine-tuned record of landscape dynamics and human impact during the last 500 years

A high-resolution (average 6 years/sampling interval) palaeoenvironmental reconstruction using pollen, charcoal and non-pollen palynomorphs was carried out on annually laminated sediments of Lake Montcortès (southern Pyrenean flank). The results were combined with historical data to better understand landscape evolution and human interaction during the last 500 years. Our results show that human activities (cropping, livestock breeding and hemp cultivation and retting) have been the most important factors responsible for vegetation changes with highest intensity between 1530 and 1900 CE. By means of a sub-decadal study we have been able to evaluate short-lasting events at local and regional scales related to climate (heavy rainfall events and, high-land forest fluctuations) or to historical and well-dated and documented socio-economic events (i.e., crop promotions (hemp) or land abandonment-population emigration). The temporal extent (400 years) and continuity of Cannabis pollen peak have been confirmed, and new evidence of water quality changes, likely as a consequence of hemp retting practices between the mid-17th to late 19th century, are provided. This is the first high-resolution palaeoenvironmental study carried out in a varved lake on the Iberian Peninsula so far. With these data we hope to contribute to filling the gap in high-resolution palaeoenvironmental data.

Vegetation history and paleoclimate at Lake Dojran (FYROM/Greece) during the Late Glacial and Holocene

Abstract. A new high-resolution pollen and NPP (non-pollen palynomorph) analysis has been performed on the sediments of Lake Dojran, a transboundary lake located at the border between Greece and the former Yugoslav Republic of Macedonia (FYROM). The sequence covers the last 12 500 years and provides information on the vegetational dynamics of the Late Glacial and Holocene for the southern Balkans. Robust age model, sedimentological diatom, and biomarker analyses published previously have been the base for a multi-perspective interpretation of the new palynological data. Pollen analysis revealed that the Late Glacial is characterized by steppic taxa with prevailing Amaranthaceae, Artemisia and Poaceae. The arboreal vegetation starts to rise after 11 500 yr BP, taking a couple of millennia to be definitively attested. Holocene vegetation is characterized by the dominance of mesophilous plants. The Quercus robur type and Pinus are the most abundant taxa, followed by the Quercus cerris type, the Quercus ilex type and Ostrya–Carpinus orientalis. The first attestation of human presence can be presumed at 5000 yr BP from the contemporary presence of cereals, Juglans and Rumex. A drop in both pollen concentration and influx together with a δ18Ocarb shift indicates increasing aridity and precedes clear and continuous human signs since 4000 yr BP. Also, a correlation between Pediastrum boryanum and fecal stanol suggests that the increase in nutrients in the water is related to human presence and pasture. An undoubted expansion of human-related plants occurs since 2600 yr BP when cereals, arboreal cultivated and other synanthropic non-cultivated taxa are found. A strong reduction in arboreal vegetation occurred at 2000 yr BP, when the Roman Empire impacted a landscape undergoing climate dryness in the whole Mediterranean area. In recent centuries the human impact still remains high but spots of natural vegetation are preserved. The Lake Dojran multi-proxy analysis including pollen data provides clear evidence of the importance of this approach in paleoenvironmental reconstruction. Cross-interpretation of several proxies allows us to comprehend past vegetation dynamics and human impact in the southern Balkans.

The last hornbeam forests in SW Europe: new evidence on the demise of Carpinus betulus in NW Iberia

Carpinus betulus L. is a mesic, usually considered late-successional tree widely distributed in Europe, but almost absent from Iberia, where it is generally assumed that disappeared during the coldest stages of the Wurm. High-resolution pollen analyses were carried out in 14C dated sediments from a drowned estuary (ria) and a small mountain lake. Carpinus pollen identification was confirmed by comparative light and scanning electron microscopy. Hornbeam dynamics are interpreted using palaeoclimatic reconstructions based on independent proxies (diatoms, chironomids and dinocysts). Our results support that hornbeam declined between ca. 60,000 and ca. 9,000 cal yr bp, when multiproxy evidence suggests a major regional relative sea-level rise. Moreover, chironomid-inferred July temperatures show an increase of more than 6 °C between 15,600 and 10,500 cal yr bp, while freshwater aquatics and diatoms indicate a general tendency towards increasing precipitation and a more oceanic climate. Carpinus survived during the Wurm in a variety of habitats in coastal valleys in NW Iberia which had adequate climatic and edaphic conditions. Such habitats might be comparable to the oak-ash, ravine, and hardwood floodplain forests currently existing in other regions of Europe. Large areas of these coastal ecosystems disappeared at the onset of the Holocene, when the sea-level rose. Later hornbeam was apparently unable to compete and expand further inland. Therefore, the sea-level rise combined with the climatically-induced Holocene tree succession and the increasing human impact during the Mid and Late Holocene led to hornbeam progressively becoming a marginal tree in the area.

Late Holocene vegetation and climate change on the southeastern Tibetan Plateau: Implications for the Indian Summer Monsoon and links to the Indian Ocean Dipole

The Indian Summer Monsoon (ISM) is one of the most important climate systems, whose variability and driving mechanisms are of broad interest for academic and societal communities. Here, we present a well-dated high-resolution pollen analysis from a 4.82-m long sediment core taken from Basomtso, in the southeastern Tibetan Plateau (TP), which depicts the regional climate changes of the past millennium. Our results show that subalpine coniferous forest was dominant around Basomtso from ca. 867 to ca. 750 cal. yr BP, indicating a warm and semi-humid climate. The timberline in the study area significantly decreased from ca. 750 to ca. 100 cal. yr BP, and a cold climate, corresponding to the Little Ice Age (LIA) prevailed. Since ca. 100 cal. yr BP, the vegetation type changed to forest-meadow with rising temperatures and moisture. Ordination analysis reveals that the migration of vegetation was dominated by regional temperatures and then by moisture. Further comparisons between the Basomtso pollen record and the regional temperature reconstructions underscore the relevance of the Basomtso record from the southeastern TP for regional and global climatologies. Our pollen based moisture reconstruction demonstrates the strong multicentennial-scale link to ISM variability, providing solid evidence for the increase of monsoonal strengths over the past four centuries. Spectral analysis indicates the potential influence of solar forcing. However, a closer relationship has been observed between multicentennial ISM variations and Indian Ocean sea surface temperature anomalies (SSTs), suggesting that the variations in monsoonal precipitation over the southeastern TP are probably driven by the Indian Ocean Dipole on the multicentennial scale.

Neolithic land use in the northern Boreal zone: high-resolution multiproxy analyses from Lake Huhdasj\xe4rvi, south-eastern Finland

Two high-resolution pollen and charcoal analyses were constructed from sediments obtained from a small bay in eastern Finland in order to gain information on human activity during the Neolithic Stone Age, 5200–1800 bc. We used measurements of loss on ignition (LOI), magnetic susceptibility and geochemical analyses to describe the sedimentological characteristics. Palaeomagnetic dating and measurements of 137Cs-activity were supported by 14C-datings. The analyses revealed human activity between 4400 and 3200 bc, which is synchronous with archaeological cultures defined through different stages of Comb Ware pottery types and Middle Neolithic pottery types with asbestos as a primary temper. Direct evidence of Hordeum cultivation was dated to 4040–3930 cal bc. According to the pollen data, more significant effort was put into the production of fibres from hemp and lime than the actual cultivation of food.

Holocene landscape development along the Portuguese Algarve coast – A high resolution palynological approach

Along the Algarve coast, multi-proxy investigations of four estuaries detail the Holocene landscape evolution through high-resolution pollen and sediment analyses. This approach focuses on palynological results and enables the reconstruction of differentiated human impact around the studied archives between the Neolithic and modern times. During the Chalcolithic and Phoenician periods anthropogenic land use increases clearly and triggers erosional processes in the catchment. The increased agricultural area and the change in land use methods since the beginning of the second Islamic epoch form the actual landscape. According to the palynological results, since 8200 cal BP highly variable climatic conditions in terms of moisture availability have occurred during the entire Holocene. Arid periods occurred during the early Holocene prior to 8000 cal BP, around 7000 cal BP and between 6400 and 6200 cal BP. During the mid Holocene, two further dry periods with very different duration could be identified between 5000 and 3300 cal BP and between 2800 and 2500 cal BP. Finally, during the late Holocene between 1300 and 1050 cal BP and between 700 and 500 cal BP, further arid periods appeared. In conclusion, climatic and anthropogenic influences caused erosion in the catchments and in this way silting up of the estuaries along the Portuguese Algarve coast.

Late Holocene vegetation changes in relation with climate fluctuations and human activity in Languedoc (southern France)

Abstract. Holocene climate fluctuations and human activity since the Neolithic have shaped present-day Mediterranean environments. Separating anthropogenic effects from climatic impacts to better understand Mediterranean paleoenvironmental changes over the last millennia remains a challenging issue. High-resolution pollen analyses were undertaken on two cores from the Palavasian lagoon system (Hérault, southern France). These records allow reconstruction of vegetation dynamics over the last 4500 years. Results are compared with climatic, historical and archeological archives. A long-term aridification trend is highlighted during the late Holocene, and three superimposed arid events are recorded at 4600–4300, 2800–2400 and 1300–1100 cal BP. These periods of high-frequency climate variability coincide in time with the rapid climatic events observed in the Atlantic Ocean (Bond et al., 2001). From the Bronze Age (4000 cal BP) to the end of the Iron Age (around 2000 cal BP), the spread of sclerophyllous taxa and loss of forest cover result from anthropogenic impact. Classical Antiquity is characterized by a major reforestation event related to the concentration of rural activity and populations in coastal plains leading to forest recovery in the mountains. A major regional deforestation occurred at the beginning of the High Middle Ages. Around 1000 cal BP, forest cover is minimal while the cover of olive, chestnut and walnut expands in relation to increasing human influence. The present-day vegetation dominated by Mediterranean shrubland and pines has been in existence since the beginning of the 20th century.

Pollen-based evidence of extreme drought during the last Glacial (32.6–9.0 ka) in coastal southern California

High resolution pollen analyses of sediment core LEDC10-1 from Lake Elsinore yield the first well-dated, terrestrial record of sub-centennial-scale ecologic change in coastal southern California between ∼32 and 9 ka. In the Lake Elsinore watershed, the initial, mesic montane conifer forests dominated by Pinus, and Cupressaceae with trace amounts of Abies and Picea were replaced by a sequence of multiple, extended severe mega-droughts between ∼27.5 and ∼25.5 ka, in which halophytic and xerophytic herbs and shrubs occupied an ephemeral lake. This prolonged and extended dry interval, which corresponds with warm waters offshore, imply strengthening of the North Pacific High and persistent below-average winter precipitation. The subsequent, contrasting monotonic occurrence of montane conifers reflects little variation in cold, mesic climate until ∼15 ka. Postglacial development of Quercus woodland and chaparral mark the return to more xeric, warmer conditions at this time. A brief reversal at ∼13.1–∼12.1 ka, as reflected by an expansion of Pinus, is correlative with the Younger Dryas and interrupts development of warm, postglacial climate. Subsequent gradual expansion of xeric vegetation post – Younger Dryas denotes the establishment of a winter hydroclimate regime in coastal southern California that is more similar to modern conditions. Pollen-based reconstructions of temperature and precipitation at Lake Elsinore are generally correlative with pollen-based paleoclimatic reconstructions and foraminifera-based sea surface temperatures from Santa Barbara Basin in marine core ODP 893. The conspicuous absence of the ∼27.5–∼25.5 ka glacial “mega-drought” in the Santa Barbara Basin pollen record highlights the sensitivity of Lake Elsinore to hydroclimate change, and thus, the importance of this new record that indicates that mega-drought can occur during the full glacial when climatic boundary conditions and forcings differed substantially from the present.

Neoholocene palaeoenvironmental changes in the Southern Roztocze region (SE Poland): The Kobyle Jezioro raised bog case study

The pollen diagram from the Kobyle Jezioro raised bog, situated in the source area of the Tanew River in the Roztocze region, covers the whole Neoholocene. The deposit thickness (about 3.5 m) has permitted high resolution pollen, peat (including macrofossils) and lithology analyses. Vegetational and palaeoenvironmental changes in this part of the Roztocze were recorded in pollen spectra and organic deposits. Palynological evidence shows the typical Neoholocene succession, which corresponds with the phenomena described from central Europe: from mixed deciduous forests at the decline of the climatic optimum, through hornbeam- and beech-dominated forests to pine forests. Peat accumulation in the Kobyle Jezioro peat-bog started during increased climatic humidity at the beginning of the Subboreal, and originally a fen peat was formed. Raised bog peat layers make up the uppermost 80 cm of the deposit. Within the fen deposits can be found layers of transitional peat, indicating short-term episodes of water deficiency in the early Subboreal phase (short-term climatic dryness) and towards its end (drainage of the bog resulting from the lowering of the groundwater table in the source area of the Tanew River). The growth of the raised bog started at the beginning of the climate deterioration in the Little Ice Age, and the unstable climatic conditions are reflected in the numerous periodical mineral (aeolian) material supplies in the developing ombrogenic bog. The accumulation of the younger section of transitional and raised peats during the Little Ice Age reflects the local hydrological changes in the source area of the Tanew River.