Non-pollen Palynomorphs Research Articles

Paleoenvironmental Reconstruction for the Last 3500 Years in the Southern Pyrenees from a Peat Bog Core in Clots de Rialba

Vegetation landscape dynamics are derived from the relationships established between anthropic activities and climate conditions over time. Paleoenvironmental research in the Pyrenees range (north-eastern Iberian Peninsula) has revealed what these dynamics were like in some regions during the Holocene. However, some fields of biogeography still present questions that need to be addressed, such as the patterns of Fagus sylvatica and Abies alba and the importance of the fire regime during the Meghalayan (late Holocene). We present a multiproxy study performed in a sedimentary record from the Clots de Rialba peat bog, located at 2093 m a. s. l. (Lleida, southern slope of the Pyrenees mountain range), that covers the last c. 3500 years. Analyses were performed on the organic matter content, pollen, non-pollen palynomorphs, and sedimentary charcoals larger than 150 μm. The palynological spectra revealed a maximum extension of Abies alba at about 3500 cal yr BP in the Bronze Age, while Fagus sylvatica showed its maximum extent between 3300 and 2800 cal yr BP. A dominance of Pinus was detected throughout the studied period. Other taxa such as cereals, herbaceous plants, aquatic plants, and coprophilous fungi have also been discussed to identify anthropic pressure and climate pulses. In addition, the study of sedimentary charcoals reveals the main forest fire episodes and their recurrences, some of them linked to anthropogenic activities and/or climate variations. These anthropogenic activities would include the use of opening and maintaining forest fires in deforestation in order to obtain pastures and spaces dedicated to cereal agriculture and the appearance of some taxa linked to or introduced by human communities.

Late-Holocene fynbos-forest dynamics in Orange Kloof, Table Mountain National Park, South Africa

Fynbos and afrotemperate forest exist as alternate stable states in the Cape Floristic Region of South Africa. In parts of Table Mountain National Park, afrotemperate forest has expanded in recent decades. The aim of this project was to explore the drivers of this change and distinguish whether this expansion represents a recovery of forest after previous clearance during the 18th century or is a novel expansion of forest range that resulted from policies of fire suppression in the 20th century. To determine the relationships between forest and fynbos and its key drivers, pollen, non-pollen palynomorphs, charcoal, stable isotope ratios (δ13C) and major and trace elements were analysed from late-Holocene sediments extracted from Orange Kloof. Pollen data show that forest cover has fluctuated over the past 3690 years. At the start of the record, under drier conditions from 1670 BCE to ~170 CE, forests contracted, and dry, asteraceous fynbos dominated the landscape. Around ~170 CE there was a shift to ericaceous fynbos as water availability increased. Weak signals of Khoekhoen pastoralists may be visible in the record around 50 CE, indicated by increased spores and charcoal. A regime shift towards increased dominance of the forest occurred ~250 CE, associated with wetter climate. Clear anthropogenic signals are associated with European settlement from 1650 CE. Reinforced by human clearance of forest, fynbos expanded during the cool conditions of the late phase of Little Ice Age (~1750–1850 CE). Forest expansion in the 20th century likely reflects fire suppression and recovery from past forest clearance. Fire needs to be managed accordingly if further expansion of forest into fynbos is to be curbed.

Application of Phytolith (Microbiomorphic) and Non-Pollen Palynomorph Analyses to the Geoarchaeological Study of the Graft Farmyard, the Netherlands

The aim of the present paper is to discuss the application of phytolith (microbiomorphic) and non-pollen palynomorph (NPP) analyses to the geoarchaeological study of a Medieval – Early Modern Time period farmyard in Graft, a settlement located in the polder region of North Holland, the Netherlands. The authors have assessed the potential of the methods chosen for studying this type of archaeological site during rescue excavations, when archaeologists often have a limited number of samples or methods for geoarchaeological analysis. The studies conducted have proved the informative value and effectiveness of microbiomorphic and NPP analyses in rescue excavations, especially when applied in combination, thus providing controlling and complementary information for each analysis. The data obtained have provided an important insight into the archaeological interpretation of the cultural layer within the farmyard. In addition, more information was gained on the local palaeoenvironmental dynamics and the phases of economic activity at the farmyard during the 13th–17th centuries CE.

Holocene Paleoenvironmental Implications of Diatom, Non-Pollen Palynomorph, and Organic Carbon Records from the Kandalaksha Bay of the White Sea (European Arctic)

Variations in sea surface conditions and sea level through the Holocene in the Kandalaksha Bay, the White Sea, were reconstructed based on the study of core sediments from the outer Kandalaksha Bay, using the modern analog technique applied to dinocysts in addition to diatoms, TOC, δ13Corg, CaCO3, and grain size data. The chronostratigraphy of the core sediments was defined from accelerator mass spectrometry 14C dates on mollusk shells. The results indicated an increase in water depth in the outer Kandalaksha Bay and in the central Dvina Bay until the late Holocene. From about 9.5 to 7.5 cal kyr BP, the data suggested a general trend of increasing sea surface temperatures (up to 14 °C), at least in areas with inflow of Atlantic waters. The last 2.5 kyr were characterized by increased freshwater runoff to the White Sea.

Vegetation History in Central Croatia from ~10,000 Cal BC to the Beginning of Common Era—Filling the Palaeoecological Gap for the Western Part of South-Eastern Europe (Western Balkans)

The aim of this study was to reconstruct the vegetation changes, fire history and local landscape dynamics of central Croatia (the western part of south-eastern Europe) from 9800 cal yr BP to the beginning of the Common Era. Pollen, non-pollen palynomorphs and charcoal were analysed for the first time in the aforementioned area by modern palynological methods. Three different assemblage (sub)zones were identified: “Pinus-Fagus-Quercetum mixtum” (Preboreal), “Fagus-Corylus” (Boreal) and “Alnus-Fagus” (Atlantic, Subboreal and older Subatlantic). Additionally, the oldest observation (~9800 cal yr BP) of beech pollen for continental Croatia was confirmed by radiocarbon dating. Our results indicated a possibly milder climate with less extreme temperatures and higher precipitation during the Preboreal chronozone, alongside intensive flooding, a transition from a mosaic of wetland/wet grassland communities to alder carr during the Boreal, and an unusually long multi-thousand-year period, the annual presence of alder on the mire itself. An increase in the number of secondary anthropogenic indicators can be tracked from the 6th century BC to the beginning of the Common Era. Although regional vegetation changes are insufficiently clear, our results fill a gap in the interpretation of vegetation/palaeoenvironmental changes before the Common Era in in this part of Europe.

Ecological impacts of the industrial revolution in a lowland raised peat bog near Manchester, NW England.

(1) Ombrotrophic peat bogs provide valuable records of environmental change on long timescales but are rarely preserved near the major centers of industrial activity. Holcroft Moss is a rare example of a stratigraphically intact lowland peat bog in NW England, which provides a valuable opportunity to trace industrial impacts on vegetation in a sensitive environmental archive close to the early industrializing cities of Manchester and Liverpool. (2) We reconstructed environmental changes at Holcroft Moss before and after the Industrial Revolution using a decadal-scale record of pollen, non-pollen palynomorphs, microcharcoal, peat composition (organic content and ash-free bulk density) and heavy metal content, constrained by a radiocarbon and SCP (spheroidal carbonaceous particle) chronology. We examine the relationship between abiotic and biotic environmental tracers using principal component analysis and evaluate the role of local and regional climatic and anthropogenic drivers using canonical redundancy analysis and partitioning of variation. (3) Results show significant changes in bog vegetation composition during the last 700 years. Prior to 1750 CE, climate and agro-pastoral activity (grazing and fires) were the main drivers of vegetation change. Subsequently, regional coal-fired industry contributed to major increases in atmospheric pollutants (dust, heavy metals, and acid deposition) that severely impacted vegetation, driving the decline of Sphagnum. Grasses rose to dominance in the 20th century associated especially with bog conversion and cumulative nitrogen deposition. Although atmospheric pollution significantly decreased in the post-industrial era, vegetation has not returned to pre-industrial conditions, reflecting the ongoing impact of global change drivers which pose challenges for conservation and restoration. (4) Synthesis. Paleoecological studies are needed to reveal the long-term history of vegetation degradation and to offer guidelines for restoration and conservation practices. This study reconstructs the last 700 years of a peat bog located between Manchester and Liverpool, revealing the timing and nature of vegetation changes across the trajectory of early industrialization and eventual post-industrial decline. Our study reveals the progressive dominance of regional anthropogenic forcing and highlights that the present-day vegetation does not have past analogs within the last 700 years. Conservation measures favoring the reintroduction of Sphagnum are justified in redressing the major biological legacy of the Industrial Revolution, while steps to increase Calluna should also be considered in light of its resilience to dry and fire-prone conditions.

Taming Fogo Island: Late-Holocene volcanism, natural fires and land use as recorded in a scoria-cone sediment sequence in Cabo Verde

Cabo Verde remained uninhabited until 1460 CE, when European sailors founded a settlement in Santiago, and soon after in Fogo island. The degree to which different island ecosystems in Cabo Verde have been transformed by humans remains uncertain because of a scarcity of historical information and archaeological evidence. Disentangling these processes from natural ones is complicated in islands with a history of volcanic impacts and other natural hazards. In this paper, we apply microfossil (pollen, non-pollen palynomorphs and phytoliths) and sedimentological analyses (granulometry, X-ray diffraction, loss on ignition and tephrostratigraphy) to a 2-m sediment sequence deposited in a scoria cone from 4100 cal year BP (calibrated years before 1950 CE) to the present. The organic-rich basal sediments indicate that between 4100 and 2600 cal year BP the pre-settlement landscape of Fogo was an open grassland, where fire was infrequent and/or small-scale. An increase in volcanic glass deposition after 2600 cal year BP, peaking ca. 1200 cal year BP, suggests that there was a progressive activation of Fogo’s volcanic activity, contemporaneous with increased fire frequency and erosion pulses, but with little impact on local grassland vegetation. While dating uncertainty is high, the first evidence of intensive local land use by early settlers was in the form of cultivation of Zea mays, abundant spores of coprophilous fungi (i.e. Sporormiella), and peaks in charcoal concentrations between 800 and 400 cal year BP. This was followed by large increases in pollen from pigeon pea ( Cajanus), a diverse array of exotic trees ( Cupressus, Grevillea), and invasive shrubs ( Lantana). The introduction of these taxa is part of recent human effort to ‘tame’ this steep, dry and hazardous island by reducing erosion and providing firewood. An important outcome of these efforts, however, is a loss of fragile native biodiversity.

Climate Change, Fire and Human Activity Drive Vegetation Change during the Last Eight Millennia in the Xistral Mountains of NW Iberia

An 8500-year record of high-resolution pollen, non-pollen palynomorph, microscopic charcoal and selected geochemical data (Ti, Zr and Pb) is presented from an ombrotrophic mire from the Xistral Mountains, Galicia, North-West Iberia. The results suggest that vegetation changes over the last eight millennia are primarily the result of human disturbance, fire and climate change. Climate and fire were the main factors influencing vegetation development during the early to mid-Holocene, including a short-lived decline in forest cover c. 8.2 cal. ka BP. Changes associated with the 4.2 and 2.8 cal. Ka BP events are less well defined. Human impact on vegetation became more pronounced by the late Holocene with major periods of forest disturbance from c. 3.1 cal. ka BP onwards: during the end of Metal Ages, Roman period and culminating in the permanent decline of deciduous forests in the post-Roman period, as agriculture and metallurgy intensified, leading to the creation of a cultural landscape. Climate change appears to become less influential as human activity dominates during the Late Holocene.

Non-pollen palynomorphs from 78 surface sediment samples reveal spatial distribution of phytoplankton in Latvian lakes and ponds

Non-pollen palynomorphs from 78 surface sediment samples reveal spatial distribution of phytoplankton in Latvian lakes and ponds

Palynology as an important tool for the reconstruction of diet, diseases and folk medicine of the population of the Classical Period settlement Namcheduri II (western Georgia)

Layers of the Namcheduri II settlement (Western Georgia) dated from the 5th-4th centuries BC have been studied by the palynological method. It revealed that cereals represented the main component of the population’s diet in the discussed period. The nutritive ratio included chestnut, hazel, walnut, and grapes. The majority of the plants apparently used for medical purposes represent medicinal remedies against rheumatism, arthritis, and diarrhea. Presumably, malaria, diabetes, and epilepsy occurred rarely since the medicinal remedies used against them were poorly evidenced. Plenty of eggs of parasitic worms discovered in the group of non-pollen palynomorphs in some samples and their taxonomic variety indicates at wide spreading of helminthosis in the population in the period under discussion. Eggs of Trichuris trichuira, Ascaris lumbricoides, Capillaria, Enterobius vermicularis, Yokogava fluke were present. The abundance and diversity of eggs of parasitic worms in the obtained material gives grounds for supposition that this part of the settlement was used as a latrine.

Palynoflora and palaeoenvironment of the early Miocene palaeolake from the Bełchatów mine, central Poland

The Bełchatów lignite deposits are a rich archive allowing palaeoenvironmental, palaeoecological and palaeoclimatic reconstructions from the Neogene and Quaternary periods. We describe the results of palynological studies (including non-pollen palynomorphs) of eight samples from the lower Miocene KRAM-P 211/214 collection of plant macroremains. The results of this palynological analysis are consistent with the results of previous studies of plant macroremains and significantly enrich our knowledge of vegetation and palaeoenvironment. Both studies indicate the presence of a freshwater body (a moderately large and deep lake) surrounded by wetland vegetation (including swamp forests with Glyptostrobus , Taxodium , Nyssa and Osmunda ) and upland mesophytic forests. Evergreen or at least semi-evergreen forest communities grew along the ancient shores of the lake and on the slopes of the Mesozoic calcareus rocks surrounding the lake. In the lake, green algae ( Pediastrum , Tetraedron and some Botryococcus ) and freshwater peridinoid dinoflagellates were major components of the algal community. The same lake was the source of previously identified animal remains: freshwater fishes, molluscs, and mammals, including Megachiroptera bats. Our analysis shows that the climate was subtropical and humid, with an estimated mean annual temperature of 16.8–17.8°C.

Neolithic dental calculi provide evidence for environmental proxies and consumption of wild edible fruits and herbs in central Apennines

Looking for a biological fingerprint relative to new aspects of the relationship between humans and natural environment during prehistoric times is challenging. Although many issues still need to be addressed in terms of authentication and identification, microparticles hidden in ancient dental calculus can provide interesting information for bridging this gap of knowledge. Here, we show evidence about the role of edible plants for the early Neolithic individuals in the central Apennines of the Italian peninsula and relative cultural landscape. Dental calculi from human and animal specimens exhumed at Grotta Mora Cavorso (Lazio), one of the largest prehistoric burial deposits, have returned an archaeobotanical record made up of several types of palaeoecological proxies. The organic fraction of this matrix was investigated by a multidisciplinary approach, whose novelty consisted in the application of next generation sequencing to ancient plant DNA fragments, specifically codifying for maturase K barcode gene. Panicoideae and Triticeae starches, together with genetic indicators of Rosaceae fruits, figs, and Lamiaceae herbs, suggested subsistence practices most likely still based on wild plant resources. On the other hand, pollen, and non-pollen palynomorphs allowed us to outline a general vegetational framework dominated by woodland patches alternated with meadows, where semi-permanent settlements could have been established.

Last 10 millennial history of Indian summer monsoon in the Bengal region – a multi-proxy reconstruction from a lacustrine archive

We combine phytoliths, non-pollen palynomorphs, stable carbon isotopes of sediment organic matter, environmental magnetic parameters and sediment texture data of a lacustrine sedimentary archive from the Bengal region to understand the ecosystem response to past hydroclimatic changes. The region experienced a high Indian summer monsoon (ISM) rainfall during c.10.2–5.6 ka corresponding to the Holocene Climatic Optimum (HCO) when the lake level was high. Our study reveals that ISM weakened at c.4.3 ka with a decline in lake level, became strong between c.3.7 and 2.1 ka and then shifted towards a drier mode. However, this weakened phase was punctuated by a stable phase between c.1–0.8 ka, and a comparatively stronger phase between c.0.2–0.1 ka corresponding to the Medieval Warm Period (MWP) and Little Ice Age (LIA), respectively. An eutrophication of the lake began at c.3.7 ka which was completely in-filled during c.0.2–0.1 ka. A comparison of the present results with published records suggests millennial-scale coherence in the Holocene ISM variability across the Bay of Bengal (BoB) moisture source regions while, the finer-scale incongruities are attributable to differential proxy response and dating uncertainty. Our proxy-based observations are also compared with a few palaeo-model outputs for selected time-spans [such as, 1550–1850 CE (0.4–0.1 ka), 900–1300 CE (1–0.6 ka), 2100–2000 BCE (4.1 − 4 ka), and 4050–3350 BCE (6–5.3 ka)] from the Palaeo Modeling Intercomparison Project Phase 3–4 (PMIP3/PMIP4) experiments which support the assumption that changes in lake ecosystem may be strongly influenced by ISM rainfall, and the region surrounding northern BoB received higher precipitation than the other parts of India since the past 10.2 ka. The millennial-scale variations in the ISM rainfall may largely be attributed to gradual decline in orbital insolation and dynamics of Inter tropical Convergence Zone (ITCZ). However, centennial scale variations may be collectively triggered by forcings like NAO, ENSO and IOD.

Forest Dynamics and Agroforestry History since AD 200 in the Highland of Sumatra, Indonesia

Understanding past forest dynamics and human influence is essential for future forest management and ecosystem conservation. This study aims to provide insights into the forest dynamics and agroforestry history in the highlands of Sumatra for the last 1800 years. We carried out palaeoecological multi-proxy analyses of pollen, spores, non-pollen palynomorphs, macro-charcoal, and X-ray fluorescence on a limnic sediment core taken from Danau Kecil in the submontane area of Kerinci Seblat National Park in Sumatra, Indonesia. Our results provide an 1800-year record of forest dynamics under climate change and human influence including the transition from forest opening to shifting cultivation and eventually permanent agroforestry. Indicators for forest openings and secondary forest formation have been present since the beginning of records (AD 200). This is followed by the possible initiation of sugar palm (Arenga) cultivation (AD 400). Since AD 500, potential agroforestry and forest gardening practices have promoted major timber trees such as Lithocarpus/Castanopsis, Bischofia, and Dipterocarpaceae combined with sugar palm (Arenga). Permanent agroforestry systems were possibly established since AD 1760, evinced by an increase in commodity trees such as Dipterocarpaceae for resin production. With the Dutch invasion ca. AD 1900, agroforestry intensified and expanded to the Kerinci Valley. This was followed by land use intensification and potential rice cultivation around Danau Kecil since the 1940s. This study provides the first details on past forest dynamics around Danau Kecil since AD 200, showing among others how appropriate forest management and a closed canopy could reduce fire vulnerability in submontane rainforest.

Vegetation and fire history of the East-European forest-steppe over the last 14,800 years: A case study from Zamostye, Kursk region, Russia

The East-European forest-steppe extends from the Carpathian to the Ural Mountains, representing a mosaic of broadleaf deciduous forest patches and meadow-steppe, where up to 80% of the territory has been converted to croplands. Here we examine the Late Glacial and Holocene history of the forest-steppe of the East European Plain to better understand its sensitivity to climate fluctuations, fire and human impact, and also the timing of its transition into the modern agro-pastoral landscapes. We studied a radiocarbon-dated sediment core from the village of Zamostye (Kursk region, Russia), which provides a continuous record of vegetation change for the last 14,800 years. We conducted an analysis of pollen, non-pollen palynomorphs, loss-on-ignition, macro- and mirco-charcoal and macroremains, and applied a modern analogue technique to the pollen data to reconstruct forest cover. The pollen data reveal high sensitivity of the vegetation in this region to moisture availability caused by the northern hemispheric climate changes and permafrost. The region was occupied by a pine forest-steppe during Bølling/Allerød but transformed into a cold steppe during the GI 1d and Younger Dryas events. Around 11.7 cal kyr BP the climate warming triggered an expansion of birch trees into the steppe but the lack of moisture and strong fire activity hindered the development of pine and broadleaf forests for more than a millennium. Vegetation turnover occurred at ∼10.3 kyr BP, when the vegetation became dominated by pine. Pine and mixed deciduous oak forests continued to dominate through the Middle to Late Holocene reaching their maximal extension by 4.4 cal kyr BP. During the Late Holocene, human impact was detected for the Late Bronze Age, Early Iron Age, Roman period and Early Middle Ages. However, natural forests were recovering after a decrease in human activities. We demonstrate that the forest-steppe of the East European Plain has experienced a total deforestation in the 17th century and has remained open although climate conditions could have allowed the recovery of pine-broadleaf mixed forests.

Ecological impacts of N-deposition in a remote, high-elevation lake in the Three River Headwaters Region, Qinghai-Tibetan Plateau

This study provides a new record of nitrogen (N) deposition and ecological response at a remote, high-elevation lake within the ecologically fragile Three River Headwaters Region, northwest China, from the early 20thCentury to the past decade. A multi-proxy investigation of a lake sediment core including analyses of chironomids (non-biting midge), lake sediment geochemistry (δ15N, δ13C, TN, TOC, OC:TN), pollen, non-pollen palynomorphs and 210Pb-dating. Results were compared with regional pollution forcings, including fertiliser application, atmospheric nitrate and dust deposition, and a localised multiscale air quality modelling system for N-deposition. Our data reflect a mesotrophic lake for the majority of the 20th Century with minimal anthropogenic impact. A shift in the lake conditions is evident after 1985 with increased nutrient enrichment. Low δ15N, OC:TN and increasing TN values, together with an increase in chironomid taxa associated with eutrophic conditions and macrophytes are exhibited in the record, particularly since 2002. These changes are consistent with nutrient loading causing a change in trophic status. Redundancy analysis (RDA) and partial RDAs verified TN as an important driver behind the shift in chironomid community composition in recent decades, explaining 22.2% of the variance on its own and 16.9% with other environmental variables partialled out. While temperature change since 1960 was not a primary control on the chironomid community of Lake Bander, a step-change increase in summer temperatures since the 1990s coincided with the disappearance of cold stenotherms from the record and seems to have exacerbated the shift to more productive conditions. This study highlights the reach of airborne N from modern agricultural and industrial activity to remote locations, and demonstrates the utility of palaeolimnological techniques as part of modern ecosystem assessment for conservation.

Multiproxy study of 7500-year-old wooden sickles from the Lakeshore Village of La Marmotta, Italy

The lakeshore site of La Marmotta is one of the most important Early Neolithic sites of Mediterranean Europe. The site is famous for the exceptional preservation of organic materials, including numerous wooden artefacts related to navigation, agriculture, textile production, and basketry. This article presents interdisciplinary research on three of the most complete and well-preserved sickles recovered from the site, yet unpublished. All the components of the tools are analysed: the stone inserts, the wooden haft and the adhesive substances used to fix the stones inside the haft. Our innovative methodology combines use-wear and microtexture analysis of stone tools through confocal microscopy, taxonomical and technological analysis of wood, gas chromatography–mass spectrometry analysis of the adhesive substances, and pollen, non-pollen palynomorphs, and phytolith analysis of the remains incorporated within the adhesive. This multiproxy approach provides a significant insight into the life of these tools, from their production to their use and abandonment, providing evidence of the species of harvested plants and the conditions of the field during the harvesting.

Long-term shoreline evolution (Late-Holocene – 2018) of the Channel 15 coast (Samborombón bay, NE – Buenos Aires province, Argentina)

Here we present an investigation with the aim of reconstructing the shoreline evolution and geomorphological changes in the central zone of Samborombón bay (Channel 15, Buenos Aires province, Argentina) during the period 2700 cal yr BP to recent times. Palynological, geomorphological and historical imagery and proxy-data analyses were combined to reconstruct the shoreline evolution and paleo-environmental changes. Palynological material (pollen and non-pollen palynomorphs -NPP-) was recovered from a continuous 117 cm long sedimentary profile extracted from an outcrop at the northern margin of Channel 15. Relict landforms, including paleo- shorelines, were reconstructed by applying enhancing filters to a Spot 6 image from 2015. Historical shorelines were identified in high-definition images (aerial and satellite imagery) between 1968 and 2018, but also by using the marsh vegetation edge as a shoreline proxy. Shoreline change was quantified using the Net Shoreline Movement and Weighted Linear Regression algorithms in ArcMap 10.1. Results based on the palynological analysis for the period 2700–2740 BP, show the passage from subtidal-intertidal to supratidal environment with influence of brackish to fresh-waters, where paleo-shorelines imprint was recognized developing over a tidal plain that was grading to marshes. Results based on aerial and satellite imagery for the period 1968–2018 show shoreline retrocession only immediately at the north of the channel mouth, while the rest of the coast prograded toward the estuary. These processes indicate that new marshes – and, therefore, wetlands – are constantly developing at the edge of Samborombón bay.

Distribution of modern dinocysts and pollen in the western Mediterranean Sea (Algerian margin and Gulf of Lion)

The Mediterranean Sea is generally described as an oligotrophic area where primary productivity is limited to a few coastal environments with nutrient-enriched fluvial input. However, several studies have revealed that the hydrology of the western Mediterranean has major seasonal productive patterns linked either to significant riverine input or to seasonal upwelling cells. This study aims to: i) discuss organic microfossils (i.e. pollen and dinoflagellate cyst assemblages, as well as other non-pollen palynomorphs) from two different productive areas of the western Mediterranean Sea, and ii) examine the importance of the interconnections between marine and continental influences responsible for modern palynomorph distributions. Based on 25 samples from the Gulf of Lion (GoL) and Algerian Margin, this study key findings are: i) that GoL marine productivity is driven by the combination of discharge from the Rhône River and seasonal upwelling mechanisms, ii) that the strong productive pattern of the northern African coast is driven by water density front mixings and related upwelling. These two patterns are discussed in the light of major links that provide a better understanding of the signatures of marine and continental bio-indicators. Typical differences in vegetation across the north-south climate gradient in the western Mediterranean Basin are highlighted by the larger ratio of Euro-Siberian to Mediterranean pollen taxa in the northern sector. Synoptic maps also illustrate the complex interactions of environmental drivers determining the distributions of continental and marine palynomorphs in the western Mediterranean Sea.

Late Holocene paleoenvironmental changes inferred from multi-proxy studies of the Kholasht-Kouh Lake sediments in the Gilan mountains, northern Iran

Past vegetation and environmental changes and the role of climate as well as human activities are of major interest. The Hyrcanian region with a high number of endemic species has a poorly known paleoenvironmental history, especially the western region of northern Iran. This study aims to investigate a radiocarbon-dated sediment core of the Kholasht-Kouh Lake (KHL) for the recorded between ca. 510 and 1180 cal yr BP. KHL is located at 2000 m elevation and surrounded with steppe vegetation above the present-day forest line. Multi-proxy analyses including pollen, non-pollen palynomorphs, charcoal, loss on ignition, and X-ray fluorescence were applied to reconstruct past environmental dynamics. The results indicate the dominance of herbaceous vegetation (mainly Poaceae, Artemisia, and Amaranthaceae) around the lake during the whole record, except for the period between 1010 and 740 cal yr BP. During this period of the Medieval Climatic Anomaly (1000–700 cal yr BP) mixed forest increased, consisting mainly of Quercus, Fagus, Carpinus, and Juniperus. The K, Ti and Si elements (as indicators for increased in detrital inputs) suggest relatively humid condition between 1180 and 1010 cal yr BP. Furthermore, higher lake levels may indicate from low values of the Mn/Ti, Ca/Ti and Sr/Ti ratios. After 1010 until 740 cal yr BP the highest value of the Si/Fe ratio, suggested warmest period of the record. While the lowest value of the Si/Fe ratio, in line with the reduction of other elements and ratios, between 740 till 510 cal yr BP represented cold and dry period. Humans were present around the study area at least since beginning of the record, but did not played an important role impacting the vegetation.