Charcoal Analysis Research Articles

Late Glacial and Holocene history of climate, vegetation landscapes and fires in South Taiga of Western Siberia based on radiocarbon dating and multi-proxy palaeoecological research of sediments from Shchuchye Lake

Abstract To investigate long-term relationships between climate, vegetation, landscape geochemistry and fires in the boreal forest zone of Western Siberia, a sediment core of 345 cm was collected from Shchuchye Lake (located in south taiga zone of southeast part of West Siberian plain) and investigated by spore-pollen, radiocarbon, LOI and charcoal analyses. Quantitative palaeoclimate was reconstructed based on pollen data. Investigation revealed 13.2 cal ka history of vegetation, climate, landscapes and fires. In the dry climate of Late Glacial, the landscape was treeless. Continuous permafrost existed in the soil. In the middle of the YD cooling 12.4–12.2 cal ka BP, our data showed warming that caused degradation of permafrost in soils and settlement of spruce in moist places. Later, thawing and accumulation of moisture in a local lowering in relief increased and a lake was formed. With the beginning of the Holocene, the climate sharply changed to warmer and wetter. Intensified surface flow caused accumulation of mineral and carbonate fraction in the lake. Dense birch forests spread on drylands. As a result, the leaching regime initiated the formation of podzols in the soil. At about 10.0 cal ka BP, Scots pine (Pinus sylvestris) quickly spread in the area of investigation. Fires became more frequent and more intense during the dry Late Glacial time, sharply decreasing with increased precipitation in the Early Holocene, and again moderately increasing with spread of pine forests in the mid Holocene. With the transition to Late Holocene (after 6.0 cal ka BP), the intensity of regional background fires and number of local fires decreased.

Multi-proxy reconstruction of climate changes from the Medieval Climate Anomaly to the Little Ice Age in Southeast China

Exploring climate fluctuations across geological eras provides crucial historical context for addressing contemporary global climate challenges. This research leverages multi-proxies records analytical techniques, including pollen and charcoal analysis, X-ray fluorescence (XRF), and assessments of humification degree and loss on ignition (LOI), alongside paleoclimate simulations based on an alpine peat bog in Jiangxi Province, Southeast China. The study aims to provide a comprehensive review of vegetation evolution, climatic shifts, East Asian summer monsoon (EASM) intensity, and the potential drivers behind EASM behavior over the past two millennia. Our findings reveal a significant transition in precipitation and temperature patterns from the Medieval Climate Anomaly (MCA, 960–1420 CE) to the Little Ice Age (LIA, 1420–1850 CE). A distinct pattern emerges, highlighting particularly wet periods occurring between 960–1050 CE, 1190–1250 CE, and 1350–1400 CE, as well as significant droughts during 1430–1550 CE, 1590–1650 CE, 1680–1720 CE, and 1750–1800 CE. When compared to our temperature reconstruction series and precipitation data, a clear correlation emerges—wet phases align with warmer period characteristic of the MCA. Based on our simulation results, we suggest that ENSO oscillations and the Indo-Pacific warm pool played a substantial role in driving climate dynamics from the MCA to the LIA.

A Holocene fire history from Terra Nova National Park, Newfoundland, Canada: vegetation and climate change both influenced the fire regime

Fire is the largest natural disturbance factor in the boreal forest and plays a critical role in the composition, structure, and succession of stands and landscapes. The island of Newfoundland, located in eastern Canada, is subjected to a greater maritime influence, which may result in longer fire return intervals. The limited data on the fire regime does not account for interactions between fire, vegetation, and climate throughout the Holocene. We used sediment cores from Arnold’s Pond, Terra Nova National Park, which covered the last ~11,800 cal. yr BP, to investigate these interactions. We recognize 4 pollen zones and macroscopic charcoal analysis detected 45 local fire events. The 250-year mean fire return interval associated with the current vegetation is longer than a previous estimate for the park, but significantly shorter than other estimates for the island. Our mean fire return interval is within the range of fire estimates from Québec with similar vegetation. Our results suggest that the fire regime was primarily influenced by vegetation and climate. The transition to an open forest from a shrub tundra resulted in increased fire activity and fire frequency, which were likely driven by additional fuel on the landscape, but could have also been influenced by unknown climatic factors. We identified several examples of changes in the fire frequencies and/or charcoal accumulation that coincided with regional climate shifts, but we also identified a non-synchronous change. The non-synchronous shift to drier conditions resulted in a ~500-year time lag between peak Pinus strobus abundance and maximum fire frequency. Synchronous shifts in fire activity and/or fire frequency coincided with the 8200 event, Medieval Climate Anomaly and Little Ice Age. We also noted a decrease in fire frequency between 2600–1500 cal. yr BP that coincided with similar changes in the fire frequency from ~3000–1000 cal. yr BP in Québec. Our study highlights the complex interactions influencing the fire regime in our study area during the Holocene.

Discovery and environmental implications of Santorini tephras (Cape Riva and Minoan) in sediments of Lake Yayla (West Anatolia)

Throughout the long eruption history of the Santorini volcano, the Cape Riva/Y-2 and Minoan/Z-2 eruptions had a profound impact on the environment. The Minoan eruptions also had a significant impact on society. These two tephras, as well as the Y-2 tephra individually, have been recorded for the first time in a lacustrine area in western Anatolia. This study examines the geochemical properties of Y-2 (23 cm) and Z-2 tephra layers (19 cm; 14 cm pure and 5 cm mixed) from 18 m sediment cores in Lake Yayla (Denizli-Buldan). Additionally, high-resolution µXRF, fossil pollen, charcoal, and dating analyses were conducted on the cores to determine the chronologies and environmental effects of the tephra layers. Fossil pollen findings show consistent forest and steppe/grassland vegetation before and after the Z-2 tephra, with the forest impact lasting for 240 years after the eruption. Increased aquatic vegetation and changes in specific taxa (e.g. Pinus sp. and Amaranthaceae increased, while Quercus deciduous, Olea europaea, and cereals decreased) were observed following the Minoan eruption. Charcoal analysis indicates heightened fire activity post-Minoan eruption, while XRF data reveal no associated climatic change. At the same time, no correlation has been identified between the Cape Riva eruption and ecological changes (climate, vegetation, and fire activity). Contribution to dating the tephra was provided by radiocarbon dating from the lowest part of the tephra layer (17,684 ± 63 years BP). This study sheds light on the extensive impacts of the Y-2 and Z-2 tephra eruptions, focusing on their dating, geochemistry, environmental effects, tephra transport directions, and thicknesses. It demonstrates the presence of a significant geological event for the settlements in the Büyük Menderes Valley.

Fuel types and use in late Western Zhou (877 – 771 BCE) industrial contexts in Northwest China

To date, the types of fuels used in pottery kilns during the Western Zhou Dynasty have not been adequately addressed. Samples from updraft kilns and semi-downdraft kilns at the Fengjing site, the capital in the late Western Zhou period, were selected for analysis. Through phytolith and wood charcoal analysis, various grasses mainly Panicoideae, Pooideae, and Eragrostidoideae, as well as millet, rice, and wheat crops were identified. Additionally, wood primarily from trees of the Quercus, Ulmus, and Liquidambar taxa was found. These findings suggest that different pottery kilns used similar fuels, demonstrating a broad-spectrum rather than specialized fuel utilization during the Zhou period.

Collaborative anthracology and cultural understandings of wood charcoal in Marra Country (northern Australia)

This paper presents results from the first collaborative anthracological (archaeological wood charcoal analysis) study in northern Australia’s southwest Gulf of Carpentaria region. The analysis focused on charcoal from a Late Holocene combustion feature and surrounding dispersed charcoal on a buried floor surface. The results suggest that the combustion feature likely functioned as a ground oven associated with a potential specific function, with the majority of fuel wood coming from wakuwaku/marnunggurrun (Callitris columellaris or White Cypress Pine) and Myrtaceae species. These species are found in low woodlands associated with hilly and freshwater springs settings, and their abundance and dispersal are influenced by fire regimes (e.g., Aboriginal fire regimes). Information provided by members of the Marra Aboriginal community about our findings focused on the social and cultural significance of wakuwaku/marnunggurrun, with particular emphasis around its role in past and present wood collection strategies (fire-making and transport, high value timber etc.). By exploring how anthracology and cultural knowledge intersect to generate new understandings about the relational qualities of wood (charcoal), we aim to highlight how collaborative archaeobotany can help reorient research questions in the discipline, providing an opportunity to make such specialised analyses meaningful to communities.

Stable hydrogen isotope evidence of late-Holocene precipitation variability on the Caribbean slope of the Cordillera Central, Costa Rica

In Central America and the Caribbean, periods of increased aridity that correspond to the Terminal Classic Drought (TCD; 1200–850 cal yr BP) and the Little Ice Age (LIA; 500–100 cal yr BP) have been documented in many paleoclimate records. Compound-specific hydrogen (δDalkane) and carbon (δ13Calkane) isotopic compositions of n-alkanes in lake sediment can be used to interpret changes in paleoprecipitation and terrestrial paleovegetation, respectively. To assess the climate forcing mechanisms that drove the TCD and LIA, we established a multidecadal to centennial-scale late-Holocene reconstruction of precipitation variability and vegetation change at mid-elevation on the Caribbean slope of Costa Rica, developed from new δDalkane, δ13Calkane, and geochemical analyses and previous pollen and microscopic charcoal analyses from a sediment core from Laguna María Aguilar. Laguna María Aguilar is a freshwater lake located at 770 m elevation on the Caribbean slope of the Cordillera Central. During the TCD, δDalkane data for María Aguilar indicate relatively wet conditions compared to the mean δDalkane value for the entire record. Other proxy records for the TCD indicate that the Pacific slope of Costa Rica and sites above 3400 m near the continental divide experienced generally drier conditions than mid- and low-elevations on the Caribbean slope. We conclude that the TCD may have been driven by both Pacific and Atlantic climate-forcing mechanisms. During the LIA, the Laguna María Aguilar δDalkane record indicates an increase in hydroclimate variability, with some of the highest recorded δDalkane values (driest conditions) during the earliest portions of the LIA, but conditions were not persistently dry for the entirety of the LIA. Based on regional paleoclimate records overall, the LIA drought appears to be more clearly expressed on the Caribbean slope than on the Pacific slope of Costa Rica, indicating that the LIA was perhaps driven primarily by Atlantic Ocean conditions and climate dynamics.

Co-pyrolysis of wheat straw with polyester-based polyurethane for nitrogenous compounds: Pyrolysis kinetic properties and synergistic effects

To re-utilize agricultural waste straw and waste plastic, the co-pyrolysis process of wheat straw (WS) and high-nitrogen polymer polyester-based polyurethane (PU) and the synergistic effects were studied. The results showed that PU facilitated pyrolysis to occur at lower temperatures. The effective apparent activation energies (Eα) of different samples were calculated at different conversion rates with three methods (Kissinger, KAS and Starink). It was found that PU decreased the Eα values and enthalpy change of WS and increased the reactivity. Both ΔG and ΔS results indicate that a heating rate of 5 ℃/min is more favorable for co-pyrolysis. PU greatly promoted the production of pyrolysis oil. Co-pyrolysis oil doped with 75 % PU gave the highest yield of 77 wt%. Co-pyrolysis effectively suppressed the production of acids, aldehydes, and phenols in pyrolysis oils. It increased the levels of alcohols and ketones, improving the pyrolysis oil's stability and calorific value. α, β-unsaturated aldehydes produced by WS during pyrolysis reacted with hydrazine derivatives produced by PU pyrolysis to produce pyrazole compounds after dehydration. In the co-pyrolysis of 50 % doped PU, the reaction of methyl and methylene produced by WS with amines (-NH2) produced by the pyrolysis of PU promotes the production of trimethylamine. The yield of amines in the nitrogenous compounds reached a maximum at this time. PU increased the yield of nitrogenous compounds and their variety. It favored the output of high-value chemicals. FT-IR analyses of pyrolytic charcoal showed that the addition of PU promoted the cleavage of WS and the dehydration and decarboxylation reactions of C-O and C-O-C. Finally, synergistic effects and nitrogen conversion mechanisms in the co-pyrolysis process are proposed. This work provided a theoretical basis for the resource utilization of WS waste and PU waste.

Relationship between extreme species richness and Holocene persistence of forest-steppe grasslands in Transylvania, Romania

The most species-rich grasslands worldwide are known from the Carpathian Mts and their periphery in East-Central Europe. They occur in forest-steppe regions, transitional between temperate forest and arid steppe biomes. Their climate, largely suitable for forests, raises questions about the origin of these grasslands. Have they been forested in the past, or locally maintained through a disturbance regime? We addressed these questions to contribute to the broader understanding of Holocene dynamics of open habitats in temperate Europe. We employed soil charcoal analysis and soil morphology to reconstruct past representation of woody species with fine spatial resolution. Our study area was Romanian Transylvania, a region renowned for a well-developed forest-steppe. Six soil profiles along a climatic gradient were assessed: four in forest-steppe grasslands, two in grasslands in adjacent forest region (forest grasslands). The results revealed profound differences between forest-steppe and forest grasslands. Forest-steppe profiles showed Phaeozems with low specific anthracomass of woody species and continuous dominance by Juniperus, suggesting a long-term presence of grasslands. Forest grasslands showed Luvisols with higher anthracomass and abundant charcoal of broad-leaved trees, indicating establishment after deforestation. The high radiocarbon ages of charcoals in basal soil horizons point to a glacial origin of soils and the link of forest-steppe grasslands to glacial forests. Siberian hemiboreal forests and related grasslands may be modern analogues of the reconstructed ecosystems, sharing many species with present day forest-steppe. We suggest that disturbances such as fire, herbivore grazing, and human activities have played an important role in shaping the forest-steppe over time, contributing to the formation of today’s richest grasslands.

Woodland in the Curonian spit during the 3rd millennium BC based on anthracological evidence from Neolithic sites

In this paper we present the first attempt to apply anthracological analysis in paleoenvironmental research in Lithuania. We present the results of charcoal analysis of three Neolithic archaeological sites in the Lithuanian part of the Curonian Spit. The formation and development of the Curonian Spit was a complex and dynamic process. Constant aeolian processes caused periods of sand deflation, which led to the movement of the dunes and drastic changes in the landscape until the 19th century when a protective dune ridge was built and systemic tree planting began. Curonian woodlands currently consist of mostly planted pine forests. Knowledge of the spit’s vegetation and its dynamics in prehistoric and historic periods is mainly based on palynological data. This study aims to gain a more detailed understanding of the composition and development of the Curonian Spit forests in the 3rd millennium BC. Anthracological analysis of charcoal samples from three sites located in the middle and northern parts of the spit show that broad-leaved tree species such as oak, maple and lime were spreading during the Neolithic and suggest that woodland vegetation in different parts of the spit was not uniform, with broad-leaved species thriving around Nida site and pine forests around Alksnynė. We propose that one of the reasons for the observed difference between the sites is the different phases of the spit formation that these sites underwent during the settlement period, as the middle part of the spit was formed earlier than the northern part and is therefore represented by less developed soils.

Examining long-term fuel and land use patterns at Ziyaret Tepe, Türkiye using an integrated analysis of seeds, wood charcoal, and dung spherulites

This study presents the results of a combined dendrological, macrobotanical, and dung spherulite analysis of flotation samples collected from Bronze Age, Late Assyrian, and post-Assyrian contexts at the site of Ziyaret Tepe, located on the southern bank of the Tigris River in southeastern Anatolia. The results of this study show shifting fuel resource exploitation between pre-urbanized phases of the site (ca. 3000–1600 BCE), the urbanized Late Assyrian occupation (882–611 BCE), and the ruralized post-Assyrian (ca. 611 BCE–1500 CE) re-occupations of the site. During the Late Assyrian period, Ziyaret Tepe is thought to have been the location of the city of Tušhan, an important provincial capital of the Neo-Assyrian empire. Evidence for local deforestation near the Tigris River and expanding reliance on dung fuel use during this period indicate overexploitation of fuel resources as larger populations and extractive imperial economic policies placed heavier pressure on local land use. Qualitative dendrological data provides evidence for the intensification of fuelwood harvesting during this period, while textual evidence documented an expansive program of timbering to the north of the site intended to fuel imperial construction projects in the Assyrian heartland. Following the abandonment of Tušhan and the collapse of the Neo-Assyrian empire, local fuel resource exploitation during subsequent occupations of the site shifted towards the direct management of wood fuel resources and increasing reliance on rural pastoralism.

Wood charcoal from the late Neolithic site of Yingpanshan, southwest China: Past vegetation and plant resources utilization

Despite the increasing archaeobotanical studies on the prehistoric southeastern Tibetan Plateau, past woodland use strategies in this region remain unknown. Here we conduct an analysis of wood charcoals recovered from the late Neolithic site of Yingpanshan (5300–4500 BP) in order to understand past vegetation and wood utilization in the north of this region. The results show a great taxonomic diversity of woody species, as well as a landscape that was characterized by the predominance of Bambusoideae, Tsuga and Pinus, followed by Prunus, Quercus and Betula. These major taxa seem to have a high availability in the surrounding environment of the settlement, given their ecological requirements and contemporary distribution. There was a preferential use of the major taxa as fuel and timber. The anthracological data, combined with the carpological remains retrieved from the site, demonstrate the exploration of multiple plant food resources, with edible woody species possibly serving as fruits and vegetables. This study suggests the significance of integration of charcoal analysis with other archaeobotanical and zooarchaeological evidence for gaining an accurate picture of the land use practices and their environmental settings on the southeastern Tibetan Plateau.

Vegetation response to Holocene hydroclimatic variability in the aseasonal forests of the north-western Amazon

Projected warming and intensification of the hydrological cycle across the Amazon threatens the functioning of some of the most biodiverse ecosystems on the planet. Interfluvial wetlands, or wetlands fed directly by precipitation or small streams, may be some of the most vulnerable to future hydroclimatic changes. In this study, we investigated a 7300-year-old sedimentary archive from an upland palm swamp in the Yasuní National Park (Ecuador) to reconstruct past vegetation dynamics, palaeo-hydroclimatic conditions and human history using pollen, charcoal and geochemical analysis. Pollen data revealed: i) a forest composition influenced by dry conditions 6000 years ago, ii) the development of a palm swamp 4500 years ago, and iii) the establishment of the modern closed-canopy Mauritia flexuosa dominated swamp (moretal) 400 years ago. X-ray fluorescence data indicated that changes in vegetation composition were related to fluctuations in relative moisture levels, which occurred coeval to identified regional climatic events, particularly the Mid Holocene Dry Event (MHDE). Analysis of charcoal revealed continuous presence of fire, albeit at very low levels, since 5000 cal yr BP, with increased values during the last millennium. Our results suggest a footprint of hydroclimatic transitions in the mid-to-late Holocene in the aseasonal forests of the northwest Amazon, highlighting the need to better understand the long-term ecology of these systems to better protect them in light of future climatic change.

Holocene vegetation and wildfire disturbance in boreal central Yukon, Canada

Sediment cores were collected from Wrong (WL) and Lenore (LL) lakes in boreal central Yukon Territory, Canada, spanning circa 6000 years. Analyses of pollen, charcoal, magnetic susceptibility, levoglucosan, and down-scaled paleoclimatic data reveal the vegetation history and character/drivers of Holocene fire disturbance. Boreal forest has persisted in the region for millennia, with a regional mid-Holocene expansion of Picea mariana followed by expansion of Pinus contorta in the latest Holocene. The shortest reconstructed fire return intervals (FRI; ca. 110-125 years) occurred in the mid-Holocene, coincident with the development of highly flammable Picea-dominated forest and warm, dry summers that were characterized by elevated JJA Z500 anomalies and associated with an eastward/intense Aleutian Low. In the late-Holocene, FRI increased to ca. 240 years at WL and 280 years LL. Drivers of this change include regional cooling and increased precipitation, with a westward/weaker Aleutian Low position delivering more moisture to interior Yukon. Longer FRIs allowed for greater fuel accumulation between fires, enhancing fire size/severity. While higher fire frequency is noted in the mid-Holocene and increased fire size/severity in the late-Holocene, recent changes in Yukon fire disturbance suggest that the fire regime may soon lie outside the natural range of mid- and late-Holocene variability.

Mid-Holocene marine faunas from the Bangkok Clay deposits in Nakhon Nayok, the Central Plain of Thailand.

Based on several field investigations, many molluscan shells and chondrichthyan teeth, together with other invertebrate and actinopterygian remains were found from the marine Bangkok Clay deposits in Ongkharak, Nakhon Nayok, at a depth of ~ 5-7 m below the topsoil surface. Animal macrofossils recovered from these Holocene marine deposits were identified and their chronological context was investigated in order to reconstruct the paleoenvironments of the area at that time. The majority of marine fossils recovered from the site consist of molluscs, with a total of 63 species identified. Other invertebrate species include a stony coral, a mud lobster, barnacles, and a sea urchin. The vertebrates are represented by fish remains, including carcharhinid shark teeth from at least nine species, stingray and trichiurid teeth, and one sciaenid otolith. The molluscan fauna indicates that the paleoenvironments of the area corresponded to intertidal to sublittoral zones, where some areas were mangrove forests and intertidal mudflats. The fish fauna is dominated by the river shark Glyphis, indicating freshwater influences and possibly occasional brackish conditions. The carbon-14 analysis of mollusc and charcoal remains shows that deposition of the marine sediment sequence began during the mid-Holocene, spanning approximately from 8,800 to 5,300 cal yr BP. This study provides in-depth insights into the diversity of fishes, marine molluscs, and other invertebrates from the Bangkok Clay deposits, supporting the existence of a marine transgression onto the Lower Central Plain of Thailand during the mid-Holocene.

A multiproxy analysis of modern environmental change within a cypress swamp forest, Collier County, FL

The Florida Everglades are a vast subtropical wetland that historically spanned over 1,000,000 hectares, but much of the Everglades has changed in the last 100 years due to anthropogenic activity. Collier County, situated in southwest FL and bordering the Gulf of Mexico, was subject to alteration in the form of logging, road building, and canal digging. These actions disrupted the natural sheet flow of water and had large environmental impacts on the region, impacts which are slowly being addressed by Everglades restoration efforts. The aim of this work was to observe environmental change at a cypress swamp forest in Collier County within the Big Cypress National Preserve. Using sediment core data including charcoal analysis, loss on ignition, and peat humification, as well as remote sensing techniques, this project uses a novel approach to assess local environmental conditions in the modern era for the region. While this analysis was based on a single core located at the study site, additional ground-penetrating radar profiles at the study site showed a consistent, laterally continuous distribution of subsurface interfaces, therefore suggesting that the core is representative of the conditions at this specific location. Historical records and contemporary data are used to evaluate environmental change over time, and satellite imagery is used to quantify vegetation health. Environmental change related to anthropogenic activity is noted, and evidence of progress from restoration efforts is observed from the last two decades in our study’s data.

Fuel-use strategies at ultrahigh elevations on the Tibetan Plateau since the last deglaciation

Often referred to as the “Third Pole”, the Tibetan Plateau combines high elevation, extreme cold temperatures, hyper-aridity, and low oxygen levels. The strategy that early populations adopted to adapt to the harsh environment of the Tibetan Plateau has always attracted much attention. However, relevant studies have predominantly focused on the relatively lower elevation northeastern part of the Tibetan Plateau (<3000 m a.s.l.), with limited study in areas of ultrahigh elevation (>3500 m a.s.l.). This paper employed the flotation method and charcoal analysis of survey profiles from thirteen archaeological sites in the ultrahigh-elevation region of the middle Yarlung Zangbo River basin on the southern Tibetan Plateau, and finds that ancient people have been active in this region since the last deglaciation. The primary fuel sources used by ancient populations were small trees such as sea buckthorn (Hippophae gyantsensis) and shrubs such as juniper (Juniperus). The widespread use of undesirable wood (dwarf thorny shrub) like Sophora moorcroftiana and Caragana, along with the phenomenon of many sites relying on a single taxon, reflects the prevalent issue of fuel scarcity in this ultrahigh-elevation region. This might have been a driving factor for the early adoption of animal dung as a primary fuel source by ancient populations on the southern Tibetan Plateau.

Multi-proxy paleoenvironmental data from Paulina Marsh inform human-environmental dynamics in the Northern Great Basin U.S.A.

Understanding the dynamics between climate change and human adaptive strategies is a longstanding question driving paleoecological and archaeological research in North America's Great Basin. We present multiproxy data from five sediment cores retrieved from Paulina Marsh in the Fort Rock Basin, Oregon, an area renowned for its archaeology but lacking the paleoenvironmental data needed to fully contextualize those records. Radiocarbon, pollen, particle size, elemental, and charcoal analyses of one core, and geochronological data from four additional cores, reveal fluctuating vegetation communities, hydrologic conditions, and fire histories during the Early and Late Holocene that are consistent with models proposed to explain changing settlement-subsistence patterns in the region. There was likely an emergent marsh or meadow and an absence of Juniperus at the core site during the Early Holocene. Middle Holocene deposits are not present due to a geologic unconformity, perhaps because of channel migration and climatic aridity. Late Holocene sediments record a more mesic meandering stream system between ∼3900 and 2200 years ago, followed by an increase in xeric-adapted vegetation in the last 2000 years. The lack of Juniperus pollen in the Early Holocene sediments inform ongoing debates about Juniperus spread in the Great Basin. These data represent the first Early Holocene pollen record from the Fort Rock Basin and are one of few lowland vegetation histories of this age in the region. This study contributes to our understanding of past ecology in semi-arid environments, provides new context for archaeological interpretations, and establishes a framework for future work in the region.

The history of Fagus sylvatica at its northern limit in Vendsyssel, Denmark

Pollen, plant macrofossils and charcoal analyses were used to study tree diversity, fire history and forest disturbance over the past c. 3500 years at three forest remnant sites in Vendsyssel, northern Denmark. All locations had a more diverse tree composition in the past including abundant Alnus, Betula, Corylus, Pinus, Quercus, Salix, Tilia and Ulmus. The changes in tree diversity through time can be attributed to a combination of factors including climate change, burning linked to shifting cultivation, grazing and felling. The balance between arboreal and non-arboreal pollen was already being influenced by human activities in the late Bronze Age c. 3000 years ago. The high pollen abundance values recorded for Tilia pre-2000 years ago are exceptional as compared to later periods at these sites. At one location, the transition from Tilia to Fagus indicated that Tilia prevailed until c. 1300 years ago. Subsequent periods of forest clearance, with charcoal and cereal cultivation, initially including Hordeum and subsequently also Secale, were recorded. There was pollen evidence for grazing followed by shrub regeneration including Calluna, Erica, Juniperus and herbaceous taxa, and following that, a forest recovery of mainly Fagus, Picea and Pinus. This recovery is also recorded in historical forest records from 1880 CE onwards, emphasising the dominant role of plantation schemes. Results are placed in a wider framework of other sites in Denmark and southern Scandinavia, which have also documented a reduction of tree diversity and forest cover over the same period. The evidence from the long-term record is used to draw conclusions to assist forest restoration programmes.

Fire dynamics and driving mechanisms on the Eastern Coast of China since the Late Pleistocene: evidence from charcoal records on Shengshan Island

Fires play a significant role in ecosystems, exerting a profound influence on climate, vegetation, and geochemical cycles, while being reciprocally affected by these factors. The reconstruction of past fire events serves as a valuable window into understanding environmental changes over time. To investigate the history of ancient fires on the Eastern Coast of China, we conducted the first charcoal analysis on a loess profile of Shengshan Island (East China Sea). Along with other biological and geochemical proxies, we successfully reconstructed the ancient fire dynamics and elucidated their driving mechanisms in this region since the Late Pleistocene. Our initial findings revealed a peak in charcoal concentration during the 60-50 ka period, but after calibrating for sedimentation rate, the concentration significantly decreased. Fire activities remained weak during 50-30 ka, likely due to the scarcity of combustible materials. Between 30-12 ka, fires were frequent in the early period, while gradually diminishing during the later stage. Dry climate and dense vegetation likely attributed to frequent fires in early period, while some extreme events (e.g., sudden change in temperature) may have decreased the fire frequency in later period. The Holocene (began ~12 ka) evidenced the most frequent fire events as a high charcoal concentration was recorded, likely caused by human activities. After comparing our findings with other paleoecological records from surrounding areas, we confirmed the accuracy of our reconstruction of ancient fires. This reconstruction captures not only local shifts but also broader regional changes. Overall, our study highlights the importance of calibrating sedimentation rate in charcoal profiles, while also contributing to an enhanced understanding of environmental changes along the Eastern Coast of China since the Late Pleistocene.