623 results on '"macrofossils"'
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2. Paleoecological History of Maplecrest Fen, Catskill Mountains (NY, USA) From Deglaciation to the Industrial Age.
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Peteet, Dorothy M., Ibe, Ralph, Stone, Emily, Zajac, Catherine, and Chang, Clara
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YOUNGER Dryas , *GLOBAL warming , *WHITE pine , *PALYNOLOGY , *RAGWEEDS - Abstract
ABSTRACT Aim Location Time Period Taxon Methods Results Main Conclusions To develop the palaeoecological and palaeoclimatic history of Maplecrest Fen, Greene County, NY.Catskill Mountains, New York.13,500 calendar years to present (ybp, present = 1950).Angiosperms, gymnosperms and bryophytes.We used pollen and spore analysis, macrofossil analysis, loss‐on‐ignition (LOI) and X‐ray fluorescence (XRF) analysis of a 7.8 m sediment core from the Fen along with AMS radiocarbon dates retrieved from the identified terrestrial macrofossils.Late‐glacial and Holocene vegetational change from ice withdrawal reveals the development of a shallow lake and then fen to the present. The boreal spruce (Picea), fir (Abies) and paper birch ((Betula papyrifera) pollen signature near the base of the core (Zone M2) suggest a Younger Dryas (YD) signal overtopping warmer Allerod aged basal sediments. The early Holocene white pine (Pinus strobus) is followed by increases in hemlock (Tsuga) and beech (Fagus), ushering in a moister climate. About 5200 ybp drought is indicated by the well‐known hemlock biostratigraphic decline in the Northeast. Drepanocladus moss and stonewort (Chara) shift to sedges (
Carex ) and violets (Viola ) locally present. For the next 5000 years, the vegetation will remain relatively stable with lower temperatures suggested by the return of spruce and fir. Ragweed (Ambrosia) rise along with other weedy taxa marks European settlement near the top 50 cm of the core, along with a striking increase in anthropogenic lead, as seen using X‐ray fluorescence.Deglaciation began in the Catskills at a high elevation about 13,500 years ago and recession of ice from the Laurentide margin proceeded at about 0.1 km/year. Temperature shifts promoted changes in the boreal forest including warming and cooling, and drought and wetter intervals both appear in the Holocene history but do not appear to be easily forecast as climate continues to warm. [ABSTRACT FROM AUTHOR] more...- Published
- 2024
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3. Stratigraphy of the Middle Jurassic Deposits of the Bureya Trough according to New Paleontological Data from the Soloni Section (Russian Far East).
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Dzyuba, O. S., Urman, O. S., Shurygin, B. N., Goryacheva, A. A., and Shamonin, E. S.
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SUBMARINE geology , *MARINE sediments , *EARTH sciences , *SEDIMENTARY basins , *BRACHIOPODA - Abstract
Some taxa of belemnites, bivalves, gastropods, and brachiopods, previously unknown in the Russian Far East (except for Eastern Siberia and Northeast Russia), of both Tethyan and Boreal Arctic origin, have been recorded in the Middle Jurassic of the Soloni River (Bureya River basin). In particular, bivalve assemblages were found to increase in abundance throughout most of the Bajocian section at the Soloni River, similar to what is observed in Siberian sections. However, the first appearance of some species of the genus Grammatodon and trigoniids was recorded in this area much earlier than in Siberia. This, combined with a revision of the taxonomic composition of previously recorded fossils, has made it possible to refine the biostratigraphic subdivisions of not only the studied section, but also the uppermost Lower–Middle Jurassic marine deposits of the Bureya Trough as a whole. The age ranges of the local lithostratigraphic units have been refined to a greater degree. It has been established that the Sinkal'tu Formation corresponds to the Upper Toarcian–lowermost Lower Bajocian, the Epikan Formation to the uppermost Lower Bajocian, the El'ga Formation to the Upper Bajocian, and the Chagany Formation to the Bathonian–Callovian. Data on the palynological assemblages identified in these formations are provided. The recent studies of cephalopods and bivalves from Siberia, the Russian Far East, and southern Alaska have led to the development of a refined interregional correlation scheme for Bajocian deposits in these regions. [ABSTRACT FROM AUTHOR] more...
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- 2024
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4. Paleoecological data on the distribution of Pinus peuce Griseb. in Southwestern Bulgaria for the last 30000 years.
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Tonkov, Spassimir
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DECIDUOUS plants ,SCOTS pine ,PALYNOLOGY ,PEAT bogs ,RADIOCARBON dating - Abstract
The paleoecological information on the distribution of the Tertiary relic and Balkan endemic Pinus peuce Griseb. (Macedonian pine) is summarized on the basis of the results from pollen analysis, plant macrofossil determination and radiocarbon dating of lake and peat bog sediments in the mountains of Southwestern Bulgaria. The oldest record is of Middle Pleniglacial age (30000-24000 cal. yrs. BP) when pollen of P. peuce, together with pollen of other coniferous and deciduous trees, was established from the West Rhodopes Mountain. During the Late Glacial (14500-11600 cal. yrs. BP) stands of pines, P. peuce included, thrived among coldtolerant herb communities in the Rila, Pirin and the West Rhodopes mountains, confirmed by the first macrofossils (needles) determined. The minor participation of P. peuce in the early Holocene (11600-8800 cal. yrs. BP) Betula forests was succeeded by its wider distribution after 8200-7900 cal. yrs. BP when a coniferous belt composed by pines and Abies was shaped in the Rila and Pirin mountains. This vegetation reconstruction is supported by numerous macrofossils of P. peuce (needles, seeds, and partly stomata). Since 2600 cal. yrs. BP in the conditions of a more humid and cooler climate, the pulsating invasion of Picea abies restricted to some extent the distribution of P. peuce. Both species, together with Pinus sylvestris, shaped the timber-line at many places. The main conclusion from this survey is that populations of P. peuce survived the harsh glacial climatic conditions in montane refugia with subsequent gradual widespread during the Holocene. [ABSTRACT FROM AUTHOR] more...
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- 2024
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5. Insight into the vegetation development of the Karkonosze Mountains (southwestern Poland) during the Late Vistulian and Holocene, based on data from glacial lakes
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Agnieszka Wacnik and Ewa Madeyska
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glacial lakes ,vegetation history ,pollen analysis ,macrofossils ,holocene ,larix ,sudetes ,Paleontology ,QE701-760 ,Botany ,QK1-989 - Abstract
New palaeoecological records from two glacial lakes (the Mały Staw – 1183 m a.s.l. and the Wielki Staw – 1225 m a.s.l.) from the Polish Western Sudetes were obtained with the aim of better understanding the long-term vegetation development, the relationship between postglacial migration patterns, climate changes and human interference in mountainous areas, as well as to verify the local survival of some cold-adapted species during the Holocene maximum warming. Vegetation changes were reconstructed using pollen, spores and macrofossils. Several major stages of plant cover evolution over the last 12 000 years were identified. The end of the Late Vistulian (~12 100–11 700 cal BP) was documented for the first time in lake sediments from the region. During this period, the local vegetation was characterized by cold alpine meadows and patches of communities with shrubs ( Betula nana , Alnus viridis , Salix , Juniperus , Ephedra ) and trees growing at some distance from the lakes. In the Early Holocene, the expansion of boreal forests, consisting of Betula , Pinus sylvestris , as well as continental Larix and Pinus cembra , reached an altitude of ~1180 m a.s.l. An important discovery was the presence of Larix macrofossils in both studied profiles, which together with pollen evidence, confirmed its local persistence from the Early Holocene to the Middle Ages. It was also demonstrtaed that Betula nana , Selaginella selaginoides , Huperzia selago most probably persisted in the area from the Younger Dryas to at least the Middle Ages or even to the modern times, surviving through the Holocene climatic optimum. The increase in grassland representatives from ~4100 cal BP and the appearance of the cultivated plants ( Triticum type pollen) from ~3300 cal BP, was due to the long-distance transport of pollen reflecting the development of agriculture and settlement outside the Karkonosze Mountains. It was not until the 10th century AD that the environment underwent a stronger anthropogenic transformation. Growing economic activities (e.g. metallurgy, mining of non-ferrous metal ores, glass production, forest industry) that developed, especially from the 12th century onwards required the supply of wood raw material. The development of agriculture in the region promoted the expansion of meadows and pastures and the greatest taxonomic diversity of herbaceous plants was recorded between the 13th and 15th centuries. more...
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- 2024
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6. Holocene history of Fiskesø, Prinsesse Ingeborg Halvø, eastern North Greenland.
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WAGNER, BERND and BENNIKE, OLE
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LAKE sediments , *ENVIRONMENTAL history , *RADIOCARBON dating , *SEA level , *GEOCHEMISTRY - Abstract
Sediment cores up to 92 cm in length were recovered with gravity and Russian peat corers from Fiskesø, Prinsesse Ingeborg Halvø, eastern North Greenland, during the summer 2014. The correlated sediment succession consists of clastic sediments that are interspersed in the upper part with layers of organic material and likely record the environmental history of the lake since deglaciation. The paucity of macrofossil remains hampered radiocarbon dating of the sediments from Fiskesø. According to published data, the deglaciation of the region took place c. 10 cal. ka BP. Relative sea-level reconstructions from the region suggest that the Fiskesø basin, which is today located at 33 m above sea level, was characterised by marine conditions until c. 8.1 cal. ka BP. Marine fossils in the lower part of the sediment succession support the prevalence of marine conditions. A reliable radiocarbon age from 5 cm above the isolation horizon in Fiskesø sediments indicates an age of 6.1 cal. ka BP and supports the isolation of the basin prior to this time. Cooling is indicated in the upper part of the sediment succession and is reported to have taken place in the region stepwise shortly after 6.1 cal. ka BP and at c. 4.5-4.0 cal. ka BP. Despite the poor chronology the data from Fiskesø support existing terrestrial and marine reconstructions from the region. [ABSTRACT FROM AUTHOR] more...
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- 2024
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7. Stratigraphic Distribution of Fossil Organisms in the Upper Vendian Deposits of the Central and Southwestern Regions of the East European Platform.
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Golubkova, E. Yu., Kushim, E. A., Kuzmenkova, O. F., Laptsevich, A. G., Plotkina, Yu. V., and Silivanov, M. O.
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New and previously obtained paleontological data from the Vendian reference sections of the central and southwestern areas of the East European Platform are analyzed. Various associations of organic-walled microfossils and macroscopic fossil organisms of Redkino and Kotlin age are widespread in the Upper Vendian terrigenous deposits of northwestern Russia, northern Belarus, and western Ukraine. It is assumed that the Redkino and Kotlin intervals correspond to two major stages of transformation in the communities of fossil organisms. Finds of new fossils, including those representing animals, in the Upper Vendian deposits of the Kotlin Regional Stage suggest a more complex composition of the Kotlin biota than previously thought. [ABSTRACT FROM AUTHOR] more...
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- 2023
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8. Trait‐based approaches as ecological time machines: Developing tools for reconstructing long‐term variation in ecosystems.
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Brown, Kerry A., Bunting, M. Jane, Carvalho, Fabio, de Bello, Francesco, Mander, Luke, Marcisz, Katarzyna, Mottl, Ondrej, Reitalu, Triin, and Svenning, Jens‐Christian
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ECOSYSTEM management , *MACHINE tools , *ECOSYSTEM dynamics , *DEEP ecology , *PALEOECOLOGY , *ECOSYSTEMS - Abstract
Research over the past decade has shown that quantifying spatial variation in ecosystem properties is an effective approach to investigating the effects of environmental change on ecosystems. Yet, current consensus among scientists is that we need a better understanding of short‐ and long‐term (temporal) variation in ecosystem properties to plan effective ecosystem management and predict future ecologies.Trait‐based approaches can be used to reconstruct ecosystem properties from long‐term ecological records and contribute significantly to developing understandings of ecosystem change over decadal to millennial time‐scales.Here, we synthesise current trait‐based approaches and explore how organisms' functional traits (FTs) can be scaled across time and space. We propose a framework for reconstructing long‐term variation in ecosystems by means of analysing FTs derived from palaeoecological datasets. We then summarise challenges that must be overcome to reconcile trait‐based approaches with palaeo‐datasets. Finally, we discuss the benefits and limitations of trait‐based reconstructions of ecosystem temporal dynamics and suggest future directions for research.Reconstructing environmental properties through time vis‐à‐vis FTs can be separated into two parts. The first is to record trait data for organisms present in modern ecosystems, and the second is to reconstruct temporal variability in FTs from palaeoecological datasets, capturing changes in trait composition over time. Translating palaeoecological datasets into FTs is challenging due to taphonomic, taxonomic and chronological uncertainties, as well as uniformitarian assumptions. Explicitly identifying and addressing these challenges is important to effectively calculate changes in FT through time.Palaeo‐trait research offers insights into questions related to short‐ and long‐term ecosystem functioning, environmental change and extinction and community assembly rules across time. As work in this area matures, we expect that trait‐based approaches integrating palaeoecology and neo‐ecology will improve understanding of past ecologies and provide a deeper insight of their implications for present‐day and future ecosystem management and conservation. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR] more...
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- 2023
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9. Submarine lateglacial lake deposits from jutland bank, the north sea.
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Bennike, Ole, Odgaard, Bent, Wiberg-Larsen, Peter, and Nørgaard-Pedersen, Niels
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LAKE sediments , *YOUNGER Dryas , *TUNDRAS , *RADIOCARBON dating , *CHIRONOMIDAE , *SEA level - Abstract
Little is known about Lateglacial environments in the North Sea, the so-called Doggerland. Here we report on submerged lake sediments from the north-eastern part of the North Sea, found in sediment core JR-14. The core contained Holocene marine sand underlain by clay and clay-gyttja with plant and invertebrate remains and sand without plant remains, interpreted as glaciofluvial sand. Radiocarbon dating of terrestrial plant remains from the Lateglacial sediments gave ages between 12 300 and 14 100 cal a BP, corresponding to the early part of the Younger Dryas stadial and the Bølling-Allerød interstadial. The Lateglacial sediments contained remains of Betula nana , Salix and Dryas plants indicating a tundra-like open landscape with dwarf shrub heaths, which is typical for the region. The sediments contained a diverse assemblage of bryophytes that throws light on the Lateglacial bryoflora of the region. Remains of macrolimnophytes indicate shallow carbonate-rich, cool lake waters. Remains of larvae of Trichoptera and Chironomidae dominated the invertebrate fauna and indicate a fairly species-rich fauna. The presence of lake sediments at ∼32.9–34.5 m below sea level shows that this part of the North Sea had not been transgressed by the sea during the Lateglacial. [ABSTRACT FROM AUTHOR] more...
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- 2023
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10. A complex insight into the Late Quaternary history of Bohemian-Moravian Highlands summit.
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Hájková, Petra, Široká, Adéla, Petr, Libor, Jamrichová, Eva, and Peterka, Tomáš
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GLOBAL warming , *DECIDUOUS forests , *WATER table , *FOREST microclimatology , *PALEOECOLOGY , *BEECH , *PINACEAE - Abstract
Peat is an important archive allowing the reconstruction of past mire environments and surrounding vegetation. The Pihoviny site, one of the oldest peat deposits in the Bohemian-Moravian Highlands, was analysed for macrofossils and pollen and compared with other profiles in the region. The local mire development started in the Late Glacial as sedge-moss quaking fen with tundra elements characterised by high mineral richness and groundwater level. During the Early Holocene, it developed through the rich fen with hummocks, willow and reed stage to the waterlogged spruce forest, which persisted for thousands of years until the post-mediaeval deforestation. The recent mire vegetation developed 300 years ago due to human-induced deforestation. Further, we revealed high regional synchronicity among pollen profiles in the Early-Holocene (10,000–9000 cal BP), when open-canopy pine-birch forests transformed into closed-canopy deciduous forests due to climate improvement. Contrary, the Late-Holocene transformation to beech-fir forests was not synchronous, suggesting another driver than climate, likely human activities. Although pollen of both late-successional trees occurred since the Early Holocene, their expansion began much later, 5500–3500 (beech) and 3500–2500 cal BP (fir). Numerous spruce macrofossils suggest its pollen's local origin in the waterlogged spruce forest. Our results support the need for active management to sustain open mire vegetation and prevent spontaneous forest regrowth, recently boosted by climate warming. Palaeoecological analyses reconstructed a mosaic of waterlogged spruce and terrestrial beech-fir forests in the landscape, which should be restored to increase forest resistance against bark-beetle breakdowns and other disturbances in future. [ABSTRACT FROM AUTHOR] more...
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- 2023
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11. A range‐wide postglacial history of Swiss stone pine based on molecular markers and palaeoecological evidence.
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Gugerli, Felix, Brodbeck, Sabine, Lendvay, Bertalan, Dauphin, Benjamin, Bagnoli, Francesca, van der Knaap, Willem O., Tinner, Willy, Höhn, Maria, Vendramin, Giovanni G., Morales‐Molino, César, and Schwörer, Christoph more...
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PALEOECOLOGY , *LAST Glacial Maximum , *CHLOROPLAST DNA , *MICROSATELLITE repeats , *PHYLOGEOGRAPHY , *MOUNTAIN plants , *HAPLOTYPES - Abstract
Aim: Knowing a species' response to historical climate shifts helps understanding its perspectives under global warming. We infer the hitherto unresolved postglacial history of Pinus cembra. Using independent evidence from genetic structure and demographic inference of extant populations, and from palaeoecological findings, we derive putative refugia and re‐colonisation routes. Location: European Alps and Carpathians. Taxa: Pinus cembra. Methods: We genotyped nuclear and chloroplast microsatellite markers in nearly 3000 individuals from 147 locations across the entire natural range of P. cembra. Spatial genetic structure (Bayesian modelling) and demographic history (approximate Bayesian computation) were combined with palaeobotanical records (pollen, macrofossils) to infer putative refugial areas during the Last Glacial Maximum (LGM) and re‐colonisation of the current range. Results: We found distinct spatial genetic structure, despite low genetic differentiation even between the two disjunct mountain ranges. Nuclear markers revealed five genetic clusters aligned East–West across the range, while chloroplast haplotype distribution suggested nine clusters. Spatially congruent separation at both marker types highlighted two main genetic lineages in the East and West of the range. Demographic inference supported early separation of these lineages dating back to a previous interstadial or interglacial c. 210,000 years ago. Differentiation into five biologically meaningful genetic clusters likely established during postglacial re‐colonisation. Main Conclusions: Combining genetic and palaeoecological evidence suggests that P. cembra primarily survived the LGM in 'cold period' refugia south of the Central European Alps and near the Carpathians, from where it expanded during the Late Glacial into its current Holocene 'warm period' refugia. This colonisation history has led to the distinct East–West structure of five genetic clusters. The two main genetic lineages likely derived from ancient divergence during an interglacial or interstadial. The respective contact zone (Brenner line) matches a main biogeographical break in the European Alps also found in herbaceous alpine plant species. [ABSTRACT FROM AUTHOR] more...
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- 2023
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12. Lateglacial to Mid-Holocene history of Vasby Mose, eastern Sjælland, Denmark.
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BENNIKE, OLE and NILSSON, BERTEL
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AQUATIC plants , *YOUNGER Dryas , *AQUATIC animals , *TUFAS , *HOLOCENE Epoch - Abstract
We retrieved a sediment core from Vasby Mose, a calcareous fen on eastern Sjælland, Denmark. The record spans the period from c. 14 700 to 6800 cal. years BP. During the Lateglacial, Vasby Mose was a lake where minerogenic sandy and clayey sediments accumulated. In the early Lateglacial, from c. 14 700 to 13 200 cal. years BP, a tundralike open, treeless vegetation with Betula nana and Dryas octopetala was found in the region. During the Younger Dryas, a rich flora of aquatic plants was found in the lake. In the Early to Mid-Holocene, Vasby Mose was a spring-fed calcareous fen, with deposition of peat and tufa. The flora included the sedges Carex rostrata and Carex paniculata, the aquatic plant Menyathes trifoliata, the calciphilous reed plant Cladium mariscus and the today nationally extinct bryophyte Meesia triquetra. The fauna included aquatic mollusc taxa such as Pisidium sp., Valvata spp. And Bithynia tentaculata and terrestrial or semi-terrestrial species such as Galba truncatula, Euconolus cf. alderi, Succinea/Oxyloma, Zonitoides nitidus and Vallonia pulchella. The Preboreal oscillation and other Early Holocene climate events are seen as short-lived, wet intervals. [ABSTRACT FROM AUTHOR] more...
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- 2023
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13. Paleontological Characteristics of the Upper Vendian–Lower Cambrian Sediments in the Section of the North Polotsk Borehole of the East European Platform, Belarus.
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Golubkova, E. Yu., Kuzmenkova, O. F., Laptsevich, A. G., Kushim, E. A., Vaskaboinikava, T. V., and Silivanov, M. O.
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REGIONAL development , *SEDIMENTS , *EDIACARAN fossils , *BOREHOLES - Abstract
In boreholes of the central regions of the East European Platform, continuous terrigenous sequences of the Vendian–Lower Cambrian are exposed, which makes it possible to consider them as reference for the development of a unified regional stratigraphic scheme for Belarus and the European Russia. This article presents the results of a paleontological and lithological study of a parametric borehole North Polotsk, drilled in the north of Belarus (Latvian saddle). An analysis of the taxonomic diversity of fossil organisms made it possible to identify six associations: association I with Striatella coriacea–Zinkovioides inclusus of the Redkino age; association II with Leiosphaeridia minutissima–Leiosphaeridia tenuissima, association III with Aataenia reticularis–Vendotaenia antiqua–Primoflagellaspeciosa, and association IV with Aataenia reticularis–Bicuspidata fusiformis of the Kotlin age; association V with Teophipolia lacerate–Gen. et sp. indet. 4 of the Rovno–Lontova age; and association VI with Granomarginata squamacea–Cochleatina ignalinica–Platysolenites antiquissimus of the Lontova age. The Precambrian–Cambrian boundary is drawn at the base of the Rudamina Formation. The data obtained significantly complement the paleontological characterization of the Vendian–Cambrian transitional deposits, which can be used in stratigraphic and paleofacies constructions. [ABSTRACT FROM AUTHOR] more...
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- 2022
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14. A review of palm macrofossils from India and perspectives.
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Kumar, Sanchita, Manchester, Steven R., Hazra, Taposhi, and Khan, Mahasin Ali
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PALMS ,FOSSILS ,ANGIOSPERMS ,INFLORESCENCES ,PLANTS - Abstract
Palms, regarded as a model group for megathermal forest evolution, are well represented in the fossil record, where they are one of the earliest recognizable modern angiosperm families. Paleobotanists and geologists have reported a large number of palm remains (leaves, petioles, stems, roots, fruits, seeds, rachillae, peduncles, inflorescences, flower, and entire palm axes) from the Cenozoic and K-Pg sediments of India. Although Rao and Achuthan (1973) reviewed the fossil palm flora from India, some occurrences were overlooked and more examples have been discovered since then. The present review work may fill the gap. The purpose of this article is to review comprehensively the palm fossils. Fossil palms are essential for understanding the deep evolutionary and geographical history of the family. The Deccan Inter-trappean beds of the Maastrichtian (Upper Cretaceous) to Paleocene age, are very rich in palm mega fossils preserved especially in the form of permineralization whereas the later epochs are rich in mainly compressed and impressed palm fossils. Unfortunately, most of the earlier reported fossils lack sufficient diagnostic morphological features to allow reasonable association with living palm taxa to genus, tribe, or even to, sub-familial level. Here, we review in detail this economically and ecologically important angiosperm group and discuss its paleobiogeography and palaeoclimatic interpretation. [ABSTRACT FROM AUTHOR] more...
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- 2022
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15. Early Cambrian Biotas of the South of the Latvian Saddle of the Eastern European Platform, Belarus.
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Golubkova, E. Yu., Kushim, E. A., Kuzmenkova, O. F., and Laptsevich, A. G.
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Terrigenous deposits from the North-Polotsk borehole drilled in the Latvian Saddle of the East European Platform were paleontologically studied. We identified two Lower Cambrian assemblages (I with Teophipolia lacerata–Tubula tortusa and II with Granomarginata squamacea–Platysolenites antiquissimus–Cochleatina ignalinica) in the Rudamina and Lontova Formations. The underlying sediments of the Upper Vendian Kotlin Formation contain the macroscopic alga Vendotaenia antiqua, which are characteristic of the Upper Vendian Kotlin Regional Stage. A new genus and species of microfossils, Tubula tortusa gen. et sp. nov., is described in the first biota. [ABSTRACT FROM AUTHOR] more...
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- 2022
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16. Early Holocene plant macrofossils indicate cool refugia for subalpine plant taxa in Acadia National Park, Maine
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Cas F. Carroll, Jacquelyn L. Gill, and Caitlin McDonough MacKenzie
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macrofossils ,conservation paleobiology ,subalpine ,refugia ,climate change vulnerability assessment ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Abstract
Identifying refugia— specifically places where species can persist during periods of regionally unsuitable climate— is increasingly important for conservation practitioners and land managers charged with protecting biodiversity in a rapidly warming world. Currently, many researchers assist in this process by building models to predict areas of refugia using climate data projected into the future under different climate scenarios; however, the coarse spatial scale of future climate data can be orders of magnitude larger than the scale of refugia on the landscape. Conservation paleobiology is an emerging field that can contribute to the identification of climate refugia by looking at the macrofossil records contained in sediments to better understand the response of species to past climate change within a small area, and allows us to ground-truth hypotheses about specific areas functioning as climate refugia. Here, we present a conservation paleobiology case study to update vulnerability assessments for subalpine plant species in Acadia National Park and locate potential future refugia on the landscape. We analyzed plant macrofossils in a sediment core from Sargent Mountain Pond in Acadia National Park (Maine, United States) at a fine spatiotemporal resolution to test the hypothesis that the area served as a past climate refugium for the subalpine species it currently hosts. We found that, when compared to a pollen record from a forest hollow core collected on Mount Desert Island, the macrofossils reflect a more stable presence of subalpine taxa throughout the Holocene Climatic Optimum (8,000–5,000 BP) than was observed at lower elevations. Our results indicate the importance of a complementary approach that combines plant macrofossils and pollen in addition to modeling to identify refugia and better understand the vulnerability of species and communities to climate change. more...
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- 2023
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17. Late-Glacial and Early Holocene environmental changes affecting the shallow lake basin of La Narce du Béage (Ardèche, Massif Central, France).
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Dendievel, André-Marie, Serieyssol, Karen, Dietre, Benjamin, Cubizolle, Hervé, Quiquerez, Amélie, and Haas, Jean Nicolas
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WATERSHEDS , *DIATOMS , *HOLOCENE Epoch , *YOUNGER Dryas , *POTAMOGETON , *CLIMATE change - Abstract
The sedimentary sequence of La Narce du Béage Basin is one of the few natural archives covering the last 18 ka cal. BP in the French Massif Central. This paper focuses on the palaeoecological reconstruction of environmental and climatic changes affecting this shallow periglacial lake from the Late-Glacial to the Early Holocene. After field surveys and geophysical mapping, two cores (cores A and D) were extracted and dated. Plant macrofossils, pollen, non-pollen palynomorphs (NPPs) and diatom assemblages were compared within the cores to study vegetation, temperature, pH, water level and ice cover changes through time. During the Oldest Dryas (18–14.75 ka cal. BP), climatic conditions were the coldest with a short ice-free season allowing the development of periphytic diatoms only (ecologically comparable to Arctic ones). A cold and dry steppe landscape – exposed to severe erosion – comprised an herbaceous and shrub flora (e.g. Artemisia , Chenopodiaceae, Helianthemum, Ephedra, Hippophaë, Juniperus). Animal presence is suggested by coprophilous fungi. Periphytic diatoms and allochtonous pollen (Cedrus) underline windy conditions, and the possible erosion of neo-formed soils. Then, during the Bølling-Allerød interstadial (14.75–12.7 ka cal. BP), the ice-free season increased and some trees/shrubs (Salix, Betula and Juniperus) established locally within open grasslands. During the Younger Dryas (12.7–11.7 ka cal. BP) cooler conditions favoured steppe taxa again (Helianthemum, Achillea, Artemisia , Caryophyllaceae, Ranunculaceae) and erosion increased. The ice cover on the lake prevailed even if the conditions were not as cold as during the Oldest Dryas. During the Preboreal (11.7–10 ka cal. BP) Isoëtes echinospora and I. lacustris developed in the eulittoral zone of the lake, which was surrounded by a swamp forest (with Betula nana and B. pubescens). Pinus sylvestris, Betula pendula, Corylus avellana and trees from the Quercetum mixtum rapidly established in the uplands. Occurrences of Gaeumannomyces and Xylomyces fungi – both phytopathogens on broadleaved trees – and decreasing herb values indirectly hint at a close forest canopy. At the beginning of the Boreal (10 ka cal. BP), aquatic and semi-aquatic taxa developed on open water due to longer ice-free seasons (diatoms, micro-algae, Alisma plantago-aquatica, Potamogeton, Typha). The final terrestrialization towards a mire occurred as a consequence of the Holocene warming and related to water chemistry changes (acidification, eutrophication). • During the last deglaciation, a very shallow lake established as demonstrated by palaeoecological data, such as epiphytic diatoms, living on rocks. • Late-Glacial steppe landscape with severe erosion, open grassland and possible mega-herbivore presence. Arctic-like conditions. • Development of shrubs or trees during the Bølling-Allerød interstadial and reduced ice-free season. • Dry and cold conditions persisted from the Younger Dryas to the Early Preboreal. Oligotrophic flora (Isoetids) established in the eulittoral zone. • During the post-glacial warming, the lake tended to acidify. Peat flora and organic matter accumulated and led to the terrestrialization of the lake. [ABSTRACT FROM AUTHOR] more...
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- 2022
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18. Multi-proxy study of the Pialeloup Bog (SE Massif Central, France) reveals long-term human environmental changes affecting peat ecosystems during the Holocene.
- Author
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Dendievel, André-Marie, Argant, Jacqueline, Dietre, Benjamin, Delrieu, Fabien, Jouannic, Gwénolé, Lemdahl, Geoffrey, Mennessier-Jouannet, Christine, Mille, Pierre, Haas, Jean Nicolas, and Cubizolle, Hervé more...
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BOGS , *ALPINE regions , *ANTHROPOGENIC soils , *PEAT , *RYE , *BEECH , *WETLANDS , *FOREST soils - Abstract
In order to reconstruct local environmental changes affecting wetlands in middle mountain ranges, this study presents a multi-proxy analysis of the Pialeloup peat record on the Béage Plateau (South-Eastern Massif Central, France). It combines macrofossil, beetle, palynological, and geochemical data. The results are compared with other palaeoecological studies and archaeological data from the Massif Central, Jura Mountains and Alpine regions to discuss the links between local environmental changes and socio-economical dynamics at larger scales. Based on this approach, early environmental changes were highlighted between 6500 and 4800 BC, most certainly due to animal trampling on the Pialeloup bog. These events seem synchronous with human presence from the Late Mesolithic to Early Neolithic. It suggested that wild animals and human/livestock might have frequented the Béage Plateau wetlands. Then, long-term landscape management was documented for the last 3000 years. Local palaeoecological insights (synanthropic plants, beech-forest clearings, increasing erosion) and archaeological evidence for human settlements (pottery, millstones, and anthropogenic soils) were revealed to start during the Iron Age (400–200 BC). From the Late Iron Age to the Early Medieval period (150 BC–AD 725), human activities combined livestock pasture and local cereal cultivation (such as rye, Secale cereale, as a winter crop). This long-term management produced an open landscape where only small beech/fir woods persisted (Fagus sylvatica/Abies alba). This step was essential for the further development of extensive livestock grazing since the Medieval period in this region. [ABSTRACT FROM AUTHOR] more...
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- 2022
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19. Environmental changes during the Late-Glacial and Early Holocene at the Gourd des Aillères mire in the Monts du Forez Mountains (Massif Central, France).
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Cubizolle, Hervé, Argant, Jacqueline, Serieyssol, Karen, Fassion, Franck, Oberlin, Christine, Dendievel, André-Marie, Deng-Amiot, Yun, Beaudouin, Célia, Hajdas, Irka, and Haas, Jean Nicolas
- Subjects
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HOLOCENE Epoch , *YOUNGER Dryas , *GOURDS , *ENVIRONMENTAL history , *DIATOMS - Abstract
In the granitic part of the eastern Massif Central (France), the Gourd des Aillères (GDA) mire provides one of the only Late-Glacial and Early Holocene sequences with a continuous sedimentation since the Oldest Dryas around 16000 years calibrated Before Present (16 ka cal. BP). Bioclimatic and hydrological changes were reconstructed based on sedimentological parameters, as well as by means of plant and animal macrofossils, pollen, and diatoms analyses through time. The environmental history of this site started with a small lake formed behind a moraine-dam. The multi-proxy study of the sedimentary sequence demonstrated that the coldest conditions took place around 14.3 ka cal. BP, at the very end of the Oldest Dryas. The Bølling period (14.2–13.9 ka cal. BP) was obviously warmer than the Allerød period (13.9–12.8 ka cal. BP) in the Monts du Forez Mountains. However, both chronozones presented a short cooling phase: the Intra Bølling Cold Period (IBCP) and the Intra Allerød Cold Period (IACP), respectively. The Older Dryas (14–13.9 ka cal. BP) was identified for the first time in this region based on pollen and diatom indicators. Thereafter, the Younger Dryas (12.9–11.7 ka cal. BP) was characterised by major temperature fluctuations. Windy conditions prevailed as indirectly demonstrated by the high frequency of Aulacoseira diatoms in the sequence. The onset of the Holocene was dated to 11.7 ka cal. BP. Peat-forming processes started thereafter due to the quick postglacial warming and the former GDA lake finally evolved into a limnogenous mire at the end of the Preboreal (10.4 ka cal. BP). [ABSTRACT FROM AUTHOR] more...
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- 2022
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20. Archaeological identification of fragmented nuts and fruits from key Asia‐Pacific economic tree species using anatomical criteria: Comparative analysis of Canarium, Pandanus and Terminalia.
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Fairbairn, Andrew S. and Florin, S. Anna
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TERMINALIA , *ARCHAEOLOGICAL assemblages , *SCANNING electron microscopy , *FRUIT seeds , *FRUIT , *HUNTER-gatherer societies , *SPECIES - Abstract
The fats, protein and carbohydrates afforded by tree nuts and fruits are key resources for communities from Southeast Asia, through Melanesia, Australia and across Oceania. They are important in long‐distance marine trade networks, large‐scale ceremonial gatherings, and are core resources in a wide range of subsistence economies, including foraging systems, horticulture and swidden agriculture. Recent archaeobotanical evidence has also shown their deep‐time importance, being amongst the earliest foods used in the colonisation of novel environments in Australia and New Guinea, as well as the later colonisation of Near and Remote Oceania. The archaeobotanical methods used to identify fruit and nut‐derived plant macrofossils have been largely limited to use of morphological characters of near whole or exceptionally preserved remains, most commonly endocarps, the hard, nutshell‐like interior layer of the fruit protecting the seed. Here we detail how anatomical characteristics of endocarps, visible in light and scanning electron microscopy (SEM), can be used with surviving morphological features to identify confidently the use of key Asia‐Pacific economic trees, in this case, Canarium, Pandanus and Terminalia. Systematic anatomical description allows the identification of these important economic taxa, and separation from the remains of others such as Aleurites and Cocos, when found in a range of archaeological assemblages. This includes the often highly fragmented charred assemblages that can be recovered routinely from most sites with appropriate fine‐sieving and flotation methods. These methods provide the basis for a more representative and nuanced understanding of ancient plant use, economy and social systems operating in the region and, being particularly useful in tropical regions, will broaden the archaeobotanical database on ancient foods globally. [ABSTRACT FROM AUTHOR] more...
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- 2022
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21. New data on the genus Cornus L. (Cornaceae) in the Bulgarian Miocene flora.
- Author
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Bozukov, Vladimir, Hristova, Latinka, and Ranguelov, Boyko
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MIOCENE Epoch ,BOTANY ,SPECIES distribution ,DATA distribution - Abstract
New data on the distribution of species of the genus Cornus on the territory of Bulgaria during the Miocene are presented. The species C. megaphylla was found for the first time in the middle Miocene flora from Satovcha (SW Bulgaria). So far, this species has been established in the middle Miocene flora from Ruzhintsi (NW Bulgaria). A revision of the species C. distans from the Satovcha paleoflora as Cornus aff. alba has also been made. A new finding of a leaf imprint from the Satovcha local paleoflora proves that the fossil material has the closest morphological features to the recent species C. alba. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
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22. The Ediacara Biota of the Wood Canyon formation: Latest Precambrian macrofossils and sedimentary structures from the southern Great Basin.
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Evans, Scott D., Smith, Emily F., Vayda, Prescott, Nelson, Lyle L., and Xiao, Shuhai
- Subjects
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FOSSILS , *SEDIMENTARY structures , *FOSSIL trees , *WOOD , *PRECAMBRIAN , *EDIACARAN fossils - Abstract
Fossils of the Ediacara Biota preserve the oldest indisputable evidence of macroscopic animal life. Although new finds continue to expand the near global distribution of such organisms, relatively abundant and diverse populations of these primarily soft-bodied taxa are known from just a handful of localities. More commonly, reports of late Precambrian fossils consist of comparably lower diversity assemblages (less than ∼10 genera), with a limited number of total specimens (less than ∼1000 reported macrofossils over a broad geographic area). Determining the factors responsible for such differences can help to fully appreciate preserved patterns of Ediacaran biodiversity. The lower member of the Wood Canyon Formation in the Death Valley region of the southern Great Basin, USA contains fossils of the Ediacara Biota. Here we redescribe previously recovered specimens based on new data from 3D surface scans and report several new finds from this unit. Although this allows the addition of two Ediacara taxa (Pteridinium and Charnia ?) to the known diversity in the region, most potential macrofauna consist of amorphous, irregular forms with minimal preserved structures wherein an abiotic origin cannot be ruled out. A combination of factors – including variable taphonomic conditions, difficulty of identification and an original depauperate community – contribute to the observed diversity of this assemblage. Many biases that impact this record are either common (e.g., age, preservation requirements, difficulty of recognition) or comparable (e.g., paleoenvironmental and taphonomic controls) to known occurrences of Ediacara macrofauana. Thus, we argue this fossil record at least partially reflects the original community composition, suggesting that fossils of the lower Wood Canyon record a signal of relatively low diversity of the Ediacara Biota in the lead up to the Ediacaran-Cambrian boundary. • Latest Ediacaran fossils of the Great Basin are rare and poorly preserved. • Taphonomy, transport and identification all contribute to this record. • Many potential macrofauna cannot be distinguished from other structures. • Despite limitations, current data support a global extinction prior to the Cambrian. [ABSTRACT FROM AUTHOR] more...
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- 2024
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23. Marine macro-invertebrate fossils from the Lower Hanifa Formation (Hawtah Member), central Saudi Arabia.
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Aba Alkhayl, Saleh S.
- Abstract
The stratigraphy and macrofaunal content of the Lower Hanifa Formation (Hawtah Member) were studied at three localities: Al-Ghat, Jabal Al-abakkayn, and Al-Gaddiyah, central Saudi Arabia. The studied succession is conquered by limestone, calcareous shales, and several beds of tightly cemented calcarenites on oncolitic bed. The basal 5–8 m of the Member are significantly more shaley. Hawtah Member is highly fossiliferous, comprising brachiopods, gastropods, bivalves, ammonites, and echinoids. Twenty-seven species are recognized, including 7 species of corals, 8 brachiopods, 2 gastropods, 5 bivalves, and 5 cephalopods. Several taxa among the identified fauna are correlated with adjacent equivalent units. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
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24. Long-term persistence of Mediterranean pine forests in the Duero Basin (central Spain) during the Holocene: The case of Pinus pinaster Aiton
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Morales-Molino, César, Postigo Mijarra, José, Morla, Carlos, García-Antón, Mercedes, Morales-Molino, César, Postigo Mijarra, José, Morla, Carlos, and García-Antón, Mercedes
- Abstract
Funding C. Morales-Molino holds a Universidad Politécnica de Madrid pre-doctoral grant. This study was funded by the research projects CGL2008-06005 BOS – SensCom (Ministerio de Ciencia e Innovación, Spain) and ‘Estudio de turberas en la Cuenca del Duero’ (code 43711816057, Junta de Castilla y León, Spain), In the southern Duero Basin of central Spain, there are vast areas of aeolian sand sheets and dune fields. A comprehensive survey of the sand quarries in this area identified a number of palaeosols in sedimentary sequences. The identification and AMS radiocarbon dating of soil charcoal fragments collected in these palaeosols indicate the persistence of Pinus pinaster in this area throughout most of the Holocene. Although potential natural vegetation models have usually considered the Pinus pinaster forests in this inland area of artificial origin, soil charcoal analysis provides firm evidence of a natural origin. Our data fit perfectly with the pattern of Holocene vegetation development for inland areas of Iberia, which are characterised by stability of pine forests throughout the Holocene. Finally, the growing body of palaeobotanical evidence from Iberia (macrofossils and pollen) is contributing to improve our knowledge of P. pinaster ecology, showing that this species has been present in most Iberian regions during the Holocene, where it has inhabited areas characterised by a very diverse set of climatic and soil conditions., Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub more...
- Published
- 2024
25. The Formation of the Species Structure of Plant Communities on the Northern Boundary of the Krasnoyarsk Forest–Steppe over the Last 6000 Years.
- Author
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Koshkarov, A. D. and Koshkarova, V. L.
- Subjects
PLANT communities ,PLANT anatomy ,DIGITAL maps ,PLANT species ,SCOTS pine ,FOSSIL plants ,SPECIES - Abstract
The results of a paleobotanical (paleocarpological) layer-by-layer study of three peat sections located near the Pogorel'skii Bor experimental station operated by the Institute of Forest SB RAS (the interfluve of the Buzim and Sukhoi Buzim rivers) are presented. The study area is located in the transitional zone between subtaiga grassy small-leaved and coniferous forests and the Krasnoyarsk nonzonal forest–steppe. The climate of the region is extreme continental, moderately warm, and insufficiently humid. The objects of paleocarpological analysis were macrofossils (macro-residues of fossil plants (generative and vegetative parts of plants). Data from each section were used to construct carpograms (histograms showing the quantitative distribution of macro-residues in the identified fossil complexes, in accordance with the section stratigraphy). As a result of a comparative analysis of the species composition of paleocarpological complexes taking the data on radiocarbon
14 C dating (nine dates) into account, the evolution of the vegetation cover of the territory of Pogorel'skii Bor was reconstructed by using hypsometric levels and seven time intervals, starting in the second half of the Atlantic period of the Blytt-Cernander chronological scheme of the Holocene. On this basis, digital maps of paleophytocenoses were compiled. Analysis of the formation of vegetation over the last 6000 years has shown that in the first half of the period the birch–larch forest–steppe with an alternation of shallow lakes prevailed on the territory. The onset of cooling and humidification (5000–3500 BP) contributed to the development of a subaiga forest-vegetation complex with the involvement of dark coniferous species. The subsequent warming (3500–3000 and 1300–800 BP) contributed to the return of forest–steppe and the development of steppe complexes. The leading tree species in the first half of the period were Siberian larch and birch, and, later, Scotch pine. A decrease in the role of larch, and an enhancement of the position of pine and steppe elements in forest phytocenoses during a later period (300 BP) were caused by climate change, as well as by the increased influence of the anthropogenic factor. The regional features of the paleoclimatic regime of Pogorel'skii Bor forest in the latest Holocene are highlighted. [ABSTRACT FROM AUTHOR] more...- Published
- 2022
- Full Text
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26. Late Quaternary history of Lammefjorden, north-west Sjælland, Denmark
- Author
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Ole Bennike, Peter Roll Jakobsen, and Jakob Walløe Hansen
- Subjects
lammefjorden ,sjælland ,quaternary ,late glacial ,holocene ,macrofossils ,Geology ,QE1-996.5 ,Geophysics. Cosmic physics ,QC801-809 - Abstract
Lammefjorden is a reclaimed fjord in north-west Sjælland, Denmark. Sediment cores from the area were collected to study its development after the last deglaciation, in particular the sea-level history. Late glacial and Early Holocene lake and bog deposits occur below marine deposits. Sparse late glacial fossil assemblages indicate tree-less environments with dwarf-shrub heaths. Early Holocene deposits contain remains of Betula sec. Albae sp. and Pinus sylvestris, which indicate open forests. The wetland flora comprised the calciphilous reed plant Cladium mariscus and the water plant Najas marina. Marine gyttja from basins is characterised by sparse benthic faunas, probably due to high sedimentation rates. In some areas, shell-rich deposits were found, with large shells of Ostrea edulis, indicative of high summer temperatures, high salinity and strong tidal currents. A marine shell dated to 6.7 cal. ka provides a minimum age for the marine transgression of Lammefjorden. more...
- Published
- 2020
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27. Representatives of the Miaohe Biota from the Ediacaran (Vendian) Pre-Shuram Strata of the Patom Highland, Siberia.
- Author
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Petrov, P. Yu. and Vorob'eva, N. G.
- Subjects
- *
UPLANDS , *BIOTIC communities , *FOSSILS , *MACROPHYTES , *BIOSTRATIGRAPHY - Abstract
The carbonaceous macrofossils which belong to multicellular algae and which were previously known from the younger (>570 Ma) Miaohe biota are found for the first time in the Lower Vendian (Middle Ediacaran, ~580 Ma) rocks of the Ura Formation of the Patom Basin in Siberia. The Ura macrofossils include phytoleims of unbranched ribbon-like thalli preserved on the surfaces of silty mudstones. Among the fossils, the species Liulingjitaenia alloplecta and Jiuqunaoella simplicis are identified. The features of their structure are considered. The in vivo forms of the organisms and their colonies are interpreted. It is shown that these organic macrofossils were a noticeable detritus-forming component of the Ura Basin. The Ura macrophytes coexisted with the Early Ediacaran microbiota and composed a common ecosystem of the paleobasin, which formed shortly before the Shuram event and was significantly transformed after it. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
- Full Text
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28. Trilobozoa, Precambrian Tri-Radial Organisms.
- Author
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Ivantsov, A. Yu. and Zakrevskaya, M. A.
- Abstract
Representatives of Trilobozoa, a group of tri-radially symmetrical animals, were re-examined based on the material from a new, extensive collection of macrofossils from the Late Ediacaran (Vendian) sediments of the southeastern White Sea region. In addition to body imprints, the collection contains specimens suggesting that trilobozoans could move independently. The shield-like body of trilobozoans consisted of three antimeres. Each antimere has a cluster of grooves on the outer surface and an inner cavity. The system of branched grooves is interpreted as a ciliary organ for gathering food particles, and the elongated inner cavities associated with it are interpreted as digestive organs. It is suggested that trilobozoans were slow-moving benthic seston-feeders of a coelenterate level of organization. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
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- View/download PDF
29. Symmetry of Vendobionta (Late Precambrian Metazoa).
- Author
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Ivantsov, A. Yu. and Zakrevskaya, M. A.
- Abstract
Vendobionta is a large group of Precambrian Metazoa, which is characterized by a set of symmetry elements arranged in a certain system of mutual subordination and typically not found in unitary multicellular animals. The radial axis of the 2nd, 3rd or 6th order, which organizes the arrangement of longitudinal antimeres of the body is the main symmetry element of vendobiont organisms. The second most significant elements are the planes of glide reflection, which connect transverse parts of the body. The elements of the lowest order are products of branching transformation and fractal multiplication, which are manifested in the organization of smaller secondary parts, including various internal structures. The unique morphology of vendobionts makes it difficult to clearly establish their position within the Metazoa. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
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30. Ecohydrological controls on apparent rates of peat carbon accumulation in a boreal bog record from the Hudson Bay Lowlands, northern Ontario, Canada.
- Author
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Davies, Marissa A., Blewett, Jerome, Naafs, B. David A., and Finkelstein, Sarah A.
- Subjects
- *
BOGS , *PEAT , *BACTERIAL cell walls , *MEMBRANE lipids , *BIOMARKERS , *WATER table - Abstract
A multiproxy Holocene record from a bog in the Hudson Bay Lowlands, northern Ontario, Canada, was used to evaluate how ecohydrology relates to carbon accumulation. The study site is located at a somewhat higher elevation and on coarser grained deposits than the surrounding peatlands. This promotes better drainage and thus a slower rate of carbon accumulation relative to sites with similar initiation age. The rate of peat vertical accretion was initially low as the site transitioned from a marsh to a rich fen. These lower rates took place during the warmer temperatures of the Holocene thermal maximum, confirming the importance of hydrological controls limiting peat accretion at the local scale. Testate amoebae, pollen, and plant macrofossils indicate a transition to a poor fen and then a bog during the late Holocene, as the carbon accumulation rate and reconstructed water table depth increased. The bacterial membrane lipid biomarker indices used to infer paleotemperature show a summer temperature bias and appear sensitive to changes in peat type. The bacterial membrane lipid biomarker pH proxy indicates a rich to a poor fen and a subsequent fen to bog transition, which are supported by pollen, macrofossil, and testate amoeba records. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
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31. Cold-seep fossil macrofaunal assemblages from Vestnesa Ridge, eastern Fram Strait, during the past 45 000 years
- Author
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Elsebeth Thomsen, Tine Lander Rasmussen, Kamila Sztybor, Nils-Martin Hanken, Ole Secher Tendal, and Alfred Uchman
- Subjects
Methane release ,macrofossils ,trace fossils ,foraminifera ,mid-late Weichselian glacial to Holocene ,Svalbard margin ,Environmental sciences ,GE1-350 ,Oceanography ,GC1-1581 - Abstract
Four cores from 1200 m water depth from Vestnesa Ridge on the western Svalbard margin in the eastern Fram Strait were studied for their content of fossil macrofaunas. Three of the cores were collected from a pockmark with active methane seepage, and one core (control core) was taken just outside the seepage area for comparison. Together the cores cover the last 45 000 years (mid-late Weichselian glacial, the deglaciation and the Holocene). The records show a range of influence of methane from no seepage (control core) and, although variable through time, from moderate seepage, to strong and very strong seepage. All cores have been analysed for the macrofossils >1 mm, trace fossils, planktic foraminifera, stable isotopes, geochemistry and sedimentology. The main purpose of the study is to improve our knowledge of the fossil macrofauna and past environmental changes related to the impact of methane emissions in the area. The core recovered outside the pockmark contained no fossil macrofaunas, while cores from inside the pockmark contained chemosymbiotic bivalves, and in some cases a rich macrofauna. The faunal relationships with the sedimentary environments confirm a close connection between the macrofauna and the variability in influence of cold seepage, particularly seen in the occurrence of chemosymbiotic bivalves Archivesica arctica, Isorropodon nyeggaensis, potentially chemosymbiotic bivalve Rhacothyas kolgae, polychaetes and an associated rich fauna of small epifaunal gastropods, showing that Arctic seeps were oases for macrofaunas in the past as they are today. more...
- Published
- 2019
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32. Early Miocene palaeoclimatic reconstruction of Tunçbilek basin
- Author
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Hüseyin Tuncay Güner
- Subjects
clamp ,batı anadolu ,akuitaniyen ,makrofosiller ,yaprak fizyonomisi ,western anatolia ,aquitanian ,macrofossils ,leaf physiognomy ,Forestry ,SD1-669.5 - Abstract
The Tunçbilek-Domaniç Basin (Western Anatolia) is one of the most important Neogene coal deposits of Turkey. The age of the basin is early Miocene (~ 23-19 Ma) based on dating of volcanic units by the Ar/Ar method. Field work was conducted about plant macrofossils in Tunçbilek in 2010. Twenty taxa were identified belonging to two gymnosperm and 18 angiosperm genera. Dicot woody plants belonging to the leaf flora were used to reconstruct palaeoclimate by Multivariate Climate Leaf Analysis Program (CLAMP) based on leaf physiognomy. For reconstruction 18 angiosperm taxa collected from the area in addition 3 taxa determined in previous studies total of 21 taxa were used. The reconstructed values for selected climatic parameters are as follows: mean annual temperature (MAT) 12.1-14.5 °C; warmest month mean temperature (WMMT) 22.5-25.2 °C; coldest month mean temperature (CMMT) 1.6-5.4 °C; length of growing season (GROWSEAS) 6.9-8.3 months; growing season precipitation (GSP) 940-1380 mm; precipitation during the three consecutive wettest months (X3.Wet) 490-790 mm; precipitation during the three consecutive driest months (X3.Dry) 170-230 mm. Overall, CLAMP values expressed as Köppen climate types indicate that the Tunçbilek basin had a warm temperate climate with hot summers (Cfa) during the early Miocene. more...
- Published
- 2019
- Full Text
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33. The Materiality of Odors: Experiencing Church Burials and the Urban Environment in Early Modern Northern Sweden.
- Author
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Kallio-Seppä, Titta and Tranberg, Annemari
- Subjects
- *
ODORS , *ENLIGHTENMENT , *AROMATIC plants , *EIGHTEENTH century , *MATERIAL culture ,URBAN ecology (Sociology) - Abstract
Archaeological material from early modern Sweden reveals that material and social meaning was intertwined in townscape odors; that is, odors and their association with unhygienic conditions affected the physical structure of the town, its material culture, and different traditions in the use of "townspace." During the latter half of the 18th century, the town of Oulu suffered from unpleasant smells related to ponds and wet areas, and the odor of decomposing flesh from under-floor church burials greeted church visitors, despite the tradition of placing fragrant plants inside coffins. In the 18th century the town underwent deliberate changes: the ponds were drained and filled, burials under the church floor were prohibited, and one of the first graveyards located outside the town and separate from the church was constructed. These actions to change the town's "smellscape" reflect emergent notions of regularity and cleanliness related to the Age of Enlightenment. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
- Full Text
- View/download PDF
34. Delayed deglaciation or extreme Arctic conditions 21-16 cal. kyr at southeastern Laurentide Ice Sheet margin?
- Author
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Guilderson, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)]
- Published
- 2012
- Full Text
- View/download PDF
35. Once a pond in time: employing palaeoecology to inform farmland pond restoration.
- Author
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Walton, Richard E., Sayer, Carl D., Bennion, Helen, and Axmacher, Jan C.
- Subjects
- *
AQUATIC biodiversity , *PONDS , *PALEOECOLOGY , *POTAMOGETON , *ZOOARCHAEOLOGY , *ECOLOGICAL succession , *AQUATIC organisms - Abstract
The restoration of highly terrestrialized farmland ponds that combines the removal of woody vegetation and pond sediment greatly enhances aquatic biodiversity. Nonetheless, questions remain regarding the historical precedent of pond restoration, and particularly if post‐restoration aquatic macrophyte communities resemble pre‐terrestrialization assemblages. We used a paleoecological approach to address these questions for a typical, recently restored farmland pond in Norfolk, eastern England. Plant and animal remains in pond sediment cores were used to infer decadal‐centennial scale changes to pond communities and to identify past pond management events. We then evaluated the resemblance of restored and historical assemblages by comparisons with contemporary post‐restoration vegetation data. Based on changes in the abundance of terrestrial leaf remains and other indicators (increases followed by declines of aquatic organisms), the study pond appears to have a long history (going back to the early‐1800s) of canopy management (at least three inferred management events), but after the mid‐1970s, steady and substantial increases in terrestrial indicators suggest cessation of management resulting in uninterrupted terrestrialization. Aquatic macrophyte communities arising after restoration showed some similarities with historical assemblages, but also contained apparently new species. This study demonstrates how paleolimnological methods can improve understanding of pond ecological histories to better inform restoration targets and practices. [ABSTRACT FROM AUTHOR] more...
- Published
- 2021
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36. Evidence on vegetative and inflorescence morphology of Chloranthaceae (Angiospermae) from the Early Cretaceous (middle–late Albian) of Spain.
- Author
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Sender, Luis Miguel, Doyle, James A., Upchurch, Garland R., Endress, Peter K., Villanueva-Amadoz, Uxue, and Diez, José B.
- Subjects
- *
ANGIOSPERMS , *FOSSIL pollen , *FOSSIL trees , *FOSSILS , *LEAF anatomy , *INFLORESCENCES - Abstract
The near-basal angiosperm family Chloranthaceae (with four living genera) is prominently represented in the Early Cretaceous fossil record by pollen and flowers, but its leaves, other vegetative parts and inflorescences are less well known. Here, we report impressions of leaves, stems and inflorescences from the middle–late Albian Escucha Formation of Teruel Province (NE Spain) that help redress this imbalance and bring into clearer focus the morphological and systematic diversity of this key group in the early angiosperm radiation. We used parsimony analysis of a morphological dataset of living and fossil Chloranthaceae to evaluate the position of the fossils on a molecular-based tree of extant taxa. Todziaphyllum elongatum gen. et sp. nov., with festooned semicraspedodromous venation and asymmetrical chloranthoid teeth, is most parsimoniously placed on the stem lineage of the living genus Hedyosmum. Leaves of Alcainea eklundiae gen. et sp. nov., with festooned semicraspedodromous venation and symmetric teeth, occur attached to stems in opposite pairs at swollen nodes with sheathing leaf bases and interpetiolar stipules, along with compound spikes of flowers with a monosymmetric androecium of three stamens, each flower subtended by a bract. This represents the first time that fossil leaves, stems and inflorescences of Chloranthaceae have been found in organic connection. Alcainea may be sister to Sarcandra, Chloranthus or the clade consisting of both genera, like the mesofossil Canrightiopsis. Leaf Type A, with festooned craspedodromous venation and symmetrical teeth, may be related to Ascarina. These observations provide direct evidence for the distinctive vegetative and inflorescence morphology of Chloranthaceae in the Early Cretaceous. They are consistent with the level of diversification inferred from coeval chloranthaceous pollen and floral mesofossils, including lines nested in crown group Chloranthaceae but not in any of living genera, and exhibiting character combinations not retained in living Chloranthaceae. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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37. Sâncraiu de Mureș (Marosszentkirály): medieval settlement network, Pauline monastery and its environment on the middle course of the Mureş river.
- Author
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Benkő, Elek, Sümegi, Pál, Törőcsik, Tünde, Bodor, Elvira, Sümegi, Balázs, and Jakab, Gusztáv
- Subjects
ENVIRONMENTAL history ,MONASTERIES ,FOURTEENTH century ,RIVERS ,MIDDLE Ages ,MEDIEVAL European history - Abstract
The study aims to contribute to the medieval environmental history of the eastern periphery of the Transylvanian Plain (Câmpia Transilvaniei/Mezőség). With the help of archaeological and historical data and the multi-aspect analysis of undisturbed core sequences, the economic life of the Pauline Monastery founded in the 14th century near Sâncraiu de Mureş (Marosszentkirály) and the surrounding villages was investigated. The multidisciplinary research focuses on the paleochannels of the Mureş and the artificial watercourses (ditches) that branch off the river, and the mills built on them. The work also provides new data on the general environmental changes in the middle course of the Mureş river during the Middle Ages and the early modern period, which are largely due to the very intense human activity here. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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38. Holocene vegetation, fire and land use dynamics at Lake Svityaz, an agriculturally marginal site in northwestern Ukraine
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Schwörer, Christoph, Gobet, Erika, van Leeuwen, Jacqueline F. N., Bögli, Sarah, Imboden, Rachel, van der Knaap, W. O., Kotova, Nadezhda, Makhortykh, Sergej, and Tinner, Willy
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- 2022
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39. Drivers of peat accumulation rate in a raised bog: impact of drainage, climate, and local vegetation composition
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N. Stivrins, I. Ozola, M. Gałka, E. Kuske, T. Alliksaar, T.J. Andersen, M. Lamentowicz, S. Wulf, and T. Reitalu
- Subjects
chronology ,macrofossils ,testate amoebae ,variation partitioning ,water level reconstruction ,Ecology ,QH540-549.5 - Abstract
We used variation partitioning to assess the relative importance of drainage, climate and local vegetation composition for the development of a raised bog. As a case study we selected Teiči (Teici) Bog in Latvia (north-east Europe). Explanatory variables together explained 74 % of the variation in peat accumulation and only the residue of 26 % remained unexplained. Our study showed that the local vegetation composition and dominant Sphagnum species significantly influence peat accumulation rates. The results of linear models revealed that, under natural conditions, minor drainage and even strong drainage of the peat is associated with a positive growth balance of the system. However, drainage systems can have a measurable impact on peatland ecosystems situated farther away. Our study demonstrates that the average peat accumulation rate in Teici Bog over the last 150 years was 3.5 mm per year. Although the peat accumulation rate has been affected by drainage over the last half-century, it is still 2.8 mm per year. There was no strong correlation with the historical climate record, suggesting that the bog area has buffered the influence of climate change over the last 150 years. more...
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- 2017
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40. Tracing Characteristics of Two Water Hole Features with Multiproxy Analysis : Using Soil Chemistry, Archaeobotany and Entomology
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Kantak, Johanna and Kantak, Johanna
- Abstract
En omfattande multiproxyanalys har utförts på provtagningar från två vattenhål belägna i Skåneregionen i Sverige. Denna mångsidiga analys involverade flera aspekter, inklusive markkemi, entomologi, mikrofossiler och makrofossiler. Resultaten från markkemianalysen avslöjade betydande skillnader mellan de två vattenhålen. Vattenhål 1 uppvisade en högre halt av organiskt material, vilket tyder på högre glödförluster och högre värden av maximal magnetisk susceptibilitet (MS550) och totalfosfat (CitPOI). För att ytterligare karakterisera egenskaperna hos vattenhålen användes även analyserna infrarödspektroskopi (NiR) och röntgenfluorescens (XRF). Vattenhål 2 visade tecken på att ha fyllts med bosättningsavfall från platsen. Detta stöddes av markkemiresultaten som visade en lägre halt av organiskt material samt närvaron av antropogena material, såsom förkolnade frön, träkol, bränd lera, ben och keramikfragment. Makrofossilanalysen avslöjade intressanta fynd. I vattenhål 1 hade växter som etternässla (Urtica urens) och kråkklöver (Comarum palustre) deponerats, tillsammans med enstaka exemplar av Thrips major Uzel. I kontrast bestod de förkolnade fröna från vattenhål 2 huvudsakligen av ogräs, inklusive svinmålla (Chenopodium album) och nattskatta (Solanum nigrum). Det fanns även spår av sädeskorn som korn (Hordeum vulgare), samt oidentifierade fragment av sädeskorn. Resultaten från makrofossilanalysen indikerade att materialet från vattenhål 1 härstammar troligtvis från forntida mänskliga aktiviteter, som odling. Mikrofossilanalysen visade att det inte fanns några kiselalger (diatoméer) i något av vattenhålen. Sammantaget antyder resultaten från multiproxyanalysen att vattenhål 1 hade genomgått minst tre olika faser i sin historia, medan vattenhål 2 hade fyllts med jord och material från en bosättningsliknande plats, vilket gjorde det svårt att entydigt tolka själva vattenhålets historia och funktion. more...
- Published
- 2023
41. Trait-based approaches as ecological time machines: Developing tools for reconstructing long-term variation in ecosystems
- Author
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Royal Society (UK), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Danish National Research Foundation, European Research Council, European Commission, Estonian Research Council, Brown, Kerry A., Bunting, M. Jane, Carvalho, Fabio, de Bello, Francesco, Mander, Luke, Marcisz, Katarzyna, Mottl, Ondrej, Reitalu, Triin, Svenning, Jens-Christian, Royal Society (UK), Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Danish National Research Foundation, European Research Council, European Commission, Estonian Research Council, Brown, Kerry A., Bunting, M. Jane, Carvalho, Fabio, de Bello, Francesco, Mander, Luke, Marcisz, Katarzyna, Mottl, Ondrej, Reitalu, Triin, and Svenning, Jens-Christian more...
- Abstract
Research over the past decade has shown that quantifying spatial variation in ecosystem properties is an effective approach to investigating the effects of environmental change on ecosystems. Yet, current consensus among scientists is that we need a better understanding of short- and long-term (temporal) variation in ecosystem properties to plan effective ecosystem management and predict future ecologies. Trait-based approaches can be used to reconstruct ecosystem properties from long-term ecological records and contribute significantly to developing understandings of ecosystem change over decadal to millennial time-scales. Here, we synthesise current trait-based approaches and explore how organisms' functional traits (FTs) can be scaled across time and space. We propose a framework for reconstructing long-term variation in ecosystems by means of analysing FTs derived from palaeoecological datasets. We then summarise challenges that must be overcome to reconcile trait-based approaches with palaeo-datasets. Finally, we discuss the benefits and limitations of trait-based reconstructions of ecosystem temporal dynamics and suggest future directions for research. Reconstructing environmental properties through time vis-à-vis FTs can be separated into two parts. The first is to record trait data for organisms present in modern ecosystems, and the second is to reconstruct temporal variability in FTs from palaeoecological datasets, capturing changes in trait composition over time. Translating palaeoecological datasets into FTs is challenging due to taphonomic, taxonomic and chronological uncertainties, as well as uniformitarian assumptions. Explicitly identifying and addressing these challenges is important to effectively calculate changes in FT through time. Palaeo-trait research offers insights into questions related to short- and long-term ecosystem functioning, environmental change and extinction and community assembly rules across time. As work in this area matures, we more...
- Published
- 2023
42. Filling the 'data gap': Using paleoecology to investigate the decline of Najas flexilis (a rare aquatic plant)
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Isabel J. Bishop, Helen Bennion, Carl D. Sayer, Ian R. Patmore, and Handong Yang
- Subjects
conservation ,macrofossils ,Najas flexilis ,paleoecology ,rare species ,Environmental sciences ,GE1-350 ,Geography (General) ,G1-922 - Abstract
In the absence of long‐term monitoring records, paleoecology can be used to extend knowledge of species and community ecology into the past. The rare and declining aquatic plant Najas flexilis is a priority species for conservation across Europe, and is an ideal candidate for paleoecological study; not only are historical records of the plant sparse, but its seeds are commonly found and well preserved in lake sediment cores. In this study, we investigate the timing and causes of decline at two UK sites at which N. flexilis has recently become extinct: Esthwaite Water (England) and Loch of Craiglush (Scotland). For both sites, multiple paleoecological indicators and available historical biological records and monitoring data are compared to numbers of N. flexilis seeds enumerated in dated sediment cores representing the last 150 years. At Esthwaite Water, N. flexilis seeds were found in abundance in association with indicators of a clear, oligo‐mesotrophic, mildly alkaline lake. Eutrophication led to the disappearance of N. flexilis in the 1980s. By contrast, far fewer N. flexilis seeds were found in a core from Loch of Craiglush, and the current period of N. flexilis absence was found to be one of several over the last 100 years. Species represented in cores taken from Loch of Craiglush were indicative of slightly more acidic conditions than Esthwaite Water. Given that N. flexilis favours circumneutral to alkaline conditions, it is possible that Loch of Craiglush has not always been favourable for the plant. These findings have important implications for future conservation efforts, particularly at Esthwaite Water where they suggest that recent failed attempts to reintroduce the species may have been premature. More generally, this study demonstrates the value of paleoecological techniques as a means to provide the long‐term context that is often missing from conservation planning and management. more...
- Published
- 2019
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43. Holocene Vegetation, Climate, and Carbon History on Western Kodiak Island, Alaska
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Dorothy M. Peteet, Jonathan E. Nichols, and Daniel H. Mann
- Subjects
Kodiak Island ,Holocene ,pollen ,macrofossils ,isotopes ,carbon sequestration ,Science - Abstract
At Phalarope Pond, western Kodiak Island, a multidisciplinary study using pollen and spores, macrofossils, stable isotopes, and carbon accumulation provides the Holocene vegetation and climate history following the deglaciation that began over 16,000 cal years ago (yr BP). Following a cold and dry Younger Dryas, a warm and wet early Holocene was characterized by abundant ferns in a sedge tundra environment with maximum carbon accumulation, similar to high latitude peatlands globally. About 8,700 cal yr BP sedge and ferns declined and climate remained warm as drier conditions prevailed, limiting carbon sequestration. The abrupt shift in D/H isotopes of about 60% indicates a shift to cooler conditions or a more distal moisture source. Neoglaciation beginning about 3,700 cal yr BP is evident from increases in Artemisia, Empetrum and Betula, signifying cooler conditions, while Alnus declines, paralleling regional trends. more...
- Published
- 2019
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44. Biomineral lipids in living and fossil molluscs
- Author
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Stern, Benjamin
- Subjects
551.9 ,Macrofossils ,Brachiopods - Abstract
It has been proposed that geochemical and biomolecular palaeontological information can be obtained from biomineral associatedli pids. The location of lipidic material within the inorganic structureo f molluscan shells has previously been unknown, with important implications for long term survival of lipids and post-depositional contamination from the environment. Discrete experimental stages have been investigated and the different mechanical and chemical methods combined for the removal of contaminating material prior to the release and analysis of surficial, intercrystalline and intracrystalline lipids. Three extraction protocols have been compared using Recent Patella vulgata shells. Sequential stages of cleaning and extraction treatments identify n-alkanes, cholesterol (free and bound) and bound fatty acids. The n-alkanes are indigenous to the shell, but laboratory contamination can be significant, and highlights the need for experimental blanks. Bound fatty acids are extracted from intercrystalline and intracrystalline fractions. Cholesterol is extracted throughout the sequential methodology. The extraction of these compounds after extensive cleaning treatments illustrates the protective role of the inorganic biomineral. An experimental protocol for sequentially extracting protected lipids from the shells of Recent molluscs has been tested to distinguish the indigenous shell lipids from laboratory contamination and postdepositional ingress. The use of a calcium carbonate blank reveals the phthalate plasticisers extracted from the shells are due to laboratory contamination. Pristane, phytane and free fatty acids were rarely extracted which limits their use for interpretation. The n-alcohols, bound fatty acids, ß-hydroxy fatty acids, cholesterol and other steroids are extracted from the shells in higher yields than the calcium carbonate blanks and are considered indigenous to the shells. Multivariate statistical analysis is used to compare the distributions of bound fatty acids and steroids extracted from different shell locations with the reported fatty acids and steroids for the soft tissues of the same species. The reported values for the soft tissues were used to indicate the original shell lipid composition. The shells lack the unsaturated bound fatty acids reported in the soft tissues. The saturated bound fatty acids of Littorina littorea shells also differ in the carbon number distributions to the reported saturated fatty acids of the soft tissues. Surficial shell extracts are characterized by steroidal ketones, representing sterols which have been oxidised by the cleaning treatments used. The steroids from both intercrystalline and intracrystalline shell locations in Littorina littorea are most similar to the soft tissues. However, the intercrystalline steroids are different to the intracrystalline steroids which may indicate a different original composition. Potential Class level phylogenetic differences between the shells of Recent molluscs are revealed by their steroidal and bound saturated fatty acid compositions. The bivalves (n=3) have bound saturated fatty acids with a carbon number maximum of C16 whilst the gastropods (n=8) have a maximum of C16 or C18 and exhibit higher yields. ß-hydroxy fatty acids may indicate phylogenetic differences below the Class level for the Gastropoda. Principal component statistical analysis of the shell steroidal composition indicates differences at the Class level. Steroidal markers indicating the dietary intake have been found in the shells. The application of a methodology for the sequential extraction of lipids from molluscan shells has been used in a preliminary analysis of shell material for the presence of hydrocarbon pollutants. The shell nalkanes require comparison of carbon number distributions and yields with an experimental calcium carbonate blank to ensure indigeneity. Different n-alkane distributions within two Artica islandica shell samples are attributed to the different sampling locations. Differences between Patella vulgata and Littorina littorea shells from the same environment have also been observed, indicating different n-alkane uptake by different species. Polyaromatic hydrocarbons and sterane biomarkers reported to be present in the soft tissues of Patella vulgata exposed to the Braer oil spill have been searched for in the shells of an exposed sample. These compounds have not been detected. No increase in the shell n-alkane yields or similarity in carbon number distribution with the spilt oil is observed. This suggests no hydrocarbon incorporation or deputation pathway into the shell. Quaternary aged mollusc shells yield n-alkanes, n-alcohols, bound fatty acids and cholesterol. These have been extracted from both intercrystalline and intracrystal line locations within the shells. When compared with the extracts from Recent shells the yields of these lipids from fossil shells are significantly lower. The n-alkanes extracted from Quaternary shells are dominated by laboratory contamination, although some indigenous intracrystalline n-alkanes have been extracted. The bound fatty acids from intercrystalline sites within the fossils maintain their carbonn umber distribution but decreasein yields with increasinga ge; no diagenetic products were observed. The previously reported phylogenetic distinctions based on the bound fatty acids betweent he gastropodsa nd bivalves are maintainedf or fossils. However,t he information obtained from this analysis is limited by the small diversity of lipid distributions found in these fossil shells. more...
- Published
- 1996
45. Historical human impact on productivity and biodiversity in a subalpine oligotrophic lake in Scandinavia.
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Jensen, Thomas C., Zawiska, Izabela, Oksman, Mimmi, Słowiński, Michał, Woszczyk, Michał, Luoto, Tomi P., Tylmann, Wojciech, Nevalainen, Liisa, Obremska, Milena, Schartau, Ann Kristin, and Walseng, Bjørn more...
- Subjects
LIMNOLOGY ,LITTLE Ice Age ,LAKE ecology ,LAKES ,PALYNOLOGY ,HUMAN settlements ,BIODIVERSITY ,FISH communities - Abstract
We conducted a paleolimnological study to examine how changes in human activity interacted with climate to influence productivity and biodiversity over the past millennium in oligotrophic Lake Atnsjøen, SE Norway. The study included analyses of sediment geochemistry, subfossil diatoms and cladocerans, and macrofossils. Results were compared with the historical record of human activities in the catchment, pollen analysis and paleoclimate inferences from the lake. During the first 750 years of the record (1000–1750 CE), a time of relatively low human activity, lake productivity and biodiversity were strongly related to climate. During the Little Ice Age (1550–1800 CE), lake productivity and diatom diversity were constrained by cold climate. A century of climate warming (1780–1880 CE) initiated an increase in productivity. Accelerated human settlement after 1850 CE, however, had an even stronger impact on productivity, mediated by increased agriculture and/or forestry, which led to greater nutrient loading of the lake. Similarly, diatoms in the lake responded to the rise in temperature, but increasing human activity also had a moderate impact on the diatom community, which displayed weak signs of nutrient enrichment. From 1980 to 1990 CE onwards, lake productivity declined as a consequence of a recent decrease in human activity and changing land use. The human-induced increase in lake productivity starting ca. 1850 CE propagated through the food web and increased consumer productivity, as reflected by greater accumulation rates of cladocerans, trichopterans and turbellarians. The cladoceran community was likely under top-down control of fish, as indicated by changes in size structure and diversity. Our study showed that increasing human activity during the settlement period had a stronger impact on lake productivity than did climate. Furthermore, the slight human-mediated increase in nutrient loading had different impacts on productivity and biodiversity in the study lake. This study demonstrates that even relatively small changes in human activities in watersheds can have measurable impacts on nutrient-poor lakes. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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- View/download PDF
46. Late Quaternary history of Lammefjorden, north-west Sjælland, Denmark.
- Author
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Bennike, Ole, Jakobsen, Peter Roll, and Hansen, Jakob Walløe
- Subjects
LAKE sediments ,WETLAND plants ,MARINE sediments ,MARINE transgression ,HOLOCENE Epoch ,TUNDRAS ,SOIL salinity ,PHRAGMITES - Abstract
Lammefjorden is a reclaimed fjord in north-west Sjælland, Denmark. Sediment cores from the area were collected to study its development after the last deglaciation, in particular the sea-level history. Late glacial and Early Holocene lake and bog deposits occur below marine deposits. Sparse late glacial fossil assemblages indicate tree-less environments with dwarf-shrub heaths. Early Holocene deposits contain remains of Betula sec. Albae sp. and Pinus sylvestris, which indicate open forests. The wetland flora comprised the calciphilous reed plant Cladium mariscus and the water plant Najas marina. Marine gyttja from basins is characterised by sparse benthic faunas, probably due to high sedimentation rates. In some areas, shell-rich deposits were found, with large shells of Ostrea edulis, indicative of high summer temperatures, high salinity and strong tidal currents. A marine shell dated to 6.7 cal. ka provides a minimum age for the marine transgression of Lammefjorden. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
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47. Conical Thecae of Precambrian Macroorganisms.
- Author
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Ivantsov, A. Yu., Vickers-Rich, P., Zakrevskaya, M. A., and Hall, M.
- Abstract
On the basis of new extensive collections, made by the present authors, a group of unsegmented three-dimensional fossil remains from the Late Precambrian of Namibia and the southeastern White Sea area, including such genera as Protechiurus, Vendoglossa, and Vendoconularia, were restudied. It is established that the fossils belong to two morphologically close genera (Protechiurus and Vendoconularia), composing the new family Protechiuridae. It is possible that they represent the same genus or even species, but the incompleteness of the preservation of the Namibian member of the group prevents their integration. The fossils initially represented conical hollow elastic objects, hexagonal in the cross-section, which were open at the wide end and closed at the pointed end. The sculpture of their surface consisted of longitudinal ridges, both single and double, bounding the rows of the short transverse ridges, scalloped along one margin. Vendoconularia had wide plates which were attached to the cone outwardly along the longitudinal unpaired ridges. In general morphology and several details the fossils resemble the thecae of conulariids and anabaritids, known from Late Precambrian and Paleozoic and classified as the scyphozoan cnidarians. The main difference lays in the theca mineralization, which consists of phosphate in conulariids, carbonate in anabaritids, and is absent in the case of protechiurids. It is proposed that the protechiurids, which appeared in the fossil record first, may belong to the basal group of ancient scyphozoans, ancestral to the conulariids on the one hand, and to the anabaritids on the other. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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- View/download PDF
48. Using species attributes to characterize late‐glacial and early‐Holocene environments at Kråkenes, western Norway.
- Author
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Felde, Vivian Astrup, Birks, Hilary Helen, and Giesecke, Thomas
- Subjects
- *
TUNDRAS , *YOUNGER Dryas , *GLACIAL melting , *PLANT indicators , *SOIL formation , *HISTOSOLS - Abstract
Aim: We aim to use species attributes such as distributions and indicator values to reconstruct past biomes, environment, and temperatures from detailed plant‐macrofossil data covering the late glacial to the early Holocene (ca. 14–9 ka). Location: Kråkenes, western Norway. Methods: We applied attributes for present‐day geographical distribution, optimal July and January temperatures, and Ellenberg indicator values for plants in the macrofossil data‐set. We used assemblage weighted means (AWM) to reconstruct past biomes, changes in light (L), nitrogen (N), moisture (F), and soil reaction (R), and temperatures. We compared the temperature reconstructions with previous chironomid‐inferred temperatures. Results: After the start of the Holocene around 11.5 ka, the Arctic‐montane biome, which was stable during the late‐glacial period, shifted successively into the Boreo‐arctic montane, Wide‐boreal, Boreo‐montane, Boreo‐temperate, and Wide‐temperate biomes by ca. 9.0 ka. Circumpolar and Eurasian floristic elements characteristic of the late‐glacial decreased and the Eurosiberian element became prominent. Light demand (L), soil moisture (F), nitrogen (N), and soil reaction (R) show different, but complementary responses. Light‐demanding plants decreased with time. Soil moisture was relatively stable until it increased during organic soil development during the early Holocene. Soil nitrogen increased during the early Holocene. Soil reaction (pH) decreased during the Allerød, but increased during the Younger Dryas. It decreased markedly after the start of the Holocene, reaching low but stable levels in the early Holocene. Mean July and January temperatures show similar patterns to the chironomid‐inferred mean July temperature trends at Kråkenes, but chironomids show larger fluctuations and interesting differences in timing. Conclusion: Assigning attributes to macrofossil species is a useful new approach in palaeoecology. It can demonstrate changes in biomes, ecological conditions, and temperatures. The late‐glacial to early‐Holocene transition may form an analogue for changes observed in the modern arctic and in mountains, with melting glaciers, permafrost thaw, and shrub encroachment into tundra. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
49. Plant communities control long term carbon accumulation and biogeochemical gradients in a Patagonian bog.
- Author
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Mathijssen, Paul J.H., Gałka, Mariusz, Borken, Werner, and Knorr, Klaus-Holger
- Abstract
Peat carbon accumulation is controlled by both large scale factors, such as climate and hydrological setting, and small scale factors, such as microtopography and plant community. These small scale factors commonly vary within peatlands and can cause variation in biogeochemical traits and carbon accumulation within the same site. To understand these within-site variations, we investigated long term carbon accumulation, peat decomposition, biogeochemistry of pore water and plant macrofossils along a transect in an ombrotrophic bog in southern Patagonia. An additional question we addressed is how historical deposition of volcanic ash on the peatland has affected its carbon balance. Variability in plant community and water table led to differences in long term peat and carbon accumulation (peat moss > cushion plant), organic matter decomposition (cushion plant > peat moss), and methane production (peat moss > cushion plant). Macrofossil analysis and radiocarbon dating indicated a relationship between plant community and carbon accumulation or decomposition during the historical succession of vegetation in the peatland. C/N ratio and isotopic signatures reflected variability in plant community as litter source, and DOC concentrations were controlled by humification level. Volcanic ash deposition had only limited effect on plant composition, but it was associated with increased decomposition in overlying peat layers. This study highlights the importance of understanding how plant communities develop, as changes in communities could significantly affect the potential of ombrotrophic peatlands as C sink. Unlabelled Image • Plant community controlled variability in carbon accumulation within the bog. • Cushion plant peat decomposed faster and produced less methane than Sphagnum peat. • Volcanic ash affected decomposition, but did not cause lasting vegetation shifts. • C/N ratio is a biased proxy for decomposition of peat from different vegetation. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
- Full Text
- View/download PDF
50. Filling the "data gap": Using paleoecology to investigate the decline of Najas flexilis (a rare aquatic plant).
- Author
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Bishop, Isabel J., Bennion, Helen, Sayer, Carl D., Patmore, Ian R., and Handong Yang
- Subjects
RARE plants ,AQUATIC plants ,PALEOECOLOGY ,BIOTIC communities ,LAKE sediments ,WILDLIFE conservation ,BIOLOGICAL monitoring - Abstract
In the absence of long-term monitoring records, paleoecology can be used to extend knowledge of species and community ecology into the past. The rare and declining aquatic plant Najas flexilis is a priority species for conservation across Europe, and is an ideal candidate for paleoecological study; not only are historical records of the plant sparse, but its seeds are commonly found and well preserved in lake sediment cores. In this study, we investigate the timing and causes of decline at two UK sites at which N. flexilis has recently become extinct: Esthwaite Water (England) and Loch of Craiglush (Scotland). For both sites, multiple paleoecological indicators and available historical biological records and monitoring data are compared to numbers of N. flexilis seeds enumerated in dated sediment cores representing the last 150 years. At Esthwaite Water, N. flexilis seeds were found in abundance in association with indicators of a clear, oligo-mesotrophic, mildly alkaline lake. Eutrophication led to the disappearance of N. flexilis in the 1980s. By contrast, far fewer N. flexilis seeds were found in a core from Loch of Craiglush, and the current period of N. flexilis absence was found to be one of several over the last 100 years. Species represented in cores taken from Loch of Craiglush were indicative of slightly more acidic conditions than Esthwaite Water. Given that N. flexilis favours circumneutral to alkaline conditions, it is possible that Loch of Craiglush has not always been favourable for the plant. These findings have important implications for future conservation efforts, particularly at Esthwaite Water where they suggest that recent failed attempts to reintroduce the species may have been premature. More generally, this study demonstrates the value of paleoecological techniques as a means to provide the long-term context that is often missing from conservation planning and management. [ABSTRACT FROM AUTHOR] more...
- Published
- 2019
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