Combining pollen and charcoal: evaluating Holocene vegetation composition and dynamics

Pollen analysis reveals vegetation change on a local and regional level over (ideally) continuous time spans but with complications when it comes to the reconstruction of spatially precise species occurrence and composition. Wood charcoal analysis provides site-related information on species occurrence and woodland composition, especially when sediments containing pollen are lacking, but is normally discontinuously available and has the danger of human bias due to potential selection of certain species for e.g. fire making, house construction or charcoal making. Combining the two methods – assuming that suitable palaeoarchives are neighbouring – might compensate for their disadvantages and strengthen the interpretations on vegetation composition and dynamics on a local, extra-local and regional scale. Three examples are given where pollen analysis from “classical” archives – mires and lake sediments – was carried out, and where additionally species identification of wood charcoals was done on samples extracted from close-by archives. The first example (Kugelstattmoos, Bavarian Forest, Germany) combines a Holocene pollen diagram derived from a small mire with late medieval/early modern times charcoal spectra from charcoal production sites which are situated on the margin of the mire. Results show the local occurrence of the main woodland species Fagus sylvatica and Abies alba, and raises new questions on the montane species composition of the formerly natural forests in the Bavarian Forest. The second example (Bargstedter Moor, Schleswig-Holstein, Germany) combines Holocene pollen diagrams from a peat bog with late medieval/early modern times charcoal spectra from charcoal production sites in a woodland close to the bog. It shows the role of Quercus, Fagus, Alnus and Carpinus in medieval and early modern times woodlands and its use by man. The third example (Kleiner Tornowsee, Brandenburg, Germany) combines pollen data from sediments of a small lake with charcoal data derived from Holocene colluvisols and soils. The examples show that anthracological and palynological data complement one another to create a more detailed picture of woodland history and landscape change than one method alone would provide.     

Charcoal scarcity in Epigravettian settlements with mammoth bone dwellings: the taphonomic evidence from Mezhyrich (Ukraine)

Fuel management during the Paleolithic periods is an important issue to understand past human subsistence. Numerous Palaeolithic sites relate an abundance of burnt bones in hearths and an absence or scarcity of wood charcoals, which leads studies to focus on burnt bone remains and the use of bones in hearths. Few works take into account the micro-residues of wood charcoals which can still be present in hearth areas and excavated sediments. We studied the Epigravettian site with mammoth bone dwellings of Mezhyrich (Ukraine) previously characterized by its high content of burnt bones and an “absence” of wood charcoal during the so-called mammoth steppe. The presence or absence and proportions of both wood charcoals and burnt bones were quantified in macro-, meso- and microscale sediment size fractions by an image analysis method. Our results show that excavations during field-works at Mezhyrich give only a partial image of the original anthracological record and that most charcoal materials are lost with standard archaeological and anthracological approaches. The scarcity of charcoals in this site was possibly due to an important mass reduction accentuated by the addition of bones in hearths. By applying our protocol we recovered a significant amount of wood charcoals which provides the first ¹⁴C dates from charcoals at Mezhyrich. Numerous charcoals are identified contributing subsequent information about vegetation, environment and burning practices. They indicate, by comparison with pollen data already collected, the presence of forest patches in a mammoth steppe landscape, which might have influenced the collecting behavior of Epigravettian populations.     

The use of wood in funerary pyres: random gathering or special selection of species? Case study of three necropolises from Poland

In this study, the analysis of charcoal remains from three prehistoric necropolises is presented. This botanical material formed part of funerary pyres and thus represents purposely gathered wood used for cremation ceremonies. Therefore, its anthracological analysis may indicate a special selection of wood, which may be a source of palaeoethnographic information about past rituals. However, a question remains as to whether or not the charcoal assemblages that originated from graves may also provide some palaeoecological information. In order to test both hypotheses, analysis of three Polish necropolises dating to the Bronze and the Iron Age were performed. In all charcoal assemblages, a taxonomic diversity among charcoals was detected, which may suggest that the wood was collected based on availability. This may also be inferred after observing that the presence of the most ubiquitous and frequently found taxa may be strongly correlated with present-day vegetation growing in the vicinity of the necropolises.     

Human impact and landscape utilization from the Mesolithic to medieval time traced by high spatial resolution pollen analysis and numerical methods

Pollen analysis in relation to archaeological excavations has been carried out by the coast of central Norway to investigate for the first time long-term human impact on the vegetation in this region. A total of 297 samples from eleven archaeological sites and connected bogs/peat profiles reveal the vegetation development from the Mesolithic until today. Principal Component Analysis (PCA) is used to identify and elucidate the development through time and space, and the results of pollen diagrams from bogs are compared to the results of on-site pollen data. Human impact has transformed the vegetation to a varying degree in different time periods. A dense population connected to the shoreline is slightly visible as opening-up of the forest in the Mesolithic, whereas re-use of Mesolithic settlement sites for cultivation and grazing in the Late Neolithic and Early Bronze Age (from c. 2300 cal BC) is clearly documented by palaeobotany but weakly recorded in the archaeological record. Areas for settlement and cultivation are found from the Late Bronze and Iron Ages and pollen analysis contributes to a detailed picture of utilization of the landscape. The investigation shows the potential of combining archaeological and botanical data and analysing several small pollen sequences within an excavation area to reveal spatial patterns in vegetation development and human impact through time.     

The Anthropogenic Use of Firewood During the European Middle Pleistocene: Charcoal Evidence from Levels XIII and XI of Bolomor Cave,Eastern Iberia (230–160 ka)

Human control of fire is a widely debated issue in the field of Palaeolithic archaeology, since it involved significant technological innovations for human subsistence. Although fire evidence has been the subject of intense debate regarding its natural or anthropogenic nature, most authors agree that combustion structures represent the most direct evidence of human control of fire. Wood charcoal fragments from these contexts represent the fuel remains that result from humans’ collection of firewood, which means they can reveal significant behavioural and palaeoenvironmental information relevant to our understanding of Middle Palaeolithic societies. In this work, we present anthracological data derived from combustion structure 2 (level XIII, ca. 230?ka, MIS 7) and combustion structure 4 (level XI, ca. 160?ka, MIS 6) from Bolomor Cave, which are chronologically among the earliest combustion structures found in Europe. The present work discusses how the presence of black pine and / or scots pine in both levels sheds light on the characterisation of the local landscape. Additional analyses focussing on the pre- and post-depositional processes affecting charcoal preservation point to biodegradation patterns. The aim of this work is to provide the first discussion concerning the anthracological data derived from Bolomor Cave in order to contribute to the general debate regarding the use of fire during the European Middle Pleistocene.     

Preliminary conclusions on the Late Glacial vegetation in south-west Anatolia (Turkey): the complementary nature of palynological and anthracological approaches

The combined analysis of charcoal fragments retrieved from epipalaeolithic settlements in Öküzini cave (south-west Anatolia, Turkey) and of pollen in samples retrieved from outside the cave reveals the transformation of the vegetation in the region over the Late Glacial Period. The analyses provide consistent information on the use of natural resources and evidence as to the protodomestication of cereals in the region.     

Sustainable management of metallurgical forest on Mont Lozère (France) during the Early Middle Ages

Mont Lozère, located in the French Massif Central region, provides an exceptional context in which to research the impact that charcoal production and metallurgy had on woodlands, along with the role that these activities played in changing the mountain landscape. This study provides an insight into the land use, forest management methods and metallurgical practices in the area during the Middle Ages (11th to 15th centuries). Medieval charcoal burning platforms, archaeological remains that have often been neglected in the past as a source of historical information, along with nearby smelting sites, were identified, sampled and analysed. In this paper, spatial analyses, radiocarbon dating and anthracological and dendro-anthracological studies have been combined in a unique manner. The results reveal that charcoal burners practiced beech coppicing, where the species and diameter of wood used remained the same over a period of four centuries. It is proposed that this form of metallurgical forest management be considered an early example of a sustainable utilisation of natural resources.     

Interdisciplinary approach for reconstructing an alder-based historical agricultural practice of the Eastern Ligurian Apennines (NW Italy)

Data from four soil profiles studied through pollen and macroscopic charcoal analyses were used to identify specific palynological assemblages associated with a traditional land-use system documented in the Eastern Ligurian Apennines (NW Italy) between the 18th and early 20th century, concerning a cyclical use of grey alder plots for temporary cultivations involving to the use of controlled fire. This is the first attempt to verify on palynological evidence some hypotheses raised by previous historical ecology studies about the consequences of this agricultural practice (recently named alnocoltura) on past and present vegetation. Our investigations underline (1) high percentages of anthropogenic pollen indicators, (2) increase of Ericaceae percentages, (3) low pollen percentages of Alnus, (4) high macrocharcoal concentrations and (5) high values of palynological richness during periods affected by the alnocoltura cycle according to the historical sources. Similar patterns are also detectable in pollen diagrams from two adjacent peat bogs. The paper shows the strength of an interdisciplinary methodology (field observations, cartographical and archival historical data, palynological and archaeological investigations) for studies of past land-use systems. By demonstrating the necessity of a long-term prospective in environmental reconstructions for the preservation of the cultural landscape, one of the important elements of this research is its potential contribution to issues of habitat management and nature-conservation policy. Further analyses are needed to test the replicability and reliability of the hypotheses derived from this study.     

Pollen evidence for major shifts in forest composition since the mid‐nineteenth‐century in the vicinity of Sudbury,Ontario

Numerous anthropogenic stressors have impacted the region surrounding Sudbury, Ontario, leading to pronounced vegetation and landscape change. Few long‐term records exist to understand the nature or timing of this change. We use pollen analysis from radiometrically dated sediments of Clearwater Lake to compare pre‐ and post‐settlement vegetation. Beginning ～1850 CE, the record shows major shifts in forest composition, coincident with settlement and the beginnings of lumbering. These changes are unprecedented for the past ～5000 years, and consist of increases in diversity and abundance of deciduous tree taxa and herbaceous disturbance indicators. While evidence of mining appears as early as 1900 CE, little effect is seen in the pollen record until ～1930 CE, when sedimentation rates increased and acidification of the lake also began. At this time, further increases in palynological disturbance indicators and minimum sediment organic matter levels indicate the period of maximum vegetation loss. As a result of reduced emissions since the 1970s, water quality began to improve in Clearwater Lake and there are some decreases in the abundances of shade‐intolerant disturbance indicators in the pollen record. However, the fact that the pollen assemblages do not resemble those prior to 1850 suggests lasting vegetation changes.     

The environmental context of a prehistoric rock carving on the Bjäre Peninsula,Scania, southern Sweden

Palaeoecological analysis of peat deposits from a small bog at Lingården, southern Sweden, have been used to examine the nature and timing of vegetation changes and anthropogenic activity associated with a nearby rock carving located close to the edge of the wetland. This study is the first of its type to investigate the environmental context of rock carvings in southern Sweden. Debate has tended to focus on chronology and iconography, with little consideration of the environmental relationships of rock carvings and how vegetation may help construct a site within its surrounding landscape. The pollen evidence from Lingården demonstrates that the rock carving was located in an isolated semi-wooded setting during the late Bronze Age. This is in stark contrast to several other pollen studies from the Bjäre Peninsula that record widespread woodland clearance and agricultural activity from the late Neolithic–Bronze Age transition. The results of this study support hypotheses that suggest complex rock carvings, such as Lingården, were separated from settled areas. This sense of separation and isolation is reinforced by the vegetation surrounding the rock carving. This paper also discusses the relationship between charcoal in the pollen sequence and evidence that the decorated outcrop had been burnt.     

Modelling land use around an early Neolithic timber ‘hall’ in north east Scotland from high spatial resolution pollen analyses

A methodology is described by which spatial patterns of land use were reconstructed from pollen analyses on anthropogenic sediments at a recently excavated early Neolithic timber ‘hall’ in north east Scotland. The anthropogenic sediments were from a deep, small diameter pit within the building. They present numerous taphonomic and interpretative challenges to the analyst, but from this type of deposit, the power to estimate quantitatively the vegetation structure around the archaeological site makes such difficult deposits very significant. A rigorous methodology is firstly described, therefore, by which confidence in ecological interpretation can be established. Secondly, the source of pollen in the deposit is evaluated. Thirdly, the possible pollen source area and structure of the surrounding vegetation are estimated by quantitative simulation modelling. Finally, these analyses are compared with region-scale pollen analyses from nearby conventional wetland deposits with much larger pollen source areas. The pollen assemblages recovered probably reflect land uses adjacent to the ‘hall’ and up to 2.5 km around. Cereal cultivation was the most important land use immediately around the ‘hall’, possibly grown between stands of scrub Corylus (hazel) woodland. These intensive but local-scale land uses cannot be discerned in region-scale pollen analyses.     

Fire and man in post-glacial woodlands of Eastern England

It has for long been suggested that English early post-glacial woodlands, particularly those dominated by hazel, were a fire-climax vegetation type. This conflicts with the evidence of fire frequency in present-day woodlands. Charcoal and pollen analyses of post-glacial lake sequences in East Anglia, England, suggest that early post-glacial woodlands were not fire-climax types. The pre-5000 BP charcoal record can be best interpreted as a record of intensity of occupation beside lake shores. After 5000 BP, charcoal deposition may reflect increasing use of fire as an agent in land clearance.     

The shrinkage cracks and the diameter of the log: a experimental approach toward fuel management by Patagonian hunter-gatherer (Paredón Lanfré site. Río Negro Province,Argentin)

The anthracological study of Paredón Lanfré (Patagonia, Argentina) highlights the presence of radial cracks with a marked difference between the percentage of affected coniferous charcoal (Fitzroya cupressoides and Austrocedrus chilensis) compared to the angiosperms (e.g., Nothofagus antarctica and Nothofagus dombeyi). The aim of this work was to obtain experimental comparison data from two Patagonian conifers to understand the prehistoric combustion behavior of the region. These results showed a discrepancy between the average of shrinkage cracks made with green wood fires and those with dry wood fires. The study of the caliber of charcoal recovered from Paredón Lanfré showed significant differences between the samples of F. cupressoides and A. chilensis. The calculation of correlation between size and shrinkage cracks suggests for both species that the size is not related to the number of registered shrinkage cracks in charcoal studied. Therefore, the gauge would not be a variable which could influence the presence of shrinkage cracks in the charcoal. Consequently, the difference of average shrinkage cracks between the two specimens may result from another variable that remains to be identified.     

Preservation of fungi in archaeological charcoal

During the analysis of wood charcoal remains from archaeological sites, it is common to find different microorganisms and different forms of degradation present in the plant tissue. However, one may encounter difficulties when attempting to identify these microorganisms and determine when their attack occurred. This paper focuses on preservation aspects related to the microorganisms in wood and demonstrates the structural changes that take place in different types of decayed wood after it was converted into charcoal. The study seeks to determine whether the microbial attack found in archaeological woods took place before the burning of the wood or after. Burning experiments were conducted using wood that had been decayed by various types of fungi including white-rot, brown-rot, and soft-rot. The laboratory burnt wood samples showed decay patterns that were comparable to those observed in archaeological charcoal samples, indicating that signs of fungal infestation and features of decay can be preserved after burning with micromorphological details of mycelium and cell wall attack evident. This indication may provide important information related to the gathering of deadwood as fuelwood. In addition, examples of decayed wood preserved in archaeological charcoal assemblages are described. Their relationship to the archaeological context and environmental conditions may suggest different interpretative models concerning wood management strategies applied by past societies.     

Combined pollen and macrofossil data as a source for reconstructing mosaic patterns of the early medieval urban habitats – a case study from Gdańsk,N. Poland

Plant macrofossils, pollen, fungal spores and other non-pollen palynomorphs (NPPs), were analyzed in three archaeological exposures established in a small area in the oldest part of the historic city of Gdańsk. One of the aims was to investigate how precisely the combined pollen and macrofossil data may reflect the diversity of local habitats within an urban archaeological site and to compare the range of information obtained using each of the methods separately. The other aim of the study was to reconstruct the environmental conditions in the earliest occupied area of the historic centre of Gdańsk. The repeatable composition and, in many points, consistency among pollen and macrofossil data in all three profiles strongly suggest that the apparently biased structure of these fossil remains in fact reflects a mosaic pattern of the vegetation in the area of the site. The combined pollen and macrofossil data enabled separation of local elements from those transported to the site by different means. The results show that already at the beginning of the 12th c., the area was almost totally deforested, but up to the mid-13th c. the settlement organization was still relatively loose, resembling a rather rural structure with well-developed ruderal plant communities and patches of semi-natural vegetation. At the coring area, strongly eutrophic riparian vegetation was bordering patches of dry grassland on a sandy holm. The large proportion of pollen of various entomophilous plants mostly from meadows and pastures is explained as a result of the presence of dung, as confirmed by the abundances of coprophilous fungal spores. The study indicates that parallel pollen and macrofossil analysis is essential for correct interpretation of fossil assemblages. Application of both methods enables broadening of the range of remains representing various organisms and obtaining more precise tools for environmental reconstruction and better understanding of the taphonomic processes at the archaeological site.     

Ashes to ashes, charcoal to dust: micromorphological evidence for ash-induced disintegration of charcoal in Early Neolithic (LBK) soil features in Elsloo (The Netherlands)

Charcoal and other forms of charred organic material - an important part of the archaeological record - consist of benzenoids. Such components are unstable in basic or alkaline conditions. Since ashes are alkaline, this means that archaeological charcoal may have been disintegrated and lost if they were buried together with ashes, e.g. as in fireplaces. Ash may also cause clay translocation in decalcified loess because of the disaggregating effect of K⁺ ions in the soil solutions. We investigated the interplay of these two processes, using micromorphological samples from the Early Neolithic site at the Joannes Riviusstraat in Elsloo. Evidence for charcoal disintegration was found in the form of cavities in charcoal fragments, most commonly filled in with thick reddish limpid clay coatings. The combination of cavities and clay coatings are evidence for the disintegration of charcoal under the influence of ash. Ash may also have been instrumental in preserving small bone fragments in these decalcified well-drained loess soils. The evidence of ash-induced charcoal disintegration implies that charcoal preservation in the archaeological record is dependent on (1) whether or not is was buried alongside with ashes, and (2) on various soil characteristics that determine that determine how quickly the ash-derived alkalinity and potassium ions are leached.     

OPTICAL DATING OF ANTHROPOGENIC SEDIMENTS AT THE ARCHAEOLOGICAL SITE OF HERRENBRUNNENBUCKEL,BRETTEN-BAUERBACH (GERMANY)*

Optical dating was applied to natural and anthropogenic silts at an Iron Age settlement in southern Germany. The natural sediments were dated accurately and allowed study of the human impact on the landscape. The studied anthropogenic sediments were infills of cellars and ditches. Again, deposits derived from soil erosion proved to be datable using infrared-optically stimulated luminescence. However, optical dating of fine grained sediments was at its limits when sediments consisted of a mixture of bleached and unbleached grains. This is shown on sediments of known age originating from cellar infills. Improvements were obtained when using the 560 nm emission and a partial bleach approach. Experimental evidence shows that the D_E versus shine-time plot discloses insufficient bleaching only in cases in which all grains are insufficiently bleached to the same degree.     

SEISMIC DESIGN AND RESPONSE OF BARE AND MASONRY-INFILLED REINFORCED CONCRETE BUILDINGS. PART II: INFILLED STRUCTURES

The effects of masonry infills on the global seismic response of reinforced concrete structures is studied through numerical analyses. Response spectra of elastic SDOF frames with nonlinear infills show that, despite their apparent stiffening effect on the system, infills reduce spectral displacements and forces mainly through their high damping in the first large post-cracking excursion. Parametric analyses on a large variety of multi-storey infilled reinforced concrete structures show that, due to the hysteretic energy dissipation in the infills, if the infilling is uniform in all storeys, drifts and structural damage are dramatically reduced, without an increase in the seismic force demands. Soft-storey effects due to the absence of infills in the bottom storey are not so important for seismic motions at the design intensity, but may be very large at higher motion intensities, if the ultimate strength of the infills amounts to a large percentage of the building weight. The Eurocode 8 provisions for designing the weak storey elements against the effects of infill irregularity are found to be quite effective, in general, for the columns, but unnecessary and often counterproductive for the beams.     

An Interdisciplinary Study on the Environmental Reflection of Prehistoric Mining Activities at the Mitterberg Main Lode (Salzburg,Austria)

A multi‐proxy study by palynological, geochemical, archaeological and dendrochronological analyses discloses the mining activities at the Mitterberg Main Lode. By these means, several mining phases with varying intensity are recorded during the Bronze and Early Iron Age, whereupon a west to east shift of the mining activity at the Mitterberg Main Lode can be observed. The initial mining phase (Phase II), from the 21st to the 15th centuries bc , is characterized by an opening up of the forest vegetation and, additionally, by slightly elevated heavy metal deposition. Phase III shows a first bloom phase of the chalcopyrite mining during the 14th and 13th centuries bc . Pollen analyses disclose extensive clearings used for pasture and settlement. The increased human impact and higher heavy metal pollution suggest intensive mining activity, which is corroborated by the dendrochronological and archaeological data. Phase IV is characterized by mining activities in progress during the 12th century bc . The pollen data reflect a stabilization of the vegetation and slightly elevated As/Cu/Sb to Sc ratios. During Phase V, in the 11th century bc , new clearings indicate a re‐intensification of the mining activities at the Mitterberg Main Lode. Phase VI, from the ninth century bc onwards, describes a human impact with lower intensity at the mining site. This interdisciplinary study at the Mitterberg Main Lode contributes new environmental data for an important area of past metal mining and extends our understanding of the relationship between miners and their landscape.