Oliver Nelle

Investigations on buried soils and colluvial layers around Bronze Age burial mounds at Bornhöved (northern Germany): an approach to test the hypothesis of `landscape openness' by the incidence of colluviation

The idea of open landscapes around prehistoric burial mounds is founded on their topographical position and findings of plaggen clots within the hills at some sites. We have investigated the surroundings of four Bronze Age burial mounds at Bornhöved (northern Germany) to test whether this assumed landscape openness enabled soil erosion and colluviation or not. The soils and colluvia within a watershed below the burial mounds were investigated in six large exposures and additional auger cores. The chronology is based on 21 AMS-radiocarbon dates, complemented by charcoal analysis and the content of selected heavy metals in the sediments. Colluvia were deposited in the Late Neolithic (~2500—2200 cal. BC), Roman Emperor Times (~ 250—400 cal. AD), Mediaeval Times (~ AD 600—1400) and Modern Times (~ AD 1800—2000). Our findings indicate that the soil surfaces were protected against soil erosion during the phase of Bronze Age funeral use (~ cal. 1800—600 BC). Either the prehistoric gravediggers practised a well suited form of pasturing to keep the scenery open or the surroundings of the burial mounds were forested at the time of funeral use. The results of charcoal analysis reflect the known succession of woody taxa in the region and underline the great potential of anthracology on colluvial layers for palaeoenvironmental reconstructions apart from traditional archives such as lakes or mires. Bulk radiocarbon dating of organic matter overestimated the time of burial of a buried soil as well as the time of deposition of colluvial layers considerably.

Assessing Holocene vegetation and fire history by a multiproxy approach: The case of Stodthagen Forest (northern Germany)

The woodland history of the forest of Stodthagen (northern Germany) was investigated by using complementary palaeobotanical indicators. Six soil profiles from the study plot were sampled, the wood charcoal pieces extracted from the soil samples were quantified, taxonomically identified, and some were radiocarbon dated. Peat sequences from a small adjacent mire were also sampled and the pollen, microcharcoal, and macrocharcoal were analysed. The pollen record shows a continuous forestation during the Holocene, with small indication of a disturbance phase during the late Holocene. This continuity of the woodland presence is confirmed by the weak quantity of macrocharcoal, indicating that fire did not have a serious impact during the Holocene in terms of canopy opening, despite the identification of three local fire events. However, large amounts of wood charcoal pieces were found in the soil samples allowing the identification of at least one more fire event, dated in the Iron Age, unrecorded in the charcoal signal from the peat sequences. The taxonomical charcoal assemblage is in agreement with the pollen data. This innovative multiproxy approach allows the assessment of the ancient and continual presence of a woodland at the study site, which highlights the biological and patrimonial interest of the area and justifies the ongoing conservation management of the woodland.

Fire and forest history of central European low mountain forest sites based on soil charcoal analysis: The case of the eastern Harz

Long-term environmental changes in some areas of Central Europe are still poorly documented due to the lack of archives suitable for well-established paleoecological approaches. However, paleorecords of such areas would provide important insights into the Holocene vegetation history of Central Europe. To contribute to fill this gap, we conducted soil charcoal analyses to investigate fire and forest history for the eastern Harz Mountains (Germany). Soil from 15 sequences at three investigation sites was analyzed, and charcoal assemblages were extracted. The taxonomic analysis shows Holocene woodland composition changes, from post-glacial pioneer woodland, dominated by pine, to broad-leaf closed forests, dominated by oak, and succeeded by beech. The temporal distribution of accelerator mass spectrometry (AMS)-14C datings of single charcoal pieces indicates that fire events occurred regionally synchronous, mainly in the late-Pleistocene/early-Holocene and late-Holocene periods. The radiocarbon dating is supported by the description of the sampled soil sequences, which permits the identification of late-Pleistocene/early-Holocene in situ formed soil horizons, as well as evidences late-Holocene erosion-sedimentation processes. Climate seems to have triggered late-Pleistocene/early-Holocene fire events. In contrast, the increase of fires, at both local and regional scales, during the late Holocene in low flammable broad-leaf forests is interpreted as related to human activities. Finally, it is highlighted that the species spectrum of the extracted charcoal assemblages and the radiocarbon ages obtained fits regional and over-regional data, also concerning the soil charcoal concentrations that appear to be included in regional and global ranges of soil charcoal pools.

Wood usage and its influence on the environment from the Neolithic until the Iron Age: a case study of the graves at Flintbek (Schleswig–Holstein, Northern Germany)

The investigated area near Flintbek (Schleswig–Holstein, Northern Germany) was used as a burial ground from the Neolithic until the Iron Age. Due to modern agriculture, the above-ground funerary monuments have been destroyed. Rescue excavations from 1976 to 1996 recovered the archaeological remains. In addition to the archaeological reassessment of the findings, further scientific analyses were carried out. The results of the charcoal analyses are presented in this paper. The overall spectrum of wood species represents the typical species composition of mixed oak forests. Over the whole investigated time span (Neolithic–Iron Age) these species alternate with a second group of taxa: species benefiting from better light conditions. In times of intensive human impact, these light-demanding taxa gained considerable importance, showing the opening of the wooded landscape. In phases with less human impact, a regeneration of mixed oak forest is detectable. For the Neolithic it was possible to develop a more detailed picture of wood usage based on 162 radiocarbon dates of 106 samples. These illustrate considerable changes during the Neolithic, which resulted in a varied pattern of open land and closed forest influenced by human presence and land use. Another important aspect of the Flintbek area is the handling of samples deriving from different contexts. While charcoal samples related to fire usage or grave constructions contain only slight contamination, samples from fillings (pits, burial layers) are characterized by charcoal dating being either too old or even too young for the archaeological context.

Contribution to the reconstruction of central European fire history, based on the soil charcoal analysis of study sites in northern and central Germany

Fire caused by humans played an important role in prehistoric clearance of woodland, which was a prerequisite for the rise of agriculture since at least the Neolithic revolution. Therefore, reconstructed fire history provides insights into the spread of agriculture. However, for central Europe, the past fire regime is still poorly known. Thus, to help to fill this gap, fire history has been investigated using data relevant at a local scale, which is the scale of woodland clearance processes according to local human practices. For this purpose, soil/soil sediment charcoal analysis has been conducted at four sites in northern Germany and five in central Germany. At each site, four to nine sequences of soil/soil sediment were excavated, described in the field and sampled. The sampled material has been differentiated by soil horizons formed in situ and colluvial sediments. The charcoal content of both types of sampled material was quantified and some of it was taxonomically analysed. Chronological information was obtained by radiocarbon dating 73 single charcoal pieces that had previously been identified taxonomically. Such data sets have permitted us to identify a minimum number of fire events for every site, which had burnt various types of woodlands and at different chronological phases. Based on the local scale data, regional trends were identified. Charcoals from the late Pleistocene and early Holocene derived from conifers only, and these most probably indicate wildfire events in flammable woodlands. Charcoals dated to the mid and late Holocene derived predominantly from broad-leaved trees probably resulting from human-ignited fires in weakly flammable woodlands. The calculated minimum fire frequency indicates an increase in fire occurrences during the Holocene following the phases of cultural human development. This supports the importance of human-made fire in northern central Europe during the Holocene. Such minimum fire frequency appears much higher during the iron age and the middle ages, but not before. This fits with the general statement of regional woodland loss and landscape opening relatively recently, during the late Holocene.

Holocene landscape dynamics at the tell Arslantepe, Malatya, Turkey – Soil erosion, buried soils and settlement layers, slope and river activity in a middle Euphrates catchment

Alluvial and colluvial sequences were studied around the prehistoric tell Arslantepe in 11 exposures and additional auger cores. The chronology is based on 11 optically stimulated luminescence (OSL) ages, four radiocarbon ages, and the embedded artifacts. Sediments contained wood charcoals, providing information on former vegetation. Fluvial activity is documented during Late Glacial times (15.4 ± 2.5, 12.8 ± 3.1u2009kyr) and frequently after Roman times. Slope and soil erosion occurred in the early (10.6 ± 1.4, 8.2 ± 0.7u2009kyr) and mid–late Holocene (6.7 ± 0.9, 5.4 ± 0.7–4.7 ± 0.7, 2.6 ± 0.2–2.5 ± 0.2, 1.9 ± 0.2–1.8 ± 0.2u2009kyr, and during the last 1000 years). The early Holocene erosion phases pre-date the so far established onset of settlement at the tell. This either indicates an earlier onset of agricultural land use than assumed or climatic influence on erosion, such as the 10.3 and 8.2u2009kyr climate events known from Western Europe. The erosion phases at around 5.0 and 2.6u2009kyr could reflect geomorphic responses to societal collapse (Late Chalcolithic state, Neo-Hittite kingdom) at Arslantepe. Most intensive Holocene soil erosion and landscape degradation occurred after occupation of the region by the Roman Empire. This is paralleled by the onset of river activity. A part of the lower neo-Hittite town as well as an early Holocene Terra Rossa–like soil that had formed rapidly were found buried. So far, no indication for mid–late Holocene fluvial activity of the adjacent creeks until Roman times has been found. Our results illustrate the large potential of slope deposits for long term reconstructions of human induced landscape transformation in Anatolia.

Archaeobotany at Oplontis: woody remains from the Roman Villa of Poppaea (Naples, Italy)

The Vesuvius area near Naples, southern Italy, is one of the richest places for archaeological finds from Roman times. The a.d. 79 volcanic eruption also caused the preservation of a huge quantity of archaeobotanical material. In this paper the available wood and charcoal remains from the timber structures as well as from the garden soils of the Villa of Poppea at Oplontis are presented. The analyses provide new evidence of the history of some significant trees of the Mediterranean region, such as Abies alba and Cupressus sempervirens, and allow us to put forward hypotheses about wood use during the Roman period. The identification of the building material confirms that the Romans had a good knowledge of the technological properties of wood and mainly used local resources. There is also evidence of trade in high quality timber, in particular Picea abies. The strong presence of climbing plants and of branches and small size stems of wild trees together with typical ornamental plants in the two gardens of the villa reveals a lack of regular gardening maintenance. This evidence is in agreement with the absence of occupants at the moment of the eruption, since the villa was under restoration after the a.d. 62 earthquake.

Too early and too northerly: evidence of temperate trees in northern Central Europe during the Younger Dryas

This paper presents highly unexpected paleobotanical data. Eight (14) C-accelerator mass spectrometry (AMS) dates of soil macrocharcoal pieces, identified taxonomically, indicate the presence of oak and beech in the Younger Dryas, and pine in the Allerød, in the northernmost low mountain range of Central Europe, the Harz Mountains, in Germany. If the presence of pine at such latitude and periods is not surprising, the presence of temperate-adapted trees is highly improbable, because they are assumed to have reached the area from a southern location several thousand years later. Two hypotheses are postulated to explain this record. Both are related to the warm periods of the Bølling and Allerød: the classically short duration of this warm period makes the migration of the temperate trees from the identified refuge areas in the southern location implausible, and so the presence of intermediary microrefugia at a medium latitude in Central Europe is postulated; recent data reveal that the warm period of the Late Glacial phase was much longer than considered in the classical view and, thus, would be long enough for a northward migration of temperate-adapted trees. Although our dataset does not permit disentanglement of these hypotheses, it provides significant innovative insights for the biogeography of Central Europe.

Climatic influence on Lake Stymphalia during the last 15 000 years

Known from the ancient myth of Heracles fighting the Stymphalian birds, the karst polje of Stymphalia (22°27’E, 37°51’N) is an ideal site to study the climate history of the area. Stymphalia is the only natural perennial lake on the Northern Peloponnesus, which provides a continuous sedimentary record of the entire Holocene and a large part of the Last Glacial. As a large and quite reliable water reservoir, Lake Stymphalia and its surrounding karst springs played an important role for the water supply of the region from ancient time until today. However, due to climate fluctuations, the water supply can change significantly, challenging the water management of the people living in the area. Here we present geochemical analyses of the uppermost part of a lake sediment core (STY-1), recording the changes in climate and water supply during the Holocene and the Late Glacial. The chronology is based on several 14C dates combined to a Bayesian age-depth model. Using XRF elemental analysis, we compare the influx of terrestrial material (indicated by K and Rb) to the carbonate precipitation in the lake (indicated by Ca and Sr). The Rb/Sr ratio as a proxy for changes between dry/warm and wet/cold conditions indicate pronounced wet phases around 6800, 4000–3700–4000, 3500–3000 and 500–200 cal BP.

A comparative review of soil charcoal data: Spatiotemporal patterns of origin and long-term dynamics of Western European nutrient-poor grasslands

The nutrient-poor grasslands of Western Europe are of major conservation concern because land use changes threaten their high biodiversity. Studies assessing their characteristics show that their past and on-going dynamics are strongly related to human activities. Yet, the initial development patterns of this specific ecosystem remain unclear. Here, we examine findings from previous paleoecological investigations performed at local level on European grassland areas ranging from several hundred square meters to several square kilometers. Comparing data from these locally relevant studies at a regional scale, we investigate these grasslands’ spatiotemporal patterns of origin and long-term dynamics. The study is based on taxonomic identification and radiocarbon AMS dating of charcoal pieces from soil/soil sediment archives of nutrient-poor grasslands in Mediterranean and temperate Western Europe (La Crau plain, Mont Lozère, Grands Causses, Vosges Mountains, Franconian Alb, and Upper-Normandy region). We address the following questions: (1) What are the key determinants of the establishment of these nutrient-poor grasslands? (2) What temporal synchronicities might there be? and (3) What is the spatial scale of these grasslands’ past dynamics? The nutrient-poor grasslands in temperate Western Europe are found to result from the first anthropogenic woodland clearings during the late Neolithic, revealed by fire events in mesophilious mature forests. In contrast, the sites with Mediterranean affinities appear to have developed at earlier plant successional stages (pine forest, matorral), established before the first human impacts in the same period. However, no general pattern of establishment and dynamics of the nutrient-poor grasslands could be identified. Local mechanisms appear to be the key determinants of the dynamics of these ecosystems. Nevertheless, this paleoecological synthesis provides insights into past climate or human impacts on present-day vegetation.