Long-term changes in floristic diversity in southern Sweden: palynological richness, vegetation dynamics and land-use

The rarefaction technique is applied to two Holocene pollen sequences (covering the last 12,000 calendar years) from two lakes in southern Sweden. One represents an open agricultural landscape, the other a partly wooded and less cultivated landscape. The inferred palynological richness is interpreted as an approximate measure of floristic diversity at the landscape scale. The overall trend is an increased diversity from the mid-Holocene to the Modern period, which is linked to a parallel rise in human impact. The pattern is similar for the two sites with peaks corresponding to archaeological periods characterised by deforestation and expanding settlement and agriculture. The highest diversity was reached during the Medieval period, about a.d. 1,000–1,400. Declining diversity during the last 200 years characterises the agrarian landscape. These results confirm, for southern Scandinavia, the “intermediate disturbance” hypothesis for biodiversity at the landscape scale and on millennial to century time scales. They have implications for landscape management in modern nature conservation that has the purpose of maintaining and promoting biodiversity.     

Studies on the Holocene history of vegetation in the region of lake Srebarna (northeast Bulgaria)

The results of pollen analysis of two sediment cores from lake Srebarna (northeast Bulgaria) are presented. On the basis of the palynological data and the radiocarbon dates a reconstruction of the past flora and vegetation is made. For the first time a continuous palaeosuccession is established for the area of the Danubian Dobrudza and the Ludogorie district of northeast Bulgaria: a dominance of mixed xero- and mesophilous oak woods with Carpinus betulus, Ulmus, Tilia, Corylus during the Atlantic period; mixed oak woods with increasing importance of Tilia, Ulmus, Acer and a considerable presence of Carpinus betulus and Fagus during the Sub-boreal period; degradation of the woodland vegetation and transition to secondary plant communities with Carpinus orientalis and herbs during the Sub-atlantic period. Received January 5, 2001 / Accepted March 13, 2001     

Data on mid-Holocene climatic, vegetation and anthropogenic interactions at Stanshiel Rig, southern Scotland

Pollen, microscopic charcoal and peat humification analyses were applied to radiocarbon-dated peat cores to examine environmental change before and after the mid-Holocene transition from hunter-gatherer (Mesolithic) to agricultural (Neolithic) communities in presently marginal upland pasture at Stanshiel Rig, Annandale, southern Scotland. The Mesolithic-Neolithic transition in northern Britain is characterised by a number kf key environmental changes as well as economic shifts, including temporal patterns of fire and the Ulmus decline. Deliberate vegetation modification by Mesolithic communities is not demonstrable at Stanshiel Rig, and openings in the woodland canopy may have been promoted by grazing by wild animals or have been a consequence of climate change. Changes in fire frequency are also correlated with peat- and pollen-stratigraphic evidence for shifts to a drier climate in the late Mesolithic, probably mediated through pedological and biomass-storage change. A single Ulmus decline occurred between ca. 5650 and 5600 cal B. P., and is related here to climate change. Neolithic-age impacts on the woodland were limited, and no cereal-type pollen were found. The difference between hunter-gatherer and opportunistic farmer/hunter-gatherer at this locally is argued to be insignificant, or not detectable palynologically. Received October 4, 2001 / Accepted July 22, 2002 Correspondence to: S. M. Cayless     

Mangroves of Oman during the late Holocene; climatic implications and impact on human settlements

Pollen and micropalaeontological analyses carried out on mangrove swamp sediments of Suwayh, Oman (22°05.589'N, 50°40.033'E) reveal environmental changes linked both to climate (monsoon) and geomorphological (sea-level) variations during the Late Holocene. A Rhizophora mangrove developed at Suwayh around 6000 years B. P. under climate conditions marked by an increased tropical influence as compared to the modern situation, with dominant summer rains. The later extension of Prosopis cineraria at Suwayh provides evidence for a different rainfall pattern, with a winter rainy season. Pollen and micropalaeontological composition shows three episodes influenced by the sea water at Suwayh. The most important corresponded to the mangrove episode centred ca 6000 B. P. This was followed by two episodes of slight seawater incursion at ca. 5100 and 4500 B. P. responsible for the formation of a brackish laagon. Comparison based on ¹⁴C measurements on shell recovered from both the sedimentary sequence of Suwayh and the nearby archaeological sites demonstrates that close relations existed between man and mangroves during the Neolithic and the Early Bronze Age. Received October 31, 2001 / Accepted January 24, 2002 Correspondence to: Anne-Marie Lézine     

Man and environment around lake Maliq (southern Albania) during the Late Holocene

The archaeological site of Sovjan is located at the edge of lake Maliq. It was occupied from the early Bronze Age to the early Iron Age. Pollen data from a short sequence of peat deposits dated between 4255±50 and 2420±45 uncal B.P. and charcoal, seeds and wood from archaeological deposits have provided new information on human activities in the region. They are discussed in the general frame of agricultural developments in the Balkans. Regional environment (regarding vegetation and hydrology) and climate are also discussed. Received June 15, 2000 / Accepted March 8, 2001     

Holocene forest dynamics and human impact in southeastern Estonia

Litho-, chrono- and biostratigraphical methods were applied in the examination of a 9.9 m thick sequence of laminated sediments in Verijärv, a lake in southeast Estonia. The vegetation history, which covers at least the time from 10300 cal b.p. to the present, was inferred from the core, which was taken from the deepest part of the lake and correlated with the studied and dated pollen diagrams nearby. Reconstruction of the past vegetation dynamics is based on pollen percentage, accumulation rate and human impact diagrams. During the Holocene two main shifts in vegetation dynamics occurred, the first one at about 7700 cal b.p. when the pine-birch forest was replaced by deciduous mixed forest, and the second at about 3200 cal b.p. marked by the regeneration of pine-birch-spruce forest. A catastrophic forest fire at about 3450 cal b.p. opened up the landscape and gave rise to erosion and the sedimentation of a thick clayey layer. The steep decline in the Alnus curve between 1500–1650 cal b.p. coincides with the start of the continuous Secale curve and evidence of extensive land-use.     

Long-term human impact as registered in an upland pollen profile from the southern Black Forest, south-western Germany

A detailed,¹⁴C-dated, pollen profile from Steerenmoos, a raised bog in the uplands of the southern Black Forest (Schwarzwald) is presented. The Late-glacial and early Holocene vegetation history conforms to the known pattern of forest dynamics for that region. At ca. 6100 cal. B.P.,Abies replaced the mixed oak forest, which is in contrast to adjacent regions whereFagus spread beforeAbies. From the Subboreal onwards,Fagus expanded and slowly largely replacedAbies. The mire developed from a fen to a raised bog. The mountain pine (Pinus mugo ssp.rotundata) on the present-day bog surface is a result of medieval burning. Cereal pollen are first recorded in the Neolithic (7600 cal. B.P.) and there is a closed curve forPlantago Lanceolata — a good indicator of human impact — since the Bronze Age (4000 cal. B.P.). On the basis of the cereal pollen record nine human impact phases (HIP) are described. HIP 1 and 2, which are short, date to ca. 7600 and 6700 cal. B.P., respectively, in a mixed oak forest context and are characterized by declines inCorylus, Tilia, Ulmus and bySalix (but no major deforestation) and peaks in charcoal and loss-on-ignition curves. HIP 3 and 4, which are short and weak, date to ca. 6000 and 5300 cal. B.P., respectively, and occur in the context of anAbies alba forest. The Bronze Age and Iron Age HIPs 5-7 are more intense and of longer duration than the Neolithic phases and result in a decline inAbies and an increase inFagus. The early medieval HIP 8, although rather weak, probably finds expression also in an archaeological artefact, namely a dug-out boat from the near-by Schluchsee. Finally, the late Medieval HIP 9 resulted in a major transformation in the landscape. It is argued that the earlier HIPs are not a reflection of distant events in the lowland valleys of the Rhine, Danube or Neckar but reflect more or less local developments.     

Effects of the sampling design and selection of parameter values on pollen-based quantitative reconstructions of regional vegetation: a case study in southern Sweden using the REVEALS model

The need for quantification of land cover from pollen data has led to the development of a Landscape Reconstruction Algorithm (LRA). The LRA includes several models of which the REVEALS model estimates regional vegetation abundance using pollen assemblages from large sites (lakes or bogs). In this paper we explore the effects of selection and number of pollen samples, and choice of pollen productivity estimates on the REVEALS results. The effect of the size of vegetation surveys is also tested. The results suggest that the differences between two sizes of vegetation surveys have little effect on the model validation. The “characteristic radius” of regional vegetation in southern Sweden was estimated as 200 km. However, the vegetation composition in a 100 × 100 km² square matches well with that estimated by REVEALS. Whether 25, 20 (outliers excluded) or 4 pollen samples are used does not change the REVEALS reconstructions much although the error estimates are larger when outliers are included, and very large when only four samples are used. Therefore validation of the REVEALS model and REVEALS reconstructions of past vegetation can be performed using a limited number of pollen samples, although with caution. The use of many pollen samples from multiple sites is always better whenever possible. REVEALS reconstructions are closer to the actual vegetation when the Danish Pollen Productivity Estimates (PPEs) are used instead of the Swedish PPEs for Cereals, Rumex acetosa/acetosella, Plantago lanceolata and Calluna, indicating that the Danish PPEs are more reliable than the Swedish ones for those taxa. It is recommended to test more than one set of PPEs in validation and applications of the REVEALS model for a better evaluation of the results.     

Towards the reconstruction of the Holocene vegetation history of Lower Provence: two new pollen profiles from Marais des Baux

Two new¹⁴C-dated Holocene pollen profiles from Marais des Baux, Bouches-du-Rhône, France, are presented. The record begins in the Younger Dryas, when the vegetation consisted mainly of grasses and mugwort (Artemisia). The Preboreal was marked by a transitory expansion of pine forests and was followed by the establishment of a rich deciduous oak-forest that included hazel (Corylus) and elm (Ulmus). During the Boreal, hazel played a dominant role within the oak-forest. The oak forests, which includedQuercus ilex, achieved a major expansion during the Atlantic period. The Subboreal was characterised by the regional establishment of, firstly, fir (Abies) and then beech (Fagus). The spread and expansion of beech coincides with the first clear evidence for farming. Agricultural activities brought about the decline of deciduous oak-forest. During the Subatlantic, forests in the vicinity of Marais des Baux were cleared for farming. Cereal growing, which included rye cultivation, was of considerable importance. Three noteworthy characteristics that serve to differentiate the Holocene vegetation history of the low-lying Provence region from other French regions are as follows: 1) the early establishment (from the onset of Preboreal) of low altitude mixed forest; 2) the expansion during the Subboreal of fir and beech in low altitude areas with a Mediterranean climate and, 3) the exceptional taxonomic richness of the pollen assemblages (120 identified taxa) and the presence of borealalpine and Euro-Siberian taxa that no longer exist in Lower Provence.     

Vegetation dynamics of south-western Italy in the last 28 kyr inferred from pollen analysis of a Tyrrhenian Sea core

A continuous pollen record covering the last 28 kyr was obtained from core C106 collected in the Bay of Salerno in the southern Tyrrhenian Basin, seven radiocarbon dates and the recognition of two tephra layers (Y3 and Pompeii Pumice) providing good chronological constraints. The clear climatic signal given by the pollen spectra integrated by isotopic data, combined with comparisons with other Mediterranean sites, allowed the Last Glacial, Late Glacial and Holocene periods to be distinguished in the core. In particular, the Last Glacial period is characterised by large quantities of herbaceous and steppe elements such as Artemisia. The beginning of the Late Glacial has been correlated with the first increase of deciduous Quercus and the reduction of steppe and herbaceous elements. The Younger Dryas event is recorded only by oxygen isotopes while the vegetation does not seem to change, as in other Mediterranean sites. The Holocene corresponds to rich deciduous and evergreen forests. The first features which could be interpreted as signs of human presence are represented by a few grains of Juglans, Castanea and cereal-type while intensive olive cultivation and deforestation seem to fall within the Middle Ages. Received October 10, 2001 / Accepted June 20, 2002 Correspondence to: Elda Russo Ermolli     

Stone Age to recent land-use history at Pegrema, northern Lake Onega, Russian Karelia

The village of Pegrema in Karelia may be regarded as a Stone Age innovation centre in the large Lake Onega area. Two pollen and plant macrofossil diagrams are presented which represent the first contribution to the study of human impact in the area using anthropogenic pollen indicators. A continuous but sporadic human presence from the Mesolithic onwards is demonstrated. While there is no archaeological evidence relating to the period 4200–3000 B.P., the pollen data suggest continuous, though rather sparse human presence. The data do not support any natural catastrophes in Pegrema as has been suggested elsewhere. Cerealia pollen is recorded earlier than expected (c. 5000 B.P.=. In the Bronce Age and Iron Age, the settlement of the Zaonezhye peninsula is reflected by a slight increase in herb pollen representation, sporadic Cerealia pollen and several periods of regression in Picea. The long introductory period of agriculture to the area, as well as the similarities and discrepancies between different sources of evidence (palaeoecological, archaeological and historical) are discussed at some length. The start of land clearance for permanent cultivation in the profile Pegrema S was dated to the late 13^th century. The beginning of more intensive field cultivation in the 15^th century is clearly seen in the pollen succession at both localities. The fluctuation in anthropogenic indicators can be related to population density based on historical data. The village of Pegrema was depopulated in 1956 which is reflected in a distinct decline in settlement indicators. Received February 17 / Accepted May 19, 2000     

On the Holocene vegetation history of the Argive Plain (Peloponnese,southern Greece)

Palynological investigations have been carried out on a sediment core from ancient Lake Lerna, a former fresh water lagoon in the western part of the Argive plain, Peloponnese, southern Greece. The sequence starts at 6800 B.P. (5700 cal B.C.). The lowest part of the pollen diagram shows a period of open deciduous oak woods, which may have been influenced by human impact already (Zone I). It is followed by a period of dense deciduous oak woods (Zone II), which lasted until the beginning of the Bronze Age ca. 4800 B.P. (3500 cal B.C.). Later, the diagram indicates strong human influence such as woodland clearance, the spread of maquis, phrygana and pine in Zones IIIa-IV. During the Archaic, Geometric and Classical periods after ca. 2700 B.P. (800 cal B.C.) there is evidence of a phase of extensive olive farming (Zone IIIb). In the same zone, after a period of scattered finds, there is an almost continuous Juglans curve. Zone IV is characterised by high pine values. In Zones I-II the evidence of evergreen Mediterranean plants is surprisingly small. In times with no discernible human influence (Zone II), deciduous oaks dominate, with no evidence for a climax vegetation of the Oleo-Ceratonion alliance. Olea europaea is the only species of that alliance traceable by its pollen in the diagram, while Ceratonia pollen is totally absent.     

Burial rituals inferred from palynological evidence: Results from a late Neolithic stone cist in southern Sweden

Soil samples from a late Neolithic stone cist in Hamneda, southern Sweden, were pollen analysed. The results of the analysis suggest that the local vegetation at the time of the burial was a half-open woodland with pasture and small-scale cereal growing, intermingled with stands ofTilia (lime),Quercus (oak) andCorylus (hazel). The analysis also gives unique information on the burial ritual. High pollen percentages ofHordeum type,Triticum type and undifferentiated Cerealia from among the shards of a pot deposited in the cist show that the pot originally contained cereal grains, bread, porridge, gruel or beer. Furthermore, the analysis shows that flowers ofAnemone nemorosa were deposited on or beneath the dead body in the cist.     

Effects of Mesolithic hunter-gatherers on local vegetation in a non-uniform glacio-isostatic land uplift area, northern Sweden

The oldest early Mesolithic settlements found so far (i.e. 8600 b.p.) in the interior of northern Sweden, in the province of Norrbotten, have been discovered through the application of a model simulating glacio-isostatic land uplift. The objective of this study was to investigate, through pollen and charred particle analyses, vegetation composition and the influence of man on vegetation and fire pattern in the vicinity of two of these early settlements. Early Holocene vegetation was characterised by Betula, Hippophaë and Salix-species, but no initial impact by hunter-gatherers on vegetation was detected. Subsequently Betula and Pinus became dominant but abrupt changes in the tree layer followed, Poaceae, Hippophaë and Salix-species increased, and Humulus occurred. These changes, which were synchronous with dates of archaeological findings at the settlements, indicated local vegetation changes caused by man. The relationship between these changes and fire was, however, subtle. Eventually Pinus forests became dominant and human impact on vegetation became less apparent. It is concluded that the impact of early Mesolithic hunter-gatherers on vegetation was detectable, but that their effect on fire pattern was difficult to evaluate. Further, we show that the glacio-isostatic land uplift must be considered in the search for Mesolithic settlements in areas previously covered by the Weichselian Ice, and that the process has influenced the biological archives through re-deposition of material.     

Biostratigraphy and <Superscript>14</Superscript>C dating of a lake sediment sequence on the north-west Estonian carbonaceous plateau,interpreted in terms of human impact in the surroundings

The sediment stratigraphy of a medium-sized mixotrophic lake (Ruila) situated below the highest shoreline of the Baltic Ice Lake in the West-Estonian Lowland is described. The lake is without natural inlets our outlets. The reconstruction of vegetation and land-use history based on pollen data, combined with available archaeological data and detailed ¹⁴C dating allows us to give a provisional reconstruction of the temporal and spatial pattern of natural and human induced environmental changes in north-west Estonia during the Holocene. Both radiocarbon dates derived from terrestrial macrofossil dating by accelerator mass spectrometry (AMS) and conventional dating of bulk lake sediment are discussed. The isolation of the lake basin from the Yoldia Sea took place ca. 9700 cal B. C. The Ancylus Lake transgression at ca. 8400 cal B. C. did not reach the basin, but caused a ground water rise, seen in the sediment stratigraphy of the lake. The first signs of human impact on the pollen record appear ca. 5400 cal B. C. (Late Mesolithic). The history of arable farming has been divided into three periods: 1) introduction of crop cultivation and animal husbandry (1500 cal B. C. – A. D. 500); 2) establishment of animal husbandry A. D. 500–1000) and 3) establishment of crop cultivation and intensive cattle breeding (A. D. 1000–today). Due to unfavourable eda-phic conditions the introduction of arable farming was delayed for more than 1000 years compared with elsewhere on the north coast of Esotnia, and intensity of land-use never reached the same proportion as in these areas. Received August 15, 2001 / Accepted August 5, 2002 Correspondence to: Leili Saarse     

Age-related changes of alpha-crystallin aggregate in human lens

Summary. Lens alpha-crystallin, composed of two subunits alpha A- and alpha B-crystallin, forms large aggregates in the lens of the eye. The present study investigated the aggregate of human lens alpha-crystallin from elderly and young donors. Recombinant alpha A- and alpha B-crystallins in molar ratios of alpha A to alpha B at 1:1, corresponding to the aged sample, were also studied in detail. We found by ultra-centrifugation analysis that the alpha-crystallin aggregate from elderly donors was large and heterogeneous with an average sedimentation coefficient of 30 S and a range of 20–60 S at 37 °C. This was higher compared to the young samples that had an average sedimentation coefficient of 17 S. The sedimentation coefficients of recombinant alpha A- and alpha B-crystallins were approximately 12 S and 15 S, respectively. Even when recombinant alpha-crystallins were mixed in molar ratios equivalent to those found in vivo, similar S values as the native aged alpha-crystallin aggregates were not obtained. Changes in the self-association of alpha-crystallin aggregate were correlated to changes in chaperone activity. Alpha-crystallin from young donors, and recombinant alpha A- and alpha B-crystallin and their mixtures showed chaperone activity, which was markedly lost in samples from the aged alpha-crystallin aggregates.     

History of Late Holocene vegetation at Quintana Roo,Caribbean coast of Mexico

A pollen record of a Late Holocene sediment core from the Mexican Caribbean coast (Quintana Roo) shows the development and changes of a mangrove system. Humid conditions seem to have persisted for the period approximately 2500–1500 ¹⁴C yr BP (pollen zone I), and mangrove Rhizophora mangle dominated with a good representation of elements from the nearby semi-evergreen tropical forest. During the period approximately 1500–1200 ¹⁴C yr BP (pollen zone II) the mangrove Conocarpus erecta dominated. R. mangle almost disappeared and other taxa appeared, suggesting drier climatic conditions and generally more open vegetation. This dry period coincided with the period of the Maya cultural decline. The following period (pollen zone III, approximately 1200–1000 ¹⁴C yr BP) was characterized by the recovery of R. mangle, indicating more humid conditions than in the preceding pollen zone. Pollen zone IV (approximately 1000 ¹⁴C yr BP till present) suggests a drier period reoccuring with C. erecta; this marks the transition to present day conditions.     

Methodological and practical aspects of the presentation and interpretation of microscopic charcoal data from lake sediments

Analysis of microscopic charcoal particles is a useful part of palaeoecological research and is mostly used in conjunction with pollen analysis. However, there is considerable variation in the methodology of charcoal analyses. This paper considers various methods for the analysis of microscopic charcoal and the presentation of charcoal data in the context of a study of the upper sediments of two lakes Estonia. The results are evaluated by comparing both the pollen and charcoal data with documentary evidence of forest fires over the past 60 years. Indications of fires both varying in extent and at different distances from the lakes are evaluated in both the pollen and charcoal diagrams. The results suggest that the total area curve for charcoal particles per unit mass of sediment dry matter (cm² g⁻¹) provides the best indicator of forest fires. Fires in the study area are reflected differently in the charcoal and pollen curves. It is suggested that the charcoal data have the potential to indicate disturbance at a greater distance from the coring site than indicated by the pollen data. Received February 5, 2002 / Accepted August 14, 2002     

Multi-disciplinary evidence of the Holocene history of a cultivated floodplain area in the wetlands of northern Colombia

An environmental reconstruction of the last 10,000 ¹⁴C years of a frequently flooded wetland ecosystem in the lower Magdalena valley in northern Colombia is presented, on the basis of a multi-disciplinary study of the sediments of the upper 15 m of the core from Boquillas (74°33'E, 9°7'N; 20 m a. s. l.). We used the following studies: pollen, lithology, organic structures, clay mineralogy, soil and sediment geochemistry, and δ¹³C values. The chronology is based on 13 AMS radiocarbon dates; the humic acid fractions were used in the case of seven samples. Pollen from local origin (swamps, open grass-rich vegetation, and gallery forest) show the development of the wetland area. River-transported pollen from a greater distance (dry forest, montane forest, Alnus) show changes in river activity and reflect large-scale changes of climatic conditions in the Momposina basin. From c. 10,010 to 9370 uncal B. P. (zone BQS-Ia) the river system was of high energy, as inferred by the lithological changes. The landscape was dominated by open grass-rich vegetation with gallery forest along the streams. A marked representation of Alnus and montane forest taxa indicate significant water transport and river dynamics. Climatic conditions were dry. From c. 9370-8430 uncal B. P. (zone BQS-Ib) wetlands were isolated from the main river system, and clayey sediments with kaolinite, smectite and illite as the main minerals accumulated in a lower-energy environment. Climatic conditions were dry and changes in the seasonal precipitation favoured the expansion of the gallery forest. From c. 8430 to 8040 uncal B. P. (zone BQS-Ic) low values of river-transported pollen indicate dry climatic conditions and open vegetation became more abundant. The flooding frequency of the Boquillas site diminished. From 8040 to 4900 uncal B. P. (zone BQS-Id) the Boquillas site was dominated by open vegetation with patches of gallery forest along the streams. Supply of river-transported allochthonous pollen (from many sources) was minimal. Clay minerals from the sediments suggest variable temperature and precipitation. From c. 4900 to 1550 uncal B. P. )zone BQS-II) the site was within the reach of the main river system as is the case today. Frequent flooding, coinciding with peaks of river-transported grains of Alnus and high sediment supply, point to high precipitation in the composite catchment area of the Magdalena, Cauca, San Jorge, and Cesár rivers. High values of phosphorous in the upper part of the core point to the presence of a pre-Hispanic civilization, approximately from 2000 uncal B. P. onward. Construction of an extensive drainage system allowed irrigation as well as drainage depending the annual cycle of precipitation. The landscape was significantly modified and allowed an extensive crop production on a system of raised fields. Received May 18, 2001 / Accepted June 15, 2001     

On the Late Pleistocene and Holocene history of vegetation and human impact in the Ücker valley, north-eastern Germany

A high-resolution Late Pleistocene and Middle to Late Holocene pollen profile of regional significance is presented. The coring site is located in a mire between two lakes. Ober- and Unter-ückersee, in Brandenburg, north-eastern Germany. The study was carried out in an archaeological context. It provides information about the history of vegetation, climate and human impact in the ücker river valley and the surrounding hills, the Uckerm?rker Hügelland. Hence, it is an important contribution for the reconstruction of the past vegetation of this area of Brandenburg. Seven AMS ¹⁴C-dates based on pollen concentrates provide a chronology for the middle Holocene part of the profile. Phases of intensive human activity can be shown from the middle Neolithic times until the Roman Iron Age. Received February 1, 2000 / Accepted January 18, 2001