Reconstruction of the Allerød Vegetation of the Neuwied Basin, Western Germany, and Its Surroundings at 12,900 Cal B.P

Veget Hist Archaeobot (2007) 16:139–156 DOI 10.1007/s00334-006-0082-6 ORIGINAL ARTICLE Reconstruction of the Allerød vegetation of the Neuwied Basin, western Germany, and its surroundings at 12,900 cal b.p. Felix Bittmann Received: 17 August 2006 / Accepted: 26 September 2006 / Published online: 5 December 2006 C Springer Verlag 2006 Abstract During the late-glacial eruption of the Laacher Introduction See volcano 12,900 b.p. the whole area of the Neuwied Basin, middle Rhine region, was covered by several metres The Neuwied or Central Rhineland Basin (Fig. 1)formsa of the Laacher See Tephra (LST) damaging but also partly geomorphological basin in the Rhenish Shield, and is a part conserving the former vegetation. This gave the unique op- of the West European Rift system running from the Alps portunity to study plant remains in situ and to estimate the through the Rhine valley to the North Sea. Since the Ter- spatial biodiversity of plant taxa within the area investigated tiary and more intensively during the Quaternary the Rhen- at the end of the last glacial as if in a snapshot of 12,900 ish Shield has been uplifted while the Neuwied Basin has years ago. Different kinds of plant material can be found be- remained unaffected or the uplift has been less pronounced. cause of different preservation conditions namely imprints, This uplift was or is accompanied by volcanic activity, lim- charcoal and waterlogged remains. Investigations of this ma- ited during the Pleistocene to the Eifel uplands west of the terial from several places within the Neuwied Basin and the basin. There are two fields of activity, the West and the East Brohl valley north of it allowed the reconstruction of the Eifel Volcanic Fields, both active since 700–600 ka b.p. The former vegetation at different scales from local to regional. late-glacial eruption of the Laacher See volcano was the last This resulted in a large scale draft of a vegetation map of the and most powerful in the East Eifel Volcanic Field up to studied area also based on the distribution and the stage of the present (Schmincke et al. 1999). This was dated to ca. soil development at that time. As to whether thermophilous 12,900 cal b.p., 200 yr before the onset of the Younger Dryas trees were already present is discussed but largely rejected. (12,880 cal b.p., based on varve counts, Brauer et al. 1999; 12,900 ± 560 b.p. by 40Ar/39Ar dating, van den Bogaard Keywords Late-glacial . Vegetation cover . Laacher See 1995; 12,836 cal b.p. in the GRIP ice core, Schwander et al. Tephra . Pollen analysis . Macro remains . Biogeography . 2000). The Laacher See tephra (LST) covered the whole Rhineland vicinity of the eruption centre to a thickness of up to 50 m and even at a distance of 120 km ENE up to 1 m (Schmincke et al. 1999; Baales et al. 2002). It was transported in two main directions, down to northern Italy and up to Scandi- navia (van den Bogaard and Schmincke 1984, 1985) and is a well-known and widespread marker horizon in sediment pro- Electronic Supplementary Material Supplementary material is available for this article at http:// files of late-glacial age, above all in lake sediments and mires. dx.doi.org/10.1007/s00334-006-0082-6 Implications for the environment therefore can be traced at great distances: e.g. Kaiser (1979, 1993); Lotter and Birks Communicated by L. Dupont (1993); Birks and Lotter (1994); Lotter et al. (1995). Sig- F. Bittmann () nals of the event have even been detected in the Greenland Lower Saxony Institute for Historical Coastal Research, ice records GRIP and GISP2 (Taylor et al. 1993; Zielinski Viktoriastr. 26/28, 26382 Wilhelmshaven, Germany et al. 1996; Johnsen et al. 1997). Near to the eruption cen- e-mail: [email protected] tre the massive tephra layers covering the former vegetation Springer 140 Veget Hist Archaeobot (2007) 16:139–156 Fig. 1 Site map of the localities where macro-remains, and in some places pollen, covered and conserved by LST (Laacher See tephra) were investigated; green circles, localities investigated in the course of the present study; red squares, localities from the literature; dashed line, margin of the central Rhineland (Neuwied) Basin; map basis by O. Joris,¨ Neuwied and conserving it at some places with excellent preservation many older volcanic layers known from the area, also bear- conditions give a great opportunity for studying it in detail – ing imprints. In a detailed study Schweitzer (1958)revised it is like a snapshot of 12,900 years ago. and corrected much of the older identifications in so far as The question for archaeology was how did the landscape the material was still extant and not lost during the two world look like at the time when people of the late Palaeolithic wars. The most recent and comprehensive investigation was Federmessergruppen lived in the area, hunting and gathering done by Waldmann (1996) with further citations therein. at the time of the eruption and before. From the botanical The aim of the present study was to characterise the former and biogeographical point of view it was most interesting vegetation at many sites representing different habitats de- to trace the development of the landscape during the de- pendent on different soils and microclimates and to draw a glaciation process at the end of the last glacial and to record (large scale) palaeovegetation map of the area at the time the biodiversity of plant taxa. The unique opportunity to of the eruption. In particular two sites where good preserva- study plant remains in situ by macro-remain analysis leading tion conditions occurred, Miesenheim 4 and Brohltal 1 in the in most cases to the species level allowed a deep insight into Brohl valley to the north of the Neuwied Basin (Figs. 1 and the ecology of the area investigated. 5), could be investigated in detail by pollen and/or macro- Due to large-scale industrial exploitation of the LST since fossil analysis. Therefore this paper is focussed largely on the middle of the 19th century many sites have become these two sites. Results from other sites, mostly with less known where such in situ plant remains from the former good preservation conditions, and from the literature give vegetation cover could be investigated. Different preserva- additional ecological information leading to a relatively pre- tion conditions led to different kinds of material: leaf imprints cise picture of the former vegetation of the Neuwied Basin and charcoal included in and covered by the LST, and occa- and the surrounding slopes. sionally well preserved organic material beneath the LST. Above all both the former and most recent studies of leaf The leaf imprints especially have been subject of many imprints raised the question of whether thermophilous trees studies since the 19th century, e.g. Zeiler (1850) Populus and like Quercus, Tilia, Ulmus, Alnus and Corylus had already Quercus and others; Wirtgen (1864) Pinus, Quercus, Alnus reached the area during the Late-glacial. This is discussed and others. However, it is not always clear if in every case in the light of the macrofossil and pollen analysis presented imprints from the LST have been described because there are here. Springer Veget Hist Archaeobot (2007) 16:139–156 141 Fig. 2 Overview of the site Miesenheim 4, showing the sampled transect; in the foreground the LST is partly uncovered for archaeological investigation, in the background the LST is being quarried Material and methods was 475 (98–1141), for percentage calculation the total sum of terrestrial pollen excluding Poaceae and Cyperaceae was At the site Miesenheim 4, a former small shallow lake, cov- used. From a trench crossing the area 5 profiles for pollen ered by about 3–4 m of LST, a nearly complete skeleton analysis were extracted, but these are not the topic of this pa- of an elk was found in the course of industrial exploita- per (the simplified main profile is given in Scharf et al. 2005). tion of the LST (Street 1995). During an archaeological During an excavation in the Brohl valley (Brohl 1, Fig. 1) search for possible artefacts around the site samples of about in 1986, 41 blocks of about 10 × 10 × 10 cm3 representing 20 × 20 × 5cm3 were taken at 1 m intervals along a transect an area of about 0.41 m2 were taken (Area A in Table 2). from near the centre to the bank (18 samples in 17 m, Fig. These consisted of about the uppermost 5 cm of the Allerød 2). In the laboratory the remaining LST was removed from soil and about 5 cm of the overlying “Trass”(a local name for the sample and the upper 3–5 mm of the remainder removed the fine grained ashes deposited in the valley). An additional (ca. 100–200 ml, 1–2 ml were left for pollen analysis of the 17 smaller samples (in total 5.6 l, not as blocks; also Area A same samples for comparison) and treated with 5% KOH for in Table 2) were taken. During a second sampling campaign at least 24 h. Most samples showed only a very thin (about at the site in 1997 a further 14 samples (fresh material) were 3 mm) layer of well-preserved remains, most probably repre- taken at about 10 m from the former sampled site (total senting the vegetation at the time of the eruption. It covered 12.4 l, representing about 1 m2; Area B in Table 2). All more strongly decomposed material. For each second sam- the samples were processed in the same way as described ple these layers were sampled separately as far as possible above, by soaking in 5% KOH and sieving.

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