Agnieszka M. Noryśkiewicz

Environmental context and the role of plants at the early medieval artificial island in the lake Paklicko Wielkie, Nowy Dworek, western Poland

AbstractThis paper reports the archaeobotanical investigation of the early medieval lake site near Nowy Dworek, in the west of Poland, focussing on the role of plants on and around the site. The construction of a small, artificial island in a lake similar to Irish crannogs, traces of a wooden bridge and archaeological artefacts all indicate that the site was a special place for the local Slav community in the 9th–10th centuries ad. Plant macroremains and pollen also demonstrate the uniqueness of the place. A large number of the cultivated and wild plant taxa are connected with the local environment and reveal an interest in plants as an element of beliefs. Pollen from dung pellets provides information about plants used as fodder and complements the picture of plant communities on the land around the island.

Leaf wax n -alkane distributions record ecological changes during theYounger Dryas at Trzechowskie paleolake (Northern Poland)without temporal delay

While of higher plant origin, a specific source assignment of sedimentary leaf wax n-alkanes remains difficult. In addition, it is unknown how fast a changing catchment vegetation would be reflected in sedimentary leaf wax archives. In particular, for a quantitative interpretation of nalkane C and H isotope ratios in terms of paleohydrological and paleoecological changes, a better understanding of transfer times and dominant sedimentary sources of leaf wax n-alkanes is required. In this study we tested to what extent compositional changes in leaf wax n-alkanes can be linked to known vegetation changes by comparison with high-resolution palynological data from the same archive. We analyzed leaf wax n-alkane concentrations and distributions in decadal resolution from a sedimentary record from Trzechowskie paleolake (TRZ, northern Poland), covering the Late Glacial to early Holocene (13 360–9940 yr BP). As an additional source indicator of targeted n-alkanes, compound-specific carbon isotopic data have been generated in lower time resolution. The results indicated rapid responses of n-alkane distribution patterns coinciding with major climatic and paleoecological transitions. We found a shift towards higher average chain length (ACL) values at the Allerød–Younger Dryas (YD) transition between 12 680 and 12 600 yr BP, coevaled with a decreasing contribution of arboreal pollen (mainly Pinus and Betula) and a subsequently higher abundance of pollen derived from herbaceous plants (Poaceae, Cyperaceae, Artemisia), shrubs, and dwarf shrubs (Juniperus and Salix). The termination of the YD was characterized by a successive increase in n-alkane concentrations coinciding with a sharp decrease in ACL values between 11 580 and 11 490 yr BP, reflecting the expansion of woodland vegetation at the YD–Holocene transition. A gradual reversal to longer chain lengths after 11 200 yr BP, together with decreasing n-alkane concentrations, most likely reflects the early Holocene vegetation succession with a decline of Betula. These results show that n-alkane distributions reflect vegetation changes and that a fast (i.e., subdecadal) signal transfer occurred. However, our data also indicate that a standard interpretation of directional changes in biomarker ratios remains difficult. Instead, responses such as changes in ACL need to be discussed in the context of other proxy data. In addition, we find that organic geochemical data integrate different ecological information compared to pollen, since some gymnosperm genera, such as Pinus, produce only a Published by Copernicus Publications on behalf of the European Geosciences Union. 1608 B. Aichner et al.: Leaf wax n-alkane distributions record ecological changes very low amount of n-alkanes and for this reason their contribution may be largely absent from biomarker records. Our results demonstrate that a combination of palynological and n-alkane data can be used to infer the major sedimentary leaf wax sources and constrain leaf wax transport times from the plant source to the sedimentary sink and thus pave the way towards quantitative interpretation of compound-specific hydrogen isotope ratios for paleohydrological reconstructions.

The history of Taxus baccata L. in the Wierzchlas (N Poland) on the basis of palynological research

Wierzchlas forest reserve forms the biggest natural stand of the Taxus baccata in Poland. The pollen analysis of biogenic sediments from Mukrz Lake registers the history of the plant cover of area surrounding Mukrz Lake starting from Vistulian Late Glacial period through the Holocene until the contemporary times and indicates that Taxus baccata may be native from the beginning of the Subboreal to the present time. Additional research was made because of the small representation of Taxus in the fossil samples. The fossil spectra were supplemented with the results of surface samples taken from the bottom of the lake and from the forest, together with the results of annual pollen deposition. The presence of yew pollen grains in surface materials from the reserve in Wierzchlas depends, thus, on both the distance between the sample taken and a male yew individual as well as the stand density. The comparison of the surface spectra from different habitats of this reserve (lake, forest floor and peatbog) and material from Tauber’s traps reflected a large discrepancy in the representation of yew. These differences are related to both the habitat from which the material originated, and also to the distance between the sampling point and the location of a male yew tree.