Studia Quaternaria

We present the last millennium of history of a peatland located in northern Poland. Our results are based on two replicate monoliths taken from a Baltic raised bog. We applied a high-resolution approach and radio car bon dating to the peat material to obtain a de tailed palaeoenvironmental reconstruction. To reconstruct past peatland moisture, we used three prox ies: testate amoebae, plant macrofossils and pollen. Despite different peat accumulation and extensive hiatus in the formerly studied core, both monoliths show a similar pattern of changes. However, the core from this study provides us with more detailed data on S. fuscum disappear ance which correlates well with the data from the other Baltic bog, S³owiñskie B³oto. Our re search shows that pris tine Bal tic bogs can be dated to AD 1350. Słowiñskie Błoto palaeohydrology confirms AD 1300 as the beginning of the hydrological disturbance. In the case of the Stążki and Słowiñskie Błoto bogs, the Little Ice Age (LIA) is recorded between AD 1500 and AD 1800. However, this climatic change might have been blurred by human impact. In the case of the Baltic bogs, their reference virgin state can be dated to AD 1200. After this date, we observed in creasing human impact and climatic in stability connected with the LIA. However, between AD 1800 and 1900, bogs were wet, most possibly due to climatic forcing. This fact suggests that despite human impact, recent peat deposits can still reflect climate. Our research provided in formation related to the time of existence, location and characteristics of the natural/pristine state. High-resolution peatland palaeoecology is crucial for restoration activities, e.g., rewetting and environmental management. The palaeohydrological context (supported by other proxies) of the last 1000 years provides a reliable answer to the question: ‘To rewet or not to rewet?’

The dynamic changes in selected heavy metal concentrations were analyzed in two ombrotrophic peat bogs from southern Poland: Puścizna Mala (PK) and Puścizna Krauszowska (PM). The highest contents of Pb and Zn occur at the top of profiles examined: 115.36 mg/kg (PM1), 90.61 mg/kg (PM2), 182.40 mg/kg (PK1), 121.68 mg/kg (PK2) and 127.43 mg/kg (PM1), 89.73 mg/kg (PM2), 170 mg/kg (PK1), 130.4 mg/kg (PK2), respectively. Concentrations of copper are similar to those of local soils varying from 9.4 to 12.8 mg/kg. Cadmium strongly varies with depth, which indicates distinct mobility of this element. Two peaks of elevated Fe concentrations are observed at the top and bottom of the Puścizna Mala profile, while the maximum in Puścizna Krauszowska was at the top of the peat bog. The Ti content distinctly varies with depth and correlates with the ash content (R 2 = 0.91-0.99). The strongest and positive correlation is observed between Zn-Pb and Ti-Pb contents. The significant differences of metal concentrations are noted between the profiles, which is probably connected with a rate of peat accumulation and plant composition of the profiles investigated, as well as with their disturbance by human activity.

Vegetation changes in the Lower San Valley near Jaroslaw are reconstructed from the Younger Dryas to the present time on the basis of palynological analysis of the peat core. The pollen profile came from a an old riverbed and was supplemented by radiocarbon datings. The Younger Dryas and early Preboreal vegetation was characterised by a high proportion of forest communities with pine (Pinus sylvestris and P. cembra) and birch (Betula), while patches of open area were dominated by the steppe with Artemisia. Climatic amelioration during the Preboreal chronozone led to the rapid spread of elm (Ulmus), which was probably a dominant taxon on the lowest terraces of the valley. Terrestrialization of the water body existing in the palaeomeaner and the subsequent beginning of peat accumulation caused a deterioration in pollen preservation. Hence, the interpretation of the profile section spanning the period between the Boreal and Subatlantic chronozones was seriously disturbed due to selective corrosion and the overrepresentation of Pinus sylvestris type and Filicales monolete sporomorphs. Between ca. 336 and 1152 AD fluctuations in woodland cover were recorded. Important components in those forests, despite the domination of Pinus sylvestris, were Quercus, Carpinus betulus, Fagus sylvatica and Abies alba. The first pollen grains of cereals (Cerealia type) were found before ca. 1605-1414 BC and may be attributed to the agricultural activity of the Neolithic and/or early Bronze tribes. Periods of strong deforestation caused by humans were probably related to the time when the Tarnobrzeska Group of the Lusatian Culture and the Przeworska Culture were active. The first groups of Slavs did not significantly influence the environment, but the subsequent development of those groups led to more visible deforestation, which was triggered after the establishment of Jaroslaw in the 11 th century AD.

We investigated sediments of three Sphagnum peatland-lake ecosystems located in Tuchola forest, both in moraine (Małe Leniwe near Rekowo) and outwash plain (Dury and Rybie Oko) landscape. Geological cross-sections were studied for each basin. Characteristic feature of these ecosystems is the presence of floating mats encroaching the lakes and deposition of highly hydrated sediments below the floating mat. Principal conditions favouring the development of peatland-lake ecosystems are (1) location of the lake in a sandy, non-calcareous catchment overgrown by coniferous forest, (2) steep ness of the lake basin, what prevents emerged macrophytes succession and (3) the depth of the basin significantly exceeding 10 m to avoid complete in filling of the lake basin. The developmental pathway in the Dury I basin indicates a shift in lake environment from neutral to acid one. After initial development of Charophytes, Potamogeton and Najas expanded, which later on, were succeeded by Sphagnum due to acidification of the lake water. Initial stages of the development of the lakes were determined mainly by allogenic factors, whereas in later stages autogenic factors (development of floating mat and peat acidifying the lake water) played fundamental role.

The objective of the paleoecological studies undertaken in the "Klocie Ostrowieckie" reserve was mainly to reconstruct the subfossil mire vegetation at a local and regional scale. This article presents the results of palynological and plant macroremain analyses of this site, and belongs to the first published studies of such a type, made in the Drawieński National Park. Based on our studies, five phases in the history of the mire development were determined. The most pronounced feature of that history, was a decline of Cladietum marisci clearly concurrent with a strong yet puzzling expansion of pine stands occurring approximately 1000 years ago.