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'Little Ice Age' (LIA) climatic deteriorations have been abundantly documented in various archives such as ice, lake sediments and peat bog deposits. Palaeoecological analyses of peat samples have identified these climatic deteriorations using a range of techniques, for example palynology, plant macrofossils, testate amoebae or carbon isotopic analyses. The use of inorganic geochemistry and the reconstruction of dust fluxes has remained a challenge in tracing the nature of LIA climatic changes. Although the idea of enhanced erosion conditions and storminess is commonly discussed, the conditions for dust deposition in peatlands over Europe during the LIAare rarely favourable, because the natural forest cover over Europe was much more important than nowadays, preventing dust deposition. This intense forest canopy masks the deposition of dust in peatlands. In northern Poland, near the Baltic shore, the Slowińskie Błota area was deforested around AD 1100, ie, just before the LIA, and therefore constitutes a key area for the reconstruction of LIA climatic change. With the support of a well-constrained chronology, climatic fluctuations are recorded in an ombrotrophic bog using inorganic geochemistry, plant macrofossils and carbon isotopic analyses. The reconstruction of LIA climatic changes is in good agreement with other records from Poland and NE Europe. However, a c. 50-year discrepancy can be observed between various records. This discrepancy is possibly due to progressive time-dependent cooling gradient from north to south Europe. [ABSTRACT FROM AUTHOR]

Fens are underestimated carbon sinks. Knowledge about their role in the sequestration of CO2 in the past is limited. The research reported here focused on identifying long-term carbon accumulation rates (CARs) in a drained fen (Bagno Bruch) and a waterlogged fen (Bagno Mikołeska) in southern Poland. On the basis of 210Pb and AMS 14C dates and age–depth modeling, 7000- and 2000-year records of changes in bulk composition and carbon and sulfur content are presented and discussed. Strong human impact is detected, especially in Bagno Bruch. However, minor climatic signals linked to the ‘Little Ice Age’ and to the influence of wind-blown sands are also evident. The sand may have influenced the plant composition, peat accumulation rates (PARs), and CARs, in addition to the bulk composition at Bagno Mikołeska. The mean value of the CAR in the youngest peat layers spanning the last 200 years is generally lower in two cores from Bagno Bruch (c. 85 and 86 g/m2/yr) than in two cores from Bagno Mikołeska (c. 140 and 142 g/m2/yr). The fens are characterized by higher CARs compared with boreal peatlands. The reproducibility of the CAR values is the most promising result, suggesting the low mobility of 210Pb and the reliability of this method in assessing the chronology of fens. [ABSTRACT FROM PUBLISHER]

The climate variability and related sea-level changes during the Holocene are still under discussion, especially in a regional context. Very little information comes from the southern and south-eastern Baltic coast. The aim of the paper is to gain insight on the history of regional environmental changes, particularly sea-level and storminess, and their driving forces. The investigations were located on a peatland on the coast of Puck Lagoon (Gulf of Gdańsk, southern Baltic Sea). The analysis of peat core comprised: radiocarbon dating, analysis of stable isotopes 18O and 13C and chemical components, as well as palynological and diatomic studies. Results showed the 1.0 m peat section accumulated over 1500 years, with a time resolution of 100 years per sample. The average water level in the Puck Lagoon rose by ca. 0.85 m during the last 1500 years in a cyclic mode, with a period cycle of ca. 600–550 years and an amplitude not exceeding 0.5 m. The accelerated sea level rise and frequent storminess occurred during the first half of the Dark Ages (1500−1300 years b2k) and LIA (750−450 years b2k) and since the beginning of the 20th century. Recognized environmental changes are well correlated with both temperature changes in the North Atlantic and changes in total solar irradiance, suggesting synchronous Northern Hemisphere-wide fluctuations. The solar forcing was an important constituent of natural climate variability in the past and of forcing climate warming during modern times - after the Little Ice Age. [ABSTRACT FROM AUTHOR]

Pollen, non-pollen palynomorphs, charcoal and geochemical analyses of sediments from Lakes Salęt and Ruskowiejskie (NE Poland) were used to reconstruct vegetation changes in the former Galindia territory (Old Prussia) related to human activity and the climatic instability of the medieval period. Among archaeologists and historians, there is a widespread opinion that the permanent transformations of the environment in Prussia (south-eastern Baltic region) began not earlier than after its conquest by the Teutonic Order and resulted from its economic activity and intensive colonization. The impact of previous inhabitants of this land on the environment has been considered as definitely weak. Our results provide entirely contrasting evidence and demonstrate that strong and permanent deforestation started as early as in the early 11th century AD, in the pre-Teutonic Order time, and were associated with the economic activity of the Prussian Galinditae tribes. In this paper, we also discuss a possible interpretation of the medieval distribution patterns of Quercus. We assume that human activity catalysed and amplified both its spreading process and decline, primarily driven by the ‘Little Ice Age’ climatic deterioration. Our palynological results indicate the significant spread of Picea from ca. AD 1000, which we interpret as reflecting hydrological and climatic changes. Moreover, we hypothesize that the spread of Carpinus in the early medieval period (11th–13th centuries), which occurred in connection with more intense human activity, was largely because of woodland pasturing. [ABSTRACT FROM AUTHOR]

Rapid ecosystem transitions and adverse effects on ecosystem services as responses to combined climate and human impacts are of major concern. Yet few long-term (i.e. >60 years) quantitative observational time series exist, particularly for ecosystems that have a long history of human intervention. Here, we combine three major environmental pressures (land use, nutrients and erosion) with quantitative summer and winter climate reconstructions and climate model simulations to explore the system dynamics, resilience and the role of disturbance regimes in varved eutrophic Lake Żabińskie (NE Poland) since AD 1000. The comparison between these independent sources of information allows us to establish the coherence and points of disagreements between such data sets. We find that climate reconstructions capture noticeably natural forced climate variability, while internal variability is the dominant source of variability during most parts of the last millennium at the regional scale, precisely at which climate models seem to underestimate forced variability. Using different multivariate analyses and change point detection techniques, we identify ecosystem changes through time and shifts between rather stable states and highly variable ones. Prior to AD 1600, the lake ecosystem was characterised by high stability and resilience against observed natural climate variability. During this period, the anthropogenic fingerprint was small; the lake ecosystem was buffered against the combined human and natural disturbance. In contrast, lake-ecosystem conditions started to fluctuate across a broad range of states after AD 1600. The period AD 1745-1886 represents the phase with the strongest human disturbance of the catchment-lake ecosystem. During that time, the range of natural climate variability did not increase. Analyses of the frequency of change points in the multi-proxy data set suggest that the last 400 years were highly variable and increased vulnerability of the ecosystem to the anthropogenic disturbances. This led to significant rapid ecosystem transformations. [ABSTRACT FROM AUTHOR]

Radiocarbon-dated spring-fed fen deposits from the Komarów site (Volhynia Upland, SE Poland) with its multi-proxy data (macrofossils, molluscs, geochemistry, pollen, stable isotopes of oxygen and carbon) enable us (1) to distinguish four main stages of fen evolution, which reflected a distinct variability of water supply conditions and (2) to reconstruct the Holocene humidity–temperature changes. The beginning of peat–tufa deposition took place in a Boreal phase, after a significant cool fluctuation of climate occurring ca. 9.4 ka cal. BP. We suggest that climate was the most important factor conditioning the development of the spring-fed fen. Permafrost degradation, and then wet periods, intensified the activity of ascending springs. The impact of humans was possible since the Neolithic period and increased during the Middle Ages: therefore, the anthropogenic influence could have partially overlapped with the regional tendencies of climate changes. Autogenic development of deposit succession in the studied fen was definitely conditioned by hydrological changes induced by climate. Based on the multi-proxy data, 12 cold events of different ranks were identified. They are also recorded in other Polish and European sites. A record of distinct variability of depositional conditions at ca. 9.4, 8.2, 5.9, 4.6, 2.8, 1.4 and 0.55 ka cal. BP corresponds to quasi-periodical global climate changes in the Holocene named the Bond events. The majority of the cold events recorded in δ13C and δ18O of carbonates can be correlated to the Greenland oxygen isotope curve. [ABSTRACT FROM AUTHOR]

In this study, we investigated morphologically and geochemically a skull from an open pit situated on the Călineasa-Şesu Gârzii Plateau, Bihor Mountains. The study presents the first 14C dating and stable isotope composition of bison skeletal remains from the Romanian Carpathians. The result of 14C determination yielded two relevant maxima: one is around AD 1550 and the second around AD 1645. The data indicate that the investigated bison died during the ‘Little Ice Age’ (LIA), approximately 200 years before the last ones were hunted to extinction. Stable isotope composition of carbon from bison tooth enamel suggests that the bison diet consisted mainly of C3 grasses, compatible with a high-altitude habitat, vegetation distribution and low mobility. Oxygen isotope composition of both phosphate and carbonate groups of tooth enamel indicates that the bison drank from stagnant water sources, such as lakes or puddles formed from rain water. This further suggests low mobility of the bison as well, as the presence of such small stagnant water sources is characteristic even today for the plateau. Calculated oxygen isotope compositions of rain and drinking water at the time the bison lived indicate a lower relative humidity, around 60–70% at that period of LIA when the bison lived, which is lower than today’s humidity of 80%. [ABSTRACT FROM AUTHOR]