Late Holocene Changes in Vegetation of the Mrągowo Lakeland (NE Poland) as Registered in the Pollen Record from Lake Salęt
Abstract Pollen analysis of sediments from the upper part of bottom deposits from Lake Salęt allowed reconstruction of main stages of the Late Holocene vegetation transformation in the Mrągowo Lake District (from ca. 3600 cal. years BC) and to correlate some of these changes with immigration and economic activity of local human groups. Significant spreading of secondary semi-natural birch forest, development of horn beam forest and increasing importance of anthropogenic open communities were the most characteristic features of vegetation evolution. A definite break down of elm took place between 2900 and 2500 cal. years BC, slightly after increased contribution of birch in wood lands. Disappearance of hazel around 1200 cal. years BC, accompanied by expansion of horn beam has been observed and should be linked with activity of the Ząbie-Szestno type culture and the Lusatian culture tribes during the Bronze Age, but not with a climate change. Considerable intensification of settlement processes recorded in the younger part of the Subatlantic chronozone was one of the important reasons that were responsible for quick changes in forest structure. Strong and continued deforestation started as early as the end of the 10th century AD and was substantially intensified in the first half of the 13th century.
Was it ‘terra desolata’? Conquering and colonizing the medieval Prussian wilderness in the context of climate change.
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.
Last nine-thousand years of temperature variability in Northern Europe
Abstract. The threat of future global warming has generated a major interest in quantifying past climate variability on centennial and millennial time-scales. However, palaeoclimatological records are often noisy and arguments about past variability are only possible if they are based on reproducible features in several reliably dated datasets. Here we focus on the last 9000 years, explore the results of 36 Holocene pollen-based July mean and annual mean temperature reconstructions from Northern Europe by stacking them to create summary curves, and compare them with a high-resolution, summary chironomid-based temperature record and other independent palaeoclimate records. The stacked records show that the "Holocene Thermal Maximum" in the region dates to 8000 to 4800 cal yr BP and that the "8.2 event" and the "Little Ice Age" at 500–100 cal yr BP are the clearest cold episodes during the Holocene. In addition, a more detailed analysis of the last 5000 years pinpoints centennial-scale climate variability with cold anomalies at 3800–3000 and 500–100 cal yr BP, a long, warmer period around 2000 cal yr BP, and a marked warming since the mid 19th century. The colder (warmer) anomalies are associated with increased (decreased) humidity over the northern European mainland, consistent with the modern high correlation between cold (warm) and humid (dry) modes of summer weather in the region. A comparison with the key proxy records reflecting the main forcing factors does not support the hypothesis that solar variability is the cause of the late-Holocene centennial-scale temperature changes. We suggest that the reconstructed anomalies are typical of Northern Europe and their occurrence may be related to the oceanic and atmospheric circulation variability in the North Atlantic – North-European region.