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We present the postglacial history of vegeta-

Northumbria University has developed Northumbria Research Link (NRL) to enable users to access the University's research output. Copyright © and moral rights for items on NRL are retained by the individual author(s) and/or other copyright owners. Single copies of full items can be reproduced, displayed or performed, and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided the authors, title and full bibliographic details are given, as well as a hyperlink and/or URL to the original metadata page. The content must not be changed in any way. Full items must not be sold commercially in any format or medium without formal permission of the copyright holder. The full policy is available online: http://nrl.northumbria.ac.uk/policies.html This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.) In this paper we present results of high-resolution multi-proxy palaeoecological 28 studies of two parallel peat cores from the Baltic raised bog Mechacz Wielki in NE Poland. 29We aim to disentangle the effect of the regional climate from the autogenic processes of the 30 raised bog itself in driving the vegetation and hydrology dynamics. Based on partly 31 synchronous changes in Sphagnum communities in the two study cores we suggest that 32 extrinsic factors (climate) played an important role as a driver in mire development during the 33 bog stage (AD 500-2012). Using testate amoebae transfer function, we found that the bog 34 revealed exceptionally stable hydrological conditions during the last 2k with a relatively high 35 water table and lack of local fire events that allowed for rapid peat accumulation (2.75 36 mm/year) in the bog. Further, the strong correlation between pH and community-weighted 37 mean of testate amoeba traits suggests that other variables than water-table depth play a role 38 in driving microbial properties under stable hydrological conditions. There is a difference in 39 hydrological dynamics in bogs between NW and NE Poland until ca CE 1500, after which the 40 water table reconstructions possess more similarities. The most different case is Linje mire, 41 which most probably driven by land-use changes partly coinciding with the Little Ice Age. 42Our results show how various functional traits relate to different environmental variables in a 43 range of trophic and hydrological scenarios on long time scales. Moreover, our data suggest a 44 common regional climatic forcing in Mechacz Wielki, Gązwa and Kontolanrahka. Though it 45 may still be too early to attempt a regional summary of wetness change in the southern Baltic 46 region, this study is a next step to the long-term perspective of peatland palaeohydrology in 47Europe. 48 49 3

The Holocene developmental history of a small kettle-hole peatland in northern Poland was studied using radiocarbon dating and analyses of pollen, plant macrofossils and testate amoebae with the aim of sorting out the influences of climate change, autogenic succession and human impact. The mire followed the classical succession from lake to a Sphagnum-dominated peatland, but peat accumulation only started about 3000 cal. BP. A rapid shift to wetter conditions, lower pH and higher peat accumulation rate took place about 110—150 years before present, when the vegetation shifted to a Sphagnum-dominated poor fen with some bog plants. While the first shift to a peat-accumulating system was most likely driven by climate, the second one was probably caused by forest clearance around the mire. This shift towards a Sphagnum-dominated vegetation mirrors both in pattern and timing the changes observed in similar situations in North America and New Zealand. While human activities have overall caused the loss of vast expanses of peatlands worldwide in recent centuries, locally they may have also allowed the development of communities that are now ironically considered to have a high conservation value. However, in the case of the site studied the likely anthropogenic shift to bog vegetation was at the expense of a species-rich poor fen, which today has even higher conservation value than ombrotrophic bogs. Thus this study also illustrates the value of palaeoecology for peatland management and biodiversity conservation.

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ABSTRACT. Macrofossils of terrestrial plants have been picked from a sediment core taken in Lake Lobsigen, a small lake on the Western Swiss Plateau. The sediments were previously analyzed for pollen composition, plant and animal macrofossils, and stable isotopes. Plant macrofossils were selected near pollen zone boundaries in Late Glacial and early Postglacial sediment for 14C dating by AMS. In the same lake carbonate and gyttja (aquatic plant) samples were dated by decay counting. The dates on terrestrial material are generally younger than those on carbonate and gyttja, ie, material reflecting the 14C/C ratio of dissolved bicarbonate in lake water. This is probably due to a contribution of dissolved limestone carbonate and thus a somewhat reduced 14C/C, ratio in the lake's water (hard water effect).

Here we present the first high‐resolution multi‐proxy analysis of a rich fen in the central‐eastern European lowlands. The fen is located in the young glacial landscape of the Stążki river valley. We investigated the fen's development pathways, asking three main questions: (i) what was the pattern and timing of the peatland's vegetation succession, (ii) how did land use and climate affect the succession in the fen ecosystem, and (iii) to what degree does the reconstructed hydrology for this site correlate with those of other sites in the region in terms of past climate change? Several stages of fen history were determined, beginning with the lake‐to‐fen transition ca. AD 700. Brown mosses dominated the sampling site from this period to the present. No human impact was found to have occurred until ca. AD 1700, when the first forest cutting began. Around AD 1890 a more significant disturbance took place – this date marks the clear cutting of forests and dramatic landscape openness. Deforestation changed the hydrology and chemistry of the mire, which was revealed by a shift in local plant and testate amoebae communities. We also compared a potential climatic signal recorded in the peat profile before AD 1700 with other sites from the region. Copyright © 2013 John Wiley & Sons, Ltd.

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