The Baltic coast of Northern Poland is an interesting region for palaeoclimatic studies because of the mixed oceanic and continental climatic influences and the fact that the dominance of one or the other of these two influences might have changed over time. Also, unlike many more intensively studied regions of Europe, human impact in the region was rather limited until the 19th century. We present a 1200-year high-resolution record from Stążki mire, an ombrotrophic bog located 35 km from the Baltic Sea coast. Using testate amoebae, stable isotopes (δ 13 C) of Sphagnum stems, pollen, plant macrofossils and dendroecological analyses, our aims were to: 1) reconstruct the last millennium palaeoenvironment in the study site and its surroundings, 2) identify the major wet-dry shifts, 3) determine if those events correlate with climate change and human impact, 4) assess the resilience of the Baltic bog ecosystem following human impact, and 5) compare the palaeo-moisture signal from the Baltic coast with records from more oceanic regions. Two dry periods are inferred at AD 1100-1500 and 1650-1900 (-2005). The first dry shift is probably climate-driven as pollen record shows little evidence of human indicators. The second dry shift can be related to local peat exploitation of the mire. In the 20th century additional limited drainage took place and since ca. AD 1950 the mire has been recovering. From 1500 AD onwards all proxies indicate wetter condition. The beginning of this wet shift occurred during the Little Ice Age and may therefore be a climatic signal. The macrofossil data show that Sphagnum fuscum dominated the pristine mire vegetation but then declined and finally disappeared at ca. AD 1900. This pattern is comparable with the timing of extinction of Sphagnum austinii (= Sphagnum imbricatum) in the UK. This study illustrates the value of high-resolution multi-proxy studies of peat archives to assess the magnitude of anthropogenic land-use changes. This study presents the first direct comparison of testate amoebae and stable isotope data from the same core. The two proxies correlate significantly throughout the record and most strongly for the latter part of the record when most of the variability was recorded.

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Peat deposits from an ombrotrophic bog (north-eastern Poland) were analysed to reconstruct peatland development and environmental changes. This paper presents reconstructions of hydrological changes and plant succession over the last 6000 years. The methods included the high-resolution analysis of plant macrofossils, pollen and testate amoebae, supported by radiocarbon dating. Three main phases were identified in the history of the bog and surrounding woodland vegetation: 4000–400 BC, 400 BC–AD 1700 and AD 1700–2011. Except for terrestrialisation and the fen-to-bog transition phase, the development of bog vegetation was mainly dependent on the climate until approximately AD 1700. The dominant taxon in Gązwa bog was Sphagnum fuscum/rubellum. Woodland development was significantly affected by human activity at several time periods. The most visible human activity, manifested by the decline of deciduous species, occurred ca. 350 BC, ca. AD 250, ca. AD 1350 and after AD 1700. These events correspond to phases of human settlement in the area. During 400–300 BC, the decline of deciduous trees, primarily Carpinus, coincided with an increase in indicators of human activity and fire frequency. At ca. AD 200, Carpinus and Tilia abundance decreased, corresponding to an increased importance of cereals ( Secale and Triticum). Since ca. AD 1350, the impact of Teutonic settlement is apparent, and after AD 1700, deciduous forests largely disappeared.

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