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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. [ABSTRACT FROM PUBLISHER]

Multidisciplinary study of a peat profile from the coast near the drowned remains of a medieval harbour at Puck have allowed the reconstruction of the environmental conditions at the time when the port was in operation. The research included AMS 14C dating, and analysis of 13C and 18O isotopes, pollen, plant macrofossils, diatoms, total organic carbon, phosphorous, and heavy metals. In the period around 800-900 AD, when the port was created, sea level was about 0.75-0.70 m lower than today and hydrodynamic conditions were relatively calm. Stable or slowly increasing level of water in the Puck Lagoon continued until about 1100-1200 AD. A decrease in port activity , during about 1300-1350 AD, occurred at a time of marked climatic cooling at the beginning of the Little Ice Age, together with frequent and heavy storms. During the interval 1100 to 1400 AD, the lagoon water level rose by about 0.4 m. However, climate and hydrological changes were not then sufficiently catastrophic to destroy the port. The decline in port activity is connected to a clear breakdown in human economic activity in the area, as reflected in the results of pollen analysis and a drop in Cu and Pb content. The sediments of this period are also characterized by a large amount of wood charcoal, suggesting the possibility of conflagration. [ABSTRACT FROM AUTHOR]

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