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Holocene relative shore‐level changes and development of the Ģipka palaeolagoon in the western Gulf of Riga are reconstructed using multiproxy analyses by combining litho‐, biostratigraphical and chronological data with remote sensing and geophysical data. The results show the development of the Ģipka basin from the Ancylus Lake/Initial Litorina Sea coastal zone (before c. 9.1 cal. ka BP) to coastal fen (c. 9.1 to 8.4 cal. ka BP) and gradual development of the Litorina Sea lagoon (c. 8.4 to 4.8 cal. ka BP) and its transition to a freshwater coastal lake (c. 4.8 to 4.6 cal. ka BP), fen (c. 4.6 to 4.2 cal. ka BP), and river floodplain (since c. 4.2 cal. ka BP). The highest shorelines of the Ancylus Lake and Litorina Sea were mapped at an elevation of 12–11 and 9 m a.s.l., respectively. A new relative shore level (RSL) curve for the western Gulf of Riga was constructed based on RSL data from the Ģipka area and from nearby Ruhnu Island studied earlier. The reconstruction shows that the beginning of the last marine transgression in the western Gulf of Riga started at c. 8.4 cal. ka BP, and concurred with the 1.9 m RSL rise event recorded from the North Sea basin. Diatom analysis results indicate the existence of the Ģipka lagoon between c. 7.7 and 4.8 cal. ka BP, with the highest salinity c. 6.1 cal. ka BP. During the existence of the brackish lagoon, settlement sites of the Neolithic hunter–gatherer groups existed on the shores of the lagoon in the period c. 6.0 to 5.0 cal. ka BP. [ABSTRACT FROM AUTHOR]

Human‐induced activities around Lake Lilaste in the central Latvian sandy coastal area have been reconstructed over a 1300‐year period. We use a combination of well‐established geoarchaeological research methods (14C dating, pollen, nonpollen palynomorphs, REVEALS modeling, diatoms, C/N ratio, magnetic susceptibility, loss on ignition) to study the human impact on the environment. Historical context aids focus on records of resource (e.g., timber) exploitation in the area. The continuous record of human indicator pollen and agricultural landscape suggests this area was suitable for habitation well before the studied time period, likely due to the ecosystem services it provided. Our proxy‐based study, combined with historical background, reveals a significant human impact on the terrestrial environment since the 14th century. Deficiency of trees in the northern outskirts of Riga during the 17th–19th century was likely. Anthropogenic activity has led to both deforestation and change in species composition. Our paleo records indicate recognizable human‐driven legacy in current seacoast landscape. [ABSTRACT FROM AUTHOR]

Two unique Pre-Viking Age ship burials were found from Salme village, Saaremaa Island, eastern Baltic Sea, containing remains of seven men in the smaller and 34 men in the larger ship. According to the archaeological interpretations, these ships belonged to a viking crew possibly from the Stockholm-Mälaren region, eastern Sweden. Geoarchaeological research was conducted in the area to reconstruct Late-Holocene relative sea-level (RSL) changes and shoreline displacement to provide environmental context to these burials. In this paper we present a Late-Holocene shore displacement curve for the Saaremaa Island and GIS-based palaeogeographic reconstructions for the Salme area. The curve shows an almost linear RSL fall from 5.5 to 0.8 m a.s.l. between 1000 BC and 1300 AD with an average rate of 2 mm/year. A slowdown in regression may be attributed to accelerated sea-level rise after the Little Ice Age and during the industrial period, being consistent with the tide-gauge measurements from the 20th century. Palaeogeographic reconstructions indicate the existence of a strait in the Salme area during the burial of the ships. The eastern part of the strait with water depth up to 2.8 m was about 80–100 m wide. The relatively steep and wind-protected shores in that part of the strait were probably the best places in the area for landing the viking ships. According to sedimentological evidence and diatom data, the narrowing of Salme palaeostrait occurred between 1270 and 1300 AD. Salme I and II ships were buried at 650–770 AD into the sandy-gravelly coastal deposits which had accumulated there in the open coastal zone about 710–450 years earlier. Reconstructions show that the ships were located about 2–2.5 m above coeval sea level and more than 100 m from the coastline. Thus, both ships were probably moved from the shore to the higher ground for burial. [ABSTRACT FROM AUTHOR]

The paper presents diatom, loss-on-ignition, magnetic susceptibility, and radiocarbon data to reconstruct the depositional history and evolution of Lake Harku, a former Limnea Sea lagoon. Harku is one of the youngest isolated lakes that has been studied bio- and chronostratigraphically in Estonia to date. Based on changes in diatom assemblages, four evolutionary stages in basin development have been recognized (lagoon, semi-enclosed lagoon, transitional and closed lake). Shoreline positions at 2000, 1500, 1000 and 800 cal BP have been reconstructed and displayed on 3D palaeogeographic maps. Lake Harku became isolated from the Limnea Sea at -800 cal BP, followed by occasional seawater incursions over the next 300 years. Plain landscape, low-lying threshold, and proximity to the sea contributed to extended basin isolation. [ABSTRACT FROM AUTHOR]

In response to glacio-isostatic rebound in Estonia, a relative sea level fall occurred during the mid- and late-Holocene, and as a result, lowland regions in northern Estonia have experienced an evolution from sea to land. The mid- and late-Holocene shoreline changes along the southern coast of the Gulf of Finland were reconstructed, using litho-, bio- and chronostratigraphical proxies from four lakes. The lakes are located within the Gulf of Finland drainage system at different altitudes between 18 and 4 m above the present sea level. The isolation from the sea and the onset of freshwater lacustrine sedimentation occurred in Tänavjärv basin at 5400 cal yr BP, in Klooga basin at 4200 cal yr BP, in Lohja basin at 2200 cal yr BP and in Käsmu basin at 1800 cal yr BP. Through the application of GIS-based analysis, a modern digital terrain model and reconstructed past water level surfaces, we present a series of scenarios of shoreline and palaeogeography changes occurring since 7800 cal yr BP. The land uplift rate, which was approximately 2.8 mm yr-1 7800 cal yr BP in the surroundings of Tänavjärv, has decreased to 2.2 mm yr-1 at present and that at Lohja from 2.4 to ca 2.0 mm yr-1, respectively. The relative sea level curves show a land uplift decrease, which is nearly linear since the mid-Holocene. [ABSTRACT FROM AUTHOR]

The marine-freshwater environmental transition, i.e. basin isolation from the Limnea Sea, has been identified in two short sediment cores with respect to their diatom composition, loss-on-ignition and magnetic susceptibility content. The isolation level of the basins was dated by accelerator mass spectrometry radiocarbon measurements. The basins are situated on the southern coast of the Gulf of Finland between altitudes 5.5 and 3.9 m above sea level. The Lohja basin became isolated from the sea around 2300 cal yr BP and Käsmu basin around 1800 cal yr BP as a result of glacio-isostatic uplift. The total land upheaval rate that has been 2.6 mm yr ⁻¹ since 2500 cal yr BP has currently decreased to 2.0 mm yr ⁻¹. We present a GIS-based 3D palaeogeographic reconstruction of the palaeocoastline changes in northern Estonia for two peninsulas, Pärispea and Käsmu, as well as compose a shoreline displacement curve for the study area, which is a compilation of previous and ongoing investigations. [ABSTRACT FROM AUTHOR]

Patchy global data on belowground litter decomposition dynamics limit our capacity to discern the drivers of carbon preservation and storage across inland and coastal wetlands. We performed a global, multiyear study in over 180 wetlands across 28 countries and 8 macroclimates using standardized litter as measures of "recalcitrant" (rooibos tea) and "labile" (green tea) organic matter (OM) decomposition. Freshwater wetlands and tidal marshes had the highest tea mass remaining, indicating a greater potential for carbon preservation in these ecosystems. Recalcitrant OM decomposition increased with elevated temperatures throughout the decay period, e.g., increase from 10 to 20 °C corresponded to a 1.46-fold increase in the recalcitrant OM decay rate constant. The effect of elevated temperature on labile OM breakdown was ecosystem-dependent, with tidally influenced wetlands showing limited effects of temperature compared with freshwater wetlands. Based on climatic projections, by 2050 wetland decay constants will increase by 1.8% for labile and 3.1% for recalcitrant OM. Our study highlights the potential for reduction in belowground OM in coastal and inland wetlands under increased warming, but the extent and direction of this effect at a large scale is dependent on ecosystem and OM characteristics. Understanding local versus global drivers is necessary to resolve ecosystem influences on carbon preservation in wetlands.