We present the results of multiproxy study of a peat deposit from Carlisle Island (the Islands of Four Mountains, Aleutians). Vegetation on the initial stage of the peat is characterized by heath vegetation dominated by Ericales indicating cold conditions at 7300–6100 cal yr BP. The appearance of Betula and Alnus is the result of long-distance transportation attributable to strong winds at this time. Sedge-grass (Cyperaceae and Poaceae) communities began replacing heath vegetation at 6100 cal yr BP because of the climatic amelioration. C/N ratios and pollen spectra remain relatively stable at 6100–2450 cal yr BP. For the CR-03 peatland, volcanic tephra contributed significantly to the Fourier transform infrared spectroscopy spectral data. Volcanic input created overlap of an aluminosilicate signal with carbohydrate vibrations. Significant changes occurred at approximately 2450 cal yr BP when there is the some evidence of cooler and wetter conditions of the Neoglacial. High values of δ15N observed at 7100–7000 cal yr BP reflect the fertilizing effect of seabird nesting colonies. A decrease in δ15N ca. 6900 cal yr BP may indicate initial settlement on Carlisle Island corresponding with harvesting seabirds. Human predation continued until a series of volcanic eruptions, which deposited Okmok II and CR-02 tephra layers at ca. 2000 and 1050 cal yr BP, respectively.

there are a lot of other drivers as well as altitude, area and geological age of islands, soils, oceanic flows, isolation, volcanic activity,

Abstract— The vegetation history of the Alсan Creek peat deposit on Shemya Island (the Near Islands of the Aleutian Arc) has been reconstructed. We chose this flat island because there are no volcanoes on it and they have less impact on the vegetation. The sedge tundra dominated until 7000 years ago. Then it was replaced by mire with a noticeable participation of Sphagnum and Equisetum during the Holocene warming maximum 7000–5000 years ago. Forb sedge-grass meadows spread about 4700 years ago as a result of a local change in humidity. As a consequence of cooling and leaching processes, heather tundra began to dominate in the inner part of the island about 3400 years ago.

Reference sections of friable sediments in central Kamchatka are studied and their present-day state is described. Previous concepts of the Middle Pleistocene age of these sediments are critically examined. Radiocarbon dates performed in the 1980s‒1990s by researchers at the Geological Institute, Russian Academy of Sciences, are revised. It is shown that some (oldest) part of dates did not pass the quality check. Results of the new (2016‒2017) radiocarbon dating agree well with the data accomplished previously and supported later by revision. Based on the combined databank with 65 determinations of different species of the buried organic material and mammal bones, the Late Pleistocene age of sediments is suggested. A new interpretation is proposed for the formation setting of some sequences in the studied sections.

A diatom analysis of a peat deposit from Shemya Island (Aleutian Arc, USA) is performed, and the dynamics of the diatom community are described. According to the radiocarbon dating, the formation of the deposit began 9300 cal. years BP. Principal component analysis made it possible to relate the dynamics of the diatom community to certain environmental conditions and the factors that influenced the coastal ecosystems during its formation. The following factors (predictors) were considered: the influence of age, zoo- and anthropogenic effects, and changes in climatic conditions. Sea level change was the main driver of the diatom community in the studied water body having a continuous direct and indirect influence on the studied small water body, i.e., by bird colony formation and more humid and coastal conditions. Since 3000–2000 cal. years BP, the anthropogenic factor (hunting depression of the bird colony) also became significant. During the whole water body lifetime and following peat formation, the diatom community was influenced by groups of factors: global factors (e.g., sea level rise) caused gradual change of local factors, which resulted in smooth shifts in community. In contrast, local factor influence (bird colony rise and fall due to human activity) caused abrupt and transient shifts. We can hypothesize that the relatively stable global environmental conditions in the Late Holocene were an auspicious background to see abrupt changes due to influence of the zoogenic and anthropogenic factors. We believe that further works on the material from other islands will make it possible to form a general picture of changes in the diatom communities in the Holocene and interpret it in connection with climatic changes in the region.