[1] It is commonly believed that fine-textured soils developed on carbonate parent material are well buffered from possible acidification. There are no data, however, that document resistance of such soils to acidic deposition exposure on a timescale longer than 30-40 years. In this paper, we report on directly testing the long-term buffering capacity of nineteenth century forest soils developed on calcareous silt loam. In a chemical analysis comparing archived soils with modern soils collected from the same locations $100 years later, we found varying degrees of forest-soil acidification in the taiga and forest steppe regions. Land-use history, increases in precipitation, and acidic deposition were contributing factors in acidification. The acidification of forest soil was documented through decreases in soil pH and changes in concentrations of exchangeable calcium and aluminum, which corresponded with changes in communities of soil microfauna. Although acidification was found at all three analyzed locations, the trends in soil chemistry were most pronounced where the highest loading of acidic deposition had taken place.

The Kamchatka Peninsula in the far east of Russia is a substantial landmass that is poorly documented in terms of most elements of biodiversity. Here we provide the first study of modern assemblages of testate amoebae, awidespread group of protists that are particularly abundant in soils. We present a data set of 78 widely distributed samples, including forest, fen, scrub and bog habitats. Testate amoebae are abundant and diverse across Kamchatka with 119 taxa identified. The assemblage is primarily composed of widespread taxa, but rarer occurrences such as Cyclopyxis puteus hint at important biogeographical differences that will require confirmation with molecular data. Assemblages from mineral soils are significantly different from those of peatlands with the former characterized by small idiosome taxa and the latter by larger taxa, often with secretion tests. Water table depth explained significant variance in the peatland samples, supporting the use of testate amoebae in palaeoecological studies. This study adds to our knowledge of the biodiversity of Kamchatka and the global biogeography of protists, and it paves the way for palaeoecological studies to understand long-term environmental change in this region.

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Russian-German project PLOT (Paleolimnological Transect) aims at investigating the regional responses of the quaternary climate and environment on external forcing and feedback mechanisms along a more than 6000 km long longitudinal transect crossing Northern Eurasia. The well-dated record from Lake El´gygytgyn used as reference site for comparison the local climatic and environmental histories. Seismic surveys and sediment coring up to 54 m below lake floor performed in the frame of the