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Researchers have increasingly recognised a profound need for more information on SOC stocks in the soil and the factors governing their stability and dynamics. Many questions still remain unanswered about the interplay between changes in plant communities and the extent to which changes in aboveground productivity affect the carbon dynamics in soils through changes in its quantity and quality. Therefore, the main aim of this research was to examine the SOC accumulation potential of semi-natural grasslands of different productivities and determine the distribution of SOM fractions over varying soil depth intervals (0-10, 10-20, 20-30 30-50 50-80 and 80+cm). SOM fractionation was considered as a relative measure of stability to separate SOM associated with clay minerals from SOM of specific light densities less than 2 g cm(-3) (size-density fractionation). Two clay-associated fractions (CF1

Recently published, improved chronologies for volcanic sulfate in Greenland and Antarctic ice permit a comparison of the growth responses of absolutely annually dated tree rings at three locations in Siberia with annual ice-core records of volcanic eruptions centered on AD 536. For the first time for this region and period, we present unique data sets for tree-ring width, cell-wall thickness, δ13C and δ18O in cellulose. These were based on multiple samples from relict wood of larch obtained from two sites close to the northern limit of tree growth on the Taimyr Peninsula and in northeastern Yakutia, and at a high-elevation, location 20° further South in the Altai Mts. An event in AD 536 was associated with different, but marked, changes in tree-ring parameters at the high-latitude sites compared with the high elevation site. An AD 541 event was associated with its own distinctive tree-ring responses across the three sites and multiple variables. The years after AD 532 were marked by a strong and sustained decrease in growth at the high-elevation, more southerly, site. The combination of improved ice-core chronology for the climatically effective volcanic eruptions of this part of the 6th century AD, and an array of tree-ring sites with different climates and multiple tree-ring variables permits a richer description of tree responses to this cluster of events. The pattern of tree-ring parameter responses at the three locations in AD 536, AD 541, and perhaps AD 532 is consistent with responses to climatically effective volcanic eruptions influencing tree response in those and subsequent years.

The 7 m thick sediment profile at Plinz in northern Thuringia (central Germany) covering the time span between 10,000 and at least 8000 14C years BP (about 11,600–9000 cal BP) was studied using radiocarbon, stable isotopes and pollen analysis. The results reflect the very fast climatic transition from the Late Glacial to the Holocene as a change from cold and dry to warmer and wetter conditions. A short climatic deterioration during the Preboreal oscillation (PBO) at around 9800 14C years BP is clearly reflected by a sharp drop in the Pinus concentration accompanied by a considerable increase in Betula, Salix, various herbs and the distinct occurrence of aquatic plants. During the Preboreal stable isotopes of biogenic carbonate show several episodes with altered levels of atmospheric moisture. Continuous climatic improvement without any oscillations can be suggested for the period covering the end of Preboreal and the Boreal.

α-Cellulose was isolated from four samples of Scots pine (Pinus sylvestris L.). Each sample was divided into two portions. One portion had the resins removed by solvent extraction prior to removal of lignins by treatment with acidic sodium chlorite solution and treatment with sodium hydroxide solution to remove hemicelluloses. The other portion was processed in the same way apart from the solvent extraction step. The isolated wood constituents were characterised by attenuated total reflectance Fourier transform infrared (ATR/FT-IR) spectroscopy. The infrared spectra of the resulting α-cellulose samples were identical indicating that treatment with acidic sodium chlorite and sodium hydroxide was sufficient to remove resins. The values of the stable isotope ratios (carbon, oxygen and hydrogen) for each pair of α-cellulose sub-samples also showed no significant differences within the reproducibility of the methods. The implication of these studies demonstrate that the customary step of resin extraction from pine is unnecessary if sodium chlorite and sodium hydroxide are used for the isolation of α-cellulose following the technique described in this paper. In addition, the study demonstrates that the oxygen isotope ratio of the water used for cellulose extraction does not influence the stable isotope values in the α-cellulose obtained. The importance of isotopic homogeneity within the cellulose sample is also highlighted.

Combined investigations of ostracod communities, pollen, and stable isotopes were carried out on Lateglacial limnic high-resolution sediment sequence from Miesenheim in Germany. The pollen data confirm the presence of Meiendorf Interstadial, the first interstadial after the Pleniglacial. The former shallow lake was formed at the end of the Pleniglacial and partly dried out between the Bolling and the Allerod. Lake Laach tephra (12,880 warve yr BP) marks the top of this profile. The intensive colonization with ostracods at the beginning of the Meiendorf Interstadial is characterized by great instability of their populations. Only ostracods from the upper littoral zones of lakes, ponds or temporary pools were found. The stable isotope data (δ18O, δ13C) of the valves of the Cypridopsis vidua, Herpetocypris reptans, and Candona candida reflect the different microhabitats of these three species and show a general climatic development during the Meiendorf Interstadial with two summer temperature peaks, one at the beginning and a weaker one in the second half of the Meiendorf Interstadial.

Data obtained from the low-elevation Khibiny Mountains (ca. 67–68jN; 33–34jE) on the Kola Peninsula, northwest Russia, indicate a period of exceptionally warm and dry conditions commenced at ca. AD 600 and was most pronounced between ca. AD 1000 and 1200. Warmer summer temperatures during this period (coeval with the ‘Medieval Warm Period’ observed in other parts of Europe) are evident in a 100–140 m upward shift in the pine (Pinus sylvestris L.) limit in the Khibiny Mountains. On average, the cellulose of pine trees that grew between ca. AD 1000 and 1300 is enriched by y 13 C values of around 1xcompared to the modern trees from the region, further suggesting warmer summer climate than at present. The Medieval Warm Period was also accompanied by a steady decline in avalanche activity and the resulting formation of soils on the current avalanche cones in the Khibiny Mountains, suggesting lower winter precipitation and thinner snow cover. Lower precipitation is also evident by currently submerged tree stumps dating to the medieval period that indicate lower lake levels on the Kola Peninsula. In the middle of the peninsula at about AD 1000, the level of small closed-basin lakes was f1 m lower than the modern time at some sites. Drier conditions may be attributable to decreased cyclonic activity. The medieval warm and dry episode was followed at ca. AD 1300 by the development of a colder climate with increased precipitation resulting in a decline in the alpine pine limits, increased avalanche activity, and higher lake levels. That phase corresponds to the modern aeolian episode reconstructed in subarctic Finland. Our results indicate that the Medieval Warm Period on the Kola Peninsula