Age control and stratigraphy of a sediment profile from the Lomonosov Ridge, Arctic Ocean

The upper 200 m of the sediments recovered during IODP Leg 302, the Arctic Coring Expedition (ACEX), to the Lomonosov Ridge in the central Arctic Ocean consist almost exclusively of detrital material. The scarcity of biostratigraphic markers severely complicates the establishment of a reliable chronostratigraphic framework for these sediments, which contain the first continuous record of the Neogene environmental and climatic evolution of the Arctic region. Here we present profiles of cosmogenic 10Be together with the seawater-derived fraction of stable 9Be obtained from the ACEX cores. The down-core decrease of 10Be/9Be provides an average sedimentation rate of 14.5 ± 1 m/Ma for the uppermost 151 m of the ACEX record and allows the establishment of a chronostratigraphy for the past 12.3 Ma. The age-corrected 10Be concentrations and 10Be/9Be ratios suggest the existence of an essentially continuous sea ice cover over the past 12.3 Ma.

(Table 1) Species richness and diversity of tundra plants in herbivore exclosure and control plots near Barrow, Alaska

To determine the role lemmings play in structuring plant communities and their contribution to the 'greening of the Arctic', we measured plant cover and biomass in 50 + year old lemming exclosures and control plots in the coastal tundra near Barrow, Alaska. The response of plant functional types to herbivore exclusion varied among land cover types. In general, the abundance of lichens and bryophytes increased with the exclusion of lemmings, whereas graminoids decreased, although the magnitude of these responses varied among land cover types. These results suggest that sustained lemming activity promotes a higher biomass of vascular plant functional types than would be expected without their presence and highlights the importance of considering herbivory when interpreting patterns of greening in the Arctic. In light of the rapid environmental change ongoing in the Arctic and the potential regional to global implications of this change, further exploration regarding the long-term influence of arvicoline rodents on ecosystem function (e.g. carbon and energy balance) should be considered a research priority.

Chronostratigraphic framework at sites GeoB14403 and GeoB14414 from the Gela Basin, Sicily Channel

A multi-proxy chronological framework along with sequence-stratigraphic interpretations unveils composite Milankovitch cyclicity in the sedimentary records of the Last GlacialeInterglacial cycle at NE Gela Basin on the Sicilian continental margin. Chronostratigraphic data (including foraminifera-based eco-biostratigraphy and d18O records, tephrochronological markers and 14C AMS radiometric datings) was derived from the shallow-shelf drill sites GeoB14403 (54.6 m recovery) and GeoB14414 (27.5 m), collected with both gravity and drilled MeBo cores in 193 m and 146 m water depth, respectively. The recovered intervals record Marine Isotope Stages and Substages (MIS) from MIS 5 to MIS 1, thus comprising major stratigraphic parts of the progradational deposits that form the last 100-ka depositional sequence. Calibration of shelf sedimentary units with borehole stratigraphies indicates the impact of higher-frequency (20-ka) sea level cycles punctuating this 100-ka cycle. This becomes most evident in the alternation of thick interstadial highstand (HST) wedges and thinner glacial forced-regression (FSST) units mirroring seaward shifts in coastal progradation. Albeit their relatively short-lived depositional phase, these subordinate HST units form the bulk of the 100-ka depositional sequence. Two mechanisms are proposed that likely account for enhanced sediment accumulation ratios (SAR) of up to 200 cm/ka during these intervals: (1) intensified activity of deep and intermediate Levantine Intermediate Water (LIW) associated to the drowning of Mediterranean shelves, and (2) amplified sediment flux along the flooded shelf in response to hyperpycnal plumes that generate through extreme precipitation events during overall arid conditions. Equally, the latter mechanism is thought to be at the origin of undulated features resolved in the acoustic records of MIS 5 Interstadials, which bear a striking resemblance to modern equivalents forming on late-Holocene prodeltas of other Mediterranean shallow-shelf settings.

Climate and soil characteristics and soil arthropod abundance on Anchorage, Signy and Falkland Islands

Over a 2-year study, we investigated the effect of environmental change on the diversity and abundance of soil arthropod communities (Acari and Collembola) in the Maritime Antarctic and the Falkland Islands. Open Top Chambers (OTCs), as used extensively in the framework of the northern boreal International Tundra Experiment (ITEX), were used to increase the temperature in contrasting communities on three islands along a latitudinal temperature gradient, ranging from the Falkland Islands (51°S, mean annual temperature 7.5 °C) to Signy Island (60°S, -2.3°C) and Anchorage Island (67°S, -3.8°C). At each island an open and a closed plant community were studied: lichen vs. moss at the Antarctic sites, and grass vs. dwarf shrub at the Falkland Islands. The OTCs raised the soil surface temperature during most months of the year. During the summer the level of warming achieved was 1.7 °C at the Falkland Islands, 0.7 °C at Signy Island, and 1.1 °C at Anchorage Island. The native arthropod community diversity decreased with increasing latitude. In contrast with this pattern, Collembola abundance in the closed vegetation (dwarf shrub or moss) communities increased by at least an order of magnitude from the Falkland Islands (9.0 +/- 2 x 10**3 ind./m**2) to Signy (3.3 +/- 8.0 x 10**4 ind./m**2) and Anchorage Island (3.1 +/- 0.82 x 10**5 ind./m**2). The abundance of Acari did not show a latitudinal trend. Abundance and diversity of Acari and Collembola were unaffected by the warming treatment on the Falkland Islands and Anchorage Island. However, after two seasons of experimental warming, the total abundance of Collembola decreased (p < 0.05) in the lichen community on Signy Island as a result of the population decline of the isotomid Cryptopygus antarcticus. In the same lichen community there was also a decline (p < 0.05) of the mesostigmatid predatory mite Gamasellus racovitzai, and a significant increase in the total number of Prostigmata. Overall, our data suggest that the consequences of an experimental temperature increase of 1-2°C, comparable to the magnitude currently seen through recent climate change in the Antarctic Peninsula region, on soil arthropod communities in this region may not be similar for each location but is most likely to be small and initially slow to develop.

High-resolution stratigraphic framework for Mediterranean sapropel S5

A high-resolution stratigraphic framework is presented for sapropel S5, which represents the low-mid latitude climate optimum of the previous interglacial period (Eemian). The framework is based on three sites along a transect from west to east through the eastern Mediterranean, and is further validated using a fourth site. This method allows expression of S5-based proxy records of Eemian climate variability along a standardised depth scale that offers unprecedented possibilities for assessment of spatial gradients and signal leads and lags in an interval where highresolution (radiocarbon-style) dating cannot be performed. Our lateral comparison of S5 sapropels suggests that the onset of S5 in ODP site 967C (Eratosthenes seamount) was 1-6 centuries delayed relative to the onsets in more westerly sites.

Statistics of the National soil test database of France

In France, farmers commission about 250,000 soil-testing analyses per year to assist them managing soil fertility. The number and diversity of origin of the samples make these analyses an interesting and original information source regarding cultivated topsoil variability. Moreover, these analyses relate to several parameters strongly influenced by human activity (macronutrient contents, pH...), for which existing cartographic information is not very relevant. Compiling the results of these analyses into a database makes it possible to re-use these data within both a national and temporal framework. A database compilation relating to data collected over the period 1990-2009 has been recently achieved. So far, commercial soil-testing laboratories approved by the Ministry of Agriculture have provided analytical results from more than 2,000,000 samples. After the initial quality control stage, analytical results from more than 1,900,000 samples were available in the database. The anonymity of the landholders seeking soil analyses is perfectly preserved, as the only identifying information stored is the location of the nearest administrative city to the sample site. We present in this dataset a set of statistical parameters of the spatial distributions for several agronomic soil properties. These statistical parameters are calculated for 4 different nested spatial entities (administrative areas: e.g. regions, departments, counties and agricultural areas) and for 4 time periods (1990-1994, 1995-1999, 2000-2004, 2005-2009). Two kinds of agronomic soil properties are available: the firs one correspond to the quantitative variables like the organic carbon content and the second one corresponds to the qualitative variables like the texture class. For each spatial unit and temporal period, we calculated the following statistics stets: the first set is calculated for the quantitative variables and corresponds to the number of samples, the mean, the standard deviation and, the 2-,4-,10-quantiles; the second set is calculated for the qualitative variables and corresponds to the number of samples, the value of the dominant class, the number of samples of the dominant class, the second dominant class, the number of samples of the second dominant class.

(Table 1) Normalized difference vegetation index in control and warming plots, Abisco Research Station

Extreme winter warming events in the sub-Arctic have caused considerable vegetation damage due to rapid changes in temperature and loss of snow cover. The frequency of extreme weather is expected to increase due to climate change thereby increasing the potential for recurring vegetation damage in Arctic regions. Here we present data on vegetation recovery from one such natural event and multiple experimental simulations in the sub-Arctic using remote sensing, handheld passive proximal sensors and ground surveys. Normalized difference vegetation index (NDVI) recovered fast (2 years), from the 26% decline following one natural extreme winter warming event. Recovery was associated with declines in dead Empetrum nigrum (dominant dwarf shrub) from ground surveys. However, E. nigrum healthy leaf NDVI was also reduced (16%) following this winter warming event in experimental plots (both control and treatments), suggesting that non-obvious plant damage (i.e., physiological stress) had occurred in addition to the dead E. nigrum shoots that was considered responsible for the regional 26% NDVI decline. Plot and leaf level NDVI provided useful additional information that could not be obtained from vegetation surveys and regional remote sensing (MODIS) alone. The major damage of an extreme winter warming event appears to be relatively transitory. However, potential knock-on effects on higher trophic levels (e.g., rodents, reindeer, and bear) could be unpredictable and large. Repeated warming events year after year, which can be expected under winter climate warming, could result in damage that may take much longer to recover.

(Table 3) Collembola species density and diversity in control and OTC plots near Abisco Research Station

Ecosystems at high northern latitudes are subject to strong climate change. Soil processes, such as carbon and nutrient cycles, which determine the functioning of these ecosystems, are controlled by soil fauna. Thus assessing the responses of soil fauna communities to environmental change will improve the predictability of the climate change impacts on ecosystem functioning. For this purpose, trait assessment is a promising method compared to the traditional taxonomic approach, but it has not been applied earlier. In this study the response of a sub-arctic soil Collembola community to long-term (16 years) climate manipulation by open top chambers was assessed. The drought-susceptible Collembola community responded strongly to the climate manipulation, which substantially reduced soil moisture and slightly increased soil temperature. The total density of Collembola decreased by 51% and the average number of species was reduced from 14 to 12. Although community assessment showed species-specific responses, taxonomically based community indices, species diversity and evenness, were not affected. However, morphological and ecological trait assessments were more sensitive in revealing community responses. Drought-tolerant, larger-sized, epiedaphic species survived better under the climate manipulation than their counterparts, the meso-hydrophilic, smaller-sized and euedaphic species. Moreover it also explained the significant responses shown by four taxa. This study shows that trait analysis can both reveal responses in a soil fauna community to climate change and improve the understanding of the mechanisms behind them.

Bacterial production in the eastern Mediteranean Sea in October 2008 during SES_GR2

The HCMR_SES_LAGRANGIAN_GR2_ MICROBIAL PARAMETERS dataset is based on samples collected in the framework of the project SESAME, in the North Aegean Sea during October 2008. The objectives were to measure the standing stocks and calculate the production of the microbial compartment of the food web, describe the vertical distribution pattern and characterize its structure and function through the water column as influenced by the BSW. Bacterial production was estimated by the 3H-leucine method (Kirchman et al. 1986, Kirchman 1993). At each depth, duplicate samples and a control were incubated with 20 nM L-[4,5 3H]-leucine. Samples were incubated in the dark, at in situ temperature.

Soil characteristics and Collembola and Acari abundance in control and warming plots at Abisco Research Station

Extreme weather events can have negative impacts on species survival and community structure when surpassing lethal thresholds. Extreme winter warming events in the Arctic rapidly melt snow and expose ecosystems to unseasonably warm air (2-10 °C for 2-14 days), but returning to cold winter climate exposes the ecosystem to lower temperatures by the loss of insulating snow. Soil animals, which play an integral part in soil processes, may be very susceptible to such events depending on the intensity of soil warming and low temperatures following these events. We simulated week-long extreme winter warming events - using infrared heating lamps, alone or with soil warming cables - for two consecutive years in a sub-Arctic dwarf shrub heathland. Minimum temperatures were lower and freeze-thaw cycles were 2-11 times more frequent in treatment plots compared with control plots. Following the second event, Acari populations decreased by 39%; primarily driven by declines of Prostigmata (69%) and the Mesostigmatic nymphs (74%). A community-weighted vertical stratification shift occurred from smaller soil dwelling (eu-edaphic) Collembola species dominance to larger litter dwelling (hemi-edaphic) species dominance in the canopy-with-soil warming plots compared with controls. The most susceptible groups to these winter warming events were the smallest individuals (Prostigmata and eu-edaphic Collembola). This was not apparent from abundance data at the Collembola taxon level, indicating that life forms and species traits play a major role in community assembly following extreme events. The observed shift in soil community can cascade down to the micro-flora affecting plant productivity and mineralization rates. Short-term extreme weather events have the potential to shift community composition through trait composition with potentially large consequences for ecosystem development.