The use of cotton blue stain to improve the efficiency of picking and identifying chironomid head capsules

Cotton blue was added to sediment samples at least 2h before chironomid head capsules were picked under a binocular microscope and mounted on slides for identification. The use of stain greatly increased the visibility of chironomid head capsules during picking and enhanced the contrast of various parts of the head capsules (pores, ventromental plates, striations on ventromental plates), which could aid identification. In the seven samples studied, there was no significant difference between the percentages of taxa found in stained and unstained samples. The number of taxa were also similar in stained and unstained samples. This method allowed samples to be picked faste

Annual pollen traps reveal the complexity of climatic control on pollen productivity in Europe and the Caucasus

Annual PAR (pollen accumulation rates; grains cm−2year−1) were studied with modified Tauber traps situated in ten regions, in Poland (Roztocze), the Czech Republic (two regions in Krkonoše, two in Šumava), Switzerland (4 regions in the Alps), and Georgia (Lagodekhi). The time-series are 10-16years long, all ending in 2007. We calculated correlations between pollen data and climate. Pollen data are PAR summarized per region (4-7 traps selected per region) for each pollen type (9-14 per region) using log-transformed, detrended medians. Climate data are monthly temperature and precipitation measured at nearby stations, and their averages over all possible 2- to 6-month windows falling within the 20-month window ending with August, just prior to the yearly pollen-trap collection. Most PAR/climate relationships were found to differ both among pollen types and among regions, the latter probably due to differences among the study regions in the habitats of plant populations. Results shared by a number of regions can be summarized as follows. Summer warmth was found to enhance the following year's PAR of Picea, Pinus non-cembra, Larix and Fagus. Cool summers, in contrast, increase the PAR of Abies, Alnus viridis and Gramineae in the following year, while wet summers promote PAR of Quercus and Gramineae. Wetness and warmth in general were found to enhance PAR of Salix. Precipitation was found to be more important for PAR of Alnus glutinosa-type than temperature. Weather did not have an impact on the PAR of Gramineae, and possibly of Cyperaceae in the same year. Care is advised when extrapolating our results to PAR in pollen sequences, because there are large errors associated with PAR from sediments, due to the effects of taphonomy and sedimentation and high uncertainty in dating. In addition, in pollen sequences that have decadal to centennial rather than near-annual resolution, plant-interaction effects may easily out-weigh the weather signa

Indications from the wooden support and from the other organic materials of the Pace di Chiavenna

In the present research Archaeobotany has been applied to the study of some organic materials of Pace di Chiavenna, that are the wooden plate, the wooden cross beneath the central golden cross and the beeswax compound beneath one enamel. The palaeobotanical analyses of the wooden elements could not clarify the geographical origin of the cross, probably black alder wood, while a subalpine or Mediterranean origin seems plausible for the walnut plate. The species found in pollen preserved in the beeswax currently have a very wide altitudinal distribution, extending from the hill to the mountain belt. All the species found were widespread during the Middle Ages in almost all of Western Europe, so it is not possible to identify or completely exclude a specific region in which the wax could have been produced. However, it seems more likely that the area of origin is Northern Italy and in particular a territory near the Pre-Alps. The palynological evidence indicates a strongly anthropized environment, that probably surrounded a city or a large inhabited center

Lateglacial environmental and climatic changes at the Maloja Pass, Central Swiss Alps, as recorded by chironomids and pollen

Chironomids and pollen were studied in a radiocarbon-dated sediment sequence obtained from a former lake near the Maloja Pass in the Central Swiss Alps (1865 m a.s.l.) to reconstruct the Lateglacial environment. Pollen assemblages imply a vegetation development around the Maloja Pass from shrub tundra at the beginning of the Allerod to coniferous forest during the early Holocene with a lowering of the timberline during the Younger Dryas. Chironomid assemblages are characterized by several abrupt shifts in dominant taxa through the Lateglacial. The occurrence of taxa able to survive hypoxia in the second part of the Allerod and during the Preboreal, and their disappearance at the onset of the Younger Dryas cold phase suggest summer thermal stratification and unfavourable hypolimnetic oxygen conditions in the palaeo-lake during the warmer periods of the Lateglacial interstadial and early Holocene. Mean July air temperatures were reconstructed using a chironomid-temperature transfer function from the Alpine region. The pattern of reconstructed temperature changes agrees well with the Greenland delta O-18 record and other Lateglacial temperature inferences from Central Europe. The inferred July temperatures of ca 10.0 degrees C during most of the Allerod were slightly lower than modern values (10.8 degrees C) and increased up to ca 11.7 degrees C (i.e., above present-day values) at the end of the Allerod. The first part of the Younger Dryas was colder (ca 8.8 degrees C) than the second part (ca 9.8 degrees C). During most of the Preboreal, the temperatures persisted within the limits of 13.5-14.5 degrees C (i.e., ca 3 degrees C above present-day values). The amplitudes of temperature changes at the Allerod-Younger Dryas-Preboreal transitions were ca 3.5-4.0 degrees C. The temperature reconstruction also shows three short-lived cooling events of ca 1.5-2.0 degrees C, which may be attributed to the centennial-scale Greenland Interstadial events GI-1d and GI-1b, and the Preboreal Oscillation