Models to predict the start of the airborne pollen season.

Aerobiological data can be used as indirect but reliable measures of flowering phenology to analyze the response of plant species to ongoing climate changes. The aims of this study are to evaluate the performance of several phenological models for predicting the pollen start of season (PSS) in seven spring-flowering trees (Alnus glutinosa, Acer negundo, Carpinus betulus, Platanus occidentalis, Juglans nigra, Alnus viridis, and Castanea sativa) and in two summer-flowering herbaceous species (Artemisia vulgaris and Ambrosia artemisiifolia) by using a 26-year aerobiological data set collected in Turin (Northern Italy). Data showed a reduced interannual variability of the PSS in the summer-flowering species compared to the spring-flowering ones. Spring warming models with photoperiod limitation performed best for the greater majority of the studied species, while chilling class models were selected only for the early spring flowering species. For Ambrosia and Artemisia, spring warming models were also selected as the best models, indicating that temperature sums are positively related to flowering. However, the poor variance explained by the models suggests that further analyses have to be carried out in order to develop better models for predicting the PSS in these two species. Modeling the pollen season start on a very wide data set provided a new opportunity to highlight the limits of models in elucidating the environmental factors driving the pollen season start when some factors are always fulfilled, as chilling or photoperiod or when the variance is very poor and is not explained by the models.

Multiproxy study of 7500-year-old wooden sickles from the Lakeshore Village of La Marmotta, Italy.

The lakeshore site of La Marmotta is one of the most important Early Neolithic sites of Mediterranean Europe. The site is famous for the exceptional preservation of organic materials, including numerous wooden artefacts related to navigation, agriculture, textile production, and basketry. This article presents interdisciplinary research on three of the most complete and well-preserved sickles recovered from the site, yet unpublished. All the components of the tools are analysed: the stone inserts, the wooden haft and the adhesive substances used to fix the stones inside the haft. Our innovative methodology combines use-wear and microtexture analysis of stone tools through confocal microscopy, taxonomical and technological analysis of wood, gas chromatography-mass spectrometry analysis of the adhesive substances, and pollen, non-pollen palynomorphs, and phytolith analysis of the remains incorporated within the adhesive. This multiproxy approach provides a significant insight into the life of these tools, from their production to their use and abandonment, providing evidence of the species of harvested plants and the conditions of the field during the harvesting.

An experience of data quality evaluation in pollen monitoring activities.

In this work we report the results of some quality control tests performed on laboratory procedures referring to aerobiological monitoring activities between 2005 and 2007. In every test, the results of each operator have been compared with the scores of a group of experts. For quality evaluation, we have used accuracy and precision to define the percentage error for identification of taxa and counts of pollen grains. Cohen's K has been estimated for the analysis of reliability. This work suggests a method to set up an intercalibration test for airborne pollen monitoring and to introduce the suitableness of measurement quality objectives (MQOs). The results show the important role of operators' training and the need for standards in pollen monitoring quality evaluation.

[Role of man in the history of vegetation of the Ellero valley (maritime Alps, Italy)]. / Rôle de l'homme dans l'histoire de la végétation de la vallée Ellero (Alpes maritimes, Italie).

The pollen analysis of a sediment core from a peat bog (Rifugio Mondovi) at the mountain belt (1760 m) in the Ellero Valley (Italian Maritime Alps) shows the postglacial vegetation history. The sequence starts at 12,000 BP during a peak of pine pollen; this first phase shows a low representation of birch and the presence of Tilia. Younger Dryas is characterised by increasing percentages of Artemisia, showing the presence of deciduous Quercus, fir and beech. Elm appears at the beginning of the Holocene during the second pine peak (9800 BP). A 3000-year hiatus is present. Sedimentation resumes at 6000 BP in a Rhododendron fir-wood. The present timberline at 1500 m, at the limit of the beech wood, is a result of the decline of the fir-wood at 2600 BP, which allowed an expansion of beech. During this period, there was a continual increase in Gramineae and deciduous oak and the first occurrences of evergreen oak are observed. The development of larch occurs at 1800 BP, together with walnut, chestnut, cereals and vine.

Elevation-induced variations of pollen assemblages in the North-western Alps: An analysis of their value as temperature indicators.

Seventy-seven modern pollen samples from various elevations (350-2680 m a.s.l.) in two different areas of the north-western Alps (the Aosta Valley, Italy and the Taillefer Massif, France) were statistically analyzed to derive correlations between pollen assemblages, elevation and temperature at the sampled points. Numerical classifications were performed on pollen data to judge similarities between the two areas. The results show that a strong relationship exists between altitude and variations in pollen taxa percentages despite some floristic differences between the two areas. As a test, transfer functions from pollen percentages to elevation and temperature were calculated from pollen data. The reconstruction appears to be reliable, with a higher reliability at sites located over 1000m. This analysis aims to serve as a basis for further quantitative reconstruction of temperature changes during the Holocene based on fossil pollen data from sensitive regions that encompass a significant altitudinal gradient.