Spatio-temporal growth dynamics of a subAlpine Pinus uncinata stand in the French Alps

Natural forests are characterised by a high level of both spatial and temporal heterogeneity. The major processes involved in the creation and maintenance of forest heterogeneity in temperate climates are small-sized canopy disturbances. The resulting openings also modify the growth conditions for the remaining trees. The analysis of tree growth responses using dendrochronological techniques allows the reconstruction of the time sequence of the disturbances. The radial growth analysis is coupled here with both a spatial analysis and a demographic analysis of the forest structure. The age classes are temporally organised in cohorts and spatially distributed in spatial aggregates. The analysis of the most documented disturbance event allowed us to determine the size of the disturbance response patch (between 0.036 and 0.073 ha) and the duration of the disturbance (six years). We considered that this small-scale disturbance event may have been caused by the fall of a single tree and has freed the surrounding trees of its competition.     

Fire and Pinus mugo Turra communities in the western Alps (Susa Valley, Italy) during the Lateglacial-Holocene transition: an evidence of refugia area

In western Italian Alps, small distinct populations of Pinus mugo Turra raise some questions concerning its ecological status and dynamics in the occidental Alps. This note present new palaeobotanical data based on cone imprints of Pinus mugo, identified in travertine systems located in the Val di Susa and dated back to the Late Dryas (11506+/-66 BP) and the Early Holocene (10145+/-225 et 9475+/-670 BP). Heliophilous species and charcoal fragments were also identified, testifying to the oldness of wildfires in this region. The data support the hypothesis that this zone was a refuge area of this pine during the last glaciation. Here we discuss about the postglacial dynamics of the Pinus mugo in the occidental Alps.     

Quantitative studies of some Jurassic belemnite assemblages

Belemnite deposits were studied in the Jurassic of Britain and the Bathonian-Callovian of the Aar Massif. Special attention was given to a Middle Callovian Belemnopsis concentration at Brora in Sutherland. Studies of guard size, ontogeny, abundance and orientation suggest that these Belemnopsis had seasonal fluctuations in growth, a low mortality rate compared to living coleoids and were probably deposited in local concentrations, by hybodont sharks. Cylindroteuthis abundance is a better guide to the sedimentation rate, than Belemnopsis.     

Le bassin lacustre miocène de Bes-Konak (anatolie-turquie): Géologie et introduction a la paléontologie des vertébrés

The tertiary lacustrine and marshy facies ofBes-Konak (Ankara-district) has provided a rich fauna of Vertebrates preserved as molds and casts in Diatomites and volcano-sedimentary beds.In this assemblage are: Cyprinid fishes (Leuciscus(P.) etiliusRückert Ulkümen) with among them a new species of Barbus, some Amphibians both Urodela (mature Triturinae) and Anura (larval forms of Pelobates sp. and mature Rana sp.), a Turtle (Chelydridae-Chelydropsis sp.) a Snake (Colubroïde-Colubridae or Viperidae) and Birds (among them a new species of cormorant).According to the others various data resulting from palaebotanical, palynological and structural investigations, this fauna is clearly suggestive of a lower or middle Miocene deposit. It supports readily the climatic features (local sub-tropical microclimate inside a regional hot-temperate context) as invertebrates, macro and microflora and sedimentology had already shown.Once more, it points out the peculiar trophic type of the limnic area of Bes-Konak and its evolution to a well-marked eutrophic condition.     

Les faunes d’ammonites du Pliensbachien inférieur des séries dauphinoises de la Durance (Jurassique inférieur, Barrage de Serre-Ponçon, Hautes-Alpes, France)

The Liassic ammonite faunas and especially those of the Early Pliensbachian are of major importance for the understanding of the stratigraphic framework of the “Dauphiné” zone of the southern subalpine ranges (“dôme de Remollon”). Until now, only listed by the authors, these faunas are, for the first time, described and illustrated in the present paper. With about twenty species, these faunas cover the whole of the Early Pliensbachian. There are poorly diversified and of clearly Euroboreal affinities. Nearly all of the species are abundant and common in most of the NW European fossiliferous localities. Despite of a paleogeographical location fairly close to the Alpine zones (Southern Alps and Austroalpine units) with rather diversified faunas of mainly Mediterranean affinities, none Mediterranean taxa are present in the studied area. Unfortunately, the current stratigraphic and paleogeographic knowledge do not allow to ascertain if this reflects a separation due to paleoenvironmental or true paleogeographic barriers. In this latter case, the general geologic implications would be remarkable.     

Indices de fréquentation humaine dans les grottes à ours au Paléolithique moyen final: L’exemple de la Caverna Generosa dans les Préalpes lombardes, Italie

Already known like a palaeontological site for the study of Ursus spelaeus, Caverna Generosa also records ephemeral traces of human visits during the late Middle Palaeolithic. The cave opens at an altitude of 1450 m on the steep southern slope of the Monte Generoso Massif between the Lugano and the Como lakes and forms a complex group of narrow galleries and inner chambers. Sedimentological and palaeontological data and radiocarbon dates place both the cave-bear and the human frequentations in the first part of the isotopic stage 3 with climatic conditions shifting from cool and dry to more temperate and wet. Environment progressively changed from scarcely arboreal to arboreal-brush with small open spaces. Few flakes and Levallois flakes have been recovered scattered in the sediment and affected in most cases by intense postdepositional alteration. These items testify incursions of mousterian groups equipped with end-products and radiolarite flakes struck from blocks provisioned at lower locations southwards. End-products, namely Levallois flakes, prove that lithic reduction sequences were spatiotemporally fractionated in the covered territory. Conversely, it cannot be excluded a priori that sublocal radiolarite has been chipped at the entrance of the cave or at the very close surroundings for extraction of rudimental tools for immediate use. It is worth to mention that the small chert slabs in the Moltrasio limestone which crop throughout the cave walls were totally ignored. Caverna Generosa can be viewed as a refugia-location used in function of more or less constrained factors strongly influenced by high-altitude and bioclimatic situations. This type of site might well be integrated within the seasonal movements of humans in the western Lombard Pre-Alps area.     

Avian fossil assemblages at the onset of the LGM in the eastern Alps: A palaecological contribution from the Rio Secco Cave (Italy)

The avian fossil assemblages from the late Pleistocene deposits of the Rio Secco Cave (north-eastern Italy) is presented herein. We studied the layers that date back to the end of MIS3 and the beginning of MIS2, which also contain evidence of Gravettian frequentation dated to 33.5–30 ka cal BP. The systematic analysis revealed the presence of 18 species and other supraspecific taxa that supported palaeoenvironmental reconstructions. Taxa indicate that, at the onset of LGM, site surroundings were characterised by conifer or mixed forests, open grasslands, slow-flowing water bodies and mountain meadows with rocky outcrops, as indicated by Lagopus muta. Today, this environment is found above the tree line (beyond 1500–2000 m) and cannot be detected near the site, located at 580 m asl. Noteworthy, is also the finding of the second Italian late Pleistocene fossil record of Picus canus.