Climate-pollen relationships AD 1901-1996 in two small mires near the forest limit in the northern and central Swiss Alps

Climatic relationships were established in two 210Pb dated pollen sequences from small mires closely surrounded by forest just below actual forest limits (but about 300 m below potential climatic forest limits) in the northern Swiss Alps (suboceanic in climate; mainly with Picea) and the central Swiss Alps (subcontinental; mainly Pinus cembra and Larix) at annual or near-annual resolution from ad 1901 to 1996. Effects of vegetational succession were removed by splitting the time series into early and late periods and by linear detrending. Both pollen concentrations detrended by the depth-age model and modified percentages (in which counts of dominant pollen types are down-weighted) are correlated by simple linear regression with smoothed climatic parameters with one-and two-year timelags, including average monthly and April/September daylight air temperatures and with seasonal and annual precipitation sums. Results from detrended pollen concentrations suggest that peat accumulation is favoured in the northern-Alpine mire either by early snowmelt or by summer precipitation, but in the central-Alpine mire by increased precipitation and cooler summers, suggesting a position of the northern-Alpine mire near the upper altitudinal limit of peat formation, but of the central-Alpine mire near the lower limit. Results from modified pollen percentages indicate that pollen pro duction by plants growing near their upper altitudinal limit is limited by insufficient warmth in summer, and pollen production by plants growing near their lower altitudinal limit is limited by too-high temperatures. Only weakly significant pollen/climate relationships were found for Pinus cembra and Larix, probably because they experience little climatic stress growing 300 m below the potential climatic forest limit.

Ein unerwünschtes Bild? Zur ältesten Porträtfotografie aus Skandinavien (1840)

Die nach heutiger Kenntnis erste Porträtfotografie, die in Skandinavien entstanden ist, stammt von dem französischen Unternehmer Aymard-Charles-Théodore Neubourg (1795–um 1865/1866) und zeigt den dänischen Bildhauer Bertel Thorvaldsen (1770–1844). Trotz der damals neuen Technik der Daguerreotypie und des prominenten Modells sollte es über ein halbes Jahrhundert dauern, bis die kleine Silberplatte von dem 1848 eröffneten Thorvaldsen Museum in Kopenhagen erworben wurde. Der vorliegende Beitrag fragt nach den Gründen für die bescheidene Rezeption dieses Bildes, das einen unbestreitbar wichtigen Stellenwert in der Geschichte des neuen Mediums einnimmt. Für die Thorvaldsen-Forschung ist diese Daguerreotypie besonders interessant, da sie als fotografisches Bild – im Gegensatz zu den auf Statusrepräsentation bedachten Darstellungen in Gemälden und Plastiken – einen anderen Entwurf vom Aussehen des Künstlers überliefert.