A catalog of high-impact windstorms in Switzerland since 1859

In recent decades, extremely hazardous windstorms have caused enormous losses to buildings, infrastructure and forests in Switzerland. This has increased societal and scientific interest in the intensity and frequency of historical high-impact storms. However, high-resolution wind data and damage statistics mostly span recent decades only. For this study, we collected quantitative (e.g., volumes of windfall timber, losses relating to buildings) and descriptive (e.g., forestry or insurance reports) information on the impact of historical windstorms. To define windstorm severity, normalized and declustered quantitative data were processed by extreme value statistics. Descriptive information was classified using a conceptual guideline. Validation with independent damage information, as well as comparison with wind measurements and a reanalysis, indicates that the most hazardous winter storms are captured, while too few moderate windstorms are detected. Strong storms in the wind measurements and reanalysis are thus added to the catalog. The final catalog encompasses approximately 240 high-impact windstorms in Switzerland since 1859. It features three robust severity classes and contains eight extreme windstorms. Evidence of high winter storm activity in the early and late 20th century compared to the mid-20th century in both damage and wind data indicates a co-variability of hazard and related damage on decadal timescales.

Biographien und Netzwerke im Kaffeehandel zwischen Deutschland und Zentralamerika, 1920-1959

Kaffee ist nicht nur ein beliebtes Getränk, sondern vernetzte auch unterschiedliche Welten: Der Kaffeehandel band Hamburg und Bremen in transnationale Netzwerke ein, die sich zwischen Europa und Lateinamerika erstreckten. Zentralamerika war für den globalen Kaffeehandel wichtig, weil die Region als erste die „nasse“ Form der Aufbereitung einführte. Die hohe Qualität dieser „gewaschenen“ Kaffees machte sie auf dem Weltmarkt begehrt. Deutsche Einwanderer prägten die Handelsverbindungen zwischen den zentralamerikanischen Kaffee-Anbauregionen und den norddeutschen Hafenstädten: Sie gründeten Exportfirmen, erwarben Kaffeeplantagen und beteiligten sich an der Vorfinanzierung der Ernten. Christiane Berth analysiert Biografien und Netzwerke deutscher Kaffee-Akteure in Guatemala, Costa Rica und Chiapas. Dabei zeigt sie, wie deren Handelsnetzwerke durch wirtschaftliche Krisen und neue außenpolitische Konstellationen brüchig wurden, im Nationalsozialismus unter Druck gerieten und während des Zweiten Weltkrieges zerbrachen. Trotzdem blieben auch in der Nachkriegszeit Handelsbeziehungen zwischen Nationalstaaten, Netzwerke in der Kaffeebranche und Biografien der Kaffee-Akteure eng miteinander verknüpft.

Pollen and charcoal in lake sediments compared with historically documented forest fires in southern Switzerland since AD 1920

Charcoal in unlaminated sediments dated by 210Pb was analysed by the pollen-slide and thin-section methods. The results were compared with the number and area of forest fires on different spatial scales in the area around Lago di Origlio as listed in the wildfire database of southern Switzerland since AD 1920. The influx of the number of charcoal particles > 75 µm2 in pollen slides correlates well with the number of annual forest fires recorded within a distance of 20-50 km from the coring site. Hence a size-class distinction or an area measurement by image analysis may not be absolutely necessary for the reconstruction of regional fire history. A regression equation was computed and tested against an independent data set. Its use makes it possible to estimate the charcoal area influx (or concentration) from the particle number influx (or concentration). Local fires within a radius of 2 km around the coring site correlate well with the area influx of charcoal particles estimated by the thin-section method measuring the area of charcoal particles larger than 20 000 µm2 or longer than 50 µm. Pollen percentages and influx values suggest that intensive agriculture and Castanea sativa cultivation were reduced 30-40 years ago, followed by an increase of forest area and a development to more natural woodlands. The traditional Castanea sativa cultivation was characterized by a complete use of the biomass produced, so abandonment of chestnut led to an increasing accumulation of dead biomass, thereby raising the fire risk. On the other hand, the pollen record of the regional vegetation does not show any clear response to the increase of fire frequency during the last three decades in this area.