BAUHINIA – Zeitschrift der Basler Botanischen Gesellschaft

Holozäne Vegetationsentwicklung im hinteren Klostertal (Vorarlberg, Österreich) und Hinweise zur prähistorischen Landwirtschaft auf Grund palynologischer Untersuchungen

Conradin A. Burga — 2025-03-17

Holocene vegetation development in the Hinteren Klostertal (Vorarlberg, Austria) and evidence for prehistoric agriculture based on palynological investigations. The subalpine peat bog located above the village of Stuben at the Arlberg pass road (Vorarlberg, Austria, 1630 m a.s.l.) consists of Late-glacial and Holocene peat beds of the last 12 300 years. Samples of a cross-section of the peat bog were analysed palynologically. They give information to the local and regional flora and vegetation history of the western Arlberg pass and the adjacent Klostertal area, including first human impact on the natural environment. The palynological diagram shows the Holocene immigration and spread of the actual dominant forest tree species Scots/ mountain pine (Pinus sylvestris / P. mugo), Norway spruce (Picea abies), European larch (Larix decidua), silver fir (Abies alba), of some deciduous trees of the oak
(Quercus spec.) and beech (Fagus sylvatica) mixed forest, and green alder (Alnus viridis). The actual dominant Norway spruce migrated from the Tyrolian Alps westwards along the Inn valley, crossed the Arlberg pass and reached the inner Klostertal area during the Older Atlantic around 7800 cal yr BP (= calibrated years before present, i.e. before AD 1950). The green alder immigrated together with Norway spruce from East to West in the subalpine belt. During the Subboreal (ca. 5700–2650 cal yr BP) and Older Subatlantic (ca. 2650–1000 cal yr BP), Norway spruce and common/grey alder (Alnus glutinosa / incana) showed signs of recession due to first human clearings, whereas green alder shows a mass spread at the tree limit from the Eastern Alps to the Northwestern Prealps. In addition, first pollen of cereals (Triticum-type), hemp (Cannabis-type) and of indicators of meadows and alpine pastures (Poaceae, Plantago lanceolata, and other herbs) are recorded at the transition from the Neolithic to the Bronze Age (ca. 2200 BC). During Roman Times the sweet chestnut (Castanea sativa) was introduced, and a lowering of the tree limit with an increasing spread of green alder due to alpine clearings were recorded, whereas pollen indicators of pastures and ruderal plants (Plantago lanceolata, P. media, Urtica, Artemisia) show higher frequencies.

Gefährdete Armleuchteralgen in der Schweiz: Chara filiformis H. Hertzsch und Nitella tenuissima (Desv.) Kütz.

Arno Schwarzer — 2025-07-25

Endangered Charophytes in Switzerland: Chara filiformis H. Hertzsch und Nitella tenuissima (Desv.) Kütz. Charophytes are macrophytic green algae represented by 25 species in Switzerland, 21 of which are listed as endangered on the Red List of Charophytes of Switzerland. New sites of Chara filiformis H. Hertzsch and Nitella tenuissima (Desv.) Kütz., both highly endangered species, were discovered during field campaigns by the canton Zurich in Summer 2022–24. Chara filiformis is currently found in only five lakes in Switzerland. In Lake Zurich they were rediscovered at a site where the species was previously recorded approximately 100 years ago, but since then it has never been found again. Due to the re-oligotrophication in Lake Zurich, the species was able to re-establish itself in less competitive localities within the littoral zone. Nitella tenuissima is very rare in Switzerland and is currently known only from two sites. The species was recorded in small waterbodies within the wet meadows of the Husemersee and in the floodplain of the river Thur
in the canton of Zurich. Cantonal action plans for resettlement of both Characeae have been developed.

Mesobromion-Flächenzunahme dank Extensivierung im Dübachtal von Rothenfluh (BL) von 1980 bis 2020

Andres Klein — 2025-08-12

Traditional semi-arid grasslands, such as calcareous grasslands, have declined dramatically throughout Europe in recent decades and have been converted into intensively managed meadows or pastures, threatening biodiversity. In Rothenfluh (Canton of Basel-Landschaft, Switzerland), local nature conservation efforts have been aiming for preserving such original meadows since the 1980s. The objective of the study was to characterize this grassland based on its flora and vegetation and to evaluate changes in the floristic composition. To this end, the vascular plant flora of 13 plots in the Rothenfluh area was analysed using actual species inventories from 2018 to 2020 and compared with historical records from 1980 to 2015. A vegetation mapping of the area from 1984 was also compared with a current mapping from 2020. Between 2018 and 2020, 333 vascular plant species were documented, 7.8 % of which are classified as vulnerable or potentially threatened in Switzerland. 60 % of the 17-hectare study area were nutrient-poor Mesobromion meadows, which is unique for the Table Jura in the Basel region. 84 grassland species that had not been observed in previous surveys were recorded. Only 6 % of the species present in previous years had no longer been observed. In addition, the area of characteristic Mesobromion grassland has increased by 48 % since the 1980s. The unusual increase in nutrient-poor grassland is attributed to the absence of intensification over the last 40 years and the efforts of local and cantonal nature conservation organizations. However, despite the increase in the area of suitable habitats, a further decline in characteristic and rare grassland species is to be expected. To protect the unique flora of Rothenfluh from future threats, adaptive management strategies are required, including land management, biodiversity monitoring and prevention of forest encroachment.