De Pilularia : Dissertatio botanica, quam consent. ampliss. philos. ord. Lundensi publice defendet Jac. Georg. Agardh.

"Respondente Henrico Leche."

Tab. 4: Vergesellschaftung von Nitella opaca in Nordwestdeutschland

New facts on the occurrence and distribution of the threatened and rare stoneworts Chara baltica, C. connivens, C. contraria, C. virgata, Nitella hyalina, N. opaca, N. gracilis, N. capillaris, N translucens and N. flexilis and the non-threatened species Chara globularis in the northwestern part of Lower Saxony (Germany) are presented. A description of the stonewort sites is given and the abundance and the degrees of endangering of the species are discussed. Data about the Vegetation of the habitats of Nitella hyalina and N. opaca are reported. Additionally former sites of Chara canescens have been checked again. References to determination problems concerning Nitella opaca and N flexilis are given. Finally the protection of stoneworts, management requirements and the need for future investigations are discussed.

Palynomorphs from the Lateglacial and Holocene of the Mt-Athos Basin, Aegean Sea

To unravel the climatic and environmental dynamics in the borderlands of the Aegean Sea during the early and middle Holocene, and notably for the interval of sapropel S1 (S1) formation, we have analysed terrestrial palynomorphs from a marine core in the northern Aegean Sea. The qualitative results were complemented by quantitative pollen-based climate reconstructions. A land-sea correlation was established based on pollen data and sediment lightness measurements from the same core, and previously published benthic foraminifer data from a nearby core. The borderlands of the Aegean Sea underwent a transition from an open vegetation to oak-dominated woodlands between ~10.4 and ~9.5 ka cal BP. A coeval increase in winter precipitation suggests that moisture availability was the main factor controlling Holocene reforestation. The ~50% higher winter precipitation during S1 formation relative to "pre-sapropelic" conditions suggests a strong contribution from the borderlands of the Aegean Sea to the freshwater surplus during S1 formation. The humid and mild winter conditions during S1 formation were repeatedly punctuated by short-term climatic events that caused a partial deforestation and a reorganisation within the broad-leaved arboreal vegetation. In the marine realm, these events are documented by improved benthic oxygenation. The strongest event represents the regional expression of the 8.2 ka cold event and led to an interruption in S1 formation. Except for the interval of S1 formation, the pollen-derived winter temperatures correlate with the smoothed GISP2 K+ series. They support the previously published, marine-based concept that the intensity of the Siberian High strongly controlled the winter climate in the Aegean region. During S1 formation in the Aegean Sea, however, climate conditions in the borderlands were more strongly affected by the monsoonally influenced climate system of the lower latitudes.

Pollen analysis of sediment profile WO1 from Wollingster See

A palynological study of a 15 m sediment core from the centre of Lake Wollingst (water depth 14,5 m) is presented. The pollen record shows 3 lateglacial thermomers, called Meiendorf, Bölling, Alleröd and the early holocene Friesland-Thermomer. The succession of forest vegetation taking place on the lake surroundings during the Holocene was typical for older moraine soils which are poor in nutrients: forest vegetation started with birch and pine, followed by hazel, oak and elm in the Boreal and by alder, lime and ash-tree in the Atlantic. Beech and hornbeam reached the area during Subboreal. However, due to the poor soils they spread out only after the Iron Age. With the deforestation during the medieval time the lake lost its character of a primeval forest lake. Lake Wollingst was oligotrophic since its origin at the end of the Pleniglacial. After medieval forest-clearing the lake has changed its quality of water particularly in connection with hemp- and flax-rotting. The modem sediments in this profile are completely disturbed. They contain reworked material, a lot of blue-green algae and remains of Bosmina longirostris indicating eutrophic conditions.