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The Blausteinfenn near the village of Gräben (fig. 1, 2) is at present a degradated mire comprising various tree and shrub succession stages and including some Molinia-Eriophorum-Carex-Sphagnum vegetation. The mire got his name from a nearby erratic boulder (blue granite rock) of penulimate glacial age (Warthe stage of the Saalian glaciation). Under local convenient local and hydrographic conditions the fen developed on a flat eastern slope position of the Verlorenwasser (‘lost water’ brook) lowland, which is connected with the Buckau valley and the Havel river. The mire development started on sandy soils by paludification forming a highly decomposed peat during the Alleröd or more probably the Preboreal chronozone. After a long lasting phase of stagnation further development continued only in the Subboreal and Older Subatlantic chronozone. Passing an alder and birch succession stage and deposition of fen peat, finally the stage of a Sphagnum mire was reached. This ultimate succession stage obviously is a result of overgrowing of peat digging sites already in medieval and at least in modern times. The situation in 2002/04 was found to be a consequence of various mire use such as drainage, continuous peat cutting and fish ponds up to the 19th century and its abandoning lateron, i.e. after 1945. During the last years measures were carried out especially to improve the water regime by regulation of the outwards flow and by dam blocking. Further projects comprise the total closing of ditches in the sensitive mire sites., Zusammenfassung: Das Blausteinfenn bei Gräben, ein breites, flach geneigtes Hangmoor am Osthang der Niederung des in Buckau und Havel entwässernden Verlorenwasserbachs, ist heute ein degradiertes Moor mit verschiedenen Gehölzstadien und Molinia-Eriophorum-Carex-Sphagnum-Beständen. Unterlagert von stark zersetzten Torfen des Alleröds oder Präboreals verlief die Entwicklung nach einer Stillstandsphase erst im Subboreal und Älteren Subatlantikum, vorwiegend jedoch im Jüngeren Subatlantikum, über ein Erlen- und Birkenstadium mit Riedtorfen zum Sphagnum-Moor. Letzteres entstand möglicherweise bereits nach mittelalterlich-neuzeitlichen Abtorfungen. Der Zustand um 2002/04 ist das Ergebnis von Entwässerungen, Torfabbau, verschiedenen Nutzungen seit dem 19. Jahrhundert und der Nutzungsaufgabe nach 1945. In den vergangenen Jahren sind Maßnahmen zum Erhalt bzw. zur Verbesserung des Moorzustandes ergriffen worden, wie Sicherung des Wasserhaushaltes durch Stauregulierung und Abdichten von Dämmen. Geplant sind Grabenverschließungen., DFG, SUB Göttingen, DGMT, research

Gametophyte and thallus fragments, respectively, may be an important or even the only mode of reproduction for many bryophytes and lichens species. Until now especially birds and mammals have been identifi ed as potential animal dispersal vectors of fragments. This study investigates the dispersal of bryophyte and lichen fragments by red wood ants which build large nest mounds from plant material and are abundant in European coniferous forests. We sampled nest material from 25 nest mounds in fi ve different pine and spruce forest types in Germany and found numerous fragments of 20 bryophyte and ten lichen species. As they occurred on almost all studied mounds and often in large numbers we conclude that collecting cryptogam fragments as nest material is a characteristic feature for the Formica rufa group in coniferous forests. Species number and composition of fragments on mounds coincided with the epigeic vegetation around ant nests to a large extent: Almost all collected species were present in the vegetation, and dominant fragment species occurred in large amounts in the vicinity of ant nests. Lichen fragments were larger than bryophyte fragments. Certain life forms (weft-forming bryophytes, reindeer lichens) were accumulated on mounds, while others (tall turfs, cup-type Cladonia species) were discriminated, refl ecting fragmentation features of species. Collected fragments may regenerate to mature plants if nest mounds are abandoned, and especially if they are lost during transport over several metres. We conclude that dispersal of fragments by red wood ants contributes to maintain epigeic bryophyte and lichen diversity of coniferous forests by supporting colonisation after disturbances, which occur on different spatial and temporal scales.