Begin and spread of raised-bog formation in NW-Germany as indicator for environmental change
by
Karl-Ernst Behre
Niedersächsisches Institut für historische Küstenforschung, Postfach 2062, D-26360 Wilhelmshaven, Germany
Coauthors: Bianka E.M. Petzelberger (Niedersächsisches Institut für historische Küstenforschung), Mebus A. Geyh (Geowissenschaftliche Gemeinschaftsaufgaben, Hannover, Germany)

The lowland of Niedersachsen is the region with most bogs in Germany, original there has been more than 6500 sq.km moor, more than 3300 sq.km of them raised bogs. Most of them started growing directly on the mineral ground. As raised bogs, in contrast to fens, are dependent on a special climate, their start of growing indicate climate change. At the beginning of the project in 1995 little was known about the starting period of raised-bog formation in NW-Germany. The available palynological investigations date the base of some of these bogs to late Atlantic or early Subboreal age, which means the raised bog formation would be connected with the onset of the Holocene climate deterioration. The aim of the project was to find out when the growth of raised bogs started, whether there had been one or several phases for the beginning and to check any possible synchroneity over large areas. Despite of extensive anthropogenic destruction of the bogs their base is in most cases still preserved undisturbed. Selected parts of the bogs were drilled in a grid 400 x 400 m. In 24 bogs nearly 500 borings have been carried out and more than 300 samples were taken from the base of these raised bogs and have been radiocarbon dated.

The most important result is the evidence that raised bog formation started in large areas considerably earlier than expected. According to the 14C-data, already in the Atlantic, during the postglacial climate optimum, more than half of the investigated raised bogs started growing. At about the same time the transgression of the North Sea reached the modern coast line and greater humidity faced NW-Germany. Obviously a climate change induced by the Holocene marine transgression of the North Sea triggered the formation of the raised bogs in NW-Germany. This regional influence of the North Sea transgression is documented in a north-south gradient of the age of the raised bogs. According to our results the onset of the formation of raised bogs reflects a regional rather than a global climatic change.

During the Atlantic period a wide spread environmental change happened in NW-Germany. At this time large woodland areas paludified and changed into raised bogs. West of the river Weser more than 60% of the modern bog areas existed already at the beginning of the Neolithic. This had considerable consequences with respect to the area available for settlements.

This poster belongs to a poster cluster of the DFG priority programme "Changes of the Geo-Biosphere during the last 15.000 years. Continental sediments as evidence for changing environmental conditions".

http://www.uni-frankfurt.de/fb11/ipg/spp/Postergallery/Postergallery.htm

Date received: March 29, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cagc-66.