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Holocene Ecosystem Development in Franconia (Germany)

Project Information


Investigation area and sites

Project Coordination:
Markus Dotterweich (Landau, Germany)

Supervisor:
Prof. Dr. Hans-Rudolf Bork (Ökologie-Zentrum, Universität Kiel)

Runtime:
1999 bis 2003

Financing:
- Cusanuswerk (Ph.D. Grant)
- Ökologie-Zentrum, Universität Kiel

Summary

Aim of this thesis is the qualitative and quantitative investigation of land use and climatic impact on Holocene ecosystem development in northern Bavaria. Holocene relief and soil formation processes were analysed in six small catchments (less than 45 hectares). The investigation areas are situated in Franconia, northern Bavaria. The region is delimited in the south by the undulating Steigerwald region and the flood plain of the river Regnitz and the north by the hilly Obermainische Bruchschollenlandschaft. The geology of the region consists of sand and clay stones that are partly topped by a loamy solifluction layer.
The chosen investigation areas of several hectares in size are characterised by well preserved geoarchives: deposition areas on concave hill slopes, in gullies and small valleys. To investigate the Holocene ecosystem development stratigraphic, sedimentologic and pedologic parameters were determined from large pits dug in the geoarchives. The sediments and soil formations were dated by physical and archaeological methods. The analysis of contemporary written documents gave information about the regional land use, settlement and climate history to complete the reconstruction of the ecosystem development. Archaeological investigations were carried out in two catchments by the Bavarian State Office for Heritage Protection.

The project has 6 sub-projects (only in german):

From the beginning of the Neolithic Revolution until the Early Medieval Times the ecosystem development was determined by several phases of shifting/altering/changing land use intensity and duration . Woodland clearings for agriculture included only small plots over a limited time span. For large areas soil formation under wood was the dominant process still.
During the Roman Times (30 BC until 450 AD) more land was used agriculturally. Extreme rainfall events caused soil loss of more than one meter.
Until the end of the High Medieval Times all investigated catchments were almost completely deforested and used for agriculture or as settlement places. Sheet erosion was low during this time though. Gullying took place in two of the catchments caused by concentrated flow along pathways developed.
During the Late Medieval Times, a period of extreme rainfall events, the extended land use led to high soil erosion intensities. Gullies, up to 100 meter in length and six meter deep developed. Single erosion events led to sheet erosion that lowered the slopes up to 12 centimetres. The fertile soil was eroded, the underlying stones exposed. Land use was abandoned and the investigation areas reforested. Only plots for whine or hop growing were still in use.
From the 16 th until the 18 th centuries land use increased again. The gullies that developed during the late medieval soil erosion period lengthened. The lower parts of the gullies filled with sediments.
From the 19 th century until today the land use intensity and subsequently the soil erosion intensity decreased continuously. Gully erosion occurred only along pathways. Since the middle of the 20 th century almost all investigation areas were reforested or used as pasture.
Comparing medieval and modern soil erosion rates for various catchments in Germany the soil erosion rates in Franconia are similar to the young moronic areas of North Germany , but up to 10 times lower than in the loess areas.

Cooperation

  • Dr. J. Haberstroh, Bayerisches Landesamt für Denkmalpflege
  • Dr. M. Nadler, Bayerisches Landesamt für Denkmalpflege
  • B.-U. Abels, Bayerisches Landesamt für Denkmalpflege
  • Prof. Dr. A. Lang, K.U. Leuven, Belgien
  • Dr. B. Mauz, Geographisches Insitut, Universität Bonn


© Markus Dotterweich, zuetzt aktualisiert am 8 September, 2008 11:39