Bult-Schlenken complex

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Bult-Schlenken complex in a regenerating rain bog in northwest Germany.
Spread of bogs and rain bogs dominated by peat mosses on earth
Bult in a regenerating rain moor in northwest Germany.
Crumbling Bult

Bult-Schlenken complexes , often also referred to as step complexes , are special surface forms in the central areas of rain bogs (rain bog width) and in intermediate bogs .

Raised peaks made of peat and peat moss (sphagnes) or brown moss ( Amblystegiaceae ) - so-called bultes - together with wet, sometimes water-filled depressions - so-called Schlenken - form a characteristic micro-relief . The different zones have different plant formations in the smallest of spaces, depending on the bog water level and the nutrient conditions as well as the different location requirements of the plant species.


Bult-Schlenken complexes occur in rain and intermediate moors. Their occurrence largely coincides with the natural distribution of these ecosystems (see figure on the right).

Location features

In rain bogs, the bulte are those locations that are driest. Depending on the development and condition of the bog, decaying bults exist in both intact and drained raised bogs. In periods of low precipitation in midsummer, the rainwater-fed gullies can dry out and reduce the growth of peat moss in this area. Slower growing peat mosses can catch up again. The Bult-Schlenken complexes are more pronounced in more continental regions. In oceanic rain moor areas, the relief is mostly only shallow undulations.

In intermediate moors, the Schlenken are groundwater-fed, while the highest elevations of the Bulte have already grown out of the groundwater influence. The juxtaposition of the drier Bulte and the wet gullies usually leads to a great diversity of species in intermediate moors.

Hazard and protection

The step complexes are very much endangered by the smallest interventions in the water balance. They are particularly sensitive to impact and damage. Footpaths are usually still visible after years.


  • WA Casparie : Bog development in southeastern Drenthe (The Netherlands). In: Vegetatio. Kluwer Acad. Publ., The Hague 25.1972, 1-272.
  • Klaus Dierssen, Barbara Dierssen: Moore . Ulmer, Stuttgart, 2001. ISBN 3-8001-3245-1