Berlin's
Peatlands and
Climate Change

Peatland Management

The following sections discuss typical aspects of peatland management in Berlin.

Management of Brown Moss Peatlands (alkaline and calcareous transition mires)

Brown moss peatlands show a specialized mesotraphent vegetation, which is most of all characterized by several brown moss species (Succow 1988, Landgraf & Thormann 2010, Mauersberger 2014). They are highly sensitive peatland ecosystems, as a relatively low extent of drainage and eutrophication already leads to competitive plant communities of the eutrophic peatland, often dominated by grey willows, black alders or reeds (Dierssen & Dierssen 2001, Mauersberger et al. 2010). While brown moss peatlands were still prevailing at the beginning of the 20th century (Zauft et al. 2014), they have become very rare in today's northeastern German lowlands because of intensive utilization and environmental impacts. The frequent occurrence of surface-near bog-bean seed and brown-moss rich sedge peat of low to medium degrees of decomposition in Berlin's peatlands is evidence that there was a high prevalence of brown moss peatlands in Berlin in the past. Special importance here had the great river valley peatland of Tegeler Fließ, but smaller lands with former occurrence were also important, such as the

• Bäkewiese
• Bollenfenn
• peatland at lake Glienicker See
• Großer Rohrpfuhl (in parts)
• peatlands in the Rosentreterbecken
• Müggelheimer Wiesen (in parts)

Brown moss peatlands are particularly valuable. In Brandenburg, for example, there are only few undisturbed sites remaining (Zauft et al. 2014). In Berlin, there are currently no hydrologically intact brown moss peatlands remaining, at all. Smallest areas with calcareous mire vegetation can be found in the Tegeler Fließ and in the Rosentreterbecken within managed landscapes in conservation areas. Without regular management of mowing, these residues would probably have been replaced by more competitive reed grass stocks. What presents a basic problem for the management of brown moss peatlands in Berlin is the eutrophication through former phases of drainage or mineralisation as well as atmospheric N-deposition from industrial and traffic emissions (UBA 2011). There a number of sites in Berlin where eutrophic variants of brown moss peatlands occur though (low-growing and tall-growing Barbilophozia-Carex reed). These do not contain the more valuable species inventory of the hooked scorpion-moss (Scorpidium scorpioides) or bent-moss reeds (Campylostelium saxicola), but are nonetheless rare and retain value through peat formation and successive depletion of nutrients. However, above all it is their development potential that is great when regular and long-term management is ensured.

A special characteristic of peatlands in Berlin is the occurrence of brown moss sedge reeds in areas, which are affected by anthropogenic deposition of sand or debris, but which have sunk down to the level of the groundwater table due to higher peat thickness, so that peat formation was reactivated. The deposited mineral substrates were combined with newly formed organic substances this way. Although their C/N ratio is clearly within the eutrophic range, the N_t contents of the artificial substrates are very low compared to those of fen peat. The soil application has basically caused (involuntarily) depletion of nutrients to occur, as the macro nutrients N and P available for plants, which are essential to the productivity of a site, were limited within the rooted area (see table). High water levels in many fens also led to peat formation in recent years, which went hand in hand with successive depletion of nutrients and compounding. This process is supported by maintenance mowing or grazing in comibination with the use of adjusted breeds of cattle, or buffalo. The continuation of maintenance concepts like this is strictly necessary to maintain and to develop these peatland sites. Removal of the top peat layer, however, is not necessary..

Soil Characteristics of Peatland Sites in Berlin with Development Potential for the Maintenance and Resettlement of Rare and Endangered Species of Brown Moss Peatlands.

Peatland Site	Thickness/Top	Corg [%]	Nt [%]	C/N	pH-Value	Underlying Peat
Inside Rosentreterbecken	2 m/sand and debris   (5–35 cm)	-	-	-	> 6.4	Sedge peat with added bog-bean seeds (Menyanthes trifoliata) and reed rhizomes (H 3–6)
Tegeler Fließ (Luebars)	> 7 m/sand (3–18 cm)	10.1	0.84	12	5.7	Sedge peat with high wood content (H 7–8)
Baekewiese	4 m/sand (12–39 cm)	14.5	0.95	14	5.7	Sedge peat with added brown moss and bog bean seeds (Menyanthes trifoliata) (H 3)
Meiereiwiese/ Pfaueninsel	6 m/sand (12–24 cm)	10.7	0.95	11	5.5	Alder-swamp peat
Ehemaliger Großer Hermsdorfer See	8.50 m/sand (5–15 cm)	32.7	2.1	15	5.7	Sedge and brown-moss peat with added bog bean seeds (Menyanthes trifoliata) (H 3–4)
Mueggelheimer Wiesen	up to 1 m (only partly covered with sand)	11.6	0.98	13	5.2	highly decomposed fen peat

With regard to ecosystem services, the nature target type of the brown moss peatland focusses on habitat services, and with it on the restoration especially of rare and endangered biocenosis with special target species, like orchids (e.g. Dactylorhiza incarnata; Epipactis palustris) or mosses (e.g. Paludella squarrosa, Helodium blandowii, Drepanocladus vernicosus).

For the above listed sites, development by resettlement of certain target species is recommended. For this purpose, transplanting mosses (e.g. Drepanocladus cossonii, Campylium stellatum) and topsoil substrates (peat) from intact parts of peatlands or from other brown moss peatlands of Brandenburg (e.g. the peatland of Oberpfuhlmoor and Knehdenmoor/Uckermark) should be carried out. For one hectare of target land, 40–50 m² from the donor land should be harvested (Hacker & Koska 2014, verbal comm.). Over and above that, the sowing of the seeds of target plants (e.g. Parnassia palustris, Carex diandra, C. panicea, C. lepidocarpa) or the transplanting of entire plants should be considered. The former distributions of target plants have been documented as important sources in Seitz et al. (2014).

Potential sites of brown moss peatlands in Berlin without soil application that show humification of the topsoil on a minor scale only, such as parts of the Tegeler Fließ, are candidates for „classic“ methods of brown moss peatland restoration. The following measures were successfully realized by the EU Life project Alkaline Fens in Brandenburg (2010 to 2015) (NaturSchutzFonds Brandenburg 2014, Zauft et al. 2014):

• deactivation of drainage ditches, often combined with filling the ditches,
• removal of the top peat layer from degraded topsoils, if slightly degraded peat existed underneath. To fill the ditches, the degraded peat from the removed topsoil was used, as well decomposed peats have very good sealing properties, i.e. only low water conductivity,
• initial mowing or grazing,
• shrub removal, and partial removal also of 25–50 year old alders (spring mire at Melangsee),
• transplanting of mosses and sowing of target plant seeds.

Further Aspects of Species and Biotope Conservation

Many plant communities of „wetlands and wet meadows“ (Code Berlin 05100; FFH-LRT 6410 Molinion caeruleae) are floristically close to the base-rich to alkaline-calcareous transition mires (Zimmermann 2013, 2014), so that there is some overlap of valuable species according to the Flora-Habitat Directive of the EEC (FFH-LRT) and the nature targets for Berlin (Seitz 2008). If the „wetlands and wet meadows“ contain peat (≥ 3 dm peat), they can considered as less wet variant of the brown moss peatland, and can be developed like this nature target.

The management of brown moss peatlands and wetlands in Berlin have in common that it is considered necessary to remove nutrients through mowing or grazing and at the same time ensure that the water levels is kept high. An important difference, however, is that brown moss peatlands (e.g. Berlin Code 04400; FFH-LRT 7230) can maintain themselves under favorable conditions and form peat, while wetlands on mineral soils (e.g. Berlin Code 051021; FFH-LRT 6410) as arable relict of the cultural heritage landscape require regular maintenance, in order to prevent overgrowth with shrubs. Due to low median water levels (water height 4+/3+) or a changing water regime, these wetlands do not show any peat growth; a management based on peatland preservation principles therefore is not productive. For biotope management of the FFH-LRT 6410, it should be noted that this type can occur either on mineral soil or peatland sites. In addition, mowing on fens can be carried out using the one-cut method (summer) or the two-cut method (summer and autumn). Alternatively, mowing in summer could be followed by grazing in autumn (Schrautzer 2014, verbal comm.)

Management of Sphagnum dominated peatlands (Oligotrophic-Acid Mires), Forested

Sphagnum dominated peatlands in Berlin-Brandenburg characteristically occur as kettle-hole mires or terrestrialisation mires, and their restoration potential is particularly good when water levels are high. Cutting the top peat layer, for example, leads to rapid restoration of native plants and vegetation in raised bogs (Bernrieder 2003). Jeschke & Paulson (2001) also state that oligo-/mesotraphent forms of vegetation may flourish already after 3–5 years in the case of overflow. In addition, the example of the peatland Kleine Pelzlaake, too, shows that a rapid resettlement of typical vegetation on open peat areas is possible already during the first vegetation period after removal of woody plants and moor-grass hummocks (Stiftung Naturschutz Berlin 2013).