Excursion 1 ‘Hike through an alder carr’
Duration: 3-4 hours
Lead: Dr. Tobias Scharnweber, University of Greifswald
The „farmers –mire“ or “Bauernmoor” is a small (about 10 ha) forested peatland near the old estate Wöpkendorf about 30 km east of Rostock. It is groundwater fed and fills a small depression in the young morainic landscape. Its history is well documented since the end of the 17th century. Back then it was used as a pasture and only sparsely forested, although most likely already (partially) drained. At the end of the 19th century forest pasture land was abandoned and an alder-ash forest developed. Around 1900 the mire was effectively drained and managed as high forest. In the centre of the mire an island-like mineral ridge is situated that was forested by pine and spruce. The wetter parts are dominated by alder (Alnus glutinosa L.) and ashes (Fraxinus excelsior L.). Poor maintenance of ditches led to an increasing occurrence of waterlogging since the 1990s. Finally, in 2003 an active rewetting of the depression was initiated with a maximum water level of 1,30 m above the surface. Due to this significant water level increase, most of the trees died. The wetscapes monitoring plot, with detailed instrumentation of above- and belowground growth and peat formation/decomposition processes, was installed at the peatland margin. Here a more moderate water level increase allowed for adaptation and survival of established alder trees. Typical for alder carrs, strong intra-annual water level fluctuations with water tables about 40 cm aboveground in winter/spring and several decimetres belowground in summer/autumn lead to interesting dynamics in biomass accumulation and decomposition. During the excursion we will circle the rewetted mire.
We will observe the vegetation change in the peatland and come across old trees on the surrounding mineral sites that have a memory of past water table fluctuations preserved in the annual increments of radial growth (tree rings). At the monitoring plot we will explain the installed instrumentation including minirhizotrons, point-dendrometers, sap-flux sensors and gas-flux measurements. On our way back we visit the remains of a nearby old Slavic fortified settlement from the 9th century.
Excursion 2 ‘Trip to a coastal mire and Baltic Sea beach’
Duration: ~ 6 hours
Lead: Dr. Gerald Jurasinski, University of Rostock
The nature reserve „Heiligensee und Hütelmoor“ which covers about 540 ha, features a vast peatland complex that is formed primarily by fen peats. In addition you find a small bog part, a beach lake, natural beaches and dunes and ancient forests of oak and beech. These various habitats are home to divers and unique biotic communities. Almost all fen parts of the area have been drained in the late 18th century and again (much more systematically, and thus, severely) in the 1960s. These parts have been rewetted in late 2009 and now they are inundated almost year round and the vegetation has changed again completely.
At the Landscape Ecology group of the University of Rostock we were lucky to be able to accompany the restoration process with our research. In 2008 we started to measure the exchange of CO2 on an ecosystem level with eddy covariance. In 2009 we started closed chamber measurements, mainly focusing on CH4 exchange.
In 2011 we added a CH4 sensor to the eddy setup and started to systematically follow the vegetation development and over the 4 years from 2011 to 2014 got really interesting results as we observed dramatic shifts in vegetation composition. In the year after rewetting the area was a strong greenhouse gas source, mainly because of very high CH4 emissions whereas net ecosystem exchange was almost unaffected (although gross primary production and ecosystem respiration both decreased strongly). In the following CH4 emissions stabilized on a much lower, but still considerable level whereas net ecosystem exchange started to vary strongly over the years.
The excursion will visit the area and the near beach of the Baltic Sea, discuss rewetting measures and success and also introduce some of our research results. It is a truely remarkable area that feels very natural and off the beaten track although it is actually located within the boundaries of the city of Rostock.
Excursion 3 ‘Historic and recent land use of river valley fens’
Duration: ~ 8 hours
Lead: Dr. Anke Günther, University of Rostock
North-eastern Germany was once covered by large areas of growing mires. Today, ~13% of the area is still covered by peat soils. The majority of remaining peatlands is degraded, while a small part has been rewetted. So, how did we get here?
During the excursion, we will visit one of the commonest peatland types of the region, namely river valley fens. They are also, in addition to coastal peatlands and alder forests, the main study areas of the “Wetscapes” project. The excursion focuses on showing typical land use histories and states of river valley fens in the region. Using study sites of the “Wetscapes” project as examples, we can still see the effects of human influences such as peat extraction, agriculture, and rewetting in a landscape that has been formed by centuries of land use. We will visit two former percolation mires that formed along the rivers Recknitz and Trebel. At the water divide between the rivers, bog peat formed on top of the fen body over the last 2000 years.
The area had been used mainly as pastures for centuries. With the rise of salt production from a local salt spring in the town Bad Sülze, peat was extracted as fuel to heat the salt pans and the surrounding peatlands were drained following the 13th century. After cessation of the salt production, many areas have been deeply drained and used as intensive grassland since the 1960s. In 1997, 3000 ha of the peatland complex were rewetted as part of an EU-LIFE effort. Hiking across the river valley, we can experience rewetted fen and bog habitats that today host a rich plant and bird life.
Excursion 4 ‘Coastal flood mire and research at the Greifswald Mire Centre’
Duration: ~ 10 hours
Lead: Dr. Franziska Tanneberger, University of Greifswald
The excursion with present both field and mesocosm research in and close to the city of Greifswald. We will spend the morning at Karrendorfer Wiesen and continue to the mesocosm compound at Greifswald University and other research facilities at the Greifswald Mire Centre.
The Karrendorfer Wiesen (Wiesen= meadows), 10 km north of Greifswald, are part of the morainic plain of Vorpommern. The shore provides a unique habitat with low salinity and without tides. After 6000 BP, a peatland developed here, over centuries with “anthropo-zoogenic” peat formation, with the peat surface gowing up above the sea level to constitute a significant coastal protection. Following periods of increasingly intensive agricultural use, as pasture, meadow and even arable land, in 1993, the removal of the dike around the Karrendorfer Wiesen polder re-exposed 360 ha of former salt meadows to the flooding regime of the Baltic Sea. Within a few years, salt meadow species re-occupied the formerly intensively used agricultural lands and soon the salt meadows functioned again as coastal protection.
Within 10 years, overexploited and degraded agricultural lands changed into a paradise for birds and birdwatchers alike. Now largely owned by Michael Succow Foundation, partner in the Greifswald Mire Centre, the site is managed by cattle and water buffalo grazing and long-term bird monitoring is carried out. Further restoration works are implemented in 2019-2021. Since 2017, the WETSCAPES project brings together researchers from Rostock and Greifswald universities for intensive integrated basic landscape-ecological research at high spatial and temporal resolution in both a drained and a rewetted part of Karrendorfer Wiesen. The EU project REPEAT links the site to a network of some 100 sites where peat formation is assessed in 2017-2020. The mesocosm compound at Greifswald University combines below-ground research in typical fen mire plant communities with greenhouse gas flux measurements. With field scales and the PlantEye multispectral 3D scanner, site condition maintenance and above-ground measurements are run largely automatically. Results of pilots as well of first-hand experience will be presented. To allow for optimal exchange and lively discussions, the group will be split into smaller groups and visit also other research facilities of the Greifswald Mire Centre: The Peatland and Nature Conservation International library (PeNCIL), the globally unique collection of ca. 25,000 publications related to peatlands; the large peat moss collection for genetic research and to facilitate cultivation; the paludarium, a special section of the Botanical Garden dedicated to peatland plants etc.