In north-western Germany more than 2,000 km² of raised bogs were destroyed or strongly altered by peat harvesting or cultivation in the past. This caused a severe habitat decline of many rare and highly specialized animal and plant species. Moreover, peat bogs represent long-term carbon sinks or when degenerated relevant sources for greenhouse gases. Thus, restoration of formerly mined peatlands become increasingly important for climate protection.
In several thousand hectares of these bogs rewetting measures have been carried out in the last 30 years and in the next years more than a third of the recent 26,000 ha peat mining area will be taken out of use and rewetted. For north-western Germany there exists no best practice guidelines for bog restoration and realized restoration measures strongly depend on the knowledge and the willingness of the acting persons. Moreover, if realized control of success is relatively short-term.
Preliminary investigations across more than 50 rewetting sites revealed that typical plant species of raised bog, particularly hummock Sphagnum species, are almost lacking. Sites that were agriculturally used before peat mining started often develop towards monocultures of Juncus effusus. Beside inappropriate site conditions in terms of hydrology and nutrient status, these unsatisfactory results of restoration activities can be mainly traced back on dispersal limitation.
Medium to long-term, this project aims to bypass this dispersal limitation by actively transferring typical raised bog species (particularly hummock Sphagnum species) to the restoration sites. Thereby, we will not only promote the mostly rare plant species, but will also enhance the development towards a living, peat accumulating bog.
This is a common project of Gramoflor GmbH & Co. KG, Stiftung Lebensraum Moor and the Institute of Landscape Ecology, Working Groups Ecosystem Research and Hydrology of the University of Münster.
This study is modularly structured and subdivided into four working packages. The first two working packages started as preliminary work based on own financial resources and with support of the Gramoflor GmbH & Co. KG. For the realization of the whole project idea we currently work on getting respective third-party funding.
(i) Experiments on the optimization of donor material, multiplication of existing diaspores
To establish larger scale diaspore transfer of hummock Sphagnum species to rewetting sites it is necessary to effectively multiply the limited amount of existing donor material. In a full factorial experiment we apply different Sphagnum species separately and in combination on a white peat matrix with optimal water level. We test picked as well as chaffed Sphagnum fragments and vary the amount of plant material used. Half of the plots receive watering from above. The growth will be determined non-destructively with cranked wires. For larger scale multiplication of donor material the most effective treatments will be established on larger areas.
(ii) Hydrological/biogeochemical inventory and monitoring of existing restoration sites
To evaluate potential restoration sites concerning the prospects of success to establish hummock Sphagnum species we perform an inventory of most important site conditions and establish a long-term monitoring. Initially, we set up continuous water level measurement in 12 sites differing in age since rewetting, use prior mining and used exploitation technique. Additionally, we will take peat cores and will regularly sample bog water for chemical analyses in the lab. Beside the hydrological and biogeochemical characterization we will perform a vegetation survey and will establish permanent plots for monitoring purposes. In perspective, we plan expand the monitoring program to more restoration sites.
(iii) Field trials for successful establishment of hummock Sphagnum species
On the 12 sites with hydrological, biogeochemmical and vegetation monitoring (ii) we will establish field trials with Sphagnum transfer plots along moisture gradients within each of the restoration sites. Amount, type of material and fragment size will follow the most promising treatments identified under (i). Additionally we will test the effect of different nurse-plants such as Eriophorum vaginatum, E. angustifolium, Juncus effusus and Molinia caerula. Growth rate and vitality of the peat mosses will be monitored and compared with the environmental data to identify the most promising conditions for a larger scale application of hummock Sphagnum species diaspores.
(iv) Application of donor material at larger scale and respective monitoring
The most promising restoration sites (see (iii)) will be chosen to establish hummock Sphagnum species at larger scale by means of diaspore transfer. Successively, further rewetting sites will be added and a long-term monitoring will be implemented. In parallel we will work on technical solutions to effectively apply donor material.
On the premises of the company Gramoflor GmbH & Co. KG, 80 planting bowls filled with white peat (40x60 cm) covered with fragments of hummock Sphagnum species. The water table is regulated to be constantly close to surface. Two watering treatments were established: forty planting bowls are regularly sprinkled, whereas the remaining 40 bowls do not receive additional watering from above.
The following treatments were realized with threefold replication for both watering treatments:
Sphagnum papillosum from intact hummocks (150g fresh weight)
Sphagnum magellanicum from intact hummocks (150g fresh weight)
Sphagnum capilifolium from intact hummocks (150g fresh weight)
Sphagnum papilllosum from cloned lawns (150g fresh weight)
Sphagnum magellanicum from cloned lawns (150g fresh weight)
Sphagnum capillifolium from cloned lawns (150g fresh weight)
mix of different Sphagnum species (150g fresh weight)
chaffed fragments of different Sphagnum species (150g fresh weight)
chaffed fragments of Sphagnum papillosum (150g fresh weight)
chaffed fragments of Sphagnum magellanicum (150g fresh weight)
chaffed fragments of Sphagnumcapillifolium (150g fresh weight)
chaffed fragments of Sphagnum papillosum (75g fresh weight)
Additionally, one planting bowl with Sphagnum imbricatum and one planting bowl with mixed chaffed Sphagnum material (75g) and two with Sphagnum rubellum were established for both watering treatments. Morover, we applied different Sphagnum species and mixtures on further 30m2 with about 600g fresh weight/m2.
Simultaneously, we installed water level data logger in altogether 12 rewetted sites in the Vechtaer Moor and in the Campemoor. For a biogeochemical characterization we plan to sample peat (cores) and bog water that will be analyzed in the lab.
The working group ecosystem research worked since 2010 at the level of thesis and student projects on different topics in rewetted cut-over bogs in north-western Germany. We collected data from more than 50 rewetting sits in about 20 bog complexes in Lower Saxony. The investigations were performed in cooperation with and with support of the engineering office Hofer & Pautz, the BUND Diepholzer Moorniederung, the governmental mire administration Meppen, the Gramoflor GmbH & Co.KG as well as other peat mining companies.
The following studies are/were prepared:
Bachelor Thesis: Vertical phosphate translocation in bog meadows (Jakob Huber)
Master Thesis: Restoration potential of cut-over raised bogs in Northwest Germany (Eva Rosinski)
Master Thesis: Testate amoebae as indicators for water regime and trophic conditions in restored cut-over bogs in NW-Germany (Peter Raabe) Poster [pdf 8,7 MB]
Master Thesis: Evaluation of bog restoration in north-west Germany by dragonflies (Annemarie Krieger)
Master Thesis: Method development for determining characteristics of peat using near-infrared reflectance spectroscopy (Manuel Goerke)
Student Project: Water regime and nutrients in rewettet bogs in north-western Germany (Eva Rosinski & Claudia Tillmann) final report [german, pdf 2,6 MB] photo documentation [german, pdf 5,8 MB]
Student Project: Water regime and nutrients in rewettet bogs in north-western Germany (Peter Raabe) Poster [pdf 0,6 MB]
Bachelor Thesis: Seedbanks of rewettet bogs (Praxis) (Svenja Agethen)
Bachelor Thesis: Rewettet bogs: seedbanks and dispersal potential of indicator species (Susanne Schild)
Bachelor Thesis: Habitat classification in restored cut-over bogs using UAV-based remote sensing data (Birte Klein)